MSK

Question 1

Answer 1

Healing/Healed NOF

Question 2

Answer 2

Fibrous Dysplasia
long lesion in a long bone

with ground glass appearance.

Question 3

Answer 3

VERY HIGH A/W ACL

The arcuate sign is often a subtle but important finding on knee x-rays and represents an avulsion fracture of the proximal fibula at the site of insertion of the arcuate ligament complex, and is usually associated with cruciate ligament injury (~90% of cases) 2. The fracture fragment is attached to the lateral (fibular) collateral ligament, the biceps femoris tendon, or both.

Question 4

Answer 4

Cortical desmoid

Dr Henry Knipe◉◈ and Dr David Dang et al.

Cortical desmoids, also known as cortical avulsive injuries, Bufkin lesion or distal cortical femoral defects/irregularities, are a benign self-limiting entity that are common incidental findings. This is a classic “do not touch” lesion, and should not be confused with an aggressive cortical/periosteal process (e.g. osteosarcoma).

Terminology

Cortical desmoid is a misnomer as this lesion does not histologically correlate to true desmoid tumours with more recent literature (c. 2020) 10 referring these to distal cortical femoral irregularities.

Epidemiology

It typically presents in adolescents (10-15 years of age). There may be a male predilection.

Clinical presentation

Patients are usually asymptomatic, and it is discovered incidentally. Occasionally pain may be present.

Pathology

Cortical desmoids are classically seen at the posteromedial aspect of the distal femur. They can be bilateral in approximately one-third of cases ref.

It is related to repetitive stress at the attachment of the medial head of gastrocnemius or less commonly the lateral head of gastrocnemius distal or adductor magnus attachment sites 10.

Occasionally similar lesions have been described involving the humerus - medially at the insertion of the pectoralis major or laterally at the insertion of the deltoid 9.

Radiographic features

Plain radiograph

Typically shows a saucer-shaped radiolucent cortical irregularity involving the posteromedial aspect of the distal femoral metaphysis at the attachment of the adductor magnus tendon. The lesion lacks an outer margin.

MRI

Defines anatomy much better and is seen as a cortically based lesion in the expected location (i.e. posteromedial distal femoral metaphysis) 3,4,10:

T1: low signal

T2: high signal and surrounding low signal rim representing sclerosis may be present

T1 C+ (Gd): most show enhancement

Nuclear medicine

On bone scan, there is an abnormal increase in activity because of the chronic stress/traumatic origin of this lesion.

Differential diagnosis

Imaging differential considerations include:

fibrous cortical defect

Practical points

cortical desmoid is one of the skeletal “don’t touch” lesions

Question 5

O’Donoghue unhappy triad

Answer 5

O’Donoghue unhappy triad

Dr Joachim Feger◉ and Assoc Prof Frank Gaillard◉◈ et al.

O’Donoghue unhappy triad or terrible triad often occurs in contact and non-contact sports, such as basketball, football, or rugby, when there is a lateral force applied to the knee while the foot is fixated on the ground. This produces an abduction-external rotation mechanism of injury (“pivot shift” in non-contact sports).

Pathology

The O’Donoghue unhappy triad comprises three types of soft tissue injury that frequently tend to occur simultaneously in knee injuries. O’Donoghue described the injuries as:

anterior cruciate ligament tear

medial collateral ligament injury

medial meniscal tear (lateral compartment bone bruise)

The triad has subsequently been revisited considering the arthroscopic findings in patients with both ACL and MCL injuries, where a lateral meniscal injury is more common than injury to the medial meniscus 2. Mechanistically this makes more sense during the pivot shift movement, as the lateral tibiofemoral compartment is compressed, causing failure of the lateral meniscus.

History and etymology

The unhappy triad is named after D H O’Donoghue, American orthopaedic surgeon, who described it in 1950 4.

Question 6

Answer 6

Lateral patellar dislocation

THINGS TO ALWAYS mention in patella injury

• • Injury to MPFL
• oestochondral fracture
• patella alta - insall salvati ratio
  
  • should be <1.3.
  • Blackburn peel ratio
    
    • normal =0.8
    • Patella alta > 1
• Inc TTTG trasnlation distance
• Femoral trocklea displasia

Dr Joachim Feger◉ and Dr Aditya Shetty et al.

Lateral patellar dislocation refers to lateral displacement followed by dislocation of the patella due to disruptive changes to the medial patellar retinaculum.

Epidemiology

Patellar dislocation accounts for ~3% of all knee injuries and is commonly seen in those individuals who participate in sports activities.

Pathology

Patellar dislocation most commonly results from a twisting motion, with the knee in flexion and the femur rotating internally on a fixed foot (valgus-flexion-external rotation) 1.

Radiographic features

Plain radiograph

lateral displacement of patella noted on skyline projection

joint effusion

sliver sign

MRI

The following features are noted:

medial retinacular abnormalities (ranging from strain to complete disruption) with adjacent periligamentous oedema and haemorrhage

lateral displacement of patella (not necessarily seen in transient dislocation)

medial patellar contusion +/- corresponding lateral femoral condyle contusion

joint effusion

The presence of an abnormal medial patellar retinaculum should suggest the diagnosis of transient lateral patellar dislocation 1.

The images should be scrutinized for the presence of chondral or osteochondral injury, especially if displaced as an intra-articular body, as this may affect surgical management.

The trochlear groove and patella may have abnormal morphology that predisposes to patellar dislocation.

Differential diagnosis

acute ACL tear: no medial patellar contusion in this injury

direct trauma to lateral knee: normally no patellar contusion 4

Question 7

Answer 7

long lesion in a long bone

Fibrous dysplasia

Question 8

Causes of this appearance

Answer 8

Lead GNOMES

Lead: lead poisoning

G: Gaucher disease

N: Niemann-Pick disease

O: osteopetrosis, osteochondromatosis

M: metaphyseal dysplasia (Pyle disease) *CASE 1* and craniometaphyseal dysplasia

E: ‘ematological, e.g. thalassaemia

S: Sickle cell

R: Rickets (*case 2*)

Erlenmeyer flask deformity

Dr Jonathan Shadwell and Assoc Prof Frank Gaillard◉◈ et al.

Erlenmeyer flask deformity (EFD), also known as metaphyseal flaring, refers to a radiographic appearance typically on a femoral radiograph demonstrating relatively reduced constriction of the diaphysis and flaring of the metaphysis as a result of undertubulation.

The name refers to the resemblance to a flat bottomed titration flask used by chemists, (known as a conical flask in British English.)

Pathology

It has been classically used with reference to the distal ends of the femora, however it is also seen in the proximal humeri, tibiae, and the distal radii and ulnae 4.

Aetiology

marrow infiltration/expansionlysosomal storage disease

Gaucher disease - osteopenia with Legg-Calvé-Perthes disease or Hass disease

Niemann-Pick disease (type B)

haemoglobinopathies

thalassaemia - coarsened trabeculation, cobweb appearance, especially if treated with desferoxamine 4

sickle cell disease

membranous lipodystrophy

fetal magnesium toxicity 4

chronic lead toxicity (contentious 4)

bone dysplasias 4craniotubular bone dysplasias

frontometaphyseal dysplasia

craniometaphyseal dysplasia

craniodiaphyseal dysplasia

craniometadiaphyseal dysplasia

diaphyseal dysplasia (Engelmann type)

oculodentoosseous dysplasia

metaphyseal dysplasia - Pyle disease

sclerotic diaphysis

dysosteosclerosis

Melnick-Needles osteodysplasty

Pyle-like dysplasias

Braun-Tinschert myelodysplasia

hypertrichotic osteochondrodysplasia (Cantu syndrome)

multicentric fibromatosis with metaphyseal dysplasia

osteopetrosis - diffuse sclerosis and sclerotic vertebral endplates (sandwich vertebrae)

infantile osteopetrosis

juvenile osteopetrosis (types II and III)

osteopetrosis with renal tubular acidosis

fibrous dysplasia

achondroplasia

Ollier disease

multiple hereditary exostoses 2

The causes can also be remembered with the mnemonics AP OF DR GHLN, CHONG or Lead GNOME.

History and etymology

The conically-shaped flask with a wide base and short narrow neck was created by the German chemist Emil Erlenmeyer (1825–1909) in 1860 3.

Question 9

Answer 9

Meniscal root tear

Tear at the junction of the posterior horn medial meniscus and its attachment of the tibial eminence. This is known as the meniscal root.

Case Discussion

These tears are unusual and occur either as an acute injury in young patients or as a degenerative process in older patients. As the meniscus is reasonably well vascularised at the root, surgical repair is recommended in younger patients. In older patients with degeneration there is often associated chondral damage thus repair is more problematic and can fail.

Meniscal root tears are a type of meniscal tear in the knee where the tear extends to either the anterior or posterior meniscal root attachment to the central tibial plateau. They often tend to be radial tears extending into the meniscal root.

Epidemiology

According to one source, they are thought to account for ~10% of all arthroscopic meniscectomies 5.

Pathology

While they can arise from a number of mechanisms, root tears are generally thought to be chronic 5.

Associations

ACL tears are associated with posterior horn root tears of the lateral meniscus

Radiographic features

MRI

Best assessed on T2 weighted sequences. When it involves the posterior root, medial root tears are easier to diagnose than lateral root tears.

On medial posterior root tears there is often 2:

shortening or absence of the root on sagittal images

vertical fluid cleft on coronal fluid-sensitive (T2) images

On posterior root radial tears of the lateral meniscus, the appearance may be similar to radial tears in other locations.

For root tears in general, sagittal imaging may demonstrate a meniscal ghost sign.

Other features include:

truncation sign on coronal images 4

features meniscal extrusion on coronal plane 4

History and etymology

They were first described by M J Pagnani et al. in 1991 6.

Question 10

NAME 3 central bone lesions and 4 eccentric bone tumours

Answer 10

• Central
  
  • Simple Bone Cyst
  • Fibrous displasia
  • Enchondroma
• Eccentric
  
  • Giant Cell Tumour
  • FOD/NOF
  • CMF (chondromyxoid fibroma)
  • Osteoma

Question 11

Answer 11

Osgood-Schlatter disease

Dr Jeremy Jones◉ and Assoc Prof Frank Gaillard◉◈ et al.

Osgood-Schlatter disease (OSD) is a chronic fatigue injury due to repeated microtrauma at the patellar ligament insertion onto the tibial tuberosity, usually affecting boys between ages 10-15 years.

Epidemiology

Osgood-Schlatter disease is seen in active adolescents, especially those who jump and kick. It is bilateral in 25-50% of patients 1-3. The typical age of onset in females may be slightly earlier (boys 10-15 years; girls 8-12 years) 8.

Clinical presentation

Clinically, patients present with pain and swelling over the tibial tuberosity exacerbated with exercise.

Radiographic features

Plain radiograph

Soft tissue swelling with loss of the sharp margins of the patellar tendon is the earliest signs in the acute phase; thus, a compatible history is also essential in making the diagnosis. Bone fragmentation at the tibial tuberosity may be evident 3 to 4 weeks after the onset.

It is important not to equate isolated ‘fragmentation’ of the apophysis with OSD, as there may well be secondary ossification centres.

Ultrasound

Ultrasound examination of the patellar tendon can depict the same anatomic abnormalities as can plain radiographs, CT scans, and magnetic resonance images. The sonographic appearances of Osgood-Schlatter disease include 3:

swelling of the unossified cartilage and overlying soft tissues

fragmentation and irregularity of the ossification centre with reduced internal echogenicity

thickening of the distal patellar tendon

infrapatellar bursitis

MRI

MRI, as expected, is more sensitive and specific, and will demonstrate:

soft-tissue swelling anterior to the tibial tuberosity

loss of the sharp inferior angle of the infrapatellar fat pad (Hoffa fat pad)

thickening and oedema of the distal patellar tendon

infrapatellar bursitis (clergyman’s knee)

a distended deep infrapatellar bursa can be a frequent finding 6

bone marrow oedema may be seen at the tibial tuberosity

Treatment and prognosis

Treatment is usually conservative and involves rest, ice, activity modification (decreasing activities that stress the insertion, especially jumping and lunging sports), and quadriceps and hamstring strengthening exercises. Analgesia and padding to prevent pressure on the tibial tuberosity are also useful. Only rarely are therapeutic casts required 4,5.

The condition spontaneously resolves once the physis closes.

In rare cases, surgical excision of the bone fragment(s) and/or free cartilaginous material may give good results in skeletally mature patients who remain symptomatic despite conservative measures.

Unresolved OSD is the term given to clinical and radiological findings of OSD that persist into adulthood.

History and etymology

It is named after American orthopaedic surgeon Robert B Osgood (1873-1956) and Swiss professor of surgery Carl Schlatter (1864-1934).

Differential diagnosis

Imaging differential considerations include:

Sinding-Larsen-Johansson disease (SLJ): similar condition involving the inferior pole of the patella

jumper’s knee: involves the patellar tendon rather than the bone, and is essentially tendinopathy with focal tenderness, although it may eventually be associated with bony changes (some authors do not distinguish between SLJ and jumper’s knee)

infrapatellar bursitis

Question 12

Answer 12

Periosteal osteosarcoma

Dr Daniel J Bell◉ and Dr Sam Kyle et al.

Periosteal osteosarcoma is a form of surface osteosarcoma.

Epidemiology

It is the second most common type of juxtacortical or surface osteosarcoma after parosteal osteosarcoma and accounts for 1.5% of all osteosarcoma cases. It affects a slightly older age group (10-20 years) cf. conventional osteosarcoma.

Pathology

Periosteal osteosarcoma arise from the inner germinative layer of periosteum. Cytologic grade of this tumour is higher than parosteal osteosarcoma and lower than conventional osteosarcomas, so it is considered as an intermediate grade osteosarcoma (grade 2). It predominantly contains chondroid matrix.

Location

lesions tend to be diaphyseal

femur and tibia most common, especially medial distal femur

arises from cortex, being attached to underlying cortex at origin; intramedullary extension is rare

Radiographic features

Typically seen as a broad-based surface soft-tissue mass causing extrinsic erosion of thickened underlying diaphyseal cortex and perpendicular periosteal reaction extending into the soft-tissue component:

predominantly chondroid matrix results in a lesion that is low in attenuation on CT images and hyperintense on T2 weighted MR images and tends to “wrap around” the circumference of the bone

a periosteal reaction common, as sunburst pattern (radiating from bone surface) or a Codman triangle

MRI

typically hypointense on both T1 and T2 sequences: may see bony spicules radiating from surface lesion (sunburst pattern)

it may appear hyperintense on T2 sequence which represents its chondroid matrix.

reactive marrow changes are commonly seen at MR imaging, but true marrow invasion is rare 2

it is difficult to differentiate periosteal osteosarcoma from the conventional high grade osteosarcoma at imaging, however conventional osteosarcomas involve entire circumference of cortex and show intramedullary extension.

Treatment and prognosis

A periosteal osteosarcoma is of intermediate grade with prognosis being better than conventional osteosarcoma, but not as good as parosteal osteosarcoma (which is usually low grade).

Question 13

Answer 13

Question 14

Parosteal lesions

Answer 14

Parosteal lesions [drawing of rectangle with circle on top]

• All osseous, cartlagenous and fibrous malignancies
  
  • Osteochondroma
  • Myositis ossificans (should be separate from bone)
  • Differential diagnosis

On imaging consider

cortical desmoid: avulsive injury of the posterior femoral cortex

myositis ossificans: the ossification pattern of parosteal osteosarcoma shows progressively increased ossification from the periphery to the centre; the ossification pattern of myositis ossificans is the opposite, with the densest ossification at the periphery and usually associated with soft tissue oedema 5

sessile osteochondroma: parosteal osteosarcoma lacks a communication between the medullary canal of the bone and the cortical tumour 5

juxtacortical chondrosarcoma

high-grade surface osteosarcoma

parosteal lipoma: radiolucent mass adjacent to the cortical surface on plain film and on cross-sectional imaging will usually show a definite fat component 8

Question 15

2019 Aug Q100

re femoral AVN Which is true?

a. Mri is more sensitive than bone scan
b. Changes commonly occur on both sides of the joint
c. Posterior more common than anterior femopral head

Answer 15

• ANSWERS
  
  • Anterior/superior most common best seen on frog leg view
  • Mri is more sensitive
  • Changes one side of joint.
• Avascular Necrosis of Hip
  
  • Involvement of one hip increases risk to contralateral hip to 70%!
  • Age: 20-50 years
• Plain film (positive only several months after symptoms):
  
  • subtle relative sclerosis of femoral head secondary to resorption of surrounding vascularized bone (earliest sign)
  • radiolucent crescent parallel to articular surface in weight-bearing portion secondary to subchondral structural collapse of necrotic segment
  • Site:
    
    • anterosuperior portion of femoral head (best seen on frog leg view)
  • preservation of joint space (DDx: arthritis)
  • lattening of articular surface
  • increased density of femoral head (compression of bony trabeculae following microfracture of nonviable bone,
  • calcification of dendritic marrow, creeping substitution = deposition of new bone)

Question 16

Answer 16

Hydroxyapatite deposition disease

Dr Mohamed Saber and Dr Prashant Mudgal et al.

Hydroxyapatite crystal deposition disease (HADD) is a disease of uncertain aetiology characterised by periarticular and intra-articular deposition of hydroxyapatite (HA) crystals.

The shoulder is the most frequently involved site with classic calcific tendinitis presentation.

Epidemiology

HADD is most commonly found in middle-aged individuals.

Clinical presentation

Localised pain is one of the primary manifestations of the disease, associated with swelling, tenderness, and variable limitation of joint motion. Often asymptomatic.

Pathology

The exact aetiology has not been described; however, it is believed that HADD will begin to accumulate in damaged tendons (secondary to trauma) via fibrocartilaginous metaplasia 6.

The disease is characterised by calcium phosphate (calcium hydroxyapatite) crystal deposition in the periarticular soft tissues, especially in the tendons (best recognised as calcific tendinitis).

Most frequently it involves the shoulder joint, where crystal deposition occurs in the supraspinatus tendon, but the disease can affect numerous other sites as well. Calcific periarthritis or enthesitis would be the most appropriate term for this condition, as it occurs most commonly in the bony attachment of tendon near the joints 1.

HADD can affect other tendons of the body, such as the gluteus medius tendon, or along the femur, as well as at various sites of tendinous attachments (e.g. elbow, wrist, hand, knee, ankle, foot, and spine) 2.

Calcifications of varying sizes and shapes can involve the para-articular tendons, bursae, and capsule. The disease can be mono- or polyarticular.

Radiographic features

The specific appearance will vary based on the calcific stage, broken into the formative, resting and resorptive phases. The formative and resting phases will appear as round-to-ovoid calcification in the soft tissue with well-defined borders. The resorptive phase will appear ill-defined with a comet tail-like appearance. The resorptive may mimic a periosteal reaction 6.

Plain radiograph

It appears as homogeneous, round-to-ovoid calcification in the soft tissue with well-defined or ill-defined margins. The most characteristic lesions are seen in the shoulder with supraspinatus and biceps tendon involvement, adjacent to the greater tubercle and the glenoid tubercle, respectively, where these tendons attach.

Deposits within the infraspinatus and teres minor tendons are not uncommon and can be seen adjacent to the greater tuberosity on internal rotation or axillary views 1.

Treatment and prognosis

Treatment is chiefly conservative, including NSAIDs, local heat application, and physiotherapy. Local corticosteroid injections may also be of benefit.

Surgical removal of calcifications may be appropriate for cases refractory to other attempts of conservative treatment.

Ultrasound ablation may prove to be of short-term benefit in particular cases. However, its long-term benefit has not yet been demonstrated 3.

Complications

When intra-articular, HA crystals can cause joint destruction. Any joint can be involved; the shoulder is most commonly affected, resulting in Milwaukee shoulder 4.

Differential diagnosis

The differential diagnosis of joint pain with calcification is extensive and occurs in many conditions such as:

calcium pyrophosphate dihydrate deposition disease (CPPD)

dystrophic calcification

renal osteodystrophy

hyperparathyroidism

hypoparathyroidism

tumoural calcinosis

collagen vascular disease

sarcoidosis

ochronosis

milk-alkali syndrome

hypervitaminosis D

Another consideration for a calcific opacity in proximity to a joint (typically knee, elbow, etc.) would be a loose body from an osteochondritis dissecans (OCD) donor site. Therefore, radiographic findings, a thorough history, as well as physical examination, appropriate lab tests and additional imaging modalities, should be utilised to identify the most likely aetiology 5.

References

Question 17

Answer 17

polyostotic Fibrous dysplasia

Question 18

Answer 18

FIBROMATOSIS

Question 19

Answer 19

Fast Forward sign

Typical sign of a displaced meniscal tear aka the flipped meniscus sign.

A displaced tear of the lateral meniscus, in which the avulsed posterior horn is flipped towards the anterior compartment. This patient also had an ACL tear and a medial posterior horn meniscal injury.

https://radiopaedia.org/cases/double-anterior-horn-sign

Question 20

Answer 20

Question 21

Answer 21

Aneurysmal Bone Cyst

Question 22

Answer 22

• Jaccoud’s Arthritis
  
  • Jaccoud arthropathy is a deforming non-erosive arthropathy characterised by ulnar deviation of the second to fifth fingers with metacarpophalangeal joint subluxation.
  • Jaccoud arthropathy is characterised by marked ulnar subluxation and deviation at the metacarpophalangeal joints that is correctable or reducible with physical manipulation
    
    • Defomities can be corrected by the patients.
    • ulnar deviations and subluxations, but no errosions
    • SLE related
    • marked contractures and subluxations in a bilateral symmetric pattern
    • swan neck deformities
    • hooked heads of the second and third metacarpals
    • juxta-articular osteopenia
    • no erosions
    • no soft tissue calcifications
    • Systemic lupus erythematosus (SLE or just “lupus”) is a connective tissue disorder that can result in multiple musculoskeletal abnormalities, including a characteristic arthropathy in the hands (sometimes called “lupus arthritis”).
    • The joints are affected in this systemic disease in 75-90% of patients and radiographic changes include:
      
      • subluxation/dislocation
      • absence of erosions or loss of joint space
      • bilateral and symmetric changes
      • juxta-articular osteopenia

Question 23

Mid zone/MCP arthritis

6 differentials

Answer 23

1. RA (usuall bilateral and symmetric, but not always the case, marginal erosions, bone marrow oedmea on MRI with enhancement)
2. CPPD (pseudogout)
3. Hemochromatosis
4. SLE
5. GOUT
6. Psoriasis (involves multiple zones, pencil cup, oesteolysis)

Question 24

Ddx of Multizone arthritis involvement

ie all three zones of hands

Answer 24

1. Gout
2. Psoriasis
3. or 2 disease process combined

Question 25

Oesteomyelitis

Most common pathogens in:

• new born
• children
• adults
• drug addicts
• Sickle cell
• Diabetics

2019 Aug Q98

Answer 25

OSTEOMYELITIS Dahnert
= infection of bone caused by bacteria, fungi , parasites, viruses

• Acute Osteomyelitis
  
  • Age: most commonly affects children
• Organism:
  
  • (a) newborns:
    
    • S. aureus,
    • group B streptococcus,
    • Escherichia coli
  • (b) children:
    
    • S. aureus (blood cultures in 50% positive)
  • (c) adults:
    
    • S. aureus (60%),
    • enteric species (29%),
    • Streptococcus (8%)
  • (d) drug addicts:
    
    • Pseudomonas (86%),
    • Klebsiella,
    • Enterobacteriae; (57 days average delay in diagnosis)
  • (e) sickle cell disease:
    
    • S. aureus,
    • Salmonella
  • (f) diabetics:
    
    • often multiple organisms like S. aureus,
    • Streptococcus, E. coli, Klebsiella, Clostridia,
    • Pseudomonas (in soil+ sole of shoes)

Cause:

• (1) genitourinary tract infection (72%)
• (2) lung infection (14%)
• (3) dermal infection (14%): direct contamination from a soft-tissue lesion in diabetic patient

Pathogenesis :

• (a) hematogenous spread
• (b) direct implantation from a traumatic/iatrogenic source
• (c) extension from adjacent soft-tissue infection

It has been reported that the most frequently isolated organism in neonates with osteomyelitis is S aureus, which is responsible for up to 70% to 90% of the cases.[8,16] Other microorganisms, including Streptococcus agalactiae, E coli, Klebsiella, and Candida albicans, are recognized as potential pathogens.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6336599/#:~:text=It%20has%20been%20reported%20that,to%2090%25%20of%20the%20cases.&text=Other%20microorganisms%2C%20including%20Streptococcus%20agalactiae,are%20recognized%20as%20potential%20pathogens.

Question 26

Nerve entrapment syndromes Guyon’s Cannal

Answer 26

Guyon’s Cannal Syndrome:

• rare
• compression injury of Ulnar nerve by a space-occupying lesion in cannal

Other Causes:

• extrinsic compression (cyclist’s arm)
• thrombosis/aneurysm of superficial palmar branch of ulnar artery
  
  • “hypotremar HAMMAR SYNDROME”

Question 27

Answer 27

Question 28

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3698891/

Answer 28

• Figure 8(A, B)
• (A) Longitudinal view of supraspinatus tendon (SSP). Full-thickness tear of the tendon (long arrow) that reaches from the bursal to the articular margin with sagging of the overlying bursa (short arrow). (B) Long-axis view of the right SSP. Partial thickness articular surface tear (black arrow) and a bright anterior aspect of humeral cartilage (white arrow) – Cartilage interface sign
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3698891/

Question 29

Answer 29

Question 30

3 location specific TUMOUR MIMICS

Answer 30

• Cortical Desmoid
  
  • posteriomedial distal femur
  • medial gastroc/adductor mag
• Pseudotumour of the humerus from the greater tuberosity
• Deltoid Tuberosity

Question 31

Clip injury

Answer 31

Pure valgus stress footy tackle/labradoor dog.

COntusion laterally, tear medially

Question 33

Answer 33

LOOSER ZONES

Looser zones

Dr Patrick Rock◉ and Assoc Prof Frank Gaillard◉◈ et al.

Looser zones, also known as cortical infractions, Milkman lines or pseudofractures, are wide, transverse lucencies with sclerotic borders traversing partway through a bone, usually perpendicular to the involved cortex, and are associated most frequently with osteomalacia and rickets.

Given that these lesions are a type of insufficiency fracture, they are not themselves diagnostic of osteomalacia. Osteomalacia is the strongly favoured diagnosis when these are bilaterally symmetric and in a classic location such as the axillary border of the scapulae, ribs, or posterior ulnae. Other frequently involved sites include the superior and inferior pubic rami, and proximal medial femora. True fractures may occur through these weakened sites.4

Terminology

The term pseudofracture is a misnomer, as they are considered a type of insufficiency fracture. Typically, the fractures have sclerotic irregular margins and are often symmetrical.

Pathology

Looser zones contain regions of demineralised osteoid, frequently with superimposed osteitis fibrosa cystica due to the presence of hyperparathyroidism.

Aetiology

osteomalacia

renal osteodystrophy

fibrous dysplasia

hyperthyroidism

Paget disease of bone

X-linked hypophosphataemia

osteogenesis imperfecta

hypophosphatasia

Location

Looser zones occur in the same locations as insufficiency fractures in weight-bearing bones:

pubic rami

medial femoral neck

medial proximal femoral shaft (c.f. bisphosphonate-related fractures that occur on the lateral cortex of the proximal femoral shaft)

In non-wieghting-bearing bones, they often occur along nutrient foramina and represent true pseudofractures:

lateral scapula

posterior proximal ulna

ribs

iliac wing

History and etymology

Looser zones are named after Emil Looser, a Swiss surgeon, working in Zurich (1877-1936) 3.

Louis Arthur Milkman (1895-1951) was an American radiologist who described the findings in seminal papers in 1930 and 1934 2,3.

Question 34

Answer 34

Question 35

What is a Ewings Sarcoma?

Most common site

Age?

Is it the most common bone tumour?

CEll type

ddx

Answer 35

Ewing sarcoma

There is a lesion located in the distal femur with typical aggressive features of a malignant tumour with:

irregular and partial destruction of cortical bone

periosteal reaction with Codman triangle formation

indistinct zone of transition

perpendicular spiculations producing a sunburst appearance

associated large soft tissue swelling

Histologically proven Ewing sarcoma.

Green: Cortical bone destruction

Pink: Periosteal reaction

Arrow: Codman triangle

Blue: Sunburst appearance

Yellow lines: Cortical thinning

Gray lines: soft tissue expansion

Case Discussion

Pathologically proven Ewing sarcoma. This is a highly malignant bone tumour seen in the first two decades of life. The main differential diagnosis is osteosarcoma.

References

Dr Subhan Iqbal◉ and Assoc Prof Frank Gaillard◉◈ et al.

Ewing sarcomas are the second most common malignant primary bone tumours of childhood after osteosarcoma, typically arising from the medullary cavity with the invasion of the Haversian system. They usually present as moth-eaten destructive permeative lucent lesions in the shaft of long bones with large soft tissue component without osteoid matrix and typical onion skin periostitis. It may also involve flat bones and appears sclerotic in up to 30% of cases.

Epidemiology

Ewing sarcoma typically occurs in children and adolescents between 10 and 20 years of age (95% between 4 and 25 years of age) and has a slight male predilection (M: F 1.5:1) 1,2.

The Ewing sarcoma family of tumours primarily occurs in white patients. In the United States, the incidence in Asians/Pacific Islanders is about one-half that in Caucasians, while the incidence among African Americans is one-ninth that in Caucasians 12.

Clinical presentation

Presentation is non-specific with local pain being by far the most common symptom. Occasionally a soft tissue mass may be palpable. Pathological fractures also occur. Systemic symptoms including fever may be present. ESR and serum LDH levels are also elevated 14.

Pathology

Ewing sarcoma is a small round blue cell tumour with regular-sized primitive appearing cells. It is closely related to the soft tissue tumours pPNET, Askin tumour and neuroepithelioma, which collectively are referred to as Ewing sarcoma family of tumours (ESFT) 1. They share not only microscopic appearances but also demonstrate a non-random t(11;22)(q24;q12) chromosome rearrangement.

Location

lower limb: 45%

femur most common

pelvis: 20%

upper limb: 13%

spine and ribs: 13% (see thoracic Ewings sarcoma)

the sacrococcygeal region most common 4

skull/face: 2%

Alternatively 3:

long bones: 50-60%

femur: 25%
tibia: 11%
humerus: 10%

flat bones: 40%

pelvis: 14%

scapula

ribs: 6% (thoracic Ewing sarcoma)

As far as a location within long bones, the tumour is almost always metadiaphyseal or diaphyseal 2-3:

mid-diaphysis: 33%

metadiaphysis: 44%

metaphysis: 15%
epiphysis: 1-2%

Radiographic features

Ewing sarcomas tend to be large with poorly marginated tumours, with over 80% demonstrating extension into adjacent soft tissues. It should be noted that pPNET often extend into bone, making the distinction difficult.

Plain radiograph and CT

The appearance of these tumours is very variable, but they usually have clearly aggressive appearance. Common findings include 2,14:

permeative: 76%

lamellated (onion skin) periosteal reaction: 57%

sclerosis: 40%

They occasionally demonstrate other appearances, including Codman triangles, spiculated (sunburst) or thick periosteal reaction and even bone expansion or cystic components.

Soft tissue calcification is uncommon, seen in less than 10% of cases 2.

MRI

T1: low to intermediate signal

T1 C+ (Gd): heterogeneous but prominent enhancement

T2: heterogeneously high signal, may see hair on end low signal striations

Nuclear medicine

Ewing sarcomas demonstrate increased uptake on both Gallium67-citrate and all three phases of the Technetium99m methylene diphosphonate bone scans 6.

Treatment and prognosis

Systemic chemotherapy is the mainstay of treatment with surgery and/or radiotherapy playing a role depending on the location and size of the tumour.

What was once a uniformly fatal tumour now has respectable survival rates, although these vary with location. Spinal tumours for example have up to 86% long term survival compared to 25% of sacrococcygeal tumours 4. The overall 5 year survival is in the order of 50-75% of patients with local disease only at the time of presentation 5.

Prognosis is significantly impacted by the presence of distant metastases at the time of diagnosis, which is far more common for the pelvis (25-30%) compared to extremities (<10%) 5.

Metastases most frequently go to lungs and bones in equal proportions. The spine is the most commonly affected bone 13.

History and etymology

It is named after James Stephen Ewing (1866-1943), an American pathologist, who first described his eponymous tumour in 1920 8,11.

Differential diagnosis

other Ewing sarcoma family of tumours

pPNET: large soft tissue component with extension into bone

Askin tumour: chest wall

osteosarcoma:

more often has amorphous calcified matrix

classically perimetaphyseal, Ewing sarcoma also occurs in other locations

more prevalent around the knee and in the proximal humerus, in other locations Ewing sarcoma is the more frequent of the two

osteomyelitis

metastatic disease

haematological malignancy

eosinophilic granuloma 9

neuroblastoma (

Question 36

describing meniscal tears

Answer 36

• horiszontal
  
  • involve an artcular surface and propogate to the periphery
  • a/w parameniscal cysts
  • usually degen. No hx of trauma
  • older patient
  • rx = debridment.
• oblique
• verticle/longitudinal tear
  
  • Most common in the ACL tears
  • Posterior horn of Lat or medial mesicus
• Wrisberg rip tear
  
  • vert and long tear
  • PH LM
  • Lig of Wrisber attaches from the inner aspect of the MCF
• Ramp lesion
  
  • vert long tear, can propgogate and turn into a bucket handle tear into the intercondylar notch
  • can cause locking
  • best tears to rx with surgery.
• longituidine
• radial
  
  • Ghost sign: mesniscus fades out on a slice
• Flap tear
• Meniscal root tear

Tears on the inner edge wont heal. they can propogate.

Question 37

Answer 37

ddx for FD = OM

THis is OM

Thick periosteal reaction.

Question 38

Answer 38

Peripheral primitive neuroectodermal tumour

pPNET in a 21-year-old man. Precontrast CT images showed a lobular iso-dense mass with necrosis in the left retroperitoneum (A) . Enhanced CT images showed the mass had heterogeneous contrast uptake (B-C) . Precontrast MRI showed the mass had an ill-defined border that was iso-intense on T1WI (D) and hyper-intense on T2WI (E) . Contrast MRI showed the mass had significant and heterogeneous enhancement (F) . Sagittal enhanced MRI images showed the mass invaded the 5th lumbar vertebrae and spinal canal (G) . The small round tumor cells were positive for CD-99 (H × 100).

https://www.researchgate.net/figure/pPNET-in-a-21-year-old-man-Precontrast-CT-images-showed-a-lobular-iso-dense-mass-with_fig2_270706146

Dr Daniel J Bell◉ and Dr Jeremy Jones◉ et al.

Peripheral primitive neuroectodermal tumours (pPNET) tend to be large and aggressive retroperitoneal tumours.

Radiographic features

The imaging characteristics of peripheral PNETs are non-specific. However, they should be considered in the differential diagnosis of a large, aggressive retroperitoneal mass.

See also

Ewing sarcoma family of tumours

small round blue cell tumours

Question 39

best view to look for subacromial spurs?

Answer 39

Shoulder (outlet view)

Jessica Hui Shi Ng◉ and Andrew Murphy◉ et al.

The outlet or Neers projection of the shoulder is a specialised projection demonstrating the coracoacromial arch often utilised in the investigation of shoulder impingement 1.

This projection is most commonly seen in orthopaedic clinics and closely resembles a lateral scapular projection but incorporates a 10-15 degree caudal angulation of the tube.

The outlet projection is not advisable in acute imaging of the shoulder as tube angulation may result in elongation of decisive structures. For lateral views of the shoulder in trauma see lateral shoulder view.

Indication

The outlet view is performed to assess subacromial impingement. This view is often performed instead of a lateral shoulder view for the impingement series only.

Patient position

erect or sitting, facing the upright detector

rotated in an anterior oblique position, so the anterior portion of the shoulder is touching the upright detector

the hand is placed on the patient’s abdomen with the arm flexed

the degree of anterior rotation can vary from patient to patient

scapula should be end-on to the upright detector, and this can be done via palpation of the scapula border

Technical factors

posteroanterior lateral projection

centring point

the level of the glenohumeral joint on the posterior aspect of the patient (5 cm below the top of the shoulder)

10-15 degree caudal angulation of the x-ray tube

central to the medial scapula border

collimation

laterally to include the skin margin

medially to cover the entirety of the medial scapula

superior to the skin margin

inferior to the inferior angle of the scapula

orientation

portrait

detector size

24 x 30 cm

exposure

60-70 kVp

10-20 mAs

SID

100 cm

grid

yes

Image technical evaluation

the scapula is demonstrated in a lateral profile, giving the clear appearance of a ‘Y’

clear visualisation of the supraspinatus outlet

acromion and the coracoid process form the upper arms of the ‘Y’

if intact, the humeral head is superimposed at the base of the ‘Y’

Practical points

The lateral scapula projection can be technically demanding, especially when patients are in pain. An anecdotal method amongst radiographers is to feel for the medial border of the scapula and line it up with the anterior portion of the acromion and x-ray straight down the line.

The idea being, if they are lined up there will be a superimposition of the medial and lateral borders of the scapula and hence a perfect lateral position, although this is not always the case.

The best defence against positional errors is having a thorough understanding of radiographic anatomy and how it changes positionally when assessing for under/over rotation of the lateral shoulder, evaluate the borders of the scapula.

Over rotation

Over rotation in this projection refers to the patient’s unaffected side sitting too far away from the image receptor, otherwise known as lying ‘too square’ to the detector.

Over-rotation is clearly established as the lateral border of the scapular (significantly thicker than the medial) is projected over the thorax along with the humeral head; to adjust this, rotated the unaffected side towards the image receptor slightly.

Under rotation

Under rotation in this projection refers to the patient’s unaffected side sitting too close to the image receptor, otherwise known as lying ‘flat’ to the detector.

The lateral border, as well as the humeral head, will be sitting overly lateral in the image; to fix this, rotated the unaffected side away from the detector to increase obliquity.

References

Question 40

causes of chondrocalcinosis

Mneomnic

Answer 40

HOGWASH

• H: hyperparathyroidism, hypothyroidism, haemophilia
• O: ochronosis
• G: gout
• W: Wilson disease
• A: arthritis (rheumatoid, postinfectious, traumatic, degenerative), amyloidosis, acromegaly
• S: pseudogout
• H: haemochromatosis

Question 41

Boxer’s Fracture

Answer 41

• Fracture of the MCP neck
• Most commonly the 5th MCP
• with volar angulation and external rotation of the distal fragment
• simple #s are reduced externally
• Votar comminution usually requires ORIF

Question 42

Answer 42

Question 43

Answer 43

Sclerosing osteomyelitis of Garré

Dr Bahman Rasuli and Dr Yuranga Weerakkody◉ et al.

Sclerosing osteomyelitis of Garré is a specific type of chronic osteomyelitis. It mainly affects children and young adults. It typically affects the mandible and is commonly associated with an odontogenic infection resulting from dental caries.

Radiographic features

Orthopantomogram (OPG)

A localised overgrowth of bone on the outer surface of the cortex. This mass of bone, which is supracortical but subperiosteal, is smooth, fairly calcified, and is often described as a duplication of the cortical layer of the mandible.

The redundant cortical layering of the bone (onion skinning) is often considered a pathognomonic feature 8.

History and etymology

It was first described by Carl Garre in 1893 6.

Question 44

Answer 44

Semimanbranous bursitis

dont mix up with a bakers cyst or a parameniscal cyst

has a classic comma shape.

Question 45

What is this?

What causes it?

Age and gender

Risk factors

5 stages

Answer 45

Gout

• crystal arthropathy
• deposition of monosodium urate crystals in and around the joints.
• Epidemiology
  
  • above 40 years
  • strong male predilection of 20:1, with this predilection more pronounced in younger and middle-aged adults. In the elderly, the gender distribution is more equal
• Clinical presentation
  
  • monoarticular red, inflamed, swollen joint, typically in the lower limb and classically affecting the first metatarsophalangeal joint (podagra)
  • during sleep, and can later involve more than one joint to become an oligoarthropathy or rarely, a polyarthropathy 12.
  • At 7-10 days, there is an intercritical asymptomatic period (intercritical gout) between acute flares.
  • Patients with chronic uncontrolled hyperuricaemia, such as those with chronic kidney disease, may develop chronic tophaceous gout. In chronic tophaceous gout, there are solid urate crystal collections (tophi) and chronic inflammatory and destructive changes in surrounding connective tissue
  • These tophi are typically yellow-white in colour, non-tender, and are typically located within the articular structures, bursae, or the ears
• Pathology
  
  • monosodium urate crystals deposition in periarticular soft tissues.
  • The crystals are needle-shaped
  • strongly birefringent in plane-polarised light
  • The synovial fluid is generally a poor solvent for monosodium urate and therefore crystallisation occurs at low temperatures.
  • The crystals are chemotactic and activate complement.
• There are five recognised stages of gout:

1. asymptomatic hyperuricaemia
2. acute gouty arthritis
3. intercritical gout (between acute attacks)
4. chronic tophaceous gout
5. gouty nephropathy

• Risk factors
  
  • hyperuricaemia
    
    • undersecretion of uric acid by the kidneys (most common) or
      
      • chronic kidney disease
        
        • hypertension
        • hyperparathyroidism
        • Etoh
        • Drugs
          
          • furosemide
          • thiazide diuretics
          • ethambutol
          • purazinamide
          • aspirin
        • lead poinsonig
        • obesity
    • overproduction of uric acid (only 10% of cases).
      
      • Myeloproliferative disorders
      • hemolysis
      • extreme exercise
      • Lesch-Nyhan Syndrome

Question 46

Answer 46

soap bubbly

intertrochanteric

Fibrous dysplasia

Question 47

Prepatellar bursitis

Answer 47

Prepatellar bursitis

Dr Magdalena Chmiel-Nowak◉ and Dr Ahmed Abdrabou et al.

Prepatellar bursitis is inflammation and fluid collection within the prepatellar bursa, located between the patella and the overlying subcutaneous tissue. It has been historically referred to as “housemaid’s knee”.

Clinical presentation

Main symptoms are anterior knee pain and swelling.

Pathology

Chronic irritation due to trauma or repetitive kneeling lead to accumulation of fluid within the prepatellar bursa and sometimes haemorrhagic transformation. Less common causes include:

rheumatoid arthritis

gout

infection

Radiographic features

Plain radiograph

May show

prepatellar soft tissue swelling

clumps of calcifications in the prepatellar soft tissues in chronic cases 3

Ultrasound

Hypoechoic fluid, sometimes containing debris, is noted anteriorly to the patellar surface 2.

MRI

Oval shaped fluid-filled sac is seen anterior to the patella and displays low T1 and bright T2/STIR signal intensity. When haemorrhage occurs T1 signal increases and T2 GRE signal reduces. The wall of the bursa may show increased thickness and irregularity.

Treatment and prognosis

Local injection of non-steroid anti-inflammatory drugs and steroids or local application of ice, and finally bursectomy in resistant cases.

Question 49

Answer 49

Patellar sleeve fracture

Dr Mohamed Saber and Assoc Prof Frank Gaillard◉◈ et al.

Patellar sleeve fractures (also commonly, patellar sleeve avulsion fracture) represent chondral or osteochondral avulsion injury commonly at the inferior pole of the patella (including cartilage from the articular surface, as well as periosteum and cartilage over the dorsal surface).

Very rarely it can involve the upper pole 5.

This is an important diagnosis as the displaced bone-forming tissue will continue to grow and ossify, enlarging, and possibly duplicating the patella.

Epidemiology

Patellar sleeve fractures occur in the paediatric population between 8 and 16 years of age, with a peak incidence at 12.7 years, predominantly boys (3:1). Adolescents are more susceptible due to rapid growth, increased sports activity, and relative patella instability.

Clinical presentation

Unlike Sinding-Larsen-Johansson disease, these injuries are acute and result from sudden and forceful contraction of quadriceps muscle (indirect mechanism). Acute focal pain and tenderness occur at the time of the injury, and a palpable gap may be present.

Radiographic features

Plain radiograph

Lateral knee x-rays demonstrate swelling at the lower pole of the patella and some degree of patella alta. If a small bony fragment has been avulsed with the cartilage, then this too may be seen. A joint effusion may not be present.

Ultrasound

Ultrasound may be helpful in the absence of a radiographically visible fracture fragment. A disruption of the cartilage may be seen, and the degree of separation estimated. Ancillary findings of soft-tissue oedema, fluid, and hyperaemia may be helpful.

MRI

MRI is critical if the diagnosis is suspected as the degree of chondral injury cannot be assessed on plain radiography, and coexistent extensor mechanism injury may be present.

Treatment and prognosis

Surgical treatment is recommended when there is significant displacement (>2 mm) of the displaced osteo/chondral fragment.

Differential diagnosis

Sinding-Larsen-Johansson disease: chronic

jumper’s knee: chronic and seen in adults

Osgood-Schlatter disease: chronic and affects the inferior attachment of the patellar tendon

patella fracture

quadriceps tendon rupture

Question 50

Answer 50

Primary synovial chondromatosis

• benign monoarticular disorder
• unknown origin
• synovial metaplasia and proliferation
• multiple intra-articular cartilaginous loose bodies of relatively similar size
• not all of which are ossified.
• Hence, the term synovial chondromatosis is preferred over primary synovial osteochondromatosis.
• It is distinct from secondary synovial chondromatosis that is the result of a degenerative change in the joint.

Epidemiology

• 4th or 5th decades of life 2.
• Men are affected more frequently (M:F ratio of 2:1 to 4:1)

Clinical presentation

• pain, swelling, and limitation of motion, which often progresses slowly for several years.
• Joint effusions
• restricted range of motion.

Pathology

• Primary synovial chondromatosis is a self-limiting benign neoplastic process
• proliferative chondroid nodules of the synovium.

Three phases of articular disease have been identified:

1. initial phase: metaplastic formation of cartilaginous nodules in the synovium
2. transitional phase: detachment of those nodules and formation of free intra-articular bodies
3. inactive phase: resolution of synovial proliferation, but loose bodies remain in the joint, and may increase in size obtaining nourishment from the joint fluid by diffusion

Location

• Usually, the condition is monoarticular affecting any joint but the large joints are preferentially affected:
  
  • knee (up to 70%) 4
  • hip (20%)
  • elbow
  • shoulder
  • Occasionally, bursa or tendon sheaths may be involved 1,2.

Question 51

Definition

common sites

Pathology

Risk factors 4

Complicatoins

Answer 51

Subchondral insufficiency fracture

Dr Yuranga Weerakkody◉ et al.

Subchondral insufficiency fracture refers to a type of stress fracture that occurs below the chondral surface on a weight-bearing surface of a bone due to mechanic failure of subchondral cancellous bone.

Pathology

They tend to occur when normal physiological forces are repeatedly applied to an area of bone. Callus formation occurs along with non-mineralised osteoid and the absence of bone infarction.

Risk factors

osteoporosis

obesity

abnormal loading through the joint

overuse

Location

Typical sites include:

knee: can progress to spontaneous osteonecrosis of the knee 5

femoral head

femoral condyles

tibial plateau

metatarsal head

Complications

secondary osteonecrosis

osteonecrosis with cavitation (crescent sign)

articular collapse

destructive arthropathy

Radiographic features

Plain radiography and CT

Radiographs are normal preceding the development of callus formation or collapse of the articular surface. Linear or patchy subchondral sclerosis may be present representing cancellous fracture.

MRI

T1: may be characteristically low signal intensity band through the affected region

parallels the subchondral bone plate whereas osteonecrosis is curvilinear

preservation of the articular cartilage whereas an osteochondral defect is involved

T2: florid marrow oedema

History and etymology

It is described in many regions but the the term subchondral insufficiency fracture of “femoral head” was coined by Bangil et al in 1996 7

Differential diagnosis

The differential diagnosis of subchondral marrow oedema includes:

osteoarthritis

stress response

marrow contusion

transient osteoporosis

See also

insufficiency fracture

subchondral fracture

case

Tear of the posterior root medial meniscus with extrusion of the meniscal body. Upper surface horizontal tear of the body lateral meniscus extending to the undersurface of the posterior horn with posterolateral parameniscal cyst formation.

Grade 4 chondral loss on both femoral and tibial surface medial compartment.

Oedema throughout the medial femoral condyle centred on a 10 mm subchondral T1 hypointensity with some cortical depression of the weight-bearing surface.

Case Discussion

Subchondral insufficiency fractures, previously known as spontaneous osteonecrosis of the knee (SONK), are often very painful. In this case, there are associated severe meniscal injuries.

Question 52

Answer 52

The anteater nose sign refers to an anterior tubular elongation of the superior calcaneus which approaches or overlaps the navicular on a lateral radiograph of the foot. This fancifully resembles the nose of an anteater and is indicative of calcaneonavicular coalition 1,2.

Question 53

Answer 53

Question 54

CPPD

? bifringent under microscope?

Answer 54

Calcium Pyrophosphate Crystal Deposition Disease

AKA (Pseudogout) (p. 1217) Robins

Calcium pyrophosphate crystal deposition (CPPD) disease typically occurs after age 50, with a 30% to 60% prevalence by age 85; the hereditary variant presents somewhat earlier and the phenotype is more severe. An autosomal dominant form of the disease is due to mutations in the ANKH gene encoding a pyrophosphate transport channel. The most common secondary form is associated with a variety of etiologies, including trauma, hyperparathyroidism, hemochromatosis, and diabetes; altered matrix synthesis and degradation of pyrophosphates are implicated.

The clinicopathologic features are similar to gout. The crystals initially form in cartilage; as deposits enlarge they rupture and seed the joint where macrophages engulf them and activate their inflammasomes to generate IL-1β. Subsequent neutrophil recruitment and recurrent bouts of inflammation result in joint damage in more than 50% of patients. Knees, wrists, elbows, shoulders, and ankles are affected (in decreasing order).

Morphology (p. 1217)

•

Gross: Crystals form chalky white, friable deposits; they rarely deposit in large masses.

•

Microscopic: Crystals stain as oval, blue-purple aggregates; they are weakly birefringent and have geometric shapes. Chronic lesions exhibit mononuclear cell infiltrates with fibrosis.

Dahnert

Calcium pyrophosphate dihydrate crystal deposition
disease = CPPD
Target areas: MCP (2nd, 3rd), radiocarpal; bilateral
symmetric I asymmetric changes
‘./ chondrocalcinosis +periarticular calcifications:
‘./ calcification of triangular fibrocartilage

>I “degenerative changes” in unusual locations:
>I narrowing ±obliteration of space between distal
radius and scaphoid ± fragmentation of surfaces
>I scapholunate separation
>I destruction of trapezioscaphoid space
>I no erosions
>I + large osteophytes = hemochromatosis

Question 55

Staging Of this condition

Answer 55

Osteochondritis dissecans

Dr Mostafa El-Feky◉ and Assoc Prof Frank Gaillard◉◈ et al.

Osteochondritis dissecans (OCD) is the end result of the aseptic separation of an osteochondral fragment with the gradual fragmentation of the articular surface and results in an osteochondral defect. It is often associated with intraarticular loose bodies.

Epidemiology

Onset is between childhood and young adults age, with the majority of patients being between 10 and 40 years of age, with approximately a 2:1 male to female ratio 3.

Risk factors

repetitive throwing / valgus stress and gymnastics / weight bearing on upper extremity

valgus stress / compressive force on the vulnerable chondroepiphysis of the radiocapitellar joint in skeletally immature patients is supported as the aetiology for OCD of the capitellum 8

ankle sprain/instability

In the talus, 96% of lateral lesions and 62% of medial lesions were associated with direct trauma 9

competitive athletics 10

family history: epiphyseal dysplasia has been postulated as a subset of OCD 11

Clinical presentation

Symptoms are variable and range from asymptomatic to significant pain and locking (suggesting loose body formation). Joint effusions and synovitis are often present.

Pathology

The exact aetiology is uncertain and controversial, with the majority of cases thought to be the result of trauma 4. In up to 40% of cases, patients give a history of trauma as the inciting event 3. Other postulated causes include 4:

avascular necrosis (AVN)

fat emboli

microtrauma

familial dysplasia

Location

Many joints can be affected, but typical locations include:

femoral condyles are most common site accounting for ~95% of all cases: osteochondritis dissecans of the knee

talus: osteochondritis dissecans of the ankle
capitellum: osteochondritis dissecans of the elbow

glenoid 7

Staging

See osteochondral injury staging and osteochondritis dissecans surgical staging.

Radiographic features

Plain radiograph

Plain radiographs should be the first step in the evaluation of knee pain, however, unless advanced changes are present and/or a meticulous technique employed, early findings of osteochondritis dissecans may be occult. The intercondylar “notch” view is very helpful.

Early findings include subtle flattening or indistinct radiolucency about the cortical surface. As the process progresses, more pronounced contour abnormalities, fragmentation and density changes (both lucency and sclerosis) become evident. If an osteochondral fragment becomes unstable and displaced, then donor site and intra-articular fragment may be seen.

CT

CT has the advantage of sectional imaging through the joint and multiplanar reformats. Findings are similar to those seen on plain radiographs.

MRI

MRI is the modality of choice, with high sensitivity (92%) and specificity (90%) 4 in the detection of separation of the osteochondral fragment. This is essential in determining management.

T1:

variable signal overall with intermediate to low signal adjacent to fragment and variable fragment signal

T2:

the high signal line demarcating fragment from bone usually indicates an unstable lesion however false positives can result from oedema 6

low signal loose bodies, outlined by high signal fluid

donor defect filled with high signal fluid

high signal subchondral cysts

T1+gad:

enhancement indicates the viability of the lesion

The four classic signs of instability described at MRI include 14 :

high signal intensity rim at the interface between the fragment and the adjacent bone on T2-weighted MR image

fluid-filled cysts beneath the lesion

high signal intensity line extending through the articular cartilage overlying the lesion

focal osteochondral defect filled with joint fluid, indicating complete detachment of the fragment

Complications

persistent pain with activity: ~ 2/3 following surgical management of knee and 40% following surgical management of elbow 12,13

articular incongruity 13

early degenerative joint disease 13

Treatment and prognosis

Spontaneous healing is usual unless there is an unstable fragment, and treatment revolves around rest and immobilisation for up to a year 5.

When the fragment is unstable or displaced, without treatment patients are susceptible to premature secondary osteoarthritis. Numerous surgical approaches have been tried, including drilling, bone grafting, replacement of bone fragment and pinning 5.

When surgery is performed, the results in most cases are only “fair”. ~50% (range 35-70%) of patients achieve a “good to excellent” clinical outcome 3 but even in these cases, the majority develop osteoarthritis.

History and etymology

It was first described by the German surgeon Franz Konig in 1888.

Differential diagnosis

normal irregular distal femoral epiphyseal ossification

avascular necrosis

osteochondral impaction fracture

stress/insufficiency fracture

See also

differential diagnosis of erosive arthritis

Osteochondritis dissecans (surgical staging)

Dr Jeremy Jones◉ and Assoc Prof Frank Gaillard◉◈ et al.

Osteochondritis dissecans can be classified at surgery into 4 stages:

stage I

stable

lesion in continuity with the host bone

covered by intact cartilage

stage II

stable on probing

partial discontinuity of the lesion from the host bone

stage III

unstable on probing

fragment not dislocated

complete discontinuity of the “dead in situ” lesion

stage IV

dislocated fragment

Classification according to International Cartilage Repair Society.

Of course distinguishing stage II from III can be difficult on MRI.

Question 56

Answer 56

https://radiopaedia.org/articles/elastofibroma-dorsi?lang=gb

Elastofibroma Dorsi Bilateral

Question 57

Patterns of bone bruise in knee injury

Answer 57

Patterns of bone bruise in knee injury

Dr Daniel J Bell◉ and Dr Henry Knipe◉◈ et al.

The pattern of bone bruise in knee injuries (a.k.a. bone contusion) can give clues for the mechanism and associated injuries.

Radiographic features

Five classic bone contusion patterns have been described 1-4:

pivot-shift injury

valgus stress to flexed and externally rotated knee

contusion pattern: posterolateral tibial plateau and mid part of lateral femoral condyle

associated with anterior cruciate ligament (ACL) tears

see also: contrecoup injury of the knee, O’Donoghue unhappy triad

dashboard injury

anterior force to tibia in a flexed knee (e.g. knees against dashboard in motor vehicle collision, or fall onto flexed knee)

contusion pattern: anterior tibia +/- posterior patella

associated with posterior cruciate ligament (PCL) tear

clip injury

valgus stress to flexed knee

contusion pattern: lateral femoral condyle and lateral tibial plateau +/- medial femoral condyle from medial collateral ligament (MCL) avulsive stress

associated with MCL injuries

hyperextension injury

direct force to anterior tibia with foot planted

contusion pattern: “kissing contusions” of anterior tibial plateau and anterior femoral condyle

associated with ACL, PCL, meniscal injuries, and in severe cases knee dislocation

lateral patellar dislocation

twisting injury to flexed knee

anterolateral lateral femoral condyle and inferomedial patella

associated with medial patellar retinaculum +/- medial patellofemoral ligament injury +/- medial patellotibial ligament injuries

Question 58

distal zone handarthritis DDx

Answer 58

1. OA
2. erosive OA
   
   1. gull wing
3. Psoriasis
   
   1. pencil in cup
   2. periostitis (look at sesamoid) shaggy appearance of the cortex
4. ReArth
5. Gout

Question 59

Erosive osteoarthritis

AKA

population

Rad findings

Answer 59

Erosive osteoarthritis =inflammatory osteoarthritis
Age: predominantly middle-aged I postmenopausal
women
• acute inflammatory episodes
Target areas: DIP, PIP, 1st CMC, trapezioscaphoid;
bilateral symmetric I asymmetric
‘./ central erosions combined with osteophytes
= subchondral “gull wing” erosions
‘./ joint space narrowing + sclerosis
‘./ rare ankylosis

Question 60

Answer 60

luck strike makes fine tabacco is the mnemonic

Question 61

Answer 61

Anterior tibial translocation sign

Dr Joachim Feger◉ and Assoc Prof Frank Gaillard◉◈ et al.

The anterior tibial translocation sign or anterior drawer sign (a.k.a. anterior translation of tibia) is seen in cases of complete rupture of the anterior cruciate ligament and refers to anterior translocation (anterior tibial subluxation) of the tibia relative to the femur of >7 mm 1. It measured on sagittal MRI sequences at the lateral femoral condyle.

Question 62

DUAL ENERGY CT

Answer 62

• Monosodium vs pyrophosphate crystals
• Green for Gout generally

Question 63

Posterolateral ligamentous complex

AKA

Structures 10

Answer 63

• Posterolateral ligamentous complex
• AKA
  
  • arcuate ligamentous complex) of the knee is an important stabiliser and consists of a number of structures.
• Structures:
  
  1. lateral collateral ligament
  2. arcuate ligament
  3. popliteofibular ligament
  4. posterior third of the lateral capsule
  5. fabellofibular ligament (when a fabella is present)
  6. tendoaponeurotic unit formed by the popliteus muscle (not always included)
  7. biceps femoris tendon (not always included)
  8. popliteal meniscal ligament (not always included)
  9. lateral gastrocnemius muscle (not always included)
• Functional classification
  
  • static stabilisers (i.e. posterolateral knee joint capsule)
    
    • arcuate ligament
    • popliteofibular ligament
    • lateral (fibular) collateral ligament
    • fabellofibular ligament (when the fabella is present)
  • dynamic stabilisers
    
    • tendoaponeurotic unit formed by the popliteus muscle
    • biceps femoris tendon
    • lateral gastrocnemius muscle (not always included)
  • other structures
    
    • popliteal meniscal ligament
    • posterior horn lateral meniscus
    • lateral coronary ligament
    • iliotibial band

Question 64

Answer 64

Freiberg disease

Dr Mohamed Saber and Dr Jeremy Jones◉ et al.

Freiberg disease, also known as Freiberg infraction, is osteochondrosis of metatarsal heads. It typically affects the 2nd metatarsal head, although the 3rd and 4th may also be affected. It can be bilateral in up to 10% of cases.

Epidemiology

It is most common in females aged 10-18 years (male to female ratio of 1:3).

Clinical presentation

Clinically they present with pain on weight-bearing with swelling and tenderness.

Pathology

The cause of Freiberg infraction is controversial and is probably multifactorial.

A traumatic insult in the form of either acute or repetitive injury and vascular compromise, perhaps due to an elongated 2nd metatarsal, are the most popular theories, and as it is more commonly seen in women, particularly during adolescence, high-heeled shoes have been postulated as a possible causative factor.

Histologically, Freiberg infraction is characterised by the collapse of the subchondral bone, osteonecrosis, and cartilaginous fissures 1.

Radiographic features

Plain radiograph

These can be split into early and late features:

Early

flattening and cystic lesions of the affected metatarsal head

widening of the metatarsophalangeal joint

Late

osteochondral fragments

sclerosis and flattening of the bone

increased cortical thickening

Some publications advocate the use of the Bragard staging classification 10, which requires two views/planes of the forefoot:

I - metatarsal head flattening and decreased subchondral bone density

II - metatarsal head sclerosis, fragmentation, and deformation, with cortical thickening

III - metatarsophalangeal osteoarthrosis with intra-articular loose bodies

MRI

Early MR imaging findings include low-signal-intensity changes in the metatarsal head on T1-weighted images with increased signal intensity on corresponding T2-weighted and STIR images.

With disease progression, flattening of the metatarsal head occurs, and low-signal-intensity changes develop on T2-weighted images as the bone becomes sclerotic.

History and etymology

Albert H Freiberg (1868-1940), was an American orthopaedic surgeon, who first described his eponymous condition in 1914 8,9,11.

Differential diagnosis

On imaging consider

normal variant: metatarsal head flattening is described in ~10% of the asymptomatic population

fracture of metatarsal head or neck

including subchondral insufficiency fracture

lesser metatarsal head instability (only identified on MRI): due to plantar plate tear

See also

osteonecrosis

Question 65

Answer 65

Osteofibrous dysplasia

• benign fibro-osseous cortical lesion
• occurs almost exclusively in the tibia and fibula.
• It is most commonly seen in the mid-diaphysis of the tibia.
• Terminology
  
  • A commonly used synonym is ossifying fibroma of the long bones.
• Epidemiology
  
  • most common in younger patients, e.g. ~ 10 years of age
  • less commonly reported in older patients, up to 63 years of age 3
  • slight male predilection (3:2 ratio 3)
• Clinical presentation
  
  • Most patients present with pain and swelling, and patients may present secondary to a pathological fracture.
• Pathology
  
  • Osteofibrous dysplasia is considered as a benign, non-neoplastic condition. Some consider it as part of a spectrum of osteofibrous dysplasia-like adamantinoma and adamantinoma.
• Microscopic appearance
  
  • Histology shows trabecular bone woven within fibrous stroma with osteoblastic rimming and mature lamellar bone.
  • It is closely related to fibrous dysplasia (fibrous dysplasia is predominantly medullary), but the zonal phenomenon and osteoblastic rimming of bony trabeculae are absent in fibrous dysplasia.
  • Osteofibrous dysplasia and ossifying fibroma of the jaw have similar histological characteristics, but osteofibrous dysplasia shows cytokeratin-positive cells, whereas ossifying fibroma of the jaw shows psammomatous calcification, which are exclusive features.
  • Although adamantinoma can contain osteofibrous dysplasia-like components, nests or strands of an epithelioid cell are the differentiating feature between adamantinoma and osteofibrous dysplasia.
  • Adamantinoma with scarce epithelioid component and mostly composed of osteofibrous dysplasia-like tissue are considered as osteofibrous dysplasia-like adamantinoma.
• Radiographic features
  
  • Osteofibrous dysplasia is classically a lytic lesion centred in the tibial cortex, often with sclerotic margins.
  • Because of its similarity to adamantinoma, a much more aggressive pathology, a primary issue is differentiating between the two.
  • Due to intralesional heterogeneity, needle biopsy may result in diagnostic misclassification, particularly with underestimation of aggressive lesions. Thus, radiologic-pathologic correlation is important with benign or equivocal biopsy results 3.
• Osteofibrous dysplasia tends to be:
  
  • smaller (mean 6-7 cm versus 10-17 cm for adamantinoma)
  • with more distinct margins
  • less likely to involve the medullary cavity
• Plain radiograph
  
  • Plain radiograph remains the initial and chief investigation.
• location:
  
  • along long axis: mid-diaphysis, especially anteriorly
  • along transverse axis: cortical with medullary encroachment
• consistency
  
  • lucent or ground-glass
  • lobular-to-bubbly in appearance
• margins
  
  • narrow zone of transition
  • sclerosis common
  • no nidus
  • no aggressive periosteal reaction
  • benign-appearing periosteal reaction is non-specific, and can be seen in all lesions along the osteofibrous dysplasia/adamantinoma spectrum 3
  • +/- pseudotrabeculation and anterior bowing
• MRI
  
  • MRI is helpful in evaluation of suspected osteofibrous dysplasia, particularly to evaluate the extent of intramedullary involvement. Complete medullary cavity involvement is more suggestive of adamantinoma.
  • T1: intermediate signal
  • T2: intermediate-to-high signal
  • T1C+: diffuse and intense enhancement.
  • +/- soft tissue component (non-specific)
  • can be seen in all lesions along the osteofibrous dysplasia/adamantinoma spectrum 3
  • no aggressive cortical destruction
  • Treatment and prognosis
  • Surgery is reserved for lesions that are large or demonstrate aggressive behaviour.
  • They usually have an excellent prognosis and usually, stabilise or spontaneously regress once the child is over 10 years old.
  • It can be locally destructive and may result in pathological fracture, subsequently pseudarthrosis.
  • Local recurrences can occur after surgery with some aggressive recurrence, possibly due to components of adamantinoma or possible transformation to adamantinoma.
• Differential diagnosis
• Consider
  
  • ossifying fibroma
  • adamantinoma
  • osteofibrous dysplasia-like adamantinoma
  • intracortical fibrous dysplasia

Question 66

Answer 66

Discoid meniscus

Dr Balint Botz ◉ and Assoc Prof Frank Gaillard◉◈ et al.

Discoid menisci are those that have a body that is too wide, usually affecting the lateral meniscus. They are incidentally found in 3-5% of knee MRI examinations.

Epidemiology

Discoid menisci are congenital, frequently bilateral (up to 50%) and have been reported in twins, although no genetic locus has been identified 2. There is a higher prevalence in Asians without any gender predilection 7. Lateral discoid meniscus is far more common than medial discoid meniscus, with the latter being rare.

Clinical presentation

Although frequently asymptomatic, discoid menisci are prone to cystic degeneration with subsequent tear. Clinical presentation may, therefore, be either incidental or with pain, locking or a ‘clunk’.

Pathology

Discoid menisci have decreased collagen fibres and loss of normal collagen orientation, which predisposes them to intrameniscal mucoid degeneration 7.

Classification

Classification is based on the degree of peripheral attachments to the tibial plateau, and the shape of the meniscus itself:

complete vs incomplete

80% coverage of the tibial plateau is often used as the cut-off between incomplete and complete 7

stable vs unstable

stable: normal peripheral attachments with an intact posterior meniscofemoral ligament

unstable (also known as a Wrisberg variant): lack or tear of a posterior meniscocapsular (in particular meniscopopliteal) ligaments with an attachment only from the meniscofemoral ligament of Wrisberg 4

anterior or posterior mega horn

Radiographic features

Plain radiograph

Radiographs may well suggest the diagnosis with the widening of the lateral joint space and cupping of the lateral tibial plateau, which is normally flat or even slightly convex. Additionally, there may be associated hypoplasia of the lateral tibial spine.

MRI

On coronal imaging, meniscal body width of 15 mm or more is typically considered diagnostic of discoid morphology. Alternatively, a ratio of the minimal meniscal width to the maximal tibial width of more than 20% may be used 7,8.

On sagittal imaging, the body of the lateral meniscus is normally only seen on two adjacent slices. A discoid meniscus is usually present if the meniscal body is seen on three or more standard sagittal slices - the opposite of the absent bow tie sign.

Treatment and prognosis

Ideally, the meniscus is preserved with conservative management. If this is unsuccessful, then partial or total resection may be carried out.

Complications

meniscal tears

intrasubstance mucinous degeneration

early bony degenerative change

Question 67

OA findings

Answer 67

Osteoarthritis =degenerative joint disease
= abnormal stress with minor+ major traumatic episodes
Target areas: DIP, PIP, 1st CMC, trapezioscaphoid;
bilateral symmetric I asymmetric
‘./ joint space narrowing
‘./ subchondral eburnation
‘./ marginal osteophytes +small ossicles
‘./ radial subluxation of 1st metacarpal base
0 Radiocarpal joint normal unless history of trauma

Question 68

ACL injuries

Dont miss

Answer 68

Popliteal fibular liament injuries

MCL Tears

Question 69

2019 AUG Q101

Answer 69

Rectus femoris AIIS avulsion

Introduction

An apophyseal avulsion injury seen in adolescent athletes

Epidemiologydemographics

most often in adolescents between the ages 14-17

males more often than females

occurs most often in sports involving kicking

Pathophysiologymechanismtypically occurs due to eccentric contraction of the rectus femoris (femoral n.)

as hip extends and knee is flexed

causes avulsion of its anatomic origin off the pelvis

Anatomy

Anterior inferior iliac spine

a bony prominence just above acetabulum

is the origin of the direct head of the rectus femoris (femoral n.)

Presentation

History

sudden “pop” in pelvis

Symptoms

pain and weakness

Physical exam

antalgic gait

anterior hip pain and hip flexion weakness

Imaging

Radiographs

show avulsion of AIIS

Treatment

Nonoperativebed-rest, ice, activity modificationindications

almost all treated nonoperatively

techniquehip flexed for 2 weeks

position lessens stretch of affected muscle and apophysis

follow with guarded weight bearing for 4 week

Complications

Loss of reduction

Delayed union

Question 70

10 Key words for this condition

Answer 70

Psoriatic arthritis

1. Rh Neg
2. a/w Psoriasis
3. distal
4. errosive + Proliferative
5. 60% are HLA-B27
6. acro-osteolysis
7. Pencil-in-cup
8. Sausage digit
9. “telescoping fingers”
10. “mouse ears”
11. ivory phalanx:

• Psoriatic arthritis (PsA) is an inflammatory arthritis associated with psoriasis.
• negative for rheumatoid factor and hence classified as one of the seronegative spondyloarthritides.
• Epidemiology
  
  • Overall prevalence is ~0.5% (range 0.1-1%)
  • ~25% (range 6-41%) of patients with psoriasis
  • no gender predilection in psoriatic arthritis
  • median age of diagnosis is 48 years
• Clinical presentation
  
  • Dermatological features of psoriasis precede arthritis in ~65% (range 60-70%) whereas arthritic symptoms proceed dermatological features in 15-20% 11.
  • There is a strong association with nail involvement, particularly for distal interphalangeal joint arthritis.
  • It most commonly presents as an asymmetrical oligo-arthritis with spondylitis common; oligo-arthritis may progress to polyarthritis in the clinical course of the disease 10,11.
• Pathology
  
  • Both environmental and genetic factors are thought to play a role. Up to 60% are HLA-B27 positive 2. A proportion of patients have serum rheumatoid factor 6.
• Extra-articular manifestations are common 11:
  
  • ocular:
    
    • uveitis, conjunctivitis
  • gastrointestinal:
    
    • inflammatory bowel disease
  • cardiac:
    
    • rhythm disturbances (e.g. bundle branch block)
  • urogenital:
    
    • urethritis, prostatitis, balanitis, cervicitis, vaginitis
• Associations
  
  • obesity
  • hypertension
  • insulin resistance / type 2 diabetes
  • hyperlipidaemia
• Radiographic features
  
  • The hallmark
    
    • the combination of erosive change with bone proliferation
    • predominantly distal distribution (e.g. interphalangeal more than metacarpophalangeal joints).
    • The disease most commonly involves the hands, followed by feet.
    • It can also affect sacroiliac joints and spine.
    • Knees, elbows, ankles, and shoulders are less frequently involved 2.
• In the hands and feet, the pattern of distribution may be that of a
  
  • symmetric polyarthropathy, or
  • asymmetric oligoarthropathy
    
    • distal predominance.
• Imaging findings include:
  
  • “pencil-in-cup” deformities are common, but not pathognomonic for PsA 3
  • bone proliferation results in an irregular, “fuzzy” appearance to the bone around the affected joint 2
  • joint subluxation or interphalangeal ankylosis may be present
  • periostitis: may appear as a periosteal layer of new bone, or as irregular thickening of the cortex itself 2
  • “sausage digit” which refers to soft tissue swelling of a whole digit; ultrasound examination of a sausage digit demonstrates underlying synovitis and tenosynovitis 4
  • acro-osteolysis 12
  • arthritis mutilans: osteolysis and articular collapse can cause a phenomenon referred to as “telescoping fingers”
  • ivory phalanx: classically involving the distal phalanx of the great toe
  • sacroiliitis: often asymmetrical
  • spondylitis: asymmetric paravertebral ossifications and relative sparing of the facet joints
• Differential diagnosis
  
  • rheumatoid arthritis
    
    • there is an MCP joint predominance in rheumatoid arthritis (RA) vs interphalangeal predominant distribution in PsA
    • bone proliferation not a feature in RA
    • osteoporosis not a feature in PsA
  • erosive osteoarthritis
    
    • “gull-wing” central erosions are present in erosive OA vs “mouse ears” peripheral bare area erosions in PsA
  • reactive arthritis (Reiter syndrome)
    
    • tends to involve feet > hands

Question 71

Answer 71

Gaucher disease

Dr Tristan Skalina and Zara Oozeerally et al.

Gaucher disease (GD) is the most common lysosomal storage disorder in humans. It is an autosomal recessive, multisystem disease arising from a deficiency of glucocerebrosidase or beta-glucosidase activity, resulting in the accumulation of a glycolipid (glucocerebroside) within the lysosomes of macrophages, particularity in the bone marrow, spleen and liver.

Epidemiology

Type 1 is the most common, affecting 1:500-1,000 Ashkenazi Jews and 1:50,000-100,000 of the general population 7. Types 2 and 3 are considered much rarer.

Clinical presentation

Age of presentation depends on the type of Gaucher disease:

type 1 (most common form)

age of presentation varies widely, with the mean age of diagnosis being 21 years of age 6

some patients present in childhood while others remain asymptomatic throughout life

clinical presentation tends to be with skeletal symptoms (bone pain, pathological fractures, osteonecrosis and bone crises ) 4, hepatomegaly, splenomegaly, and haematological disturbances

type 2: evident by 6 months of age, with progressive neurological deterioration resulting in death by the age of 1 or 2

type 3: presents with mild neurological complications by late adolescence or early childhood 6

Pathology

Genetic changes

The glucosylceramide beta (GBA) gene provides instructions for making ß-glucocerebrosidase. Mutations in the GBA gene reduce or eliminate the function of this lysosomal enzyme leading to a build-up of toxic glucocerebroside and related substances in various tissues and organs 7.

Classification

Three types of Gaucher disease are described, each with different manifestations 1:

type 1 (non-neuropathic form or adult form): commoner type; progressive hepatomegaly, splenomegaly, anaemia and thrombocytopenia, and marked skeletal involvement; lungs and kidneys may also be involved, but the CNS is spared

type 2 (acute neuropathic form or infantile form): severe progressive neurological involvement with death by 1 to 2 years of age; hepatomegaly, splenomegaly, is also present (usually evident by 6 months of age)

type 3: type 1 with neurological involvement

Radiographic features

Plain radiograph

Skeletal involvement is seen in 70-100% of patients and primarily involves long bones (tibia, humerus, femur) as well as vertebrae. Ribs, hands and wrists, ankles and feet, and mandible may also be involved 6. Features of skeletal involvement include:

osteopenia

osteonecrosis

pathological/crush fractures

endosteal scalloping

Erlenmeyer flask deformities

H-shaped vertebrae

paranasal sinus obliteration due to medullary expansion 9

MRI

spleen

massive splenomegaly

splenic nodules (30%) 1

splenic infarcts (33%)

liver

hepatomegaly: less marked than the degree of splenomegaly

T2: hyperintense stellate areas representing inflammation and fibrosis 3

areas of hepatic ischaemia

skeletal system

long bones are most severely affected

reduced T1 and T2 signal from involved bone marrow (due to infiltration of Gaucher cells)

bone marrow burden (BMB) score may be obtained from MRI images 4

may give a “salt and pepper pattern” due to scattered involvement

features of superimposed osteonecrosis

metaphyseal notching of humeri

pathological fractures

Erlenmeyer flask deformity

Treatment and prognosis

Enzyme replacement with macrophage-targeted glucocerebrosidase has been shown to be highly effective in type 1 GD, halting the progression and even reversing both bone marrow and visceral infiltration 5. Radiographically, hepatomegaly and splenomegaly respond more rapidly than skeletal changes.

Glucosylceramide synthase inhibitors are available for patients with type 1 GD who cannot receive enzyme replacement therapy 8.

Complications

osteonecrosis of the hip 8

pathological fracture and pyogenic osteomyelitis 10

lung involvement 8

pulmonary infiltration by Gaucher cells (type 2)

parenchymal infiltration with fibrosis (type 3)

pulmonary hypertension 12

increased frequency of multiple myeloma, Parkinson disease and Lewy body dementia 8

Gaucheromas: rare pseudotumours comprising a mass of Gaucher cells 11

History and etymology

First described by French physician Philippe CE Gaucher (1854-1918) in 1882, while still a medical student 2.

Question 72

Answer 72

Hereditary multiple exostoses/

Dr Yusra Sheikh◉ and Assoc Prof Frank Gaillard◉◈ et al.

Hereditary multiple exostoses, also known as diaphyseal aclasis or osteochondromatosis is an autosomal dominant condition, characterised by the development of multiple osteochondromas.

Epidemiology

Hereditary multiple exostoses demonstrate an autosomal dominant inheritance pattern, with incomplete penetrance in females. The number of exostoses, the degree, and type of angular deformity, and even the rate of malignant transformation varies significantly, even within families.

Clinical presentation

Most patients are diagnosed by the age of 5 years, and virtually all are diagnosed by the age of 12 years. Patients may be asymptomatic with a few small lesions or may be significantly deformed by multiple large osteochondromas.

Radiographic features

Except that they are multiple, imaging features are identical to solitary osteochondromas. The skeletal distribution of lesions can significantly vary, with some authors noting that the typical distribution is bilateral and symmetric, whereas others report a strong unilateral predominance.

Often associated with a broadened shaft at the end of long bones, hence the term diaphyseal aclasis.

Complications

Are also similar or those of solitary osteochondroma and include:

vascular impingement

neural impingement

fracture

bursitis

deformity and ankylosis

malignant transformation

Malignant transformation is more common than in sporadic cases, with transformation rates reported as high as 25% (lower rates of 3-5% have also been published) 3. The mnemonic GLAD PAST 1 lists the associations with sarcomatous transformation.

Refer to the generic osteochondroma article for more information.

See also

exostosis

Question 73

hyperextension knee injury

Answer 73

over kick of a ball

Question 74

Answer 74

Question 75

? % of Blood culture negative Osteomyelitis

2019 Aug Q98

Answer 75

Laboratory Studies

A complete blood count (CBC) is useful for evaluating leukocytosis and anemia. Leukocytosis is common in acute osteomyelitis before therapy. The leukocyte count rarely exceeds 15,000/µL acutely and is usually normal in chronic osteomyelitis. the erythrocyte sedimentation rate (ESR) and the C-reactive protein (CRP) level are usually increased. [24, 2, 25] In metastatic and some metabolic bone disease, alkaline phosphatase (ALP), calcium, and phosphate are elevated, but they are within normal limits in osteomyelitis. [26]

Blood cultures are positive in only 50% of cases of osteomyelitis. [9] They should be obtained before or at least 48 hours after antibiotic treatment

Question 76

what sign is this?

Answer 76

2019 Aug q100

Crescent sign of osteonecrosis

Dr Magdalena Chmiel-Nowak◉ and Assoc Prof Frank Gaillard◉◈ et al.

The crescent sign refers to a linear cleft due to subchondral fracture in the setting of osteonecrosis.

It was originally described as a radiographic finding, however, it can also be seen on cross-sectional imaging.

In the setting of Legg-Calve-Perthes disease, it heralds the beginning of the fragmentation phase (stage 2).

Pathology

The cause of the crescent sign is bone trabeculae failure, leading to subchondral fracture. The fracture may propagate through the subchondral bone plate to the joint space, with a formation of an unstable osteochondral flap.

Location

The crescent sign is most often seen in the femoral and humeral head, as well as the scaphoid, lunate and talus.

Radiographic features

Radiograph

The crescent sign is seen as a curvilinear lucent subchondral line. If articular surface flattening is present, it suggests an impending articular collapse.

In the femoral head, it is present usually in its anterior or anterolateral part. Both frontal and frog-leg views should be obtained for assessment.

CT

A subchondral fracture line is seen. Additionally, a presence of gas may be detected within the fracture cleft.

MRI

Subchondral fracture cleft may be filled with fluid. A presence of bone marrow oedema distally from the fracture line indicates stress reaction and a very high likelihood of trabeculae collapse.

Radiology report

Various classification systems of osteonecrosis use the presence of the crescent sign in the assessment of the adult femoral head osteonecrosis 5.

Its presence (without more advanced findings) indicates:

grade III of Ficat and Arlet classification

grade III of Steinberg classification (mentioning the extent of involvement as mild, moderate or severe)

grade III of ARCO classification

Question 77

Three risk factors for secondary osteosarcoma

Answer 77

• Paget disease
• Previous Radiation (3-50yrs)
• dedifferentiated chondrosarcoma

Question 78

Answer 78

Fish vertebra

Dr Rohit Sharma and Dr Jeremy Jones◉ et al.

Fish vertebra, also known as codfish vertebra, describes the biconcave appearance of vertebrae (especially lumbar vertebrae).

Pathology

Seen in:

osteoporosis

sickle cell disease

hereditary spherocytosis

homocystinuria

renal osteodystrophy

osteogenesis imperfecta

thalassemia major (rarely)

History and etymology

The term fish vertebrae is attributed to by Fuller Albright (1900-1969), American endocrinologist. In 1941, he used the term to describe the likeness of the biconcave shape of human vertebrae to the biconcave shape of fish vertebrae; although the species was unspecified. In 1948, Fuller Albright and Edward Reifenstein (1908-1975), an American endocrinologist, provided images of codfish vertebra to illustrate the deformation of vertebral bodies seen in postmenopausal osteoporosis 5, hence the term codfish vertebrae.

Question 79

Answer 79

Elbow terrible triad

• fracture of the coronoid process
• Radial head and
• Posterior elbow dislocation

The terrible triad of the elbow is a severe elbow fracture-dislocation pattern and is so-called because it has poor medium-to-long term outcome.

Epidemiology

The terrible triad primarily occurs in adults; the flexibility of ligaments in children make this constellation unlikely 4.

Pathology

Mechanism

Most commonly due to a fall onto an outstretched hand, not necessarily high-energy, with the arm in semi-flexion and supination 3.

Radiographic features

The terrible triad of the elbow is the association of 1,2:

posterior elbow dislocation

coronoid process fracture

radial head fracture

Question 80

OA

Answer 80

• Sclerosis, joint spaces narrowing
• Osteophytes
• Subchondral cysts/geodes
• Asymmetric JSN due to chondromalacia
• Subcondral nbone sclerosis
• Subchondral cysts (geods)
• Marginal osteophytes
• Hand and wrist
  
  • DIP - herbedens
  • PIP - bouchards
  • Thumb - zig zag BOT
    *

Question 81

Grading MCL tears

Answer 81

Medial collateral ligament (MCL) injuries are graded into three groups on MRI, much in the same way as many other ligaments:

grade 1: (minor sprain) high signal is seen medial (superficial) to the ligament, which looks normal

grade 2: (severe sprain or partial tear) high signal is seen medial to the ligament, with high signal or partial disruption of the ligament

grade 3: complete disruption of the ligament

As a general rule, the MCL is not repaired in the general population if it is an isolated injury. In athletes, grade 3 injuries often require surgical repair 1.

After a few weeks, it may appear as a Pellegrini-Stieda syndrome or a Pellegrini-Stieda (PS) lesion, a post-traumatic/post-avulsion calcification of the proximal medial collateral ligamen

Question 82

Answer 82

ABC that looks like a NOF

Question 83

Answer 83

Arcuate sign (knee)

Dr Dai Roberts◉ and Assoc Prof Frank Gaillard◉◈ et al.

The arcuate sign is often a subtle but important finding on knee x-rays and represents an avulsion fracture of the proximal fibula at the site of insertion of the arcuate ligament complex, and is usually associated with cruciate ligament injury (~90% of cases) 2. The fracture fragment is attached to the lateral (fibular) collateral ligament, the biceps femoris tendon, or both.

Clinical presentation

The fracture results most often from a direct blow to the anteromedial tibia when the knee is extended, resulting in posterolateral subluxation of the tibia in external rotation 1,3. Alternatively, sudden hyperextension of the knee with the tibia internally rotated may cause the same injury 1.

The importance of this injury is that if it is not diagnosed acutely, posterolateral instability may develop which is challenging to correct, and may result in failed cruciate ligament reconstruction 1,3.

Radiographic features

The shape and size of the avulsed fracture vary according to which ligaments are responsible.

Plain radiograph

The avulsion fracture is usually small, <1 cm in size, and involves the styloid process of the fibula. It is displaced superiorly and medially. Occasionally the fracture may be larger and extends to include the lateral aspect of the proximal fibula.

Slight internal rotation AP films are usually best to radiographically demonstrate this injury 3.

MRI

MRI can delineate the soft tissue component of the injury as well as to evaluate associated injuries that are common. Associated findings include 2:

cruciate ligament injuries

especially posterior cruciate ligament 3

bone bruises

anteromedial femoral condyle: 50%

anteromedial tibial plateau: 28%

meniscal tears

medial meniscus: 28%

lateral meniscus: 22%

popliteus muscle injury: 33%

medial collateral ligament injury: common 3

Differential diagnosis

Segond fracture

avulsion is from the tibia

fragment more medial and anterior

Question 84

TLICS

Answer 84

Based on MRI (where as AO based on CT).

Gives values/points to 3 categories:

• Injury morphology
• PLC intergtity
  
  • (intact 0
  • inderterminate 2
  • disrupted 3
    
    • LFlavum
    • Facet joint capsule
    • Spra spinouslifgament
    • interspinous ligament
• Involvement of the neuraxis
  
  • Intact
  • nerve root injury
  • c SCI
  • Incomple SCI
  • Cauda equina injury
• Fractues can be divided into
  
  • compression
    
    • 1 simple
    • 2 Burst
    • 2 Coronal plane deformity >15
  • translation 3
    
    • • distraction 4
        *

Question 85

two syndromes which condition is associated with

markers

which marker is more specific

Answer 85

Rheumatoid arthritis

• SYNDROMES
  
  • Felty syndrome:
    
    • rheumatoid arthritis, splenomegaly, and neutropenia
  • Caplan syndrome
    
    • rheumatoid arthritis and pneumoconiosis
• MARKERS
  
  • rheumatoid factor (RF):
    
    • is an IgM antibody against FC portion of the IgG antibodies, and is a traditional marker but is non-specific; associated with several autoimmune and chronic infectious diseases
  • anti-cyclic citrullinated peptide (anti-CCP)/anti-citrullinated plasma antibody (ACPA):
    
    • it is more than 80% sensitive and more than 95% specific
  • elevated CRP or ESR
• ​KEY WORDS
  
  • Proximal (PIP, MCP, wrists)
  • Pannus
  • Ulnar styloid
  • Symmetrical
  • Osteoporosis (periarticular)
  • soft tissue swelling
  • triquetrum
  • DIP joints are spared.
  • ulnar deviation of the MCP joints
  • boutonniere
  • swan neck deformities
  • hitchhiker’s thumb deformity
  • scallop sign: erosion of the ulnar aspect of the distal radius which may be predictive of extensor tendon rupture (Vaughan-Jackson syndrome)
  • pencil-in-cup deformity: classically psoriatic arthropathy but well-recognised in rheumatoid arthritis

Question 86

Answer 86

Die-punch fractures result from an axial loading force on the distal radius. It is an intra-articular fracture of the lunate fossa of the distal radius 1. It is by definition depressed or impacted and is named after the machining technique of shearing a shape, depression or hole in a material with a die implement or cutter used in the tool-and-die trade (Figure 1). The die-punch mechanism classically involves the lunate fossa of the radius but can occur from any loading injury 2.

Question 87

Answer 87

• GOUT
• Overhanging juxta-articular erosions, dense soft tissue tophi. multilocular intraosseous tophi
• any joint
• May not see calcs/crystals. Looks like clouding/hazing
• Overhanging edges
• small joints of the hands and feet
• Joint spaces are typically preserved until late in the course of the disease
• Bursal inflammation
• No oedema in adjacent bone -> a lack of oedema on MRI would make you think of gout
• MRI
  
  • TOPHI Low intermediate sig on T1 and T2
  • little enhancement

Question 88

Trasnverse ligament meniscus

Answer 88

runs thru hoffas fat pad

can look like a tear

tears in the anterior horn are rare

Question 89

Answer 89

Case courtesy of Dr Benoudina Samir, Radiopaedia.org, rID: 51849

On the frontal view:

Stylo-scaphoid osteoarthritis.

Radio-scaphoid osteoarthritis.

Capitolunate osteoarthritis.

On the lateral view:

Dorsal tilting of the lunate with dorsal subluxation of the capitate.

DISI deformity.

Case Discussion

SLAC (scapholunate advanced collapse) refers to a specific pattern of degenerative arthritits and subluxation which results from untreated chronic scapholunate dissociation.

Watson staging is often used by hand surgeons:

I: osteoarthritis of the articulation between the radial styloid and the scaphoid

II: osteoarthritis involving the whole radioscaphoid articulation

III: osteoarthritis of the radioscaphoid and capitolunate articulations

IV: osteoarthritis of the radiocarpal and intercarpal articulations +/- distal radioulnar joint (DRUJ)

In this case, it is a Stage III SLAC wrist.

Question 90

108. Osteosarcoma most common subtype – LEAST LIKELY
     a. Primary
     b. Intracortical
     c. Metaphyseal
     d. High grade
     e. Osteoblastic

Answer 90

Osteosarcoma

Dr Mohamed Saber and Assoc Prof Frank Gaillard◉◈ et al.

Osteosarcomas are malignant bone-forming tumours. They are the second most common primary bone tumour after multiple myeloma, accounting for ~20% of all primary bone tumours. They can be classified into primary and secondary forms, as well as histologic types, of which conventional osteosarcoma is the most common.

Epidemiology

Primary osteosarcoma typically occurs in young patients (10-20 years) with 75% taking place before the age of 20 because the growth centres of the bone are more active during puberty/adolescence 3. There is a slight male predominance.

Secondary osteosarcoma occurs in the elderly, usually secondary to malignant degeneration of Paget disease, extensive bone infarcts, post-radiotherapy for other conditions, osteochondroma, and osteoblastoma.

Associations

Paget disease of bone

irradiation

Rothmund-Thomson syndrome

fibrous dysplasia (more common in the polyostotic form)

Mazabraud syndrome (rare)

Clinical presentation

Patients often present with bone pain, occasionally accompanied by a soft-tissue mass or swelling. At times, the first symptoms are related to pathologic fracture.

Pathology

Location

Primary osteosarcomas typically occur at the metadiaphysis of long bones in the appendicular skeleton, most commonly at the following sites:

femur: ~40% (especially distal femur)
tibia: ~16% (especially proximal tibia)
humerus: ~15%

Other sites are less common:

fibula

innominate bone (i.e. os coxae)

mandible (gnathic osteosarcoma)

maxilla

vertebrae

Secondary tumours, on the other hand, have a much wider distribution, largely mirroring the combined incidence of their underlying conditions, and thus much have a higher incidence in flat bones, especially the pelvis (a favourite site of Paget disease).

Osteosarcomas can be further categorised by anatomic relationship to the bone 3,8:

intramedullary/central: ~80%

surface: ~10-15%

intracortical osteosarcoma: rare

extraskeletal osteosarcoma: ~5%

Classification

The WHO classification of bone tumours lists the histologic types of osteosarcoma, which can be further organised by the state of underlying bone and site of origin within the bone:

primary osteosarcomaintramedullary/central

conventional osteosarcoma: most common (75-80%) and discussed in this article

low-grade central osteosarcoma

telangiectatic osteosarcoma

small cell osteosarcoma

surface

parosteal osteosarcoma

periosteal osteosarcoma

high-grade surface osteosarcoma

secondary osteosarcoma

Conventional osteosarcomas can be further divided by histological subtype:

osteoblastic (most common)

chondroblastic

fibroblastic

Macroscopic appearance

Osteosarcomas are bulky tumours where a heterogeneous cut surface demonstrates areas of haemorrhage, fibrosis, and cystic degeneration. Their extension within the medullary cavity is often much more extensive than the bulky part of the tumour would suggest. Areas of bone formation are characteristic of osteosarcomas, with the degree of bone formation varying widely.

Microscopic appearance

Poorly formed trabecular bone is seen with (in the typical high-grade conventional subtype) cellular pleomorphism and mitoses. Variable amounts of fibrocystic and chondroblastic appearing cells may also be encountered.

Markers

Serum alkaline phosphatase (ALP) may be raised (particularly with advanced disease).

Radiographic features

Although plain radiography can provide a lot of information, MRI is used for local staging by assessing intraosseous tumour extension (e.g. growth plate/epiphysis, skip lesions) and soft-tissue involvement. Chest CT and bone scanning have a role in distant staging.

Plain radiograph

Conventional radiography continues to play an important role in diagnosis. Typical appearances of conventional high-grade osteosarcoma include:

medullary and cortical bone destruction

wide zone of transition, permeative or moth-eaten appearance

aggressive periosteal reaction

sunburst type

Codman triangle

lamellated (onion skin) reaction: less frequently seen

soft-tissue mass

tumour matrix ossification/calcification

variable: reflects a combination of the amount of tumour bone production, calcified matrix, and osteoid

ill-defined “fluffy” or “cloud-like” compared to the rings and arcs of chondroid lesions

CT

The role of CT is predominantly utilised in assisting biopsy and staging. CT adds little to plain radiography and MRI in the direct assessment of the tumour. The exception to this rule is predominantly lytic lesions in which small amounts of mineralised material may be inapparent on both plain film and MRI 4.

MRI

MRI is proving an essential tool to determine accurate local staging and assessment for limb-sparing resection, particularly for evaluation of intraosseous tumour extension and soft-tissue involvement. Evaluation of the growth plate is also essential as up to 75-88% of metaphyseal tumours do cross the growth plate into the epiphysis 4.

T1

soft tissue non-mineralised component: intermediate signal intensity

mineralised/ossified components: low signal intensity

peritumoral oedema: intermediate signal intensity

scattered regions of haemorrhage will have a variable signal (see ageing blood on MRI)

enhancement: solid components enhance

T2

soft tissue non-mineralised component: high signal intensity

mineralised/ossified components: low signal intensity

peritumoral oedema: high signal intensity

Treatment and prognosis

Cure, if achievable, requires aggressive surgical resection often with amputation followed by chemotherapy. If a limb-salvage procedure is feasible, a course of multidrug chemotherapy precedes surgery to downstage the tumour, followed by wide resection of the bone and insertion of an endoprosthesis. The outcome depends on different factors such as age, sex, site, size, and type but the most important predictor is the histologic degree of necrosis post-induction chemotherapy; 90% histologic necrosis is associated with much better prognosis 6. Currently, the 5-year survival rate after adequate therapy is approximately 60-80% 4.

The most frequent complications of conventional osteosarcoma are a pathologic fracture and the development of metastatic disease, particularly to bone, lung, and regional lymph nodes.

Differential diagnosis

General differential considerations include the following:

osteomyelitis

other tumours

metastatic lesion to bone

Ewing sarcoma

aneurysmal bone cyst

When the lesion is at the posteromedial distal femur, consider

cortical desmoid

Practical points

When planning to biopsy a potential sarcoma, the treating surgeon should be consulted to plan the biopsy track as this will require excision to reduce the chance of seeding. A poorly planned track that crosses compartments can result in a more extensive resection, potentially with poor outcomes for the patient.

Question 91

Proximal Zone ddx arthritis

Intercarpal

Radio carpcal

DRUJ

Answer 91

1. RA
2. CPPD
3. Gout
4. psorisis

Question 92

Answer 92

• Bone bruise
  
  • marrow contusion of the lateral femoral and tibial condyles and moderate joint effusion.
• AKA
  
  • bone contusion
  • trabecular microfracture
• Definition
  
  • are an osseous injury that results from compression of bone structures.
• Pathology
  
  • Bone bruises represent trabecular microfractures with haemorrhage and without a discrete fracture line or contour abnormality
  • They typically appear within 48 hours of injury
  • can persist for up to six months
• Aetiology
  
  • Most bone contusions are a result of a direct blow to the bone, traction from avulsion trauma, or load to a subchondral surface
  • Depending on where bone contusion is seen, the underlying trauma mechanism can be identified.
• Complications
• They can progress to osteochondritis dissecans.
• Radiographic features
  
  • Plain radiography will not demonstrate cancellous features but can show regions of impaction, for example, a Hill-Sachs lesion.
• MRI
  
  • MRI is the modality of choice when investigating bone marrow.
  • Bone (marrow) contusion is typically focal and ill-defined with the following signal characteristics 4:
    
    • T1: focal hypointense area of bone marrow
    • T2 fat-saturated: focal hyperintense area of bone marrow

Question 93

Sundovail based arthorpathies

Answer 93

1. RA
2. Psoriasis

Effects the bare areas, get marginal errosions

effects synovial

Question 94

Septic Arthtirs

Answer 94

ANY ACUTE MONO arthritis this must be top of DDx

soft tissue swelling

jont distension due to effusions

joint narrowing due to rcartilage

Question 95

What is this?

Which 5 Structures are involved?

Associations

Signs

complications

Answer 95

Posteromedial corner injury of the knee

• Complication
  
  • increased stress on the cruciate ligaments and can result in anteromedial rotatory instability (AMRI) of the knee.
• ​Clinical
  
  • seen in athletes
  • sustained with the knee in valgus.
  • tenderness along the medial joint line.
• Pathology
  
  • The structures that comprise the posteromedial corner (PMC) are located between the:
    
    • posterior margin of the tibial collateral ligament
    • and medial border of the posterior cruciate ligament
• Structures:
  
  • posterior oblique ligament:
    
    • injury in virtually all cases with associated instability
    • made of three parts
      
      • superficial arm
      • tibial arm
      • capsular arm
  • oblique popliteal ligament
  • meniscotibial ligament
  • semimembranosus tendon
  • medial meniscus: posterior third
• ​ASSOCIATIONS
  
  • 88% of injuries can be associated with a cruciate ligament injury, overwhelmingly the ACL 1.
• Xray
  
  • lipohaemarthrosis
  • fracture of the medial tibial corner
  • Weight-bearing views can reveal a valgus deformity.

.

Question 96

Types of Juxtacortical Osteosarcoma (3)

Answer 96

• Parosteal OSA
• Periosteal OSA
• Highgrade surface OSA

Question 97

Location of conventional osteosarcoma

Answer 97

Tubular Bones 80%

• Femur 40% -> 75% around knee
• tibia 15%
• humerous 15%

Other bones 20%

• flat bones
• vertebral bodies

Question 98

Answer 98

Question 99

clip injury

Answer 99

valgus stress to flexed knee

contusion pattern: lateral femoral condyle and lateral tibial plateau +/- medial femoral condyle from medial collateral ligament (MCL) avulsive stress

associated with MCL injuries

Question 100

Answer 100

Long head of biceps tendon dislocation

Dr Joachim Feger◉ and Assoc Prof Frank Gaillard◉◈ et al.

Dislocation of the long head of biceps tendon is one of the complications of shoulder injury. The long head of biceps (LHB) tendon is usually located inferiorly in the bicipital groove held there by the biceps pulley (the stabilisation role of the transverse humeral ligament is controversial) 3. As it moves superiorly it arches through the rotator cuff interval where it is held by a sling formed by the superior glenohumeral ligament and the coracohumeral ligament.

When this ligament is deficient the tendon is free to dislocate medially. It is often associated with degenerative or traumatic tears of the rotator cuff, specifically tears of the subscapularis tendon.

If the tendon of the subscapularis is intact then the tendon is seen lying anterior to it. If, as is common, the subscapularis tendon is also deficient then the tendon of the long head of biceps can prolapse into the glenohumeral joint.

Radiographic features

MRI

Diagnosis is best made on axial MR images, where the bicipital groove is seen to be empty, and the tendon can be identified medially. If the tendon cannot be identified then a complete tear of the tendon should be sought.

Ultrasound

Non visualisation of long head of biceps tendon in bicipital groove with medially displaced tendon.

References

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Question 101

MCL layers

Answer 101

arises from medial fem condyle and attahces to prox tibia

3 layers

superirical adeventitial

middle MCL proper

Deep

Question 102

Answer 102

Findings: Marked widening of the distal radial growth plate across its entire area, with metaphyseal irregularity and cystic change. Band of metaphyseal sclerosis with no osseous destruction beyond this. Metaphyseal erosion and widening with a sclerotic border at the distal radial growth plate is compatible with gymnast wrist

Gymnast wrist is a term that is used to describe a variety of chronic overuse injuries of the wrist in gymnasts with an immature skeleton. Gymnast wrist comprises a combination of osseous and ligamentous injuries and usually manifests as a chronic Salter-Harris type I fracture of the distal radial physis on radiography 1.

Epidemiology

Distal radial physeal injury is common in gymnasts, and occasionally occurs in other sports 2. The distal radius is mostly involved because it bears the primary stressful forces in the wrist joint 1.

Clinical presentation

Pain with gradual onset and exaggeration by weight-bearing activities while the wrist in extension position. Often, range of motion is normal on physical examination, and frequently swelling and tenderness over the distal radius presents 2.

Pathology

Gymnast wrist results from repetitive compressive forces applied to the distal radial physeal plate during participation in sports like gymnastics and weight-lifting that place a great tension on the physis and adjacent structures 1.

Radiographic features

physeal plate widening

physeal plate irregularity

metaphyseal and less commonly epiphyseal sclerosis and irregularity 1,4

physeal plate bridging/fusion in late stage of the disease 1

Plain radiograph

Most of the above-mentioned physeal, metaphyseal and epiphyseal changes are usually evident on radiography 1-3.

MRI

MRI may be used when radiographs are inconclusive. MRI can demonstrate the greater detail about the physeal cartilage and oedema in the adjacent bones before these changes become visible on radiographs 4.

It is worth mentioning that MRI is crucial in high-risk patients with chronic wrist pain because early detection is essential in preventing further damage to the distal radial physis 1.

Treatment and prognosis

As with similar injuries, the mainstay of treatment is rest with ice packs and anti-inflammatory agents as required.

The prognosis is dependant on the stage of the injury and radiographic findings at the time of diagnosis, with splint/cast immobilisation, recovery may take anywhere from one to six months 2.

Complications

Complications of untreated fracture include:

early physeal closure of the distal radius leading to positive ulnar variance and Madelung-type deformity in cases that lack proper treatment or experience a prolonged healing process 1,3,4

triangular fibrocartilage complex (TFCC) injury 4

Question 103

Answer 103

chordoma of the clivus

Question 104

Anterior cruciate ligament tear

Associations 4

Signs 5

Bone contusion pattern

Secondary signs

Answer 104

Anterior cruciate ligament tear

Dr Mohamed Saber and Radswiki◉ et al.

Anterior cruciate ligament (ACL) tears are the most common knee ligament injury encountered in radiology and orthopaedic practice.

Clinical presentation

Patients typically present with symptoms of knee instability, usually after acute trauma. The following signs and symptoms are common:

popping sensation at the time of injury, followed by swelling

initial inability to weight wear, which improves in a short period

knee felt to “gives way” especially during pivoting movement

apprehension with an attempt at non-linear movements

The combination of the Lachman, pivot shift and anterior drawer tests are used to clinically confirm diagnosis 9.

Pathology

The anterior cruciate ligament is the most commonly disrupted ligament of the knee, especially in athletes who participate in sports that involve rapid starting, stopping, and pivoting (e.g. soccer, basketball, tennis, netball, and snow skiing).

Associations

O’Donoghue’s unhappy triad

Segond fracture

posteromedial corner injury of the knee

Meniscocapsular separation

Radiographic features

In younger patients, avulsion of the tibial attachment may be seen.

Plain radiograph

deep lateral sulcus sign - depression of lateral femoral condyle representing impaction fracture

anterior tibial translocation sign

Segond fracture

arcuate fracture

joint effusion

CT

Considered to have high specificity and sensitivity in detecting anterior cruciate ligament disruption 6. CT is helpful in characterising the avulsion bone fragment when it is present.

MRI

Imaging of anterior cruciate ligament tears should be divided into primary and secondary signs.

Primary signs are those that pertain to the ligament itself. Secondary signs are those which are closely related to anterior cruciate ligament injuries.

Primary signs

swelling

increased signal on T2 or fat-saturated PD

fibre discontinuity

abnormal anterior cruciate ligament orientation relative to intercondylar (Blumensaat’s) line

ACL fibres subjectively less steep than a line tangent to the intercondylar roof (Blumensaat’s line)

ACL angle (angle between the intercondylar line and ACL) >15° with the apex of the angle located anteriorly, indicating a less steep ACL line - this indicates a ruptured and collapsed ligament

empty notch sign: a fluid signal at the site of femoral attachment at the intercondylar notch, denotes avulsion at the femoral attachment.

ACL tears typically occur in the middle portion of the ligament (midsubstance tears) and appear as discontinuity of the ligament or abnormal contour. The signal of the ACL can be more hyperintense on T2. If the angle is still normal and there is a hyperintense signal, a partial rupture is more likely than a complete rupture.

ACL tear may only involve one bundle. Imaging signs of isolated posterolateral bundle tear are as follows:

gap sign: fluid signal and/or a gap between the medial aspect of the lateral femoral condyle and the lateral aspect of the mid-ACL, can be seen on either axial or coronal MRI images.

footprint sign: incomplete coverage of the lateral aspect of the tibial spine of the tibia by the distal ACL attachment, seen only on coronal MRI images 8

Secondary signs

Secondary signs include 7:

bone contusion in lateral femoral condyle and posterolateral tibial plateau

>7 mm of anterior tibial translation, also known as the anterior tibial translocation sign or anterior drawer sign

uncovered posterior horn of the lateral meniscus

Segond fracture, and to a lesser degree arcuate sign

reduced PCL angle due to buckling of PCL

positive PCL line sign

medial or lateral collateral ligament injury