MCQ Flashcards
TB v pyogenic discitis
TB: multiple levels (5-10), skip lesions, no reactive sclerosis, disc spared until late, gibbus deformity as preference for anterior endplates, can cause ivory vertebra, vertebra plana, erosions generally present by presentation. Tends to be thoracic
Pyo: Staph in 60%, strep viridans in IVDU, gram negatives. Tends to be lumbar
IVDU can have funny organisms
Sympathetic dystrophy
Osteopaenia
Subperiosteal bone resorption
Soft tissue swelling, eventually atrophy
Preserved joint space
Three phase increased uptake on NM
Patchy subcortical bone marrow oedema on MR, and soft tissue oedema / enhancement
NF1 MSK manifestations
Increased risk of rhabdomyosarc, leiomyosarc Ribbon ribs Vertebral scalloping Tibial or ulnar pseudoarthrosis Limb bowing Rib notching
Fluid-fluid level bone lesions
ABC, which may be primary or secondary to: GCT, fibroxanthoma, chondroblastoma, osteoblastoma,
UBC, esp after fracture
Telangiectatic osteosarc
Uncommon causes: mets (esp RCC, lung), synovial sarc, synovial haemangioma, myositis ossificans, adamantinoma, neurogenic tumour
Mnemonic: GOATS CSF
GCT, osteoblastoma, ABC, telangiectatic osteosarc, sarcomas, chondroblastoma, solitary bone cyst, fibroxanthoma
SLAC wrist
Most commonly from scapholunate ligament injury but also
Typically found in CPPD
Progressive wrist OA pattern - starts at radioscaphoid, then involves capitolunate and DRUJ and others.
Osteoid osteoma
Usually cortical but can occur anywhere in bone (medullary, within joint capsule)
Central lucent nidus may have some central mineralisation
Surrounding sclerosis - medullary lesions may not have sclerosis.
Can occur in posterior elements, fingers, but big long bones most common (50% lower limb - blastoma more frequently spine, does not induce marked bony reaction)
Double denstiy sign on NM (not donut, which is activity around lucent centre, e.g. ABC, UBC, GCT)
Surgical resection was traditional management. Now RF ablation.
Male prediliction
Nidus is bone at various stages of development in a highly vascularise connective tissue stroma
Sclerosis less in medullary and intracapsular lesions
Can cause leg length discrepancy
Major bone bruising patterns
Lateral patellar dislocation - self explanatory
Pivot-shift - Posterolateral tibial plateau and mid lateral femoral condyle - ACL tear associated (may also have postero medial tibial plateau)
Clip
Hyperextension
Dashboard
Median time to resolution of 42 weeks. Influenced by presence of OA.
ACL injury
Segond fracture (probably lateral capsular liagment but may be ITB or other - LCL)
Arcuate sign - avulsion of tip of fibula from arcuate ligament
Bone bruising pattern
Anterior drawer sign (7mm)
ACL should be steeper than intercondylar roof
Anterior ligamentous border may appear concave
Associated with MCL injury
PCL angle may be reduced on MR
May have meniscal tear or meniscocapsular separation (posterior horn medial meniscus)
Associated with meniscal tears lateral > medial in 65%
Associated with posteromedial corner injury, and posterolateral
Scapholunate angle
30-60 degrees
Increased in scapholunate dissociation and DISI
Decreased in VISI
Capitolunate angle
<30
Increased in both VISI and DISI
Scapholunate dissociation
Scapholunate interval >4mm (or 3mm)
Exacerbated by clenched fist views and PA with ulnar deviation
Also increased scapholunate angle
Risk of SLAC wrist
Perilunate dislocation
60% associated with scaphoid fracture and termed trans-scaphoid perilunate dislocation
Carpus tends to dislocate dorsal relative to lunate - normal radiolunate articulation
Reduce scapholunate angle, increased capitolunate angle
Carpal instability (perilunate instability)
1 - scapholunate dissociation
2 - perilunate dislocation
3 - midcarpal dislocation - 2 + lunotriquetral ligament injury or triquetral fracture
4 - lunate dislocation
VISI and DISI
Scapholunate angle is increased in DISI and decreased in VISI
Capitolunate angle increased in both
Lunate tilts dorsally in DISI, volarly in VISI
Bohler angle
20-40
Less than 20 in calcaneal fracture
Morton neuroma
Perineural fibrosis around an intermetatarsal nerve
Low MR signal with intense enhancement
Well defined and hypoechoic on USS
10% bilateral
Intermetatarsal nerve lies plantar to the deep intermetatarsal ligament
Muscle denervation
Early increased T2, best seen on STIR
Chronic increased T1
Sinus tarsi syndrome
Lateral hindfoot pain between ankle and heel
Sinus tarsi separtes anterior and posterior subtalar joints, and is positioned laterally
Inflammation, fibrosis, or ligamentous disruption - T1 hyperintense fat is replace by fluid or fibrosis
Rotator cuff
Supra - abduction
Infra and teres - ext rot
Subscap - int rot
Supra tears occus in critical zone, 1cm from insertion, relatively hypovascular, and start anterior and propogate posterior
Bursal fluid is sensitive but not always present
Full thickness tears in 30% of >80 with minimal functional impairment
Joint effusion not present in majority
Subdeltoid fat plane an unreliable indicator
<7mm acromiohumeral distance in tear
Shoulder ultrasound
Supra - shoulder internally rotated and extended (arm behind back) (note calc better seen in external rotation on xray)
Infra - hold opposite shoulder - internal rotation and flexed (arm on opposite shoulder)
Teres - doesn’t seem to be part of normal protocol
Subscap - externally rotated, elbow at 90 degrees
Biceps - supinated, elbow flexed 90 degrees
Posterior element lesions
GCT Osteoblastoma TB ABC Pagets Eosinophilic granuloma (Goat PE - not goats csf which is fluid fluid level)
Carpal ossification
Start at capitate and go anticlockwise (right) but skip pisiform which is last Capitate Hamate (both 1st year) Triquetrum Lunate (both 2-4 years) Scaphoid Trapezium Trapezoid (three are 4-6 years) Pisiform (8-12 years)
Myositis ossificans (circumscripta)
Peripheral calc at 4-6 weeks
cf osteosarc (parosteal) where calc starts centrally
Can have fluid levels
Post traumatic
Myositis ossificans progressiva is a rare hereditable conditions, separate, with progressive ossification of muscles, fatal at 45, with microdactyly and progressive fusion of cervical spine (facet joints), monophalangic 1st toe
Reiters
Bony proliferation (like psoriatic) - enthesopathy or periostitis (and parasyndesmophytes) Can cause acro-osteolysis
Salmonella, yersinia, shigella, campylobacter, E. coli, chlamydia
Predominantly feet, with appearance similar to psoriatic
Calcaneus in particular
Chondromyxoid fibroma
Lucent, eccentric, metaphyseal
Benign
Differential of ABC, GCT, NOF (younger), chondroblastoma
DISH
Flowing osteophytes (and calc, at least 4 contiguous vertebrae)
Commonly thoracic spine, and also cervical
No disc-space narrowing
Lack of facet joint arthropathy
Fusion of non-synovial superior SI, and sympysis pubis
Lateral acetabular osteophyte
Enthesopathic bony proliferation
Retinoid therapy can give similar appearance (favours cervical)
Fluorosis also in differential
Ossification of iliolumbar, sacroiliac and sacrotuberous ligaments
Tarlov cyst
Most common at S2-3
May cause erosion
Symptomatic in 20%
Disc disease
Bulge if >90 degrees, circumferential or asymmetric
CPPD
1/8 have pressure erosions from the crystals
Osteoporosis / paenia
T score - compared to 30yo
Z score is age adjusted
Each SD change in T doubles fracture risk
T <2.5 is porosis, 1-2.5 is paenia
Osteoblastoma
Rare to involve sacrum (although radiopaedia says 17%) May be blastic or lytic Doesn't respond well to salicilates 50% have speckled calcification Pronounced NM uptake >80%
40% spine
Otherwise diaphysis and metaphysis of long bones
Typically larger than 2cm
Marrow conversion
Begins peripherally
Epiphysis then diaphysis then metaphysis - distal then proximal
Red marrow confined to axial skeleton by 25
Islands of red marrow, particularly subcortical or subchondral in proximal humeri and femora
Osteosarcoma
4% extra-skeletal, 80% intramedullary (conventional, low grade, telangiectatic), 15% surface
50-55% of conventional are around the knee
Tend to be metaphyseal (90-95% conventional) (or metadiaphyseal)
15% of all primary bone tumours (2nd after myeloma)
Parosteal often posterior distal femur 60% - 30-40% have lucent line separating from bone - lowest grade with excellent prognosis. Early adulthood and middle aged.
Telangiectatic fluid levels in 90%
Periosteal often diaphyseal, esp. anteromedial diaphysis of proximal tibia, medial distal femur (most common). (parosteal is still metaphyseal, like others)
Slightly older than conventional, but not as much as parosteal or gnathic.
Parosteal more common than periosteal
Parosteal - outer fibrous layer of periosteum
Periosteal - inner germinous layer of periosteum
Gnathic are older patients - 30-40, slightly male
Snapping hip
Thickened glut max aponeurosis over greater troch
Periarticular osteopaenia
RA, reactive arthritis, septic arthritis, scleroderma, SLE
Radiation induced bone tumours
Osteochondroma most common benign
Osteosarc most common malignant (90%)
Also fibrosarc, malignant fibrous histiocytoma
Lag time of 11-14 years
Arise in areas of pre-existing radiation change
Radiation osteitis
Potentially reversible changes e.g. temporary cessation of growth, periostitis, sclerosis, fragility
Meniscal cyst
Associated with complex tear, radial split tear, radial + horizontal (mostly those with a horizontal component)
Medial:lateral 2:1 (Some literature says equal, Radiopaedia says possibly lateral more common)
Medial mostly posterior (same with tears), lateral mostly anterior - LAMP
O’Donoghue’s triad
ACL tear
Medial meniscal tear
MCL tear
Patella dislocation
Patella alta predisposes - long tendon
Tarsal coalition
Bilateral in 50%
90% talocalcaneal or calcaneonavicular
Talocalcaneal best seen on coronal CT, lateral radiograph - middle facet
Calcaneonavicular best on T2 sag MR, oblique radiograph
Cartilaginous, bony, or fibrous, oedema adjacent to fibrous
Norgaard view
AKA ballcatcher view
SLE
May cause avascular necrosis secondary to steroids and vasculitis
Avascular necrosis
STARS Steroids Trauma Alcohol Radiation (RA) Sickle cell
Also Gauchers, pancreatitis, SLE, Caissons,
ASEPTIC Anaemia - sickle cell Steroids (sickle cell, SLE) Ethanol Pancreatitis, pregnancy Trauma Idiopathic, infection Caisons, connective tissue disease (includes SLE, RA)
Spondyloepiphyseal dysplasia
Dysplasia, spine and proximal epiphyseal centres
Abnormal collagen synthesis
Congenital and tarda forms
Short proximal limbs, normal size hands and feet
Coxa vara, flattened femoral head
Atlantoaxial instability
Craniovertebral junction stenosis
Scoliosis
Platyspodyly
Short neck and short trunk with protruding abdomen
Normal IQ and life span
Associations: myopia, retinal haemorrhage, hearing loss, nephrotic syndrome
Cortical desmoid
Misnomer
High T2, enhances
Normal or increased bone scan uptake (eventually becomes cold)
Adductor magnus or medial gastroc insertion
Adolescents, slightly more in males
Usually asymptomatic but may cause pain
Saucer shaped radiolucent cortical irregularity posteromedial femur
May have periosteal new bone
Melorrheostosis
Associated with by vascular and lymphatic tumours
And by overlying skin and muscular changes - scleroderma, hyperpigmentation, muscle atrophy, contractures
Dripping candle wax sclerosis
Periosteal cortical thickening, may be endosteal also. Thick, undulating ridges of bone.
Tends to be monomelic, may be mono or polyostotic. (confined to sclerotome)
May have osteosarc of MFH, possibly (according to radiopaedia, although only vascular malformations mentioned in Dahnert)
Axial skeleton rare
May require tendon release, osteotomy, amputation
27% ossified soft tissue masses
May cross a joint, with fusion
May coexist with osteopathia striata (celery stalk metaphyses - also see these with rubella) and osteopoikilosis
Acromion types
1 flat
2 concave down
3 hooked down
4 convex down
3 has highest rate of rotator cuff tears (associated with impingement)
4 has not been assoicated with impingement
Os acromiale increase risk of impingement - bilateral in 60% (although no difference in tear rates)
Magic angle
55 degrees to magnetic field
Bright on Short TE (PD and T1), disappears on T2
Due to orientation of collagen bundles
Common locations: proximal PCL, patellar tendon tibial insertion, peroneal tendons around lateral malleolus, supraspinatus, TFCC
Multiple myeloma staging
1-3
1: < or = 1 plain film lesion, normal calcium, small amount of monoclonal antibody in blood/urine, small number of myeloma cells, slightly decreased RBC
3 - > or = 3 lesions, hypercalcaemia, large monoclonal antibody, severe anaemia, large number of myeloma cells
Chordoma
Mets can be intradural (drop) or intraosseous (lung and bone mets are rare)
Physaliferous cells - bubble like vacuolated - cords and clusters
Lobulated tumour with pseudocapsule
Bone lesions with large soft tissue mass
Most common primary malignant tumour of spine exc lymphoproliferative
Rare <30
Main differential is chondrosarcoma
Calcify
Heterogeneous MR signal
Craniocervical junction assessment
BDI < 12mm xray, 8.5mm CT
BAI (to posterior dens) < 12mm
Anterior atlantodens <2mm (<5mm in children)
Lateral 2-3mm difference
Occipital avulsion fractures are associated with atlanto-occipital instability
Cervical spine radiograph children
Atlantoaxial subluxation 5x more common in children
Anterior wedging of C3 normal variant
Up to 6mm C1 overhanging C2 laterally in a 4 year old
SCIWORA 5-65% of injuries - can have delayed onset, up to 48 hours
(SCIWORA associated with hyperextension)
Cervical facet joints are more horizontal in young children
Lucent transverse metaphyseal bands
LINING Leukaemia Illness - scurvy, rickets Normal variant Infection - congenital syphilis, TORCH Neuroblastoma mets Growth lines
Dense metaphyseal bands
LINES Lead poisoning Infection (TORCH) Neoplastic- lymphoma, leukaemia Endocrine (congenital hypothyroidism) Scurvy, sickle cell, syphilis
Femoral head AVN
Anterior weight bearing portion affected first
Cartilage intact until late
MR more sensitive than bone scan
Toddler fracture
Tibial, calcaneal, cuboid, fibula
Achilles
Tear 2-6cm proximal to calcaneal insertion, or at myotendinous junction
Anterior margin usually flat or concave - if convex tendon is thickened (posterior margin is convex)
1mL fluid in retrocalcaneal bursa normal
No tendon sheath, so can’t have tenosynovitis
Should be low signal on all sequences.
May have magic angle (T1 and PD - not T2)
Chronic tendinopathy has thickening without necessarily increased signal - increased signal in tear
Scaphoid fracture
Proximal third - 20%, 90% fail to unite
Middle third - 60%, 30% fail to unite
Distal third - 20%, unite
Overall the requisites suggest only 10% fail to unite.
AVN risk if non-union, of proximal pole.
Displaced and unstable fractures require fixation
UBC
Young patients - long bones, esp humerus, then femur
Older, flat bones (and e.g. posterior elements)
Intramedullary, metaphyseal, abut growth plate
Migrate to diaphysis with time
Fallen fragment sign 20%
Path fracture paeds
UBC (40%) Non ossifying fibroma (19%) Fibrous dysplasia (16%) Osteosarcoma (15) ABC (10%)
Down syndrome
Flared iliac wings with small acetabular angles Increased iliac angle DDH SUFE Atlantoaxial subluxation in 25% 11 ribs Persistent metopic suture Wormian bones Hypersegmented manubrium Clinodactyly Hypoplasia of middle phalanx of 5th
Fibrous cortical defect
2-10 years T1 hypo, T2 variable Multiloculated Cortical Can be expansile Thin rim of sclerosis No periosteal reaction Most commonly distal femur Metadiaphysis / diaphysis Involute over 2-4 years Asymptomatic
NOF > 3cm
NOF vit D resistant hypophosphataemic rickets
Male prediliction
associated with fibrous dysplasia, NF1, and Jaffe camanaci
Shepherd fracture
Fracture of lateral tubercle of posterior proces of calcaneus
Inversion in extreme equinus
Cervical flexion teardrop
Unstable
Associated with ventral cord injury (posterior displacement of bone fragments)
Vert body may look shortened AP
Compressed disc space, interspinous widening
Sagittal fracture through body as well as the
Anteroinferior corner
C5/6
Note, extension C2, widened disc space, still anteroinferior corner, stable in flexion, unstable in extension (ALL disrupted)
Atlanto-occipital interval (condyles)
<4mm (xray) 2mm (CT)
Wackenheim line
Down clivus, usually intersects Dens
Powers ratio
Basion to posterior arch / opthision to anterior arch
Abnormal is >1
GCT
2nd most common primary sacral tumour after chordoma
Heterogeneous due to haemorrhage, necrosis, fibrosis
Locally aggressive
Most around knee - distal femur, then other long bones, but also posterior elements
Can cross SI joints
Donut sign NM
Female prediliction, but malignant transformation more common in men
Closed growth plate - 20s,30x
Abut growth plate Well defined non-sclerotic margin Eccentric Thinned cortex 10-30% periosteal reaction May have soft tissue mass Cortex may be expanded, thinned, or deficienc
Well circumscribed expansile
Sacral lesion
SPACE MONGREL Sarcoma (osteo, chondro)/SC teratoma Plasmacytoma ABC Chordoma Ependymoma Mets Osteomyelitis Neuroblastoma GCT Rectal Ewings Lymhoma / leukaemia
Superscan
Mets - prostate, breast, TCC, lymphoma HPT Myelofibrosis Mastocytosis Wide spread Pagets
Eosinophilic granuloma
Intra-osseous High T2, low T1, may enhance
Calvaria in 50%, long bones next (note ribs most common place in adults)
Monostotic in 50-75%
Long bones: diaphysis 58%, metaphysis 28%
Often have spontaneous resolution, 6-18 months
30% bone scan negative
Male 2:1 female
Skeletal system the most commonly involved in LCH
Tends to be older children, asymptomatic, incidental
Floating teeth
Bevelled edge skull lesion
Respects growth plates
Periosteal reaction and endosteal scalloping
Sclerosing osteomyelitis of Garre
Chronic osteomyelitis, typically of mandible following caries.
Low grade non-necrotic non-purulent infection
Bone age
Utilises sex, size and shape of epiphysis, width of physis
Blount disease
Localised growth disturbance, proximal medial tibial epiphysis
AVN
Results in tibia vara
Can be unilateral or asymmetric but can be bilateral
Infantil type 80% bilateral. Later forms less common.
RF: obesity, early walking, black.
