MSK Flashcards
1 primary benign bone lesion
osteochondroma
causes osteonecrosis/AVN
- idiopathic (37%)
- steroids (35%)
- alcoholism (22%)
- trauma
- hemoglobinopathy
- collagen vascular disease
- dysbaric disorder
- gaucher
- pregnancy
- radiation
- pancreatitis
osteonecrosis pathology progression
zone of cell death centrally
- hematopoietic elements 6-12 hrs
- bone cells 12-48 hrs
- marrow fat cells 48 hrs - 5 days
zone of ischemic injury
- creeping substitution
- reinforcing trabecular bone
- marrow reaction
N bone marrow
normal alpha angle adult
~40
≥55 abN (CAM impingement)
normal centre edge angle
N <39 degrees
increased = pincer decreased = ddh
osteopoikilosis - bone scan features
cold
osteopoikilosis - bone segment prediliction
epiphyses & metaphyses
and carpus, tarsus, pelvis
most common site osteoma
frontoethmoid sinus region (75%)
genetic association multiple osteomas
gardner syndrome (APC gene 5q22)
osteoid osteoma on bone scintigraphy
hot, double density sign
median age osteoblastoma, M:F ratio
18 yo, 2-3:1 M:F
most common location of osteoblastoma in spine
posterior elements (>60%)
normal thickness plantar fascia
<3 mm
rugger jersey spine is seen in…
renal osteodystrophy
rhizomelia means…
shortening of proximal appendicular skeleton
hand site predilection for OA & erosive OA
- PIP
- DIP
hand site predilection for psoriatic arthritis
- DIP
hand site predilection for RA
- MCP
- PIP
hand site predilection for gout
- MCP
- DIP
- PIP
hand site predilection for CPPD
- MCP
hand site predilection for scleroderma
- DIP
most common bone dysplasia
achondroplasia
inheritance pattern multiple hereditary exostoses
chance of malignant degeneration
autosomal dominant
1-10%
bone scan and xray of pagets
lytic phase: bone scan hot, xray negative
mixed: both positive
sclerotic: bone scan less, xray findings
suprascapular vs spinoglenoid notch denervation
suprascapular - supra & infraspinatus
spinoglenoid - infraspinatus
causes SLAC
- trauma
- RA
- CPPD
seronegative spondyloarthropathies
PAIR
- psoriatic
- ank spon
- IBD associated arthritis (enteropathic)
- reactive
gout mimickers
- sarcoid
- amyloid (chronic dialysis)
- psoriatic arthritis
- cystic RA
- hyperlipidosis
- multicentric histiocytosis
origin AIIS
rectus femoris
inserts on patella
dorsal intercalated segment instability (DISI)
- dorsal tilt of lunate
- scapholunate angle >60deg (sign of scapholunate lig dissociation)
- capitolunate angle >30deg
- after radial sided injury (scapholunate side); assoc with SL lig injury
volar intercalated segmental instability (VISI)
- volar tilt of lunate
- scapholunate angle <30deg
- capitolunate angle >30deg
- after ulnar sided injury (lunotriquetral side); assoc with LT lig injury
- RA may result in any deformity, but esp ulnar translocation & VISI
capitolunate angle
- angle btwn long axis of capitate & mid axis of lunate
- N <30deg
- increased (capitate displaced posteriorly compared to distal radius) in both DISI and VISI (scapholunate angle used to differentiate btwn the two)
scapholunate angle
- angle btwn long axis of scaphoid & mid axis of lunate
- N 30-60deg
- increased in scapholunate dissociation
- increased in DISI (w increased capitolunate angle)
- decreased in VISI (w increased capitolunate angle)
SLAC wrist (scaphoid lunate advanced collapse)
progressive carpal collapse
1st radioscaphoid jt space narrowing, then arthrosis in triscaphe, capitolunate, & scaphocapitate jts
- d/t trauma & lig laxity: + scapholunate diastasis; radiolunate jt usu not involved
- d/t CPPD: both radioscaphoid & radiolunate jts
SNAC wrist (scaphoid non-union advanced collapse)
- progressive carpal collapse w scaphoid # nonunion
- 1st radial styloid beaking, then arthrosis in distal radioscaphoid jt, midcarpal jts
- minimal arthrosis of proximal scaphoid pole fragment-radius, radiolunate articulations
greater trochanter facets
- anterior: glut minimus
- posterior: no attachment, GT bursa
- lateral: glut medius
- superoposterior: glut medius
magic angle effect
55deg from B0, the angle at which tightly bound collagen appear hyperintense if TE is short (PD or T1W)
- mistaken for tendinopathy
- disappears on T2 or if 55deg angle is changed
osteoblastoma: comparison to osteoid osteoma
- larger >2cm
- more aggressive; unlim growth potential, malig transformation reported
- symptoms milder & more variable (even though more aggressive)
- more common in vertebra, flat bones
Sinding-Larsen-Johansson syndrome
osteochondrosis of inf pole of patella
- at insertion of prox patellar tendon
chronic traction injury of the immature osteotendinous junction
active adolescents 10-14 yo, related to Osgood-Schlatter
Sprengel deformity
congenital elevation of the scapula
cosmetic & functional (restricted motion of scapula & glenohumeral jt)
associated w:
- omovertebral bar (fibrous, cartilaginous or osseous connection btwn scapula & cspine)
- Klippel-Feil
- spina bifida
H-shaped vertebra seen in…
sickle cell disease
Gaucher disease
aka Lincoln log vertebra
anatomic landmark for glenohumeral anterior-inferior approach injection
junction of
- physeal scar in humeral head
- humeral head & glenoid overlap (crescent)
secondary signs ACL injury
- deep sulcus (>2 mm)
- bone contusions (lateral femoral condyle and posterolateral tibial plateau)
- segond #
dorsal defect of the patella
round lucency in superolateral patella
normal variant, do not touch
location of liposclerosing myxofibrous tumor
intertrochanteric region of femur
Essex Lopresti fracture-dislocation
radial head #
DRUJ dislocation
(rupture of antebrachial interosseous membrane)
Tillaux fracture
Salter-Harris III # in older children
anterolateral aspect of distal tibial epiphysis
(medial aspect started to fuse)
fibrolipomatous hamartoma of the nerve
benign neoplasm of nerves, anomalous growth of fibroadipose tissue of nerve sheath
median (80%), ulnar, radial nerves
axial: coaxial cable-like appearance
coronal: spaghetti-like appearance
little leaguer shoulder
Salter Harris I # of proximal humerus
- widening of the proximal humeral physis
- sclerosis +/- fragmentation of adjacent bone
Malgaigne fracture
unstable pelvic # involving 1 hemipelvis, from vertical shear energy vectors
comprises of 2 ipsilat vertically oriented pelvic ring #s:
- anterior to acetabulum
- posterior to acetabulum
MC: ipsilat sup & inf pubic rami + SIJ (variants: ilium or sacral wing instead of SIJ)
- results in unstable lateral fragment, containing acetabulum
rotator cuff interval - contents
i) superior glenohumeral ligament (SGHL)
ii) long head of biceps tendon (LHBT)
iii) coracohumeral ligament (CHL)
rotator cuff interval - boundaries
anterior: posterior aspect of subscapularis tendon
posterior: anterior border of supraspinatus tendon
medial: lateral margin of base of coracoid process
roof: rotator interval capsule, reinforced by CHL
T sign (elbow)
interposition of joint fluid btwn ulnar collateral ligament (UCL) and sublime tubercle of ulna
- partial undersurface tear of the distal anterior bundle of UCL d/t recurrent trauma
Bennett vs Rolando fractures
Bennett: 2-part intra-articular fracture of 1st metacarpal base
Rolando: 3-part or comminuted intra-articular fracture-dislocation of 1st metacarpal base
Bennett “Bad”, Rolando “Really bad”
Panner disease
osteochondrosis of the capitellum
5-10 yrs; also in throwers
- no intra-articular loose bodies (cf. osteochondritis dissecans of the elbow which also affects capitellum)
clay-shoveler fracture
avulsion fracture of spinous process of a lower cervical vertebra, usually C7
radiographic features of osteomalacia
demineralization: smudgy/fuzzy, “erased”
coarsened trabecular pattern
pseudofractures/Looser zones (bone scan more sensitive)
distal femoral metaphyseal irregularity (cortical desmoid)
- saucer-shaped radiolucent cortical irregularity
- posteromedial aspect of distal femoral metaphysis at attachment of adductor magnus tendon
- do not touch lesion
- adolescents (10-15 years of age)
most important capsular ligament for glenohumeral stability
inferior glenohumeral ligament
IGHL also attaches to the anteroinferior labrum, which can avulse during shoulder dislocations
resorption of distal clavicle
"SHIRT" scleroderma hyperparathyroidism infection (osteomyelitis) rheumatoid arthritis trauma
dermatofibrosarcoma protuberans (DFSP)
low grade malignant spindle cell tumor
surface tumor: arises in dermis, spreads to subQ tissue & muscles, often exophytic
MC on trunk > extremities
excellent prognosis after complete excision, but tend to recur locally
DDx: sebaceous cyst, epidermal inclusion cyst
extensor compartments of wrist
“e” = “extensor” in front of each except APL
1: abductor pollicis longus (APL), e pollicis brevis (EPB); both affected in deQuervain’s
2: e carpi radialis longus, e carpi radialis brevis, Lister’s tubercle
3: e pollicis longus (EPL); delayed rupture after nondisplaced radial #
4: e digitorum, e indicis
5: e digiti minimi
6: e carpi ulnaris (ECU); tenosynovitis in RA
quadriceps tendon rupture - predisposing factors
connective tissue disease (SLE, RA)
renal osteodystrophy
steroid use
Madelung deformity
short bowed distal radius volar subluxation of hand wrt ulna V-shaped prox carpal row exaggerated radial inclination MRI: thick volar Vickers ligament
- d/t premature closure or defective devel’t of medial dist radial epiphysis
- rare congenital (manifests at 10-14 yrs) or acquired (growth plate trauma)
- bilat: 50-66%
trough line sign
- represents reverse Hill Sachs of anteromedial humeral head on AP shoulder XR
- from posterior shoulder dislocation
- appearance: 2 nearly parallel lines in superomedial aspect of humeral head
MSK manifestations of NF1 (non-spine)
- multiple NOFs
- ribs: ribbon deformity, notching, dysplasia
- other dysplasias: esp tibia
- tibial or ulnar pseudoarthrosis
- thin/absent fibula
- deficient bone form’n: thin cortex, erosive defects, sclerosis, periosteal prolif
- limb hemihypertrophy
- bowing: lat & ant
- lambdoid suture defect
MSK manifestations of NF1 (spine)
- kyphoscoliosis
- scalloped VBs
- intrathoracic meningocele
- neurofibromas, enlarged neural foramina
- dural ectasia
- hypoplastic posterior elements: thinning of pedicles, transverse processes, lamina
- transverse process spindling: (50% loss of height of TP measured halfway btwn lateral edge of VB & tip of TP)
Mazabraud syndrome
single or multiple intramuscular myxomas with fibrous dysplasia
contents of quadrilateral space
axillary nerve
posterior circumflex humeral artery & vein
borders of quadrilateral space
medial: lateral border of long head of triceps brachii
lateral: medial cortex of surgical neck of humerus
superior: teres minor m.
inferior: teres major m.
anterior: subscapularis m.
posterior: teres minor m.
acromion types
Type I: flat undersurface
Type II: concave undersurface parallel to humeral head
Type III: inferior hook anteriorly
Rockwood classification of acromioclavicular joint injury
I: mild sprain of AC lig
II: clavicle elevated but not above sup border of acromion
III: clavicle elevated above sup border of acromion but coracoclavicular dist <25 mm
IV: clavicle displaced post into trapezius
V: clavicle is markedly elevated, coracoclavicular dist >25 mm
VI: clavicle inf displaced behind coracobrachialis & biceps tendons (rare)
subscapularis recess vs subcoracoid bursa
subscapularis recess
- intra-articular
- above superior margin of subscapularis
- arthrogram: contrast pools under coracoid process ie in joint
subcoracoid bursa
- extra-articular
- anterior to subscapularis, inferior to coracoid process
- arthrogram: contrast collects at needle
sublabral sulcus criteria (distinguishing from SLAP tear)
- follows curve of glenoid
- uniform thickness
- thickness up to 2mm
- does not extend posterior to where biceps attaches to labrum
tendons affected in de Quervain’s
abductor pollicis longus (APL)
extensor pollicis brevis (EPB)
carpal tunnel contents
median nerve
1 flexor pollicis longus (FPL) tendon
4 flexor digitorum superficialis (FDS) tendons
4 flexor digitorum profundus (FDP) tendons
- middle & ring finger more superficial to index & little finger
NOT in tunnel: flexor carpi radialis (FCR), flexor pollicis brevis (intrisinc hand muscle), palmaris longus
risk factors for soft tissue sarcomas
(most de novo) chemical carcinogens prior radiation viral infxn or immunodeficiency genetic susceptibility: Li-Fraumeni, NF1
dedifferentiated liposarcoma def’n
an atypical lipomatous tumour showing progression, primary or recurrent sarcoma of variable histological grade
- amplification of MDM2 (most cases)
T2 target sign
neurofibroma
T2 hypointense centrally: nerve fiber
T2 hyperintense rim: myxoid content
Mirels score
pathologic fracture prediction
1-3 points for 4 features (max 12):
- site, size, appearance, pain level
score of 9 = 33% chance of fracture after XRT
Felty syndrome
rheumatoid arthritis
splenomegaly
leukopenia
hemophilia in knee - findings
squaring of inferior pole of patella
widening of intercondylar notch
hemophilia of ankle - finding
medial talar tilt
WHO classification of liposarcoma
- well differentiated
- dedifferentiated
- myxoid (extrapulm mets)
- pleomorphic
2 most common benign hand tumors
- ganglion
2. GCT of tendon sheath
hemophilia xray findings
Squaring inferior pole of patella Widening of the interchondylar notch Medial talar tilt Periarticular osteoporosis Gracile bones Epiphyseal enlargement Dense effusion (hemarthrosis)
rhabdomyosarcoma subtypes
- embryonal (most common, esp in head & neck)
- botryoid
- alveolar
- pleomorphic
high risk stress fractures
- lateral femoral neck
- anterior tibial shaft
- tarsal navicular
- fifth metatarsal
ways to reduce metal artifact on MRI
- ↓ magnetic field strength (1.5T)
- ↑ bandwidth during slice selection
- STIR for fat suppression (spectral frequency selective fat suppression performs better in a homogeneous field)
- spin echo instead of gradient echo
- ↑ matrix: 512 pixel
- maintain good SNR by ↑ number of excitations (NEX)
- shorter echo spacing
- thinner slices
- view-angle-tilting (VAT)
calcaneal tuberosity avulsion association
diabetes
achilles tendon rupture association
fluoroquinolones
chordoma location by frequency
sacrum
clivus
vertebral body (MC C2)
epiphyses equivalents
carpals patella calcaneus all apophyses: - greater trochanter - lesser trochanter - iliac crest - tuberosities
Marrow reconversion appearance
- Diametaphysis with sparing of epiphysis
- symmetric and bilât
- less C+
- brighter than muscle on T1
- bright on T2 fat sat
Which joint spaces communicate?
- Glenohumeral joint and subacromial bursa
- Ankle joint and common peroneal tendon sheath
- Achilles’ tendon and posterior subtalar joint
- Pisiform recess and radiocarpal joint
- No - means full thickness rotator tear
- No - calcaneofibular lig tear
- No - Achilles not true tendon sheath
- Yes - normal
Tendon classically injured in lateral epicondylitis
Extensor carpi radialis brevis
Lateral epicondylitis more common than medial
Most common rotator cuff to tear?
Least?
Supraspinatus - 1-2 cm from footplate (avascular critical zone). HADD most common here
Least = teres minor
Markers elevated in pagets
Lytic phase - none
Mixed phase - elevated alkaline phosphate
Sclerotic - elevated hydroxyproline
Myxoid liposarcoma
<20 yo
T2 bright
T1 dark (confusing)
Need gad+
Not a cyst
Signal characteristics amyloid
Low T1
Low T2
Rhizomelic and mesomelic dwarfism types and example
Rhizo - Proximal long bones (humerus, femur) - (achondroplasia, achondrogenesis)
Mezo - Distal long bones (forearm and tib fib) - (rare - mesomelia synostosis syndrome)
Second most common primary malignant bone tumor
Osteosarcoma
nerve to make ‘ok’/pinch thumb & index
AIN
anterior interosseous nerve
nerve injured in galeazzi #
anterior interosseous nerve
nerve injured in monteggia #
posterior interosseous nerve
high malignant transformation rate in exostoses
mafucci syndrome (up to 20%)
anterior shoulder dislocation associated with?
bankart
hill sachs
greater tuberosity # in >50 yo
tx glomus tumor
surgical resection
ollier disease
- predom unilat or asymmetric
- metaphyses long bones
- skull & spine are spared
- stabilize/regress after skeletal maturity
- ^ risk sarcoma degen
multiple hereditary exostoses
- auto dom
- symmetric widening metaphyses
- multiple osteochondromas
gardner’s disease skeletal manifestation
osteomas
1 location osteoid osteoma
#1 femur #2 tibia
LCH most common locations
#1 bone #2 skin majority 1-10 year olds
most common locations of osteomyelitis in the diabetic foot
1st & 5th MT heads
phalanges
calcaneus
intramuscular hemangioma
- phleboliths
- C+
- T2 bright
1 location nodular fasciitis
upper extremity
adamantinoma
- expansile
- narrow zone transition
+/- cortical breakthrough w/ soft tissue
Gorham disease
- disappearing bone (usually one)
splenic cysts
soft tissue changes
nec fasc causes
85% polymicrobial
15% monomicrobial (10% of this GAS)
gangrene
look for devitalized tissue that doesn’t enhance
fascicular sign, split fat sign, eccentric to nerve
fascicular - both (schwann/NF)
split fat - both
eccentric to nerve - schwann
osteopetrosis
impaired osteoclast dysfunction
1 location malorrheostosis
lower extremity
meniscal ossicle #1 location
posterior horn medial meniscus
plantaris muscle % population
90%
1 accessory muscle
peroneus quartus
scheuermann disease
^ AP diameter
ant wedging ≥5 deg
3+ vert bodies
schmorl’s nodes
shoulder, hip, wrist injection volumes
shoulder/hip - 10 cc
wrist - 3-5 cc
ct arthro contrast:saline/anesthesia
1:1
mr arthro gado:iodinated C+/saline/anesthetic
0.1-0.2 mL gado: 20mL rest
1/100-1/200
