MSK - Arthritis

Question 1

Features of Primary OA

Answer 1

Asymmetrical joint space narrowing, subchondral sclerosis and cystic change, osteophytosis

NO periarticular osteopenia, NO erosions

Question 2

Features of Rheumatoid Arthritis

Answer 2

Hands: Diffuse, symmetric joint space narrowing, marginal erosions, periarticular osteopenia, soft tissue swelling, joint subluxations (ulnar deviation at MCPs), ankylosis in late stage

Feet: MTP joints most common

Cervical spine: leading to anterior or vertical atlantoaxial subluxation

Shoulder: erosions in lateral aspect of humeral head, penciling of clavicle, chronic cuff tearing and high riding humerus

Question 3

What conditions classically cause bilateral and symmetric SI joint involvement

Answer 3

Ankylosing spondylitis, IBD
vowels of PAIR
Erosions first involve the lilac side of the joint (cartilage is thinning and has areas of fissuring)

Question 4

What conditions classically cause unilateral, asymmetric SI joint involvement

Answer 4

Reiter’s, psoriasis consonants in PAIR
+ infection, DJD, gout
Erosions first involve the lilac side of the joint

Question 5

Features of Psoriatic Arthritis

Answer 5

Hands: Bilateral, asymmetric soft tissue swelling (sausage digit), marginal erosions in DIP and PIP jts, pencil-in-cup, fluffy periostitis +/- ankylosis and arthritis mutilans (severe cases) +/- opera glass hand deformity

Feet: Great toe IP and MTP jts most commonly affected, ivory phalanx (specific for PA), plantar calcanea spur with periosteal reaction

Spine: Bulky, lateral outgrowths

PRESERVED MINERALIZATION

Question 6

Features of Gout

Answer 6

Well-defined punched our erosions (overhanging edges), soft tissue nodules, random distribution

*no osteopenia, joint spacing preserved until late!

Question 7

Diseases associated with chondrocalcinosis

Answer 7

Cations - calcium, copper, iron)
Crystals - CPPD, gout
Cartilage - OA, acromegaly, ochronosis

Question 8

Characteristic feature of lupus

Answer 8

Reducible subluxations of MCP and PIP joints (best seen on Norgaard/ball catcher/AllState view)

Question 9

Collagen vascular diseases causing soft tissue calcification

Answer 9

Scleroderma (subcutaneous), dermatomyositis/ polymyositis (intramuscular - sheet like), SLE (very rarely seen in lupus, usually subcutaneous and lower extremity)

Question 10

Classic appearance of hemochromatosis

Answer 10

Primarily involves the MCP joints, hook-like osteophytes of metacarpal heads and joint space narrowing

Question 11

5 D’s of Charcot joint (hypertrophic variant)

Answer 11

Destruction, debris, disorganization, dislocation, density

Question 12

Imaging appearance in hemophilia

Answer 12

Recurrent bleeding into joint = synovial hypertrophy and hyperaemia

Epiphyseal overgrowth and early growth plate fusion; gracile diaphyses; secondary degenerative changes including periarticular erosions, JS narrowing etc.

Key findings: knee>elbow>ankle> hip>shoulder
Elbow - enlarged radial head, widened trochlear notch
Knee - squaring of patella and widened intercondylar notch

MRI: Increased ST around joints due to iron deposition, low T2 signal synovium from hemosiderin

NB: Pseudotumour of hemophilia - intraosseous/ subperiosteal bleeding leading to hematoma/soft tissue mass (well circumscribed, sclerotic margins, endosteal scalloping)

Question 13

Lumpy, bumpy arthridides

Answer 13

Gout, amyloid, sarcoidosis, multi-centric reticulohistiocytosis

Question 14

Features of DISH

Answer 14

Bridging anterior osteophytes, spanning at least 4 levels, preserved intervertebral joint spacing, associated with ossification of the posterior longitudinal ligament (OPLL)

Question 15

Imaging findings in erosive OA

Answer 15

Gull-wing appearance at DIP joints from central erosions
Soft tissue swelling
Same distribution as degenerative OA
Elderly females

Question 16

Normal atlantodental interval

Answer 16

<2.5 mm (adults)

<5 mm (children)

Question 17

Imaging findings in ank spond

Answer 17

First involvement of SI joints, symmetric
Then spinal involvement including erosions (Romanus lesions, shiny corner), syndesmophytes (bamboo spine)
shoulder (hatchet deformity), hips (bilateral axial migration and collar osteophytes)

Question 18

Features of reactive arthritis

Answer 18

Predominantly affects the FEET
Similar findings to PA - ST swelling, joint space loss, marginal erosions, osteopenia
Calcaneus - proliferative changes, erosions, enthesophytes

Question 19

Features of scleroderma

Answer 19

Dystrophic soft tissue and periarticular calcs, contractures, atrophy, acroosteolysis

Question 20

DDx acro-osteolysis

Answer 20

1) Collagen vascular disease (scleroderma)
2) Neuropathy i.e. Diabetes
3) Polyvinyl chloride
4) Thermal injury
5) HyperPTH
6) Hajdu-Cheney (short stature, craniofacial abN, progression acroosteolysis)

Question 21

Findings in CPPD

Answer 21

Most commonly seen in wrist, hands, knees, pubic symphysis

TFCC –> SLAC wrist
Hook like osteophytes, diffusely in MC heads (versus hemochromatosis which is 2nd and 3rd)
Chondrocalcinosis, isolated patellofemoral involvement or large subchondral cysts suggest the diagnosis in knee

Question 22

DDx: hook like osteophytes metacarpal heads

Answer 22

Hemochromatosis (2nd and 3rd metacarpals)

CPPD (diffuse involvement of MCPs)

Question 23

Imaging findings in acromegaly

Answer 23

Widened joint space first due to cartilage hypertrophy, narrowing later in disease from secondary OA
Beak-like osteophytes in metacarpal heads
Spade-like enlargement of terminal tufts

Question 24

Imaging findings amyloid arthropathy and causes

Answer 24

Infiltration of bones, soft tissue and joints with amyloid
Periarticular soft tissue swelling, joint effusion and large subchondral erosions/cysts - mimics inflammatory arthritis
Shoulder pad sign - bulky soft tissue in the shoulders with atrophic musculature

Low signal on MRI due to amyloid deposition

most commonly related to chronic hemodialysis

Question 25

Imaging findings in multi-centric reticulohistiocytosis

Answer 25

Infiltration of histiocytes into soft tissues and joints (1/4 cases seen in malignancy - breast and ovarian)
Bilateral symmetric involvement
Sharp, well defined marginal erosion (striking, symmetric)
Soft tissue nodules
Arthritis mutilans in severe cases

*Can mimic inflammatory arthropathy (RA) and gout, but has rapidly progressive joint destruction

Question 26

JIA imaging findings

Answer 26

Epiphyseal overgrowth, elongated/gracile bones
Premature fusion of GPs
Ankylosis in wrist and facet joints of c-spine (ddx cervical spine ankylosis: Klippel-Feil syndrome)

Question 27

Imaging findings atrophic variant of Charcot joint

Answer 27

Humeral head resorption, sharp margins (looks like Hill Sachs), debris in joint

Often associated with syringomyelia

Question 28

Classic bone findings in sarcoid

Answer 28

Occur in 20% of pt’s with sarcoid
Lace-like lytic lesions in middle or distal phalanges
Articular surface is spared
Can have dactylitis, tenosynovitis
Nodular soft tissue and muscular granulomatous deposits (erythema nodosum)

Question 29

What is Jaccoud arthropathy?

Answer 29

Previously thought to be related to rheumatic fever, also seen in psoriatic arthritis, malignancy, IBD
–> Ligamentous laxity
Reducible subluxations MCP joints (similar to SLE)

Question 30

Which condition gives Hatchet deformities?

Answer 30

Humeral head/GT erosions from AS, related to enthesopathy at RC insertion
- ddx: hill sachs

Question 31

Causes of chondrocalcinosis

Answer 31

3 C’s

• crystals - CPPD, sodium urate (gout)
• cations - calcium, copper, iron
• cartilage degeneration - OA, acromegaly, ochronosis