• • • B) Axial spondyloarthritis (axSPA)

• • • A) Bone marrow oedema
    • B) Joint space fluid
    • D) Erosions
    • E) Sclerosis

Explanation:
There are areas of bone marrow oedema in the left SI joint, with a small amount of joint space fluid in the upper segments, along with increased subchondral sclerosis and erosions. No features of capsulitis, no evident backfill or ankylosis visible. Joint space enhancement cannot be confirmed—this was a non-contrast study.

• • • Chronic back pain lasting more than three months
    • Onset of pain before age 45

Explanation:
To be eligible for the ASAS criteria, patients must have chronic back pain (lasting more than three months) with onset before age 45.
They can then be classified into one of two groups: the “imaging arm” if they have evidence of sacroiliitis (on X-ray or MRI) and at least one other feature of spondyloarthritis, or the “clinical arm” if they are HLA-B27 positive and have two or more other features of spondyloarthritis (e.g. uveitis, enthesitis, dactylitis, positive family history for axSPA, psoriasis, increased C-reactive protein level, etc).

• • Bone marrow reconversion: Signal intensity is that of normal red marrow being low T1 signal but still higher than skeletal muscle. Marrow reconversion occurs in the reverse order of normal red to yellow marrow conversion.

• • Physiological (e.g. cigarette smoking, obesity, high altitude), iatrogenic (e.g. post erythropoietin treatment), pathological (e.g. diabetes mellitus, severe chronic anaemia).

• • Obesity (BMI 35)

• • https://radiopaedia.org/articles/bone-marrow-reconversion

Adhesive capsulitis

There is a thickening and edema of the inferior joint capsule in the axillary recess which is characteristic of adhesive capsulitis.

Additionally, there is an interstitial tear of supraspinatus tendon.

Explanation:

Adhesive capsulitis, also known as frozen shoulder, is an inflammatory condition characterized by shoulder stiffness, pain, and significant loss of passive range of motion.
The joint capsule exhibits inflammation, thickening and fibrosis, leading to pain and loss of ROM.
In most cases, adhesive capsulitis is a self-limited disease with high spontaneous recovery rates within 18 to 30 months.

Pellegrini-Stieda lesion

There is an ossified lesion adjacent to medial femoral condyle, at the insertion of medial collateral ligament (MCL).

MCL fibers are intact.

No signs of osteoarthritis.

Slight degenerative changes within the body of medial meniscus.

Explanation:

Pellegrini-Stieda lesions are defined as post-traumatic ossifications of the medial collateral ligament (MCL) at or near its proximal insertion on the medial femoral condyle.
Pellegrini-Stieda disease (or syndrome) is defined as the combination of the radiographic findings and concomitant medial knee joint pain or restricted range of motion.

• Undisplaced scaphoid fracture

• Acute boxer’s fracture

• Dorsal avulsion fracture of the triquetrum

• No abnormality

• Undisplaced scaphoid fracture – FALSE

• Acute boxer’s fracture – FALSE

• Dorsal avulsion fracture of the triquetrum (Red arrow) – TRUE

• No abnormality – FALSE

Explanation:

• Notice also the dorsal soft tissue swelling with air lucencies (Located inside the orange line).






Triquetral fractures:

• Second most common carpal bone fracture (after the scaphoid)

• Fall onto an outstretched hand in ulnar deviation and carpal extension or direct blow to the dorsum of the hand (latter in this case)

• Almost always dorsal avulsion type

• Usually only seen on lateral radiographs with the classic “pooping duck” sign

• Deep lateral notch (sulcus) sign on lateral projection

• Suprapatellar effusion

• MRI of the knee, due to high index of suspicion for ACL tear

Full-thickness ACL tear

• Patient had additional abnormalities of the knee not shown.

Capitellum fracture

The case represents a classic capitellum fracture, with a mildly displaced fragment on the lateral projection, which can easily be missed if one is not familiar with the double-arc sign.

D3/D4 intermetatarsal space