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Imaging of sports and musculoskeletal injuries

Plain radiographs first, and MRI when the question is a ligament, meniscus, tendon or occult fracture; indirect radiographic signs — Segond fracture, Hill-Sachs, avulsion fracture — point to the soft-tissue injury behind them.

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Why it matters in the exam

Knee: ACL tear — discontinuous fibres or fibres flatter than Blumensaat's line, "bone bruises" in the lateral femoral condyle and the posterolateral tibia (pivot-shift mechanism), anterior tibial translation. A Segond fracture — a small avulsed fragment off the lateral tibial margin — accompanies an ACL tear in most cases. Meniscal tear: signal reaching the articular surface on at least 2 consecutive slices; the commonest — the posterior horn of the medial meniscus; a "bucket-handle" tear appears as a "double PCL". Transient patellar dislocation: bone bruises in the medial patella and lateral condyle and an MPFL tear. Knee dislocation — suspect popliteal artery injury and do CTA.

Shoulder: anterior dislocation (the commonest) — Hill-Sachs (a defect in the posterolateral humeral head) and Bankart (injury to the anteroinferior labrum, with or without a bony fragment). Posterior dislocation — a "light bulb" humeral head on the radiograph, reverse Hill-Sachs, after a seizure or electric shock. Rotator cuff: the most frequently torn tendon — supraspinatus; full-thickness tear — fluid across the whole tendon thickness, retraction, and later muscle atrophy and fatty infiltration. US and MRI are comparable for full-thickness tears. Acute shoulder pain in a middle-aged woman without trauma — calcific tendinitis (hydroxyapatite). The Achilles tendon usually ruptures 2–6 cm above its insertion on the heel.

Wrist: scaphoid fracture — commonest at the waist; at the proximal pole there is a high risk of avascular necrosis. A normal radiograph with snuffbox tenderness — MRI (or CT), or immobilisation and a repeat radiograph. Scapholunate dissociation — a gap above 3 mm between scaphoid and lunate. Avulsion fractures by tendon: ASIS — sartorius; AIIS — rectus femoris; ischial tuberosity — hamstrings; lesser trochanter — iliopsoas (in an adult — suspect a pathological fracture); base of the 5th metatarsal — peroneus brevis. Femoral neck: a displaced subcapital fracture — the high risk of necrosis. A stress fracture on the tension (superolateral) side of the femoral neck in a runner — at risk of displacement; MRI is the test. CAM-type FAI — a bump on the femoral neck (alpha angle above 55°); Baker cyst — between the medial gastrocnemius and semimembranosus. In a toddler — a non-displaced spiral fracture of the distal tibia (toddler fracture).

Key points

• Segond — ACL tear.
• Meniscus — signal to the articular surface on 2 slices.
• Anterior dislocation — Hill-Sachs and Bankart.
• Supraspinatus — the most frequently torn tendon.
• Scaphoid with a normal radiograph — MRI.

Summary table

In the full version for subscribers

• A simple algorithm
• Memory aid
• Exam traps
• 5 review cards
• Enough for IMLE

The full version is open to subscribers of: Diagnostic radiology, Medical licensing exam (IMLE), Orthopedic surgery, Emergency medicine.

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Sources

• ACR Appropriateness Criteria: Acute Trauma to the Knee, 2019 — Radiography and MRI
• ACR Appropriateness Criteria: Acute Hand and Wrist Trauma, 2018 — Suspected scaphoid fracture
• ACR Appropriateness Criteria: Shoulder Pain — Traumatic, 2017 — MRI and US for rotator cuff

Sources are given for further reading; the text is written afresh and not copied from them.

Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.