Free UKMLA musculoskeletal questions with explanations

B. Scaphoid fracture

A fall on an outstretched hand with anatomical snuffbox tenderness and difficulty gripping is the classic presentation of a scaphoid fracture, which is frequently occult on initial plain radiographs. NICE guidance (NG38) advises considering MRI as first-line imaging after thorough clinical examination; in practice the wrist is immobilised empirically and, where MRI is unavailable, radiographs are repeated at 10 to 14 days, given the risk of avascular necrosis from the retrograde blood supply to the proximal pole.

E. Acute compartment syndrome

Acute compartment syndrome is the correct answer: pain disproportionate to injury and exacerbated by passive stretch of the compartment muscles (here, ankle dorsiflexion stretches the superficial and deep posterior compartments) are hallmark features. Closed tibial shaft fractures are the commonest cause in the UK, and the BOA standard requires immediate fasciotomy once diagnosed clinically or by compartment pressures (delta pressure <30 mmHg).

A. Hemiarthroplasty

Hemiarthroplasty is the correct intervention because replacement arthroplasty is recommended for displaced intracapsular femoral neck fractures, with hemiarthroplasty favoured over total hip replacement in patients who are not independently mobile outdoors or who are not expected to stay independent beyond 2 years. This patient's moderate dementia and indoor-only mobility with a Zimmer frame place her firmly in this category.

D. In situ screw fixation of the epiphysis

A slipped epiphysis is fixed where it lies with a screw passed across the growth plate, which stops further slipping and lets the physis close. It is done promptly because a stable slip can become unstable with a minor injury, and the child is kept non-weight-bearing until surgery. Attempting to reduce the slip by manipulation is avoided because it tears the retinacular vessels supplying the femoral head and causes avascular necrosis, the most feared complication. Physiotherapy and observation allow the slip to progress, and osteotomy is a later reconstructive operation for residual deformity once the physis has fused.

B. Abduction splinting in a Pavlik harness

In an infant under about 6 months a dislocatable or dislocated hip is treated with a Pavlik harness, which holds the hips flexed and abducted so that the femoral head sits in the acetabulum and stimulates it to deepen. Worn continuously for several weeks with ultrasound checks, it succeeds in most cases, and the younger the baby the better. Closed reduction with a spica cast is used when the harness fails or when the child presents after about 6 months, and open reduction and osteotomies are for older children with established dislocation. Simply watching an unstable hip wastes the window in which the acetabulum can still remodel, and an untreated dislocation produces a limp, leg shortening and early arthritis.

C. MRI

MRI is the imaging modality of choice for suspected acute osteomyelitis in children (plain radiographs of the affected bone or joint are required first-line, with MRI the preferred second-line modality, ideally within 48 hours) because it detects bone marrow oedema, periosteal reaction, and soft tissue abscesses within 1–2 days of infection onset, well before plain radiographs show changes. It also provides anatomical detail to guide surgical drainage if needed and avoids ionising radiation. UK paediatric orthopaedic practice (BSCOS) supports MRI as the investigation of choice once acute osteomyelitis is clinically suspected.

A. Ewing sarcoma

Ewing sarcoma classically affects the diaphysis of long bones in adolescents and produces a permeative lytic lesion with a lamellated 'onion-skin' periosteal reaction, often accompanied by systemic features (fever, weight loss, raised inflammatory markers) that mimic infection. Urgent referral is recommended for bone pain with a permeative lesion in a child or young adult; diagnosis is confirmed by biopsy showing small round blue cells with the t(11;22) EWSR1–FLI1 fusion.

D. Giant cell arteritis

Giant cell arteritis (GCA) is a large/medium-vessel granulomatous vasculitis affecting branches of the external carotid and ophthalmic arteries, classically presenting in patients over 50 with new headache, jaw claudication, sudden visual loss and ESR typically >50 mm/h. Immediate high-dose prednisolone (40-60 mg daily, or IV methylprednisolone if visual symptoms) is given before confirmatory temporal artery biopsy to prevent permanent blindness.

C. Limited cutaneous systemic sclerosis

The combination of long-standing Raynaud phenomenon, sclerodactyly limited to distal to the elbows and the face, telangiectasia, calcinosis and oesophageal dysmotility is the classic CREST phenotype of limited cutaneous systemic sclerosis. In limited disease skin thickening spares the trunk and proximal limbs, and pulmonary hypertension is the main long-term threat, in contrast to the early diffuse skin and renal/lung involvement of diffuse systemic sclerosis.

D. Captopril

Accelerated hypertension with a rapidly rising creatinine in early diffuse systemic sclerosis is a renal crisis, driven by intense renin release from ischaemic kidneys. Treatment is an angiotensin-converting enzyme inhibitor started immediately and titrated every few hours; short-acting captopril is preferred because it can be adjusted quickly. The ACE inhibitor is continued even if creatinine rises further, because it is the only therapy shown to restore renal function. Angiotensin receptor blockers do not achieve the same outcomes and other antihypertensives are added only once the ACE inhibitor is at full dose.