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Progressive collapsing foot deformity due to posterior tibial tendon dysfunction — MSRA MCQ

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HardAnkle and FootProgressive collapsing foot deformity due to posterior tibial tendon dysfunctionMSRA

A 56-year-old woman presents with 4 months of progressively limiting pain and swelling behind the left medial malleolus and along the instep. Over the past month, she has noticed that her left arch has flattened and that her foot points outwards when walking. She has obesity and hypertension but no diabetes, inflammatory arthritis, peripheral neuropathy or recent trauma. Examination shows unilateral flexible pes planovalgus, forefoot abduction with a positive “too many toes” sign, and tenderness with swelling along the tibialis posterior tendon. She cannot perform a single-leg heel rise on the left. The deformity is passively correctable. Pedal pulses, capillary refill and sensation are normal. There is no warmth, erythema, skin break or calf swelling. What is the most appropriate management today?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: A — Arrange weight-bearing foot and ankle radiographs and refer to community podiatry or MSK physiotherapy for suspected progressive collapsing foot deformity

Explanation lettering: E = shown as B · B = shown as C · C = shown as E

This is progressive collapsing foot deformity (PCFD), also termed posterior tibial tendon dysfunction: new posteromedial ankle pain and tendon swelling are accompanied by progressive unilateral arch collapse. Failure of a single-leg heel rise, flexible deformity and the “too many toes” sign indicate more advanced tendon dysfunction with flexible flatfoot, rather than isolated early tendinopathy. Neurovascular normality and absence of diabetes, neuropathy, marked warmth or erythema make acute Charcot arthropathy unlikely. Weight-bearing foot and ankle radiographs are appropriate to assess alignment and exclude bony or joint pathology before MSK referral. Progressive deformity is itself an indication for referral to podiatry or physiotherapy; this enables offloading/bracing, footwear and orthotic management, gait rehabilitation and escalation if symptoms progress. B may suit stage I disease without deformity or heel-rise failure, but delays assessment in progressive deformity. C is premature: MRI is generally reserved for diagnostic uncertainty, inconclusive ultrasound or progression where surgical planning is being considered. D would be appropriate for a neuropathic, warm, swollen foot where Charcot is suspected. E would be more appropriate with an inflammatory pattern, such as persistent synovitis, prolonged morning stiffness or multisystem inflammatory features.

Reference: East Sussex MSK Community Partnership: Foot & Ankle Triage Guidelines (July 2025) — https://eastsussexmsk.nhs.uk/wp-content/uploads/2025/10/Foot-Ankle-Triage-Guidance-2025.pdf East Sussex MSK Community Partnership: Foot & Ankle Triage Guidelines (July 2025) — https://eastsussexmsk.nhs.uk/wp-content/uploads/2025/10/Foot-Ankle-Triage-Guidance-2025.pdf