This patient's clinical features suggest tarsal tunnel syndrome, which is due to posterior tibial nerve compression as it passes under the flexor retinaculum posterior to the medial malleolus. Tarsal tunnel syndrome is most common following an ankle fracture or dislocation involving the talus, calcaneus, or medial malleolus, in which scar tissue, bony spurs, or bone/cartilage fragments can compress the nerve. Other etiologies include malignancy or inflammatory conditions (eg, rheumatoid arthritis).
Patients usually develop pain and paresthesias in the distribution of the nerve (sole of the foot, distal foot, or toes). The pain can radiate up to the heel and calf and is worse at night or with standing. Taking off shoes often relieves the discomfort. Examination can show a positive Tinel's sign (tingling sensation on light percussion over the nerve) and/or sensory loss. Severe nerve injury can lead to atrophy of intrinsic foot muscles. Diagnosis is mainly clinical, although electrodiagnostic testing may be helpful. Treatment includes anti-inflammatory medications (eg, nonsteroidal anti-inflammatory drugs), shoe modification, or corticosteroid injection, with decompressive surgery in refractory cases.