Review Question - QID 5299

This patient presents with a dorsal bunion after a corrected clubfoot (talipes equinovarus) procedure.

A dorsal bunion develops after clubfoot procedure due to a strong anterior tibial tendon overpowering a weak peroneus longus. Secondary imbalances consist of weak gastrocnemius–soleus complex, which is compensated for by strong secondary plantar flexors, such as the flexor hallucis longus/brevis (FHL/FHB). Over time, a functional contracture of the FHL/FHB develops, resulting in plantar flexion of the great toe and a dorsal bunion. This typically causes patients to complain of deformity, dorsal callosities and metatarsalgia.

McKay et al. reviewed 17 children with a dorsal bunions. They transferred the tendons of the abductor hallucis, both heads of the flexor hallucis brevis, and the oblique and transverse heads of the adductor hallucis from the base of the proximal phalanx to the neck of the first metatarsal to create a myotendinous ring to correct the dorsal bunion.

Burger et al. reviewed the management of the overcorrected clubfoot deformities in the adult patient. They provide the evaluation and management of four common deformities in this population, including dorsal bunions, hindfoot valgus, dorsal subluxation of navicular and flat top talus.

Figure A shows clinical and radiographic images of a dorsal bunion. In this patient, notice the elevation of the first metatarsal bone and plantar flexion of the proximal phalanx (due to contracture of the flexor hallucis brevis).

Incorrect Answers:
Answer 1: Charcot-Marie-Tooth disease is characterized by strong peroneal longus and tibialis posterior muscles, and weak tibialis anterior and peroneal brevis muscles.
Answer 2: Skew foot deformity consists of adducted forefoot, hindfoot valgus and plantar flexion of the talus.
Answer 4: Congenital vertical talus is an irreducible dorsal dislocation of the navicular on the talus. The deformity includes contracture of the extensor digitorum, peroneal and Achilles tendon.
Answer 5: Children with Duchenne muscular dystrophy present with toe-walking and flatfeet at a young age. They do not present with the deformity as shown in this patient.