An unusual aberrant muscle in congenital clubfoot: an intraoperative finding.

Congenital clubfoot is a common congenital deformity, characterized by equinus of the hindfoot and adduction of the midfoot and forefoot, with varus through the subtalar joint complex. A cavus deformity will also be present. The etiology of this congenital deformity remains elusive. Muscle anomalies are not commonly found in patients with idiopathic clubfoot, and, when present, their significance is not clear. The presence of a flexor digitorum accessorius longus muscle and an accessory soleus muscle found at surgical correction of clubfoot deformity has been previously reported. Our case was a female child, aged 2 years, 3 months, who developed bilateral relapsed congenital clubfoot. She was found to have an unusual aberrant muscle in both legs. This was discovered accidentally during surgical correction of her deformity through posteromedial soft tissue release. This muscle might have contributed to the hindfoot varus and equinus in the clubfoot deformity, because the latter were completely corrected after release of the muscle from its insertion. Awareness of such a new anatomic variant, with the other anatomic variants found in clubfoot deformity, will not only improve our understanding of normal lower limb development, but could also lead to improved genetic counseling and diagnostic and treatment methods of such a common congenital deformity.