Clinical implications of clubfoot histopathology

Ipsilateral peroneus brevis muscle histopathology was studied in 64 childre n with idiopathic rigid equinovarus at the setting of initial posteromedial -lateral release. Fifty percent of biopsies demonstrated abnormal muscle fi ber morphology, classified as congenital fiber-type disproportion or fiber- size variation. Forty-one infants (59 feet) underwent initial surgical inte rvention within the first year of life with a minimum 2-year follow-up. Fee t with abnormal muscle histology had a significantly greater incidence of r ecurrent equinovarus deformity requiring reoperation: the relative risk of clubfoot recurrence in children with fiber abnormalities was 5.6. Male pati ents with bilateral deformity and abnormal peroneus brevis histology had a particularly high incidence of recurrent equinovarus. Developmental interna l tibial torsion requiring surgical intervention was also greater in the ab normal-fiber histology group. The incidence of postoperative metatarsus add uctus/varus necessitating surgery was comparable despite histologic finding s. Thus muscle-fiber abnormalities are prevalent in idiopathic equinovarus, Such fiber-type anomalies may predict recurrent limb deformities.