Histologic and histochemical analysis of muscle specimens in idiopathic talipes equinovarus.

Congenital idiopathic talipes equinovarus is a relatively common disorder of uncertain etiology with a wide variance of clinical severity. Many theories have been postulated over the years without universal agreement in regard to the cause of this disorder. These hypotheses include vascular, viral, genetic, anatomic, compartment syndrome, environmental, and positioning considerations. A great deal of recent discussion has focused on a neuromuscular etiology for this condition. Muscle biopsies from the gastrocnemius, abductor hallucis, flexor digitorum longus, flexor hallucis, and tibialis posterior were obtained during posteromedial surgical release for idiopathic talipes equinovarus from September 1994 to October 2000 at the authors' institution. Ninety-five feet in 68 patients yielded a total of 431 muscle specimens. All of the specimens were processed and examined by light microscopy by an expert neuromuscular pathologist. In addition, 95 tissue samples were further processed for histochemical studies and electron microscopy. Three hundred seventy-two specimens (86.3%) showed no evidence of a pathologic diagnosis with normal fiber-type ratios and no type I fiber grouping indicative of neuromuscular pathology. Only 4 specimens (0.9%) showed type I fiber predominance, and 55 specimens (12.8%) revealed muscle fiber atrophy. The results of this study do not support the theory that a neuromuscular abnormality may be significant in the etiology of idiopathic talipes equinovarus.