Connective tissue structures in clubfoot: a morphologic study.

A morphologic study of connective tissue structures in clubfoot, with special emphasis on the presence of myofibroblasts, was undertaken to investigate the theory of retracting fibrosis as an etiologic factor. Nine idiopathic clubfeet from six patients were studied. Specimens from the medial and lateral capsule, medial and lateral fascia, spring and lacinate ligaments, and flexor digitorum longus, flexor hallucis longus, posterior tibialis, and Achilles tendon sheaths were investigated. Fifty specimens were examined using light microscopy and hematoxylin and eosin staining, and 26 were examined by transmission electron microscopy. Light microscopy failed to reveal any myofibroblast-like cells or any qualitative differences between specimens from capsule, fascia, ligaments, and tendon sheath. Using transmission electron microscopy, the authors identified two cell types: fibroblasts and mast cells. Some fibroblasts contained a network of microfilaments but all lacked microbundles, basal lamina, or plasmalemmal attachment plaques seen in typical myofibroblasts. Mast cells were rarely identified in capsular specimens. The absence of myofibroblast-like cells or typical myofibroblasts in clubfoot connective tissue structures does not support the theory of retracting fibrosis as a likely cause of contracture in idiopathic clubfoot.