Results of ultrastructural analysis of the calf muscles in clubfoot.

Open biopsies were carried out on the muscles of 23 clubfoot patients, ages 9 months to 4 years. Electron microscopic analyses of the so-called "clubfoot muscles" and the peroneal muscles were performed. The changes found were not present in every area of the muscles, but were surrounded by fields of normal structure. Fatty degeneration with fibrosis was observed as the consequence of immobilization. More marked loss was found in the contractile elements. The authors believe that neuromuscular atrophy is a primary cause of congenital clubfoot. The most seriously affected muscles in this study were the tibialis posterior and peroneal muscles. The material failed to prove correlation with age. Based on their observations, the authors suggest finishing all types of immobilization before 1 year of age, when children begin to walk.