Muscle abnormalities in idiopathic toe-walkers.

The cause of toe-walking is unknown. Muscle biopsies were taken from a group of 25 toe-walkers who were treated at this hospital to try to identify the pathological cause of the condition. The most common abnormality noted was an increase in the proportion of type I muscle fibers with type grouping; other less common changes included the presence of angulated atrophic fibers and thickened capillaries and cases in which occasional fibers were undergoing active degeneration and regeneration. The combination of these changes suggests that there may be an underlying neuropathic process in idiopathic toe-walkers.