Natural history of multiple hereditary osteochondromatosis of the lower extremity and ankle.

In this study the authors evaluated the natural history of the ankle joint in patients with multiple hereditary osteochondromatosis. Thirty-eight subjects with an average age of 42 years completed a detailed subjective questionnaire and underwent clinical and radiographic evaluation of their ankles. Three subjects (8%) indicated their ankle involvement affected their vocation, and 12 (32%) were limited in recreational sports. Seven patients (18%) had pain in at least one ankle on a weekly basis, with an average ankle pain score of 2.2. Ankle range of motion averaged 50 degrees and subtalar motion was considered normal in two thirds of ankles. Radiographic evaluation documented an average tibiotalar tilt of 9 degrees of ankle valgus, with evidence of degenerative joint disease noted in 14 ankles (19%). Those with arthritic changes had significantly more tibiotalar tilt and diminished ankle range of motion compared with those without radiographic signs of osteoarthritis. These findings document measurable decreases in ankle function and suggest that correction or prevention of excessive tibiotalar tilt may be warranted to improve outcome.