Lengthening of short bones by distraction osteogenesis--results and complications.

We performed bone lengthening surgery on 12 metacarpals and 14 metatarsals of 15 patients. The mean age for metacarpal and metatarsal lengthening was 14.5 (10-21) and 17.5 (10-25) years, respectively. We used a unilateral or a circular external fixator. The mean healing index of the metacarpals and metatarsals was 1.6 (1.1-2.3) and 1.6 (1.0-2.0) months/cm, respectively. The mean increase in metacarpal and metatarsal length was 17.6 (13-26) and 24.3 (20-30) mm, respectively. The functional scores of the metatarso-phalangial (MTP) joint of lengthened metatarsals for the lesser toe were excellent in 12 and good in two cases based on the American Orthopaedic Foot and Ankle Society (AOFAS) scoring system. Complications were seen in six of the metatarsal lengthening cases including four angulations, one subluxation and one non-union. We conclude that the periosteum must be protected with percutaneous osteotomy and lengthening should be performed at a rate of 0.25 mm twice a day and should not exceed 40% of the original bone length (or >20 mm).