LENGTHENING OF SHORT BONES BY DISTRACTION OSTEOGENESIS-RESULTS AND COMPLICATIONS

Abstract

Background: The occurrence of congenitally short metatarsals is associated with an abnormal gait and an aesthetically displeasing appearance. Similarly, short metacarpals result in severe cosmetic disfigurement, particularly in young female patients.

Methods: We examined and performed bone lengthening surgery in 13 female and 2 male patients. Of these, procedures were conducted on 12 metatarsals of 8 patients, 4 metacarpals and 1 metatarsal of a single patient, 1 metacarpal and 1 metatarsal of a single patient and 7 metacarpals of 5 patients. The mean age of the patients who underwent metacarpal procedures was 14.5 (10–21) years while the mean age of those who underwent metatarsal procedures was 17.5 (10–25) years. The callotasis method was employed for these procedures and we used either a unilateral external fixator and/or a circular external fixator.

Results: The mean healing index and increase in metacarpal length was 1.6 (1.1–2.3) months/cm and 17.6 (13–26) mm, respectively. The mean follow-up period for patients who underwent metacarpal lengthening was 57.5 (12–96) months. The mean healing index and increase in metatarsal length was 1.6 (1.0–2.0) months/cm and 24.3 (20–30) mm respectively. The mean follow-up period for patients who underwent metatarsal lengthening was 48.3 (12–72) months. The preoperative AOFAS (American Orthopaedic Foot and Ankle Society) scores were good in 5 and excellent in 9 cases. The functional scores of metatarso-phalangial (MTP) joint of lengthened metatarsals for the lesser toe were excellent in 12 and good in 2 cases based on the AOFAS scoring system. All patients who underwent metacarpal lengthening reported that they were satisfied and could conduct their daily activities with good functional and aesthetic results. Complications included 4 angulations, 1 subluxation and 1 non-union and were seen in 6 of the metatarsal lengthening cases that exceeded 40% (or > 20 mm) of the total length of the original bone.

Interpretation: There are recommendations in the literature that allow for the avoidance of severe complications and for the shortening of the consolidation period. We conclude that the periosteum must be protected with percutaneus osteotomy and lengthening should be performed at a rate of 0.25 mm twice a day, should not exceeding 40% of the original bone length (or > 20 mm). If the anticipated lengthening exceeds these predefined values then we suggest that the procedure should be performed using a circular external fixator with temporary fixation of the MCP or the MTP joint and the inclusion of the proximal phalanx in the frame.