Functional results of lower extremity lengthening by motorized intramedullary nails

Objective: The aim of this study was to evaluate the outcome of patients undergoing limb lengthening using motorized intramedullary nails. Methods: This study included eleven femora and 4 tibiae from 14 patients (9 male, 5 female; mean age: 26.9 years; range: 14 to 51 years) who underwent limb lengthening using motorized intramedullary femoral nails (Fitbone (R) TAA). Average preoperative limb shortening was 4.9 (range: 2.5 to 7.5) cm. Distraction was initiated on the seventh postoperative day. Serial radiographs and Paley's bone and functional outcome scoring systems were used to evaluate the results. Results: Mean follow-up period was 33.5 (range: 7 to 88) months. Mean distraction index value was 1.2 (range: 0.7 to 2.1) days/mm and mean bone-healing index value was 43.7 (range: 13.8 to 144) days/cm. The average lengthening achieved was 51.7 (range: 25 to 75) mm. The distraction mechanism of the nail did not function properly in two patients, restricted transient knee motion was observed in four patients, and delayed consolidation was observed in four patients. Other complications included valgus deformities and superficial infections surrounding the antenna of the intramedullary nail, as well as femur fractures at the proximal end of the nail. Bone scores were excellent in 11 segments and were good in one segment. Functional scores were excellent for all 12 patients. Conclusion: While usual complications related to the external fixators, such as pin-track infections and mobilization difficulties were not encountered, the development of additional complications such as dysfunction of the distraction mechanism should be monitored with the use of motorized intramedullary nails in limb lengthening.