Internal Extramedullary Lengthening of the Femur With an Intramedullary Lengthening Nail: Outcomes and Technical Considerations From 2 Centers

BACKGROUND: Surgical techniques for internal limb lengthening continue to advance. This study evaluates outcomes and technical aspects of extramedullary motorized femoral lengthening in young children. METHODS: A retrospective review of extramedullary motorized femoral lengthening at 2 centers was performed. Variables of interest include complications, the magnitude of lengthening, and technical factors, including antegrade versus retrograde techniques. RESULTS: Forty-five extramedullary motorized femoral lengthenings in 40 patients were included with a median follow-up of 27 months (range: 7.7 to 98.4 mo). Antegrade lengthening was performed in 40% of cases (18/45) and retrograde lengthening in 60% of cases (27/45). A median lengthening of 3.8 cm (14% of the femoral segment) was performed. At least one complication occurred in 56% of cases with 12 complications classified as modified Clavien-Dindo III (requiring a reoperation). There were no statistically significant differences in complication rates between antegrade and retrograde techniques. CONCLUSIONS: Motorized extramedullary femoral lengthening is a viable treatment option for femoral lengthening in young children. The complication profile is comparable to other femoral lengthening techniques. LEVEL OF EVIDENCE: Level IV.