Retrograde Extramedullary Limb Lengthening of the Femur in Children: Surgical Technique and Early Results

Objective: Internal lengthening nails improve patient comfort compared with external fixation, but intramedullary placement may be unsafe or not feasible in skeletally immature patients. Extramedullary limb lengthening (EMLL), in which a lengthening nail is placed in a submuscular plane along the femur, may address this limitation. We describe our retrograde femoral EMLL technique and report clinical outcomes. Materials and Methods: We performed a retrospective review of consecutive patients undergoing femoral lengthening with a retrograde extramedullary lengthening nail. Recorded variables included preoperative limb length discrepancy, length gained, distraction parameters, bone healing index, and complications. Descriptive statistics were used. Results: Twenty-three retrograde extramedullary femoral lengthening procedures were performed in 23 segments (20 patients; 65% male; mean age 7.7±2.5 y), including 1 bilateral and 2 sequential lengthening procedures. The most common diagnoses were fibular hemimelia (39%) and congenital femoral deficiency (26%). All segments were treated with a PRECICE nail using 2 proximal and 2 distal interlocking screws (8 nails 8.5 mm; 15 nails 10.7 mm), frequently with concomitant guided growth/epiphysiodesis. Mean length gained was 4.0±0.68 cm (13% of femoral length). Mean bone healing index was 32±7 days/cm. Five complications occurred: 4 symptomatic distal bursae (one draining) and one proximal interlocking screw fracture. Conclusion: Retrograde extramedullary femoral lengthening with an internal lengthening nail provided effective lengthening in young patients while avoiding external fixation. No regenerate deformation and no need for supplemental fixation were observed, supporting this approach as a viable alternative when intramedullary nail placement is not possible.