Lengthening with Monolateral External Fixation versus Intramedullary Nail in Congenital Femoral Deficiency

Introduction: Our aim was to determine the outcomes/complications of lengthening with monolateral external fixation or magnetically-driven intramedullary nails for congenital femoral deficiency (CFD).

Methods: Medical records of 62 patients (62 femora) with CFD (some with concurrent fibular hemimelia) were retrospectively reviewed. All underwent femoral lengthening: 32 patients had monolateral external fixation (Group A) and 30 patients had internal lengthening nails (Group B). Mean age for Group A was 9.4±3.8 years and for Group B was 15.4±4.9 years. Mean follow-up was 4.5±2.7 years for Group A and 1.9±0.7 years for Group B.

Results: Mean lengthening achieved was 5.6±1.7 cm for Group A and 4.8±1.4 cm for Group B (p=0.05). Mean distraction index was 0.7±0.2 mm/day for Group A and 0.7±0.2 mm/day for Group B (p=1.00). Mean consolidation index for Group A was 29.3±12.7 day/cm and 34.8±11.2 day/cm for Group B (p=0.08). Mean arc of motion for Group A was 1º±2º to 123º±12º before surgery, -1º±4º to 70º±30º at completion of distraction, and 1º±5º to 81º±30º after consolidation. Mean arc of motion for Group B was 1º±3º to 128º±23º before surgery, 1º±3º to 96º±28º at completion of distraction, and 0º±2º to 122º±23º after consolidation. While preoperative flexion was similar between both groups (p = 0.35), Group A had significantly less range of motion at the end of distraction (p = 0.0007) and at final follow-up (p < 0.0001) than Group B. Obstacle and complication rates were similar for both groups, but Group A had a 63% problem rate while Group B had a 23% problem rate (p=0.004).

Discussion and Conclusion: When compared with limbs treated with monolateral external fixation, limbs treated with the intramedullary lengthening nails had superior final range of motion, lower rate of problems, and similar distraction/healing indices. Internal lengthening nails appear to represent a substantial improvement in treatment.