BACKGROUND: Intramedullary (IM) nailing is the method of choice for the treatment of most femoral shaft fractures. However, despite successful solid union, great initial fracture comminution can lead to significant leg length discrepancy affecting normal gait mechanics. Femoral osteotomy and distraction osteogenesis over the pre-existing IM nail could restore this limb inequality.METHODS: Five patients with an average post-traumatic femoral shortening of 3.83 cm were presented in our department with the nail in situ. Limb lengthening was achieved with the application of a distal hybrid external rail frame over the pre-existing nail. We assumed that the choice of a distal external fixator ring with wires could facilitate the procedure and minimize the possibility of friction-contact problems with the large diameter nail.RESULTS: The amount of length discrepancy, calculated preoperatively, was restored in all patients. The mean time in frame was 57.6 days and the external fixator index 16.978 d/cm. The mean time of total healing was 152.6 days and the average bone-healing index 44.9d/cm. No deep infection or hardware loosening was observed. One superficial pin track infection was treated successfully with oral antibiotics.CONCLUSION: This technique utilizes the principles and advantages of lengthening over an IM nail, avoids the necessity of nail removal and minimizes the complication rates and the overall time for complete recovery.