A 24 year-old female was struck by a trolley as an adolescent and sustained a severe Grade 3C open femur fracture. After a multistage limb salvage procedure which required vascular repair and soft tissue reconstruction, she presented to our clinic more than a decade after the injury. The patient stood 1.6 m and weighed 64.8 kg, with a calculated Body Mass Index (BMI) of 25.3. She acquired a leg length discrepancy of 30 mm, right shorter than left, had right hip pain, walked with a limp and complained of symptomatic hardware about her hip (Fig. 1). She underwent a proximal femoral osteotomy and placement of a 10.7 mm antegrade PRECICE  expandable femoral IMN (Fig. 2). Although she required four units of pRBC transfusion post-operatively, she tolerated the procedure well with no other complications. The femur was left in situ after the osteotomy to allow surgical wounds to heal.
Ten days post-operatively, she followed up with uncomplicated healing wounds to begin her lengthening, 1 mm per day for a goal of 30 mm total lengthening. She was followed weekly with physical exams and plain film radiographs (Fig. 3). After four weeks of lengthening, physical exam demonstrated equal iliac crest height on standing and symmetric rotation. Bilateral long leg Weight-Bearing (WB) plain films demonstrated that the right femur was within 2 mm of length compared to the left femur (Fig. 4) and regenerate was visible in the osteotomy gap. There was some backing out of one of the distal interlocking screws. We believed that she had achieved goal length and started her on 25% WB and physical therapy for hip and knee range of motion and strengthening.
Four weeks afterwards, the patient reported increased pain in her right thigh and felt that her right leg had shortened. On physical exam, she was grossly 2 cm short on her right lower extremity with tenderness to palpation over the distal interlocking screw. Plain films demonstrated a 25 mm leg length discrepancy (Fig. 5). Closer inspection of the radiographs revealed that the flange of the nail was flared distally (Fig. 6) and the lengthening mechanism had failed.
We attempted to resume her original lengthening protocol, with the hope of regaining some of the lost length. She continued the protocol and stayed non-WB for the duration of her lengthening, however only an additional 5 mm were gained (Fig. 7) as the mechanism would not lengthen any further, presumably due to the mechanical failure. Over the next several months, she continued to have pain in her right thigh and was unable to weightbear without crutches. Her osteotomy went on to nonunion and she eventually underwent exchange nailing (Fig. 8).