Medial Open-wedge Osteotomy with Double-plate Fixation for Varus Malunion of the Distal Femur.

OBJECTIVE: To present our clinical experience of treating varus malunion of the distal femur through a medial open-wedge osteotomy with double-plate fixation.

METHODS: A prospective cohort study was performed. From January 2005 to February 2015, 15 consecutive patients with varus malunion following distal femur fractures were surgically treated at a single level I trauma center. The coronal and sagittal deformity were corrected by a medial open-wedge osteotomy of the distal femur. A medial buttress plate was used to maintain the realignment. A lateral locking plate was additionally used as a protection plate. The mean age of patients at the time of the surgery was 35.5 years (range, 22-58 years). The radiographical evaluation included the mechanical femorotibial angle, the mechanical lateral distal femoral angle, the anatomic posterior distal femoral angle, and the leg length discrepancy. Clinical outcome evaluation consisted of the range of motion (ROM) and Hospital for Special Surgery (HSS) score.

RESULTS: Mean follow-up was 7.4 years (range, 4-11.5 years). Varus and flexion malalignment and limb discrepancy were adequately corrected in all patients. The mechanical femorotibial angle, the mechanical lateral distal femoral angle, and the anatomic posterior distal femoral angle were restored from 17.5° (range, 13°-25°) to 2.3° (range, - 2°-7°), 102.3° (range, 95°-112°) to 85.2° (range, 81°-92°), and 77.1° (range, 65°-87°) to 82.7° (range, 76°-88°), respectively. The leg length discrepancy was diminished from 3.4 cm (range, 2.4-4.5 cm) to 0.8 cm (range, 0-1.7 cm). The average bone healing time was 4.1 months (range, 2.5-6 months). The average ROM of the affected knees at 24-month follow-up was 3.4°-112.55°. The score of HSS at 4-years follow-up was 76.1 (range, 64-88). No internal fixation failure or secondary operation was noted until the last follow-up.

CONCLUSION: Medial open-wedge osteotomy can adequately correct the posttraumatic varus malunion of the distal femur. With fixation of the double plate, non-displaced bone healing and good functional outcome are expected.