Single Cut Distal Femoral Varus Osteotomy (SCFO): A Preliminary Study

Background: Genu valgum usually originates from a deformity of distal femur that is often corrected by distal femoral varus osteotomy. The osteotomy includes both components of angulationcorrection and translation because the site of osteotomy is not commonly at the apex of deformity. Improvement of patellar tracking not only depends on valgus correction, but also it may be partially due to centralization of the trochlear groove under the femoral anatomical axis (FAA). We asked whether we could accurately correct the deformities based on our preoperative goals for the correction of the mechanical axis and centralization of the trochlear groove under the FAA by using a single bone cut. This study describes a new lateral single cut distal femoral osteotomy (SCFO) that enables concurrent correction of angulation and translation. Methods: This study was done on 12 young adult patients with femoral juxta-articular genu valgum deformity using SCFO. The average age at operation was 21 years (range: 16-25). SCFO is a type of closing-opening distal femoral osteotomy that corrects the valgus deformity of the distal femur while the translation of the distal fragment is done using one oblique cut. It centralizes the trochlear groove under the FAA. We compared the pre and postoperative radiographic and clinical variables including mechanical tibiofemoral angle, knee range of motion (ROM), International knee documentation committee (IKDC) score and the time to union. Mean follow-up of the patients was 24 months. Results: The average mechanical tibiofemoral angle improved from 16 degrees (10-23) to 1 degrees (-2 to +2). IKDC subjective score slightly improved from preoperative (65) to 2-year follow-up (71). Centralization of the trochlea was achieved in all patients. Conclusion: SCFO can be a reasonable alternative for correction of the distal femur genu valgum deformity. It can centralize the patellar groove under the FAA with satisfactory clinical outcomes.