Open Wedge Distal Femoral Osteotomy: Accuracy of Correction and Patient Outcomes.

BACKGROUND: There is a renewed interest in joint preservation surgery, and lateral opening wedge distal femoral osteotomy (DFO), a joint-preserving procedure, has been used to treat symptomatic genu valgum when the deformity originates in the distal femur.

QUESTIONS/PURPOSES: This study aimed to measure the accuracy of lateral opening wedge DFO in achieving deformity correction using radiographic parameters. In addition, the ability of lateral opening wedge DFO to improve patient outcomes as measured by Short Form Health Survey (SF-36) scores and American Academy of Orthopedic Surgeons (AAOS) lower limb module (LLM) scores leading to successful joint preservation was assessed.

METHODS: The clinical charts and radiographs of 28 consecutive patients that underwent 41 DFOs (15 unilateral and 13 staged bilateral) using a locking plate construct were retrospectively reviewed. The mean age of patients undergoing DFO was 44 years (range 22-72), and 22 of the patients were female. The mean follow-up was 26 months (range 12-57 months). Preoperative and postoperative radiographs were evaluated for mechanical axis deviation (MAD), lateral distal femoral angle (LDFA), and the patella congruence angle (PCA). These measurements were compared to determine the accuracy of deformity correction. Clinical outcomes were assessed with preoperative and postoperative SF-36 and AAOS LLM, as well as Oxford knee scores at follow-up.

RESULTS: The accuracy of deformity correction was 95%. The MAD significantly improved from 25.3 mm lateral to the midline to 8 mm medial to the midline ( p  < 0.01). The LDFA significantly improved from 83.4° to 91.7° ( p  < 0.01). The PCA significantly improved from 30.4° lateral to 5.7° lateral ( p  = 0.02). Mean SF-36 scores significantly improved from 37.5 to 50.2 ( p  = 0.01); mean LLM scores improved from 71.6 to 85.9 ( p  = 0.021), and the mean postoperative Oxford knee score was 35 ± 6.2 (range 23-46). No patients required total knee arthroplasty at the time of final follow-up.

CONCLUSION: Opening wedge lateral DFO is a reliable procedure for the treatment of valgus knee malalignment with or without arthritic changes in the lateral compartment. Deformity correction is accurate, and patient outcomes reveal significant improvement after surgery. Longer follow-up is required to access the survivorship of this procedure.