The biplanar cut in medial closing‐wedge distal femoral osteotomy is associated with a four‐fold lower rate of lateral hinge fractures at non‐inferior coronal correction

PURPOSE: This study compares the outcomes of medial closing-wedge distal femoral osteotomy (MCW-DFO) performed with a monoplanar versus a biplanar technique, evaluating radiological correction as primary outcome and hinge fracture incidence, overall complication profile and patient-reported outcome measures as secondary outcomes. METHODS: A retrospective analysis was conducted on a consecutive series of 82 patients (86 knees) with genu valgum who underwent MCW-DFO between 2010 and 2024. Patients were divided into a monoplanar group (44 knees) and a biplanar group (42 knees). Primary outcome was the evaluation of the hip-knee-ankle angle (HKA) and lateral distal femoral angle (LDFA), assessed on weight-bearing full-length radiographs pre- and postoperatively. Secondary outcomes included hinge fracture incidence, overall complication rate and patient-reported outcome measures (PROMs) comprising the International Knee Documentation Committee score, Knee Society Score, Knee Injury and Osteoarthritis Outcome Score, Tegner Activity Scale and Visual Analogue Scale for pain. RESULTS: Both groups achieved equivalent and significant coronal correction, with no between-group differences in postoperative HKA (180.1° ± 2.5° vs. 179.8° ± 4.4°, p = 0.502) or LDFA (90.7° ± 2.6° vs. 91.5° ± 4.1°, p = 0.339). Hinge fractures were significantly more frequent in the monoplanar group (75.0% vs. 19.0%, p < 0.001), and non-inferiority of the biplanar technique was formally demonstrated for all radiographic parameters. All PROMs improved significantly from baseline in both groups, with the magnitude of improvement exceeding the minimal clinically important difference thresholds for all scores. CONCLUSIONS: Biplanar MCW-DFO protocol was associated with a lower incidence of lateral hinge fractures than monoplanar procedure, while achieving comparable coronal correction, as formally confirmed by non-inferiority testing. Although trends toward better activity level and pain relief were observed in the biplanar group, these differences did not retain statistical significance and should be considered hypothesis-generating. These findings warrant prospective investigation of the biplanar technique as a potentially preferable approach for MCW-DFO. LEVEL OF EVIDENCE: Level III, case-control study.