Unicondylar fractures of the distal femur.

ABSTRACT

BACKGROUND: Unicondylar fractures of the distal femur are rare, complex, intra-articular fractures. The objective of this multicentre study was to assess the reduction and fixation of unicondylar fractures. HYPOTHESIS: Anatomic reduction followed by strong fixation allows early rehabilitation therapy and provides good long-term outcomes. MATERIAL AND METHODS: We studied 163 fractures included in two multicentre studies, of which one was retrospective (n=134) and the other prospective (n=29). Follow-up of at least 1 year was required for inclusion. The treatment was at the discretion of the surgeon. Outcome measures were the clinical results assessed using the International Knee Society (IKS) scores and presence after fracture healing of malunion with angulation, an articular surface step-off, and/or tibio-femoral malalignment. RESULTS: Mean age of the study patients was 50.9 ± 24 years, and most patients were males with no previous history of knee disorders. The fracture was due to a high-energy trauma in 51% of cases; 17% of patients had compound fractures and 44% multiple fractures or injuries. The lateral and medial condyles were equally affected. The fracture line was sagittal in 82% of cases and coronal (Hoffa fracture) in 18% of cases. Non-operative treatment was used in 5% of cases and internal fixation in 95% of cases, with either direct screw or buttress-plate fixation for the sagittal fractures and either direct or indirect screw fixation for the coronal fractures. After treatment of the fracture, 15% of patients had articular malunion due to insufficient reduction, with either valgus-varus (10%) or flexion-recurvatum (5%) deformity; and 12% of patients had an articular step-off visible on the antero-posterior or lateral radiograph. Rehabilitation therapy was started immediately in 65% of patients. Time to full weight bearing was 90 days and time to fracture healing 120 days. Complications consisted of disassembly of the construct (2%), avascular necrosis of the condyle (2%), and arthrolysis (5%). The material was removed in 11% of patients. At last follow-up, the IKS knee score was 71 ± 20 and the IKS function score 64 ± 7; flexion range was 106 ± 28° (<90° in 27% of patients); and 12% of patients had knee osteoarthritis. CONCLUSION: Anatomic reduction of unicondylar distal femoral fractures via an appropriate surgical approach, followed by stable internal fixation using either multiple large-diameter screws or a buttress-plate, allows immediate mobilisation, which in turn ensures good long-term outcomes. LEVEL OF EVIDENCE IV, cohort study.