Summary

The use of patient specific instrument-guided biplanar osteotomy can accurately correct valgus deformities of the knees, especially in complex cases.

Abstract

Background

Distal femoral varus osteotomy (DFVO) is used to correct valgus malalignment combined with lateral compartment osteoarthritis. Clinical outcomes depend on construct stability, bony union time, and correction precision. This study aimed to evaluate the radiographic and functional outcomes of patient-specific instrument (PSI)-guided, distal femur varus-producing biplanar osteotomy in the knee joint.

Methods

Seventeen knees in fifteen patients with valgus deformity and a mechanical lateral distal femoral angle (mLDFA) < 85° were included in this study. Three of these cases involved post-traumatic malunion. All patients underwent PSI-guided osteotomy using either the medial closing wedge (MCW) or lateral opening wedge (LOW) technique. The correction targeted the mechanical axis (MA) at 50% of the tibial plateau width. Outcome measurements included MA, mLDFA, bony union time, and Oxford Knee Score (OKS). The mean follow-up period was 12.6 months.

Results

The MA was corrected from a mean of 81.8 ± 11.3% to 48.6 ± 6.7% at the final follow-up. The deviation between the planned and executed MA was 1.3%. The mean time to bony union was 3.0 ± 1.0 months in the MCW group and 7.5 ± 2.7 months in the LOW group. The OKS improved significantly from 25.3 ± 6.2 to 42.1 ± 3.4 points (P < 0.01).

Discussion

This study demonstrates that PSI-guided DFVO yields favorable outcomes for valgus knees using both MCW and LOW techniques. DFVO provides effective long-term pain relief and functional improvement, with survival rates of up to 90.5% for LOW and 81.5% for MCW. In cases of femur fracture with malunion and leg discrepancy, the LOW procedure was preferred due to its ability to correct both varus and leg length discrepancies. The biplanar technique allows faster bone healing, greater stability, and avoids disturbing the patellofemoral joint and anterior femur gliding surface, offering advantages over single-plane methods. PSI improves surgical precision and reduces time, though higher costs limit widespread adoption.

Conclusion

The use of PSI-guided biplanar osteotomy accurately corrects valgus deformities, making surgeries more efficient, especially in complex cases.