Biomechanical Implications of an Oblique Knee Joint Line.

Surgical correction of multiapical deformities of the lower limb requires careful preoperative planning. Surgeons must account for the potential creation of secondary deformity, such as knee joint line obliquity, and the risks associated with accepting these changes in limb alignment. In this study, we evaluate the effect of knee joint obliquity on tibial plateau contact pressures and knee instability. Three cadaveric knees were dissected and put through biomechanical testing to simulate loading of an oblique knee joint. We observed < 1 mm femoral displacement (proxy measure of instability) between 15 degrees of varus tilt and 10 degrees of valgus tilt, and greater increases in tibial plateau contact pressures with valgus tilt than with varus tilt. Our results suggest that, if the creation of a secondary coronal plane deformity at the knee joint cannot be avoided, up to 15 degrees of varus or 10 degrees of valgus alignment can be tolerated by an otherwise structurally normal knee.