Sagittal flexion angle of the femoral component in unicompartmental knee arthroplasty: is it same for both medial and lateral UKAs?

The flexion of the femoral component in the sagittal plane in unicompartmental knee arthroplasty (UKA) was analyzed radiographically in this study. Thirty medial and 30 lateral UKAs were included. The sagittal flexion angles were measured both relative to the posterior femoral cortex and midline sagittal distal femoral axis. Both of the measurement methods revealed that the femoral components were inserted in a significantly more flexed fashion in the medial UKA group. Neither preoperative nor postoperative tibial slope did have any significant effect on the sagittal flexion angle. To the best of our knowledge, this is the first study demonstrating an angular difference in the sagittal flexion of the femoral components between medial and lateral UKAs.