The influence of patellar dislocation on the femoro-tibial loading during total knee arthroplasty

Purpose Balancing the gap is essential in total knee arthroplasty (TKA). The purpose of this study was to quantify the influence of patellar position on femoro-tibial joint load in TKA. We hypothesized that resetting of the patella increased medial joint load and decreased lateral joint load. Methods Our original tensor system was used during posterior-stabilized (PS) and cruciate-retaining (CR) total knee arthroplasty (TKA) using medial para-patellar approach (MPP) or sub-vastus approach (SV). Results In PS-TKA, by resetting the patella, the ratios between medial and lateral compartments were not changed in both extension and flexion position using MPP and were significantly changed in flexion position using SV. In CR-TKA, by resetting the patella, the load of the lateral component decreased and the ratios between medial and lateral compartments were changed significantly in both extension and flexion position using SV. Conclusion It is important to be aware that, when performing CR-KA, the load of the lateral compartment will decrease by resetting the patella using SV. Level of evidence Therapeutic studies investigating the results of treatment, Level II.