Numerical study of osteophyte effects on preoperative knee functionality in patients undergoing total knee arthroplasty

Osteophytes are routinely removed during total knee arthroplasty, yet thepreoperative planning currently relies on preoperative computed tomography (CT)scans of the patient's osteoarthritic knee, typically including osteophytic features.This complicates the surgeon's ability to anticipate the exact biomechanical effectsof osteophytes and the consequences of their removal before the operation. The aimof this study was to investigate the effect of osteophytes on ligament strains andkinematics, and ascertain whether the osteophyte volume and location determinethe extent of this effect. We segmented preoperative CT scans of 21 patients,featuring different osteophyte severity, using image‐based active appearancemodels trained to identify the osteophytic and preosteophytic bone geometriesand estimate the cartilage thickness in the segmented surfaces. The patients'morphologies were used to scale a template musculoskeletal knee model.Osteophytes induced clinically relevant changes to the knee's functional behavior,but these were variable and patient‐specific. Generally, severe osteophytic kneessignificantly strained the oblique popliteal ligament (OPL) and posterior capsule (PC)relative to the preosteophytic state. Furthermore, there was a marked effect on thelateral collateral ligament and anterolateral ligament (ALL) strains compared to mildand moderate osteophytic knees, and concurrent alterations in the tibial lateral‐medial translation and external–internal rotation. We found a strong correlationbetween the OPL, PC, and ALL strains and posterolateral condylar and tibialosteophytes, respectively. Our findings may have implications for the preoperativeplanning in total knee arthroplasty, toward reproducing the physiological kneebiomechanics as close as feasibly possible.