Intraoperative assessment of tibiofemoral contact stresses in total knee arthroplasty

The production of polyethylene wear debris in total knee arthroplasty (TKA) is due to multiple factors. In particular, inadequate implant alignment an d high bearing surface contact stresses are associated with polyethylene fa ilure. Optimal implant placement and soft tissue balancing may contribute t o reducing wear and the production of polyethylene particles. We present a case in which a quantitative technique was used to measure tibiofemoral con tact stresses during implantation of a total knee prosthesis in vivo. In a knee with preoperative varus and fixed flexion deformity, medial compartmen t contact stresses after initial resection were reduced from 14.3 MPa to 11 .3 MPa in neutral alignment by additional bone resection. Posterior cruciat e release was required to reduce contact stresses further and to provide sa tisfactory balance between medial and lateral compartments, as determined b y the operating surgeon, and was confirmed by the measurement system (3.8 M Pa medially; 3.0 MPa laterally). This technique has potential to fine-time implant positioning and ligament balancing during TKA.