Finite element lifetime prediction of a miniature adjustable orthopedic device

In Total Knee Arthroplasty (TKA), accurate balancing of the medial and lateral collateral ligaments is considered by orthopedic surgeons as one of the most challenging and complicated tasks to achieve. Therefore, an efficient solution is needed to assist the surgeons in achieving this crucial task without resulting in tibiofemoral misalignment. The required solution consists in developing either a completely automated smart ligament balancer for intraoperative use or adjustable tibial implant for postoperative use. The smart ligament balancer allows the surgeon to accurately balance the collateral ligaments at the time of surgery while the adjustable tibial implant can be controlled in the postoperative period in order to correct the residual ligament imbalance. In this paper, we propose a miniature device that can be used as a smart ligament balancer during TKA or as an adjustable tibial implant in the period following the surgery. Three designs of the smart ligament balancer have been developed using 3-Dimensional (3D) Computer Assisted Design (CAD) software. The proposed balancer can also be used as an adjustable tibial implant after slightly modifying its design. Finite element study of each design has been conducted in order to predict the lifetime of this implant in both cases of intraoperative or postoperative uses.