Analysis of Finger PIP Implants

Total joint arthroplasty (TJA) is implemented primarily for the relief of pain, and secondarily for achieving better function by increasing the joint’s strength and motion. In order to keep health costs low, it is desirable that the TJA achieves and maintains a long-term and secure fixation of the implanted components. Unfortunately, clinical follow-up shows that the prosthetic finger implant components have long-term complications including bone resorption, wear, loosening, and failure of the implant components. Although the mechanism of complications is not fully understood, it is well known that the wear and failure of prostheses are highly related to the mechanical forces or stresses of implant components. It is therefore desirable that reliable 3-D computational finite element analysis (FEA) models can be developed and used for the stress analysis of implants. In this study, the finger proximal interphalangeal (PIP) prosthetic components were analyzed using a nonlinear finite element method. Implant components under different joint flexion angles as well as different forces were studied. The stress distribution on the contact surface of the implant component was obtained. The developed FEA models can be used to examine the contact situations (contact stress, contact region, and stress distribution), which are critical to the wear and potential failure of the implant components. Based on FEA results, the design of the current finger PIP implants can be improved for optimum performance and a long-term fixation.