Effect of microseparation and third-body particles on dual-mobility crosslinked hip liner wear.

Large heads have been recommended to reduce the risk of dislocation after total hip arthroplasty. One of the issues with larger heads is the risk of increased wear and damage in thin polyethylene liners. Dual-mobility liners have been proposed as an alternative to large heads. We tested the wear performance of highly crosslinked dual-mobility liners under adverse conditions simulating microseparation and third-body wear. No measurable increase in polyethylene wear rate was found in the presence of third-body particles. Microseparation induced a small increase in wear rate (2.9mm(3)/million cycles). A finite element model simulating microseparation in dual-mobility liners was validated using these experimental results. The results of our study indicate that highly crosslinked dual-mobility liners have high tolerance for third-body particles and microseparation.

Review: biomechanical issues in total hip replacement.

During total hip arthroplasty, the biomechanics of the joint may be altered by removal of bone and by a change in the center of rotation of the joint. Joint pathologies existing at the time of reconstruction may also affect post-operative joint motion. In order to achieve optimized biomechanics of the replaced joint, it is important to understand the muscle actions that are involved in joint movement and the forces that are imposed on the construct by patient activity. To ensure survivorship of the replacement, intraoperative and long-term stability of the components making up the joint within host bone must be achieved. The patients receiving total hip replacements in the twenty first century tend to be younger, heavier, more active and longer lived than the patients who first received hip implants. Thus, biomechanical decisions are becoming even more important for long-term survivorship of the reconstruction.