Knee and hip replacements and the risk of revision

conclude that one can expect a hip replacement to last 25 years in around 58% of patients. Although this finding is based on registry data, the implants used 25 years ago are not the same as the ones used today. More importantly, the polyethylene with which the femoral component articulates has changed dramatically, which has resulted in a substantial improvement in implant longevity. The polyethylene used today is called highly cross-linked polyethylene and has been commercially available for approximately 20 years. Most of the studies, including registry data, comparing highly cross-linked polyethylene with conventional polyethylene have shown that revision rates have been reduced by at least 50%.

Hip registry data only examines highly cross-linked polyethylene hip replacement for 15 years. Therefore, data longer than 15 years is associated with conventional polyethylene, with a substantially higher revision rate. We do not yet know the 25-year survivorship rate of hip replacements with highly cross-linked polyethylene, but the rate will clearly be much better than the rate reported by Evans and colleagues.