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Results of Knee Replacements After 15 Years

Most total knee replacements (TKRs) last 10 to 15 years. In this study, long-term results of the low contact stress (LCS) meniscal-bearing knee replacements were reviewed. Wear pattern and survival rates are reported at the 15-year follow-up and beyond.

All patients were older men from a Veterans' Hospital in Kentucky. Surgery for a TKR was indicated by pain from arthritis. The pain could not be controlled by conservative measures. X-rays were used during the follow-up period to look for implant loosening and position.

The most common reason for failure of the mobile-bearing knee replacements was loosening. Uncemented parts were more likely to come loose. Infection, fracture or dislocation of the polyethylene (plastic) liner, and instability were the other modes of failure reported.

The authors make note that fracture of the liner was the most common reason for implant failure after 10 years. In the LCS meniscal-bearing TKR, a bearing fracture occurs when the bearing is subluxed (shifted back) while the knee is bent.

The overall survival rates of the LCS TKR were 90 per cent at nine years and 71 per cent at 15 years. After 15 years, the survivor rates declined dramatically. These results are similar to reports by the groups who first designed and studied the LCS implant.

References: James M. Hartford, MD, et al. Primary Meniscal-Bearing Knee Replacements. In Clinical Orthopaedics and Related Research. Number 465. Pp. 227-231.

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