Ten-year survival and seven-year functional results of cementless Oxford unicompartmental knee replacement: A prospective consecutive series of our first 1000 cases.

BACKGROUND: Cementless fixation is an alternative to cemented unicompartmental knee replacement (UKR), with several advantages over cementation. This study reports the ten-year survival and seven-year clinical outcome of cementless Oxford unicompartmental knee replacement (OUKR).

METHODS: This prospective study describes the clinical outcome and survival of the first 1000 consecutive cementless medial OUKRs implanted at two centres for recommended indications.

RESULTS: The 10-year survival was 97% (CI 95%: 92-100%), with 25 knees being revised. The commonest reason for revision was progression of arthritis laterally, which occurred in nine knees, followed by primary dislocation of the bearing, which occurred in six knees. There were two dislocations secondary to trauma and a ruptured ACL, and two tibial plateau fractures. Although there were no definite cases of aseptic loosening, two early revisions were related to tibial fixation: one for pain and a radiolucent line and one for incomplete seating of the component with a radiolucent line. There were four revisions for pain, but the cause of the pain was uncertain: in one there was tibial overhang and in two there was patellofemoral degeneration, which possibly contributed to the pain. There were no deep infections. The mean OKS improved from 23 (SD 8) to 42 (SD 7) at a mean follow-up of 7.0 years (p < 0.001). There was no significant difference in survival or clinical outcome between the designer and independent centre.

CONCLUSIONS: The cementless OUKR is a safe and reproducible procedure with excellent 10-year survival and clinical results in the hands of both designer and independent surgeons.