Long-term outcomes of the cementless Oxford Unicompartmental Knee Replacement: a 16-year follow-up study.

AIMS: Cementless fixation is an alternative to cemented unicompartmental knee arthroplasty (UKA), with several advantages over cementation. This study reports on the 16-year survival and ten-year clinical and radiological outcomes of the cementless Oxford Unicompartmental Knee Replacement (OUKR).

METHODS

This is a prospective study of the first 693 consecutive cementless medial OUKRs implanted in New Zealand.

RESULTS

The 16-year survival was 89.2%, with 46 knees being revised. The most common reason for revision was progression of arthritis, which occurred in 24 knees. The other reasons for revision included ten bearing dislocations, eight of which were for trauma, one ruptured anterior cruciate ligament (ACL), two tibial plateau fractures, three cases of polyethylene wear, three cases of aseptic loosening, one impingement secondary to overhang of the tibial component, one deep infection, and one revision where the reason was not stated. At the 14 to 16 years survey, the mean Oxford Knee Score (OKS) improved from 23.3 (SD 7.4) to 40.59 (SD 6.8). Radiological analysis at ten years demonstrated no evidence of femoral loosening, subsidence, or radiolucent lines. There were 42 complete radiolucent lines in zone 7 around the tibial baseplate, and ten incomplete radiolucent lines seen in other tibial zones with no progression.

CONCLUSION

The cementless OUKR is a safe and reproducible procedure with excellent 16-year survival, clinical outcomes, and radiological outcomes in the hands of surgeons who are independent of the design centre.