Cementless fixation is an alternative to cemented unicompartmental knee replacement (UKR), with several advantages over cementation. This study reports on the 15-year survival and 10-year clinical outcomes of the cementless Oxford unicompartmental knee replacement (OUKR). This prospective study describes the clinical outcomes and survival of first 693 consecutive cementless medial OUKRs implanted in New Zealand. The sixteen-year survival was 89.2%, with forty-six knees being revised. The commonest reason for revision was progression of arthritis, which occurred in twenty-three knees, followed by primary dislocation of the bearing, which occurred in nine knees. There were two bearing dislocations secondary to trauma and a ruptured ACL, and two tibial plateau fractures. There were four revisions for polyethylene wear. There were four revisions for aseptic tibial loosening, and one revision for impingement secondary to overhang of the tibial component. There was only one revision for deep infection and one revision where the indication was not stated. The mean OKS improved from 23.3 (7.4 SD) to 40.59 (SD 6.8) at a mean follow-up of sixteen years. In conclusion, the cementless OUKR is a safe and reproducible procedure with excellent sixteen-year survival and clinical outcomes

Introduction. The precise indications for tibial component metal backing and modularity remain controversial in routine primary total knee arthroplasty. This is particularly true in elderly patients where the perceived benefits of metal backing such as load redistribution and the reduction of polyethylene strain may be clinically less relevant. The cost implications for choosing a metal-backed design over an all-polyethylene design may exceed USD500 per primary knee arthroplasty case. Methods. A prospective randomised clinical trial was carried out at the QEII Health Sciences Centre, Halifax, Nova Scotia, to compare modular metal-backed versus an all-polyethylene tibial component. Outcome measures included clinical range of motion, radiographs, survivorship, Knee Society Clinical Rating System, WOMAC and SF-12. Results. 116 patients requesting primary knee arthroplasty were recruited and randomised between the Smith & Nephew Genesis I non-modular (57) and modular (59) tibial designs between September 1995 and August 1997. At 10 years clinical follow-up, 4 implant revisions or intention-to-revise decisions were recorded in the metal-tray/modular group of which 2 were for aseptic tibial component loosening. 2 implant revisions in the all-polyethylene non-modular group were recorded, neither of which were for tibial component loosening. At 5, 7 and 10 year review; the KSCRS, WOMAC and SF12 scores were similar in both groups. As most patients randomised were over seventy years of age, this impacted significantly on the numbers available for longer term review and data was analysed by comparing pre- and post-operative scores for individual patients. Conclusion. There was no difference in performance between the all-polyethylene tibial component and the metal-backed tibial component. The case for using the all-polyethylene tibia in elderly patients is justified on both clinical efficacy and cost-containment grounds