Clinical Orthopaedics and Related Research®

, Volume 471, Issue 11, pp 3533–3539

The Oxford Unicompartmental Knee Fails at a High Rate in a High-volume Knee Practice

Authors

    • St Louis Joint Replacement Institute, SSM DePaul Health Center
  • C. Lowry Barnes
    • Arkansas Specialty Orthopaedics
  • Paul Diesfeld
    • St Louis Joint Replacement Institute, SSM DePaul Health Center
  • Angela LeMarr
    • St Louis Joint Replacement Institute, SSM DePaul Health Center
  • Rachel Ingrassia
    • St Louis Joint Replacement Institute, SSM DePaul Health Center
  • Diane J. Morton
    • St Louis Joint Replacement Institute, SSM DePaul Health Center
  • Mary Reedy
    • St Louis Joint Replacement Institute, SSM DePaul Health Center
Clinical Research

DOI: 10.1007/s11999-013-3174-5

Cite this article as:
Schroer, W.C., Barnes, C.L., Diesfeld, P. et al. Clin Orthop Relat Res (2013) 471: 3533. doi:10.1007/s11999-013-3174-5

Abstract

Background

The Oxford knee is a unicompartmental implant featuring a mobile-bearing polyethylene component with excellent long-term survivorship results reported by the implant developers and early adopters. By contrast, other studies have reported higher revision rates in large academic practices and in national registries. Registry data have shown increased failure with this implant especially by lower-volume surgeons and institutions.

Questions/purposes

In the setting of a high-volume knee arthroplasty practice, we sought to determine (1) the failure rate of the Oxford unicompartmental knee implant using a failure definition for aseptic loosening that combined clinical features, plain radiographs, and scintigraphy, and (2) whether increased experience with this implant would decrease failure rate, if there is a learning curve effect.

Methods

Eighty-three Oxford knee prostheses were implanted between September 2005 and July 2008 by the principal investigator. Radiographic and clinical data were available for review for all cases. A failed knee was defined as having recurrent pain after an earlier period of recovery from surgery, progressive radiolucent lines compared with initial postoperative radiographs, and a bone scan showing an isolated area of uptake limited to the area of the replaced compartment.

Results

Eleven knees in this series failed (13%); Kaplan-Meier survivorship was 86.5% (95% CI, 78.0%–95.0%) at 5 years. Failure occurrences were distributed evenly over the course of the study period. No learning curve effect was identified.

Conclusions

Based on these findings, including a high failure rate of the Oxford knee implant and the absence of any discernible learning curve effect, the principal investigator no longer uses this implant.

Level of Evidence

Level III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Copyright information

© The Association of Bone and Joint Surgeons® 2013