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. 2020 May;28(5):1479-1487.
doi: 10.1007/s00167-019-05544-w. Epub 2019 Jun 17.

Ten-year clinical and radiographic results of 1000 cementless Oxford unicompartmental knee replacements

Hasan R Mohammad  1   2 , James A Kennedy  3   4 , Stephen J Mellon  3 , Andrew Judge  3 , Christopher A Dodd  4 , David W Murray  3   4
Affiliations

Ten-year clinical and radiographic results of 1000 cementless Oxford unicompartmental knee replacements

Hasan R Mohammad et al. Knee Surg Sports Traumatol Arthrosc. 2020 May.

Abstract

Purpose: Unicompartmental knee replacement (UKR) has substantial benefits over total knee replacement (TKR) but has higher revision rates. The cementless Oxford UKR was introduced to address this but there are concerns about fixation and tibial plateau fractures. The first long-term study of the device with clinical and radiographic outcomes is reported.

Methods: The first 1000 medial cementless Oxford UKR were prospectively identified and followed up by independent physiotherapists. Survival was calculated using the endpoints reoperation, revision, revision to TKR, major revision requiring revision TKR components and patient mortality. The Oxford Knee Score (OKS), Tegner Activity Score and American Knee Society Score (AKSS) were recorded and radiographs analysed.

Results: The ten year survival was 96.6% (CI 94.8-97.8), 97.5% (CI 95.7-98.5), 98.9% (CI 97.7-99.4) and 99.6% (CI 98.8-99.9) using reoperation, revision, revision to TKR and major revision as the endpoint, respectively. Commonest causes for revision were bearing dislocation (n = 7, 0.7%), disease progression (n = 4, 0.4%) and pain (n = 2, 0.2%). There was one lateral tibial plateau fracture and one femoral component loosening. At 10 years, the mean OKS was 41.2 (SD 9.8), Tegner 2.8 (SD 1.3), AKSS-O 89.1 (SD 13.0) and AKSS-F 80.4 (SD 14.6). There were no pathological radiolucencies or complete radiolucent lines. There were no implant-related deaths.

Conclusions: The cementless Oxford UKR is a safe procedure with excellent long-term clinical results. Our results suggest that reliable fixation was achieved with only one (0.1%) revision for loosening (femoral), no radiographic evidence of loosening in the remaining cases and no fractures related to implantation.

Level of evidence: III.

Keywords: Cementless fixation; Long-term outcomes; Unicompartmental knee replacement.

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Conflict of interest statement

Hasan R Mohammad: Henni Mester Scholarship from University of Oxford and Institutional grant to University of Oxford from Zimmer Biomet; Christopher Dodd: Royalties, consultancy payments related to knee replacements—Zimmer Biomet; James Kennedy: Institutional grant—Grant to University of Oxford from Zimmer Biomet; David Murray: Royalties, consultancy payments related to knee replacements—Zimmer Biomet and Institutional grant—To University of Oxford from Zimmer Biomet. Andrew Judge and Stephen Mellon have no potential conflict of interest.

Figures

Fig. 1
Fig. 1
Zones assessed for radiolucencies on radiographs. a Anteroposterior radiograph, b lateral radiograph
Fig. 2
Fig. 2
Implant survival based on revision as the endpoint
Fig. 3
Fig. 3
Patient survival in the cementless cohort
Fig. 4
Fig. 4
Worst tibial radiolucency observed in the cohort
See this image and copyright information in PMC

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