Retrospective Cohort Study
Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Orthop. Apr 18, 2016; 7(4): 251-257
Published online Apr 18, 2016. doi: 10.5312/wjo.v7.i4.251
Promising short-term clinical results of the cementless Oxford phase III medial unicondylar knee prosthesis
Karin B van Dorp, Stefan JM Breugem, Daniël J Bruijn, Marcel JM Driessen
Karin B van Dorp, Stefan JM Breugem, Daniël J Bruijn, Marcel JM Driessen, Orthopedium Clinics, 2616 LS Delft, Zuid-Holland, the Netherland
Author contributions: All the authors contributed equally to this paper.
Institutional review board statement: The study was reviewed and approved by the medical research ethics board of Rotterdam.
Informed consent statement: All study participants provided informed written consent prior to study enrollment.
Conflict-of-interest statement: All the authors declare not to have a conflict of interest related to the manuscript.
Data sharing statement: All study participants agreed with anonymous data sharing. The original anonymous dataset is available on request from the corresponding author.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Karin B van Dorp, MD, Orthopedium Clinics, Olof Palmerstraat 20, 2616 LS Delft, Zuid-Holland, the Netherland. k.b.vandorp@gmail.com
Telephone: +31-8-80088444 Fax: +31-8-80088445
Received: May 29, 2015
Peer-review started: June 1, 2015
First decision: August 25, 2015
Revised: December 17, 2015
Accepted: January 8, 2016
Article in press: January 11, 2016
Published online: April 18, 2016
Abstract

AIM: To investigate the short-term clinical results of the Oxford phase III cementless medial unicondylar knee prosthesis (UKP) compared to the cemented medial UKP.

METHODS: We conducted a cross-sectional study in a tertairy orthopedic centre between the period of May 2010 and September 2012. We included 99 medial UKP in 97 patients and of these UKP, 53 were cemented and 46 were cementless. Clinical outcome was measured using a questionnaire, containing a visual analogue scale (VAS) for pain, Oxford Knee score, Kujala score and SF-12 score. Knee function was tested using the American Knee Society score. Complications, reoperations and revisions were recorded. Statistical significance was defined as a P value < 0.05.

RESULTS: In a mean follow-up time of 19.5 mo, three cemented medial UKP were revised to a total knee prosthesis. Reasons for revision were malrotation of the tibial component, aseptic loosening of the tibial component and progression of osteoarthritis in the lateral- and patellofemoral compartment. In five patients a successful reoperation was performed, because of impingement or (sub)luxation of the polyethylene bearing. Patients with a reoperation were significant younger than patients in the primary group (56.7 vs 64.0, P = 0.01) and were more likely to be male (85.7% vs 38.8%, P = 0.015). Overall the cementless medial UKP seems to perform better, but the differences in clinical outcome are not significant; a VAS pain score of 7.4 vs 11.7 (P = 0.22), an Oxford Knee score of 43.3 vs 41.7 (P = 0.27) and a Kujala score of 79.6 vs 78.0 (P = 0.63). The American Knee Society scores were slightly better in the cementless group with 94.5 vs 90.2 (P = 0.055) for the objective score and 91.2 vs 87.8 (P = 0.25) for the subjective score.

CONCLUSION: The cementless Oxford phase III medial UKP shows good short-term clinical results, when used in a specialist clinic by an experienced surgeon.

Keywords: Knee osteoarthritis, Unicondylar knee arthroplasty, Cementless, Treatment outcome, Reoperation

Core tip: The higher revision rate in unicondylar knee arthroplasty compared to total knee arthroplasty is a concern. The cementless unicondylar knee prosthesis (UKP) eliminates one of the technical errors related to failure; the cementing technique. The cementless Oxford UKP also shows reduced radiolucent lines at one year follow-up, whereas the cemented UKP shows occurrence of radiolucent lines. The developing hospital has published encouraging results of the cementless Oxford phase III medial UKP. In our independent retrospective cohort study we observed three revisions of cemented UKP. There were five successful reoperations. The cementless UKP seems to perform better, but no significant difference could be found.