MALALIGNMENT AFTER UNICOMPARTMENTAL ARTHROPLASTY DOES IT MATTER?

Gulati A, Jenkins C, Chau R, et al. MALALIGNMENT AFTER UNICOMPARTMENTAL ARTHROPLASTY DOES IT MATTER?. Orthop Procs. 2009;91-B(SUPP_III):412-412. doi:10.1302/0301-620X.91BSUPP_III.0910412b

Gulati, A, et al. “MALALIGNMENT AFTER UNICOMPARTMENTAL ARTHROPLASTY DOES IT MATTER?.” Orthopaedic Proceedings, vol. 91-B, no. SUPP_III, 2009, pp. 412-412., https://doi.org/10.1302/0301-620X.91BSUPP_III.0910412b

Gulati, A., Jenkins, C., Chau, R., Pandit, H. G., Dodd, C. A. F., Price, A. J., Simpson, D. J., Beard, D. J., Gill, H. S., & Murray, D. W. (2009). MALALIGNMENT AFTER UNICOMPARTMENTAL ARTHROPLASTY DOES IT MATTER?. Orthopaedic Proceedings, 91-B(SUPP_III), 412-412. https://doi.org/10.1302/0301-620X.91BSUPP_III.0910412b

Gulati, A., Jenkins, C., Chau, R., Pandit, H. G., Dodd, C. A. F., Price, A. J. et al. (2009) “MALALIGNMENT AFTER UNICOMPARTMENTAL ARTHROPLASTY DOES IT MATTER?.” Orthopaedic Proceedings, 91-B(SUPP_III), pp. 412-412. Available at: https://doi.org/10.1302/0301-620X.91BSUPP_III.0910412b

Gulati, A, C Jenkins, R Chau, H G Pandit, C A F Dodd, A J Price, D J Simpson, D J Beard, H S Gill, and D W Murray. “MALALIGNMENT AFTER UNICOMPARTMENTAL ARTHROPLASTY DOES IT MATTER?.” Orthopaedic Proceedings 91-B, no. SUPP_III (2009): 412-412. https://doi.org/10.1302/0301-620X.91BSUPP_III.0910412b

Gulati A, Jenkins C, Chau R, Pandit HG, Dodd CAF, Price AJ, et al. MALALIGNMENT AFTER UNICOMPARTMENTAL ARTHROPLASTY DOES IT MATTER?. Orthop Procs. 2009 Sep 1;91-B(SUPP_III):412-412. https://doi.org/10.1302/0301-620X.91BSUPP_III.0910412b

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Abstract

Purpose: Varus deformity after total knee replacement (TKR) is associated with poor outcome. This aim of this study was to determine whether the same is true for medial unicompartmental arthroplasty (UKA).

Methods: 158 patients implanted with the Oxford UKA, using a minimally invasive approach, were studied prospectively for five years. Leg alignment was measured with a long-arm goniometer referenced from Anterior Superior Iliac Spine, centre of patella and centre of ankle. Patients were grouped according to the American Knee Society Score (AKSS). Group A: > 0° varus (n=13, 8.2%); Group B: 0 to 4° valgus (n=39, 24.7%); Group C: 5–10° valgus (normal alignment, n=106, 67.12%). Comparisons were made between the three groups in terms of the absolute and the change in Oxford Knee Score (OKS) and AKSS over the five year period, and the presence of radiolucency.

Results: There was no significant difference in any outcome measure except for Objective-AKSS (p< 0.001). The means and standard deviations of the ΔOKS for the groups were:

24 ± 5,
22 ± 10, and
22 ± 9 and for Objective-AKSS were 84 ± 12, 82 ± 15 and 91 ± 11 respectively.

The frequency of five year radiolucency for the groups A, B, and C were 42%, 35%, and 45% respectively.

Conclusion: The aim of the Oxford UKA is to restore knee kinematics and thus knee alignment to the pre-disease state. Therefore, as demonstrated by this study, about 30% of patients have varus alignment. This study also demonstrates that post-operative varus alignment does not compromise the outcome. The only score which did show worse outcome was the Objective-AKSS. This is because 10 or 20 points are deducted for varus alignment, which is not appropriate following UKA. Therefore, AKSS in its present form is not a reliable tool for assessment of UKA.

Correspondence should be addressed to Mr T Wilton, c/o BOA, BASK at the Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PE, England.