• Orthop Traumatol Sur · Oct 2019

    Impact of preoperative varus deformity on postoperative mechanical alignment and long-term results of "mechanical" aligned total knee arthroplasty.

    • Sung-Mok Oh, Seong-Il Bin, Jae-Young Kim, Bum-Sik Lee, and Jong-Min Kim.
    • Department of Orthopedic Surgery, Nanoori Incheon Hospital, 156, Jange-ro, Bupyung-gu, 21353 Incheon, Republic of Korea.
    • Orthop Traumatol Sur. 2019 Oct 1; 105 (6): 1061-1066.

    PurposePreoperative varus deformity may affect postoperative mechanical alignment and outcomes of total knee arthroplasty (TKA). In this study, we aimed to determine whether (1) greater degrees of preoperative varus deformity increase the incidence of varus-aligned TKAs and (2) residual varus alignment improves the long-term survival rate in TKAs with preoperative varus deformity.MethodsWe retrospectively reviewed 905 primary TKAs for varus-type osteoarthritis from November 1998 to June 2009. The mean follow-up was 8.23 years (±3.47 years). We measured pre- and postoperative mechanical hip-knee-ankle axis angle (HKA) on full-length standing radiographs to assess the severity of preoperative varus deformities, defined as mild (0°15°). Postoperative alignment was divided to four groups: valgus (HKA<-3°), neutral (-3°≤HKA≤3°), mild varus (3°6°). We performed survival analysis in all cases for mechanical failure.ResultsVarus-aligned TKAs increased proportionally to increasing preoperative varus deformity (p<0.001). The survival rate showed no significant difference according to the preoperative varus deformity (p=0.147). However, the survival time for postoperative neutral alignment (16.13±0.10 years, 95% CI 15.94-16.33 years) was longer than the survival time for mild varus (15.32±0.35 years, 95% CI 14.64-16.00 years) and severe varus (13.38±0.53 years, 95% CI 12.35-14.42 years) alignment (p<0.001).ConclusionPostoperative varus malalignment appears to increase proportionally to the severity of preoperative varus deformity. Also, postoperative neutral alignment results in longer TKA survival time than residual varus alignment.Level Of EvidenceIII, Retrospective comparative cohort study.Copyright © 2019 Elsevier Masson SAS. All rights reserved.

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