Computer navigation for total knee arthroplasty achieves better postoperative alignment compared to conventional and patient-specific instrumentation in a low-volume setting

Background: Procedure volume is an important determinant of total knee arthroplasty (TKA) outcomes. We aimed to determine whether computer navigation or patient-specific instrumentation (PSI) would improve postoperative alignment in a low-volume setting. Hypothesis: PSI for TKA achieves better limb and implant alignment compared to conventional TKA and to computer navigated TKA. Materials and methods: This is a retrospective cohort study of 385 primary TI(As (Women = 59%. Mean age = 67 years. Mean BMI =30.1 kg/m(2)), which were performed using conventional instrumentation (n= 117; 30%), computer navigation (n= 209; 54%), or patient-specific instrumentation (n= 59; 15%) in a low-volume center (< 50 TKAs/year). The risk of postoperative leg and implant mechanical alignment outliers in the coronal plane (>3 degrees from neutral), average alignment and operation time were assessed. Results: The risk of postoperative mechanical alignment outliers (>3 degrees) was reduced by 89% in the navigated group (4% outliers) compared to the conventional group (35%) (RR = 0.11; p < 0.0001). No significant improvement was observed in the PSI group (27%) (RR = 0.91; p = 0.772). The risk of postoperative femoral component coronal alignment outliers was reduced by 63% in the navigated group (11%) compared to the conventional group (31%) (RR= 0.37; p = 0.018). No significant reduction in outliers was observed in the PSI group (32%) (RR= 1.08; p = 0.816). There was a reduction in the risk of tibial component coronal malalignment of 66% in the navigated group (5%) compared to the conventional group (13%) (RR= 0.33; p = 0.070). There was a two-fold increase in the risk of tibial component alignment outliers in the PSI group (29%) (RR= 1.94; p = 0.110). Discussion: Computer navigation improved postoperative alignment in TKA. No evidence of improved alignment was seen with patient-specific instrumentation. The routine use of patient-specific instrumentation in low-volume centers is not supported by the currently available data. Type of study: Retrospective cohort study. (C) 2018 Elsevier Masson SAS. All rights reserved.