One long-held tenet of total knee arthroplasty is that implant durability is maximized when postoperative limb alignment is corrected to 0° ± 3° relative to the mechanical axis. Recently, substantial health-care resources have been devoted to computer navigation systems that allow surgeons to more often achieve that alignment. We hypothesized that a postoperative mechanical axis of 0° ± 3° would result in better long-term survival of total knee arthroplasty implants as compared with that in a group of outliers.
At the time of the latest follow-up, 45 (15.4%) of the 292 implants in the mechanically aligned group had been revised for any reason, compared with 14 (13%) of the 106 implants in the outlier group (p = 0.88); 27 (9.2%) of the 292 implants in the mechanically aligned group had been revised because of aseptic loosening, mechanical failure, wear, or patellar problems, compared with 8 (7.5%) of the 106 implants in the outlier group (p = 0.88); and 17 (5.8%) of the 292 implants in the mechanically aligned group had been revised because of aseptic loosening, mechanical failure, or wear, compared with 4 (3.8%) of the 106 implants in the outlier group (p = 0.49).
A postoperative mechanical axis of 0° ± 3° did not improve the 15-year implant survival rate following these 398 modern total knee arthroplasties. We believe that describing alignment as a dichotomous variable (aligned versus malaligned) on the basis of a mechanical axis goal of 0° ± 3° is of little practical value for predicting the durability of modern total knee arthroplasty implants.
Copyright remains with the authors and publisher.
One long-held tenet of total knee arthroplasty is that implant durability is maximized when postoperative limb alignment is corrected to 0° ± 3° relative to the mechanical axis. Recently, substantial health-care resources have been devoted to computer navigation systems that allow surgeons to more often achieve that alignment. We hypothesized that a postoperative mechanical axis of 0° ± 3° would result in better long-term survival of total knee arthroplasty implants as compared with that in a group of outliers.
At the time of the latest follow-up, 45 (15.4%) of the 292 implants in the mechanically aligned group had been revised for any reason, compared with 14 (13%) of the 106 implants in the outlier group (p = 0.88); 27 (9.2%) of the 292 implants in the mechanically aligned group had been revised because of aseptic loosening, mechanical failure, wear, or patellar problems, compared with 8 (7.5%) of the 106 implants in the outlier group (p = 0.88); and 17 (5.8%) of the 292 implants in the mechanically aligned group had been revised because of aseptic loosening, mechanical failure, or wear, compared with 4 (3.8%) of the 106 implants in the outlier group (p = 0.49).
A postoperative mechanical axis of 0° ± 3° did not improve the 15-year implant survival rate following these 398 modern total knee arthroplasties. We believe that describing alignment as a dichotomous variable (aligned versus malaligned) on the basis of a mechanical axis goal of 0° ± 3° is of little practical value for predicting the durability of modern total knee arthroplasty implants.
Copyright remains with the authors and publisher.