Is computer-assisted surgery in total knee arthroplasty as accurate as it can be?

Three hundred and eighty computer-assisted total knee arthroplasty cases were reviewed for accuracy of mechanical alignment. The 331 patients in the first set, designated Group A, showed a consistent valgus error of 1 degrees from neutral alignment. It was hypothesized that a manual 1 degrees varus correction during femur resection would yield a significantly greater level of accuracy in the second set of 49 patients, designated Group B. A mechanical alignment of +/- 3 degrees was achieved in 91% of the uncalibrated Group A patients, which was significantly lower (p = 0.035) than the rate of 98% achieved in the calibrated Group B. Further statistical analysis of the data showed the time expenditure was not significantly changed once a new target value was recalibrated. By quantifying mean errors of measures at an early timeframe, enhanced accuracy in CAS can be achieved.