Total knee arthroplasty with conventional or navigated technique: comparison of the learning curves in a community hospital.

We performed a comparative study of the short-term radiological and clinical results after implantation of an unconstrained TKA with preservation of the posterior cruciate ligament with a conventional (50 cases--group A) or navigated (50 cases--group B) technique. The primary criterion was the postoperative leg coronal alignment measured on 3-month postoperative anteroposterior long-leg radiographs by the HKA angle: the expected alignment was 180 degrees +/- 3 degrees. The mean post-operative HKA angle was 180 degrees +/- 3 degrees in group A and 180 degrees +/- 1 degrees in group B (p = 0.15). Thirty-four cases in group A and all 50 cases in group B were in the desired range (p < 0.001). The navigated system used in this study allowed for a significantly better alignment accuracy than the conventional implantation technique. Acceptable routine implantation was achieved during the time of the study (first 50 cases). We can thus hypothesise that the learning curve of the navigated technique used is not any longer than the learning curve of a conventional implantation technique.