Minimally invasive total knee arthroplasty: comparison of jig-based technique versus computer navigation for clinical and alignment outcome.

Objective: Correct alignment of the leg and positioning of the components are important factors in good long-term outcome of total knee arthroplasty (TKA). Computer-assisted navigation systems were introduced to improve component alignment accuracies. The three main hypotheses of this study were that the navigated compared to jig-based patient will show the following: (1) No difference in clinical outcomes. (2) Better alignment in the frontal and sagittal plane. (3) Better rotational positioning of components.

Methods: The authors evaluated 100 patients who had minimally invasive TKA using either an image-free computer-assisted navigation system (n=50) or a jig-based technique (n=50). Six months postoperatively, clinical and radiological evaluations were performed using full-length standing anteroposterior and lateral radiographs and CT scans of the knee.

Results: Knee Society knee score, function score, and range of motion were comparable in the two groups after surgery. The percentage of patients with a frontal tibiofemoral angle within ±3° of the ideal was significantly higher in the navigated group than in the jig-based group (94% vs. 78%, respectively; P=0.041). No significant differences were found between groups in terms of the frontal and sagittal planes as well as rotational alignment of the femoral or tibial components.

Conclusions: Computer-assisted TKA gives a better correction of alignment of the leg compared with jig-based TKA when combined with a minimally invasive surgical approach.