Influence of total knee arthroplasty approaches on component positioning

Purpose: The aim of this study was to evaluate the influence of subvastus and medial parapatellar total knee arthroplasty approaches on component positioning and to explore the possible negative effects of potentially more restrictive approaches especially in highly deformed knees. Materials and Methods: 88 knees of 84 patients (46 knees operated with medial parapatellar approach (group 1), and 46 knees operated with subvastus approach (group 2)) who had undergone total knee arthroplasty. The patients were also regrouped according to their preoperative mechanical axis deviations. Postoperative femoral and tibial component positioning on frontal and sagittal planes were evaluated. Results: Frontal femoral (alpha) and tibial (beta) component angles as well as sagittal femoral and tibial component angles were not significantly different between two groups (mean values of alpha of groups 1&2: 96.79 +/- 2.86 degrees and 96.81 +/- 3.22 degrees, respectively, of beta 89.07 degrees +/- 3.45 degrees and 89.97 degrees +/- 3.00 degrees respectively, of sagittal femoral angle 4.85 degrees +/- 3.84 degrees and 3.31 degrees +/- 3.58 degrees, respectively, of sagittal tibial angle 5.10 degrees +/- 3.88 degrees and 4.08 degrees +/- 3.18 degrees, respectively). Postoperatively, posterior tibial slope was significantly decreased in both groups. Conclusion: None of the total knee arthroplasty approaches tested in this study found to exert a significant effect on component positioning even in highly deformed knees. The components can be placed properly utilizing both approaches.