Comparison with Navigation of a Novel Three-Step Technique for Improving Accuracy of the Distal Femoral Resection during Conventional TKA: A Case-Control Study.

Abstract

Correct placement of the femoral component in the coronal plane during primary total knee arthroplasty (TKA) is related to long-term survival. The aim of this radiographic study was to determine the accuracy of a novel three-step technique for improving the accuracy of the distal femoral cut during conventional technique and compare it with computer navigation during TKA. A total of 458 TKAs were retrospectively analyzed (178 conventional TKAs with the novel technique and 280 navigated TKAs) for postoperative femoral component coronal alignment and compared between the two groups. Mean femoral component coronal alignment was not significantly different (p\u2009=\u20090.314) between the two groups. There was no significant difference in the mean femoral component coronal alignment between varus and valgus knees. The number of outliers (90\u2009±\u20093\u2009degrees) for femoral component coronal alignment was not significantly different between the two groups when assessed separately for varus and valgus deformities. The mean value of femoral component alignment using the conventional technique in knees with varus deformity <10\u2009degrees was 88.8\u2009degrees, in knees with varus deformity 10 to 20\u2009degrees was 89.4\u2009degrees, and in those with varus deformity >20\u2009degrees was 90.2\u2009degrees. Femoral component alignment in knees with varus <10\u2009degrees was significantly different from those >20\u2009degrees (p\u2009=\u20090.006); there was no significant difference between knees with varus <10\u2009degrees and those with 10 to 20\u2009degrees varus (p\u2009=\u20090.251), nor between 10 and 20\u2009degrees varus knees and those with varus >20\u2009degrees (p\u2009=\u20090.116). Using the novel three-step technique during conventional TKA to perform the distal femoral cut can help achieve femoral component coronal alignment comparable to the navigation technique.