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Distal femoral deformity results in excessive internal rotation in patients after TKA
The presence of distal femoral deformity can result in excessive internal rotation of the femoral component, as well as a decrease in femoral anteversion of the lower extremity, according to results of this study.
In the study, 75 patients who underwent total knee arthroplasty (TKA) with image-free computer assisted navigation systems between January 2006 and January 2009 were grouped according to the presence of distal femoral deformity (DFD). The posterior condylar angle (PCA), the angle between the line which is perpendicular to the Whiteside’s line and posterior condylar line (PCL) and femoral anteversion (FA) were evaluated on a CT scan.
Researchers found a significant difference between the groups in postoperative femoral component rotation, with 80% of the femoral components rotated less than 5° from the reference transepicondylar axis in both groups. There was no significant difference between the groups in FA preoperatively. Postoperative FAs were significantly different between the groups with similar preoperative and postoperative FAs seen in the patients without DFD. However, the mean preoperative FA was 13.63° and the mean postoperative FA was 9.77° for patients with DFD. Range of motion and the Knee Society scores did not differ between the groups at final follow-up.
“The femoral anteversion should be taken into consideration when the rotational alignment of the femoral component is decided because significant change of femoral anteversion can occur after TKA,” the researchers stated. “Our study thus suggests that preoperative CT-based studies can be a reasonable option to decide femoral components rotation during TKA.”
Disclosure: The researchers had no relevant financial disclosures.