Does Femoral Component Rotation Matter in Functionally Aligned Total Knee Arthroplasty? The Effect of Deviations From the Transepicondylar Axis on Patient-Reported Outcomes at 1 Year

John E. Farey; Jordan Chew; Jil A. Wood; Darren B. Chen; Samuel J. Macdessi

doi:10.1055/a-2693-0881

The Journal of Knee Surgery, Table of Contents

J Knee Surg
DOI: 10.1055/a-2693-0881

Original Article

Does Femoral Component Rotation Matter in Functionally Aligned Total Knee Arthroplasty? The Effect of Deviations From the Transepicondylar Axis on Patient-Reported Outcomes at 1 Year

Authors

John E. Farey

¹Sydney Knee Specialists, Kogarah, New South Wales, Australia
Jordan Chew

¹Sydney Knee Specialists, Kogarah, New South Wales, Australia
Jil A. Wood

¹Sydney Knee Specialists, Kogarah, New South Wales, Australia
Darren B. Chen

¹Sydney Knee Specialists, Kogarah, New South Wales, Australia
Samuel J. Macdessi

¹Sydney Knee Specialists, Kogarah, New South Wales, Australia

²Department of Medicine, University of New South Wales, Medicine and Health, Sydney, Australia

Abstract

Femoral component rotation (FCR) in total knee arthroplasty (TKA) is critical for flexion balance and patellofemoral tracking. Deviations from the transepicondylar axis (TEA) have been linked to poor outcomes. This study aimed to assess the impact of FCR on patient-reported outcomes in functionally aligned (FA) TKAs. A total of 448 robotic-assisted FA TKAs with preresection gap balancing were performed in 393 patients between June 1, 2018, and December 31, 2021. Demographic, radiographic, and patient-reported outcome measures (PROMs) were prospectively collected at baseline and 1 year postoperatively. FCR was set within a range of ± 6 degrees relative to the TEA as part of an FA TKA alignment strategy. The primary outcome was the relationship between final intraoperative FCR and PROMs at 1 year, including the Knee injury and Osteoarthritis Outcome Score-12 (KOOS-12) and the EuroQol 5-Dimension-5-Level (EQ5D-5L) score. Mean FCR was 0.0 degrees (SD ± 2.1 degrees, range: −5.8 to 7.0 degrees). At 1 year, KOOS-12 increased by a mean of 44.1 points (p < 0.01), and EQ5D-5L by 7.6 points (p < 0.01). No significant correlation was found between FCR and KOOS-12 (r = −0.09, p = 0.3). A weak negative correlation existed between increasing external FCR and EQ5D-5L (r = −0.12, p = 0.03). Categorizing FCR into internal (<-2 degrees), neutral (± 2 degrees), and external rotation (≥2 degrees) showed no significant differences in outcomes. FA TKA leads to significant improvements in PROMs, regardless of FCR within a functional range, at 1 year postoperatively. The study is a cross-sectional study providing Level III evidence.

Keywords

alignment - arthroplasty - femoral component rotation - functional alignment - robotic

Full Text

References

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