Knee Arthroplasty Component Malrotation Does Not Affect Function or Quality of Life in the Short to Medium Term

Background: Component rotation in total knee arthroplasty is thought to affect patella tracking, flexion gap, and balancing and hence is hypothesized to affect function, pain, and longevity. Few studies have directly correlated post-operative component rotation to function and quality of life in the short to medium term post-operatively, with findings in the current literature conflicting. Methods: A retrospective study of prospectively collected data was used to determine the effect of femoral, tibial, and combined component rotation in primary total knee arthroplasty with primary outcomes being function as measured by the Knee Society Score, pain and quality of life as measured by the Short-Form 12 score, and secondary outcome being prosthesis failure. Malrotation was defined using the current literature as being internally rotated from neutral, or externally rotated greater than 5 degrees for the femoral component, internally rotated greater than 6 degrees for the tibial component, or internally rotated from neutral for the 2 components combined. Results: No clinically relevant correlation between function or quality of life and component rotation could be found at 5 years. However, it was noted that those patients with combined component malrotation ( femoral rotation added to tibial rotation resulting in overall component internal rotation) improved less in overall pain scores than those that were not malrotated. Conclusion: In the mid-term, component malrotation may result in a decreased level of improvement from pain compared to pre-operative results. However, component malrotation does not make a significant difference to function or quality of life. (c) 2019 Elsevier Inc. All rights reserved.