Correlation of External Rotational Alignment of the Tibial Component with 2-Year Clinical Outcomes after Guided-Motion Total Knee Arthroplasty

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BACKGROUND: Proper rotational alignment of the femoral and tibial components is critical for successful total knee arthroplasty (TKA). However, few studies have focused on the effect of external rotation of the tibial component on patient-reported outcomes after guided-motion TKA. This study assessed the association between tibial rotational alignment and patient-reported outcomes in patients with neutral alignment in all other planes. METHODS: This retrospective cohort study at a regional institutional hospital analyzed data from patients who underwent primary TKA for knee osteoarthritis and had no postoperative coronal malalignment, malrotation of the femoral component, internal tibial rotation, or component rotational mismatch. Rotational alignment of the tibial component was evaluated using computed tomography, and its association with postoperative 2011 Knee Society Score was evaluated using Spearman correlation analysis. RESULTS: The study included 32 knees from 32 patients. The tibial component was 4.8°±6.2° externally rotated postoperatively. An externally rotated tibial component was associated with a smaller flexion angle (at 6 months: r=0.37, p=0.04; at 2 years: r=0.43 p=0.02), lower objective score (at 2 years: r=0.32, p=0.02), symptoms (at 6 months: r=0.50, p=0.003), and satisfaction (at 6 months: r=0.37, p=0.04). CONCLUSIONS: Tibial rotational alignment may affect flexion angle and clinical outcomes of TKA. Excessive external rotation should be avoided in guided-motion prostheses. Future studies should attempt to identify thresholds for rotational alignment of the tibial component.

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