Surgical and clinical impact of arithmetic hip-knee-ankle angle and joint line obliquity changes in total knee arthroplasty with hybrid adjusted mechanical alignment

초록

Background: This study aimed (1) to evaluate changes in and restoration of arithmetic hip-knee-ankle angle (aHKA), joint line obliquity (JLO), and coronal plane alignment of the knee (CPAK) phenotype following total knee arthroplasty using hybrid adjusted mechanical alignment (aMA-TKA), and (2) to determine whether these parameters affect soft tissue release or clinical outcomes. Methods: This retrospective study analyzed 200 TKAs performed with hybrid aMA, comprising 100 cases from 2020 and 100 cases from 2023 to assess reproducibility over time. Radiographic parameters-including aHKA, JLO, and CPAK type-were assessed preoperatively and at >= 2 years postoperatively. We investigated whether soft tissue release was performed. The impact of changes in aHKA, JLO, and CPAK type on the requirement for soft tissue release and on clinical outcomes was analyzed. Results: Across both cohorts, hybrid aMA-TKA produced consistent changes in aHKA, JLO, and CPAK type. Postoperatively, 69% of knees were within classic aMA boundaries and 76.5-99% within restricted kinematic alignment boundaries. CPAK restoration was rare (n = 5). Out of 200 knees, medial soft tissue release was required in 32. Logistic regression analyses showed that change in aHKA was the only significant predictor of medial soft tissue release (odds ratio = 1.253, p < 0.001), whereas changes in aHKA, JLO, and CPAK type were not associated with Western Ontario and McMaster Universities Osteoarthritis Index score and range of motion. Conclusion: These results support targeting the preoperative aHKA within defined coronal boundaries as a consistent and pragmatic alignment strategy in the hybrid aMA-TKA. Level of evidence: III. (c) 2026 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

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