Coronal Plane Alignment Phenotypes and Their Association with Anterior Cruciate Ligament Integrity and Medial Tibial Wear in Varus Knee Osteoarthritis: A Cross-sectional Study from Nepal

Aim and background: Coronal plane alignment influences knee biomechanics and has gained increasing importance in individualized alignment strategies for total knee arthroplasty (TKA).The coronal plane alignment of the knee (CPAK) classification provides a comprehensive description of constitutional alignment; however, data from the Indian subcontinent remain limited, and its relationship with anterior cruciate ligament (ACL) integrity and medial tibial wear has not been evaluated in the Nepali population.The study aimed to characterize CPAK phenotypes in Nepali patients undergoing primary TKA for varus knee osteoarthritis and determine their association with ACL integrity and medial tibial wear patterns.Materials and methods: This analytical cross-sectional study included 99 knees from 69 consecutive patients undergoing primary TKA for varus knee osteoarthritis at a tertiary referral center.Preoperative full-length standing radiographs were used to determine the lateral distal femoral angle, medial proximal tibial angle (MPTA), varus angle, joint line convergence angle, arithmetic hip-knee angle, and CPAK phenotype.Anterior cruciate ligament integrity and medial tibial wear pattern were assessed intraoperatively.Associations between radiographic variables, ACL status, and tibial wear were evaluated using univariable analyses and multivariable logistic regression.Results: Coronal plane alignment of the knee type I was the predominant phenotype (61.6%), followed by type IV (20.2%), type II (17.2%), and type V (1.0%).Anterior cruciate ligament insufficiency was identified in 36.4% of knees, while posteromedial tibial wear was present in 52.5%.Knees with posteromedial wear demonstrated significantly greater varus deformity, higher lateral distal femoral angle, lower MPTA, higher joint line convergence angle, and a higher prevalence of ACL insufficiency (all p < 0.001).Anterior cruciate ligament-insufficient knees exhibited greater coronal deformity, advanced osteoarthritis, and posteromedial wear significantly more frequently than ACL-intact knees (all p < 0.001).On multivariable logistic regression, increasing age (OR: 1.12; 95% CI: 1.03-1.22;p = 0.009), greater varus angle (OR: 1.20; 95% CI: 1.05-1.37;p = 0.008), and ACL insufficiency (OR: 32.4; 95% CI: 5.3-198.4;p < 0.001) were independent predictors of posteromedial tibial wear.Conclusion: Type I CPAK was predominant in Nepali patients undergoing primary TKA for varus knee osteoarthritis.Anterior cruciate ligament insufficiency was strongly associated with severe coronal deformity and emerged as the strongest independent predictor of posteromedial tibial wear.These findings enhance understanding of arthritic knee morphology and may improve preoperative assessment and surgical planning in TKA.Clinical significance: Recognition of CPAK phenotype together with radiographic indicators of ACL insufficiency and posteromedial tibial wear may facilitate preoperative planning, anticipation of soft-tissue balancing requirements, and intraoperative decision-making during TKA for varus knee osteoarthritis.