Abstract
BACKGROUND: The Coronal Plane Alignment of the Knee (CPAK) classification describes knee phenotypes based on limb alignment and joint-line obliquity (JLO). This study evaluates CPAK distribution in the Hong Kong population and assesses how prosthesis design affects CPAK reproducibility and clinical outcomes. METHODS: This retrospective study included patients who underwent navigated total knee arthroplasty (TKA) with adjusted mechanical alignment in a single institution in 2021. First, we analyzed the epidemiology of CPAK phenotypes in our population. Second, patients were divided into 2 propensity score-matched groups based on implant design: Journey II BCS TKA (JLO prothesis) vs Persona PS TKA (joint line neutral prothesis). Radiological outcomes (mechanical hip-knee-ankle angle, lateral distal femoral angle, medial proximal tibial angle) and clinical outcomes (range of motion, Knee Society Knee Score, Western Ontario and McMaster Universities Osteoarthritis Index score, Forgotten Joint Score) assessed preoperatively and at 6 and 12 months postoperatively. RESULTS: Our CPAK distribution was comparable to that of other East Asian populations. The Journey II BCS TKA more effectively restored JLO and CPAK phenotypes compared to the Persona PS TKA. However, there was no statistically significant clinical correlation between the restoration of JLO, arithmetic HKA, and CPAK. CONCLUSIONS: Although radiological restoration improves with JLO prostheses, short-term clinical outcomes remain unaffected.