Abstract
INTRODUCTION: Coronal tibiofemoral subluxation (CTFS) is a frequently observed radiological feature in varus osteoarthritis (OA) of the knee and may reflect underlying biomechanical misalignment and osseous changes. Understanding its correlation with bone morphometry can help in surgical planning and risk stratification. AIMS: To analyze the coronal tibiofemoral (CTF) in varus OA knee and its correlation with bone morphometry in patients undergoing total knee arthroplasty. MATERIALS AND METHODS: This retrospective and prospective study was conducted between January 2024 and January 2025. A total of 98 patients with varus OA knees planned for total knee arthroplasty were included. Radiographic parameters, including arithmetic hip-knee-ankle (HKA) angle, joint line obliquity, CTF, lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), coronal plane alignment of the knee (CPAK), and posterior condylar offset ratio (PCOR), were evaluated using standardized full-length scanograms. RESULTS: Among 98 patients, 60.2% were over 60 years old, and 61.2% were female. Body mass index classification showed that 42.9% were overweight and 25.5% were obese. Right knee involvement was observed in 53.1% of cases. CTF was present in 64 patients (65.3%) with a mean subluxation distance of 6.2 ± 1.5 mm. Most cases (75%) had subluxation distances between 0 and 6 mm. CPAK Type I was predominant (93.9%), whereas Type IV was seen in 6.1%. CTF prevalence was similar between CPAK Type I (65.2%) and Type IV (66.7%) (P = 0.887). Patients with CTF had higher LDFA (89.8° ± 2.1 vs. 87.9° ± 1.8), lower MPTA (84.5° ± 2.2 vs. 87.2° ± 1.9), higher PCOR (0.52 ± 0.06 vs. 0.48 ± 0.05), and more negative HKA angle (-7.2° ± 2.4 vs. -4.9° ± 2) than those without CTF (all P < 0.005). Correlation analysis showed a significant positive correlation of CTF with LDFA (r = 0.36, P = 0.004), PCOR (r = 0.3, P = 0.015), and HKA (r = 0.44, P = 0.003), and a negative correlation with MPTA (r = -0.42, P = 0.002). CONCLUSION: CTF is highly prevalent in varus OA knees and is significantly associated with specific morphometric alterations, including increased LDFA and PCOR, decreased MPTA, and a more negative HKA angle. While CPAK Type I predominates in this population, the CPAK classification did not significantly correlate with subluxation presence. These findings underscore the importance of assessing CTFS and bone morphology preoperatively for individualized surgical planning and improved outcomes.