Purpose <p>This study aimed to identify the key factors influencing post-operative range of motion after total knee arthroplasty. The primary determinants investigated were preoperative range of motion, intra-operative posterior condylar offset (PCO), posterior condylar offset ratio (PCOR), posterior tibial slope (PTS), and joint line height (JLH).</p> Methods <p>This prospective study enrolled 68 patients. PCO, PCOR, PTS, and JLH were assessed radiologically in both pre-operative and post-operative X-rays. The knee range of motion and Oxford Knee Score (OKS) were assessed at 2-year follow-up. Statistical analysis, including Student’s t test and correlation analysis, was employed to compare and correlate pre-operative and post-operative parameters.</p> Results <p>Pre-operative range of motion correlated with post-operative range of motion (<i>p</i> = 0.001). The study did not find a significant correlation when post-operative range of motion was correlated with PCO (<i>p</i> = 0.923), PCOR (<i>p</i> = 0.278), PTS (<i>p</i> = 0.604), and JLH (<i>p</i> = 0.488). Post-operative changes in PCO (<i>p</i> = 0.001) and PTS (<i>p</i> = 0.001) when compared to pre-operative values were significant. PCOR (<i>p</i> = 0.468) and JLH (<i>p</i> = 0.108) had no significant correlation with their respective pre-operative values. Pre-operative OKS: 18.23 ± 8.53, Post-operative OKS: 40.92 ± 4.0 (<i>p</i> = 0.001). Pre-operative maximum flexion: 93.31° ± 7.73°, post-operative maximum flexion angle: 111.83° ± 9.69° (<i>p</i> = 0.001).</p> Conclusion <p>Amongst the measured parameters, pre-operative range of motion was the primary factor influencing the range of motion attained after total knee arthroplasty (TKA).</p>