Osteoarthritis (OA) is a chronic degenerative joint disease characterized by the breakdown of cartilage in joints, potentially altering joint biomechanics such as the quadriceps (Q) angle. The biomechanics of the patellofemoral joint is influenced by the direction and magnitude of force exerted by the quadriceps muscle, which may also impact foot biomechanics. This study aimed to determine the relationship between foot arch index (FAI) and Q-angle among patients with knee osteoarthritis (KOA). An exploratory cross-sectional study was conducted with 58 adults with KOA from the National Orthopaedic Hospital, Enugu. Q-angle, pain intensity (PI), and FAI were assessed using a goniometer, numerical pain rating scale, and the Staheli's equation, respectively. Data were analyzed using descriptive statistics and Pearson's correlation coefficient at an alpha level of 0.05. The results indicated no significant relationship between right (r=0.066, p=0.624) and left (r=0.171, p=0.199) FAI and their ipsilateral Q-angle. Additionally, no significant relationship was found between right (r=0.19, p=0.15) and left (r=0.05, p=0.76) knee pain PI and their ipsilateral Q-angle. However, a significant relationship was observed between right foot PI and right Q-angle (r=0.41, p=0.001), while no significant relationship was found between left foot pain intensity and left Q-angle (r=0.41, p=0.76). The findings suggest that foot deformity may lead to patella lateral rotation, increasing the Q-angle and potentially predisposing the knee to osteoarthritis. Evaluating the Qangle and arch index could provide additional insights for treating patients with knee osteoarthritis. Therefore, physiotherapeutic assessment should include an evaluation of the Q-angle.