Objective: To study knee’s angulation required for Thai Buddhist monks whose activity based on floor sitting basis. And to identify an inter-observer reliability of knee flexion measurement based on radiologic reading.
Material and Method: Descriptive analysis study comprised of measuring bilateral knee flexing angulation in 4 postures of floor activities; kneeling, monk’s position in both right and left manner, and sit cross-legged position, in 35 Thai Buddhist monks at Priest Hospital using plain radiograph image. The radiograph imaging for each patient was performed by one radiologist and two orthopedics. The measurement result was also analyzed for inter-observer reliability.
Results: Mean knee flexion angle in kneel, left monk’s position, right monk’s position and sit cross-legged postures were 163.21, 146.49, 148.89 and 138.38 degree, respectively. No statistical difference between knee flexion measurements among 3 investigators.
Conclusion: Daily floor activity of Thai Buddhist monks need more flexion capacity than that can achieve by total knee arthroplasty instrument using nowadays.

Keywords: Range of motion of the knees in Thai Buddhist monks, Reliability of measurement by radiograph, Kneeling position, Cross-legged position, Left monk’s position and right monk’s position