Purpose: To design an evaluation method for lumbar spine and hip joint function using dynamic radiography using a flat-panel detector (FPD) system. Method: Sixteen healthy subjects (males; age range, 22-60 years; median, 27 years) and 9 patients (7 males and 2 females; age range, 67-85 years; median, 73 years) with L4 degenerative spondylolisthesis were examined using a dynamic FPD system (CANON Inc.). Sequential images were captured with the subjects in the standing position with maximal forward bending followed by backward bending for 10 s. The lateral lumbar radiographs were obtained at 2 frames/s (fps). The flexion-extension angles of L1 and S1 were measured on those images. Results and discussion: The range of motion (ROM) of the lumbar joints was significantly larger in the healthy group (82.4±8.7°) than in the disease group (50.4±8.5°; p<0.05). The ROM of the pelvic region was significantly smaller in the healthy group (26.9±17.1°) than in the disease group (53.1±17.6°; p<0.05). The healthy subjects exhibited a normal lumbar-pelvic rhythm. In the disease group, hip joint movements tended to be completed earlier compared with those in the healthy group. In the disease group, the loss of lumbar flexibility was compensated by an increase in hip joint motion due to the lumbar disease. Conclusion: The dynamic FPD system is a convenient imaging modality for the diagnosis of lumbar diseases through the assessment of locomotive function in the lumbar spine and hip joints.