Sagittal Femur-Pelvis Balancing Mechanism and Linear Correlation Chain in Patients With Spinal Disorders

A linear correlation chain exists in the sagittal plane in patients with spinal disorders. The back tilt of a longer femur increases posterior offset more efficiently, shifting the center of gravity backward in patients with spinal disorders. Anterior pelvic tilt relative to the femur reduces the Pelvic-Femur Angle (PFA) to maintain lumbar lordosis and economic sagittal alignment. These collaborative compensatories are crucial for understanding the sagittal balance and alignment of the spine, pelvis, and lower extremities.