Spinal and Pelvic Motion after Hip Resurfacing Arthroplasty and Metal on Metal Total Hip Arthroplasty

Introduction In normal individuals, hip flexion involves combined motion of the femur with respect to the pelvis and flexion of the lumbar spine. Conflicting reports site insufficient head to neck diameter ratio and fear of instability as limiting factors of post-hip resurfacing (SRA) and total hip replacement (THR), respectively. Restoring anatomical range of motion is important for THR and SRA, especially for active patients or those with pre-existing co-morbidities or spondylitis. Distinguishing the femoral and spinal components of hip flexion will lend more insight to spinal and pelvic motion after hip arthroplasty. In this study we investigate the spinal, pelvic, and hip motion during flexion and extension in patients who had undergone resurfacing (SRA) and metalon-metal total hip replacement (THR).