Lumbofemoral rhythm during hip flexion in young adults and children

A two-group experimental design with repeated measures on one factor was used.

To describe the relation between movement of the hip and lumbar spine during active hip flexion in healthy young adults and children.

Many descriptions of hip movement and procedures for clinically assessing the range of hip joint flexion do not take into account the substantive range of lumbar spine motion that normally accompanies hip flexion. Posterior pelvic rotation, representative of lumbar flexion during hip flexion, has been incorrectly regarded as a compensatory movement.

Unilateral full range active hip (knee) flexion was examined using computer-aided video analysis in 22 healthy young adults and 22 healthy children.

Except for the first 3 degrees to 5 degrees of the upward movement of hip flexion, hip and lumbar spine motion was concurrent in both phases of the test movement in children and adults. On the average, every 3 degrees of hip motion was accompanied by 1 degrees of lumbar motion. Throughout the upward movement, the relative contribution of hip movement decreased while that of the lumbar spine increased. During the downward movement, the hip returned nearly to its original starting position while the lumbar spine remained noticeably flexed.

There is a concurrent motion of the lumbar spine-pelvis and hip during normal hip flexion that is analogous with the well-known scapulohumeral rhythm accompanying elevation of the shoulder. Failure to measure or account for the contribution of the lumbar spine to hip flexion could overestimate the range of hip flexion by as much as 33.3%.