Axial Rotation and Lateral Bending in the Normal Lumbar Spine Measured by Three-Dimensional Radiography

TLDR

A 3‑D radiographic method was employed to measure active axial rotation, lateral bending, and associated cross‑plane rotations in two groups of normal male volunteers. Axial rotation averaged ~2° per joint (L3–4 and L4–5 slightly more mobile), lateral bending ~10° at upper levels dropping to 6° at L4–5 and 3° at L5‑S1, with opposite‑direction coupling in the upper lumbar spine, same‑direction coupling at L5‑S1, and a transitional pattern at L4‑5, indicating no simple mechanical coupling and suggesting lordosis and muscle control govern the relationship.

Abstract

A three-dimensional radiographic technique was used to investigate the ranges of active axial rotation and lateral bending plus the accompanying rotations in the planes other than that of the primary voluntary movements in two groups of normal male volunteers. There was approximately 2° of axial rotation at each intervertebral joint with L3–4 and L4–5 being slightly more mobile. Lateral bending of approximately 10° occurred at the upper three levels, while there was significantly less movement of 6° and 3° at L4–5 and L5-S1, respectively. In the upper lumbar spine, axial rotation to the right was accompanied by lateral bending to the left and vice versa. At L5-S1, axial rotation and lateral bending generally accompanied each other in the same direction, while L4–5 was a transitional level. These measurements in vivo demonstrated that there was no simple mechanical coupling of the rotations, and that the lordotic shape of the lumbar spine together with muscular control are probably the two principal factors determining the relation between the primary and accompanying rotations.