Lumbar segmental mobility according to the grade of the disc, the facet joint, the muscle, and the ligament pathology by using kinetic magnetic resonance imaging.

STUDY DESIGN: The kinematic study of human lumbar spinal movements.

OBJECTIVE: To investigate how disc degeneration and the degeneration of facet joint, ligaments, and paraspinal muscles are associated with lumbar segmental mobility.

SUMMARY OF BACKGROUND DATA: Previous studies revealed relationship between spinal motion and osteoarthritic changes of facet joint as well as disc degeneration; however, little is known about the association of disc, facet joint, ligament, and muscle degeneration with lumbar segmental motion characteristics.

METHODS: The 1580 lumbar motion segments from 316 patients (200 male, 116 female) underwent Kinetic magnetic resonance imaging, which were used to assess disc degeneration (grade I-V) and facet joint degeneration (grade 1-4), interspinous ligament (ISL) degeneration (grade 1-4), ligamentum flavum hypertrophy (LFH), and fatty degeneration of muscles. Segmental translational and angular motion in the flexion, extension, and neutral postures were digitally automatically measured by MR analyzer.

RESULTS: Grade II (46.77%) disc, grade 1 (48.35%) facet joint degeneration, and grade 1 (64.1%) ISL were most common. LFH was most common in L4-L5 (49/330, 14.8%). In younger age (<35), grade I disc and grade 1 facet joint were predominant compared with the older age (35< or = and <45) in which grade III, IV, and V disc and grade 2 facet joint were predominant (P < 0.05). Translational motion increased significantly in high grade of disc and facet joint (except grade V disc and grade 4 facet joint) and with LFH in L1-L5 (P < 0.05). Angular motion significantly decreased in grade V disc, grade 4 ISL, and without LFH in L1-L5 (P < 0.05). According to muscle fatty degeneration, translational and angular motions were not significantly changed.

CONCLUSION: Our results support that facet joint degeneration is followed by disc degeneration according to age. Increased translational movements of the lumbar segments occurred in severe disc degeneration accompanied by facet joint degeneration or the presence of LFH even if the movements were stabilized in the advanced status. Therefore, the current status of the intervertebral discs, facet joints, and ligamentum flavum should be taken into consideration when evaluating stability within the lumbar spine.