Facet joint osteoarthritis as main factor effecting on the stability of degenerative lumbar spine

Objective In order to explore the exact relations among disc degeneration, facet joint osteoarthritis, and the stability of the degenerative lumbar spine. Methods Seventyeight consecutive patients had both magnetic resonance imaging and flexion and extension radiographs of the lumbar spine. The lumbar instability was classified into abnormal tilting on flexion, rotatory instability in the sagittal plane, and trans latory instability. Translatory instability was subdivided into anterior, posterior, and anteroposterior translatory instability. Disc degeneration as seen on T 2-weighted sagittal images was classified into five grades. Facet joint osteoarthritis as seen on axial T 1-weighted images was divided into four grades. The data were performed by using statistical method. Results The results showed that abnormal tilting movement on flexion and anteroposterior translatory instability both had negative associations with facet joint osteoarthritis. However, anterior translatory instability was positively associated with disc degeneration and facet joint osteoarthritis. Rotatory instability in the sagittal plane and posterior translatory instability were not associated with the disc degeneration and facet joint osteoarthritis. Conclusion The disc degeneration and facet joint osteoarthritis are the main factors affecting on the stability of the kinematics of lumbar motion segment.