| Objective: To evaluate the relationship between lumbar instability and disc degeneration, facet joint osteoarthritis and ligament flavum hypertrophy in the functional spinal unit.Methods: According to the Kong′s criteria, lumbar instability was investigated in 79 cases (237 functional spinal units) who were placed in the upright axially loaded neutral position, upright axially loaded flexion and extension positions. Segmental motion was measured at three levels (L3-L4, L4-L5, L5-S1). Then three radiographic parameters including disc degeneration, facet joint osteoarthritis and ligament flavum hypertrophy were used to evaluate the correlation on lumbar instability.Results: Lumbar instability cases were more at L4-L5 than at L3-L4 and at L5-S1., Disc degeneration, facet joint osteoarthritis and ligament flavum hypertrophy(+) at L3-L4, L4-L5 and L5-S1 were individually associated with lumbar instability (P<0.05). GradeⅣdisc degeneration with grade 3 facet joint osteoarthritis, grade 3 facet joint osteoarthritis with ligament flavum hypertrophy(+) and gradeⅣdisc degeneration with ligament flavum hypertrophy(+) at L3-L4, L4-L5 and L5-S1 were individually associated with lumbar instability (P<0.05).Conclusion:Radiographic parameters including gradeⅣdisc degeneration, grade 3 facet joint osteoarthritis and ligament flavum hypertrophy(+) are good indicators for lumbar instability. At L4-L5, especially, gradeⅣdisc degeneration with grade 3 facet joint osteoarthritis, grade 3 facet joint osteoarthritis with ligament flavum hypertrophy(+) and gradeⅣdisc degeneration with ligament flavum hypertrophy(+) are important radiographic parameters for forecasting lumbar instability. These three radiographic parameters should be simultaneously evaluated when we diagnose lumbar instability. Clinically, kinetic MRI is a valuable adjunct in patients suspected of having lumbar segmental instability. It is also a promising medium for investigating conditions considered to lead to spinal instability. |
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