XXXX immediately upon sitting down and relieved by standing up is often associated with radiologic lumbar instability or marked anterior loss of disc space.

@entity1 @entity1643 @entity158
STUDY DESIGN: Comparison of functional radiographs in consecutive @entity1 with @entity1643 with or without @entity158 on sitting down and relieved by standing up. OBJECTIVES: To detect radiologic signs possibly associated with a clinical symptom. SUMMARY OF BACKGROUND DATA: No link has been established between increased vertebral mobility and a specific @entity158 pattern or a clinical symptom. METHODS: Forty-two @entity1 seen consecutively with @entity1643 occurring immediately on sitting down and relieved on standing up were compared with 32 controls whose @entity1643 did not show this pattern. Dynamic radiographs were taken in extension, erect, flexion, and sitting in the @entity158 position. The segments thought to be responsible for the @entity158 were identified by comparing clinical, radiographic, and magnetic resonance data. Endplate angles, rotation, and translation were measured. The radiographs were read twice each by two independent observers. RESULTS: Eighty-six percent (95% confidence interval, 72-99%) of the @entity1 with the symptom were female. The segments identified as the source of @entity158 were as follows: L4-L5 in 20 cases and L1-L2 to L3-L4 in 22 cases. Mean rotation of these segments was 13.9 +/- 4.5 degrees in the @entity1 group versus 7.5 +/- 4.3 degrees in the control group (P < 0.001). In 14% of the @entity1 (vs. 3% of controls), it exceeded 20 degrees (P = 0.13). Anterior or posterior translation >10% was seen in 31% of the @entity1 (vs. 0% of controls; P < 0.001). In flexion, the endplate angle was -5.2 +/- 3.6 degrees ( @entity1 ) versus 1.2 +/- 5.7 degrees (controls) (P < 0.01) and <-5 degrees in 55% of @entity1 versus 12.5% of controls (P < 0.001). This value of <-5 degrees was associated with marked anterior loss of disc space. CONCLUSION: @entity1643 occurring immediately on sitting down and relieved on standing up was statistically associated with instability (specificity 100%, sensitivity 31%) or marked anterior loss of disc space in flexion (specificity 87%, sensitivity 55%).
