Abnormal change of paravertebral muscle in adult degenerative scoliosis and its association with bony structural parameters.

PURPOSE: While many studies have explored the association between paravertebral muscle (PVM) change and low back pain/lumbar spinal stenosis, little is known about PVM change in adult degenerative scoliosis (ADS). The present study explored the PVM change in ADS and investigated its association with bony structural parameters.

METHODS: We evaluated 78 patients in ADS without radiculopathy (ADS group) and 65 healthy persons without degenerative lumbar diseases (control group). Percentage of fat infiltration area (%FIA) of multifidus muscle at L1 to S1 disk level was measured by MRI, using ImageJ software. Lumbar scoliosis Cobb's angle, lumbar lordotic angle, lateral vertebral translation, and apical vertebral rotation were recorded in ADS group, and relationship between PVM change and these factors was analyzed.

RESULTS: In the control group, the mean %FIA of multifidus muscle was not significantly different between the bilateral sides at all levels (P > 0.05). In the ADS group, the mean %FIA was significantly higher on the concave side than the convex side at all levels (P < 0.05). Asymmetric degree of multifidus muscle change was 8.55% ± 4.91%, which was positively correlated with lumbar scoliosis Cobb's angle, lateral vertebral translation, and apical vertebral rotation (0 < r < 1, P < 0.05), but negatively weak-correlated with lumbar lordotic angle (- 1 < r < 0, P < 0.05).

CONCLUSIONS: Asymmetric PVM change in ADS is more often seen on the concave side, which is positive to evaluate the progression of scoliosis. Its asymmetric degree increases with progression of lumbar scoliosis Cobb's angle and decreased lumbar lordotic angle. Apical vertebral rotation and lateral vertebral translation can aggravate the asymmetric degree.