Radiological Changes of Paraspinal Muscles: A Comparative Study of Patients with Isthmic Spondylolisthesis, Patients with Degenerative Lumbar Spondylolisthesis, and Healthy Subjects

OBJECTIVE: To investigate the differences, correlations, and clinical significance of the paraspinal muscles among patients with isthmic spondylolisthesis (IS), degenerative lumbar spondylolisthesis (DLS), and age-matched healthy subjects. METHODS: This study involved 159 age-matched patients with L4 anterior spondylolisthesis. The patients were divided into the IS group (n = 81) and DLS group (n = 78). Eighty-four age-matched healthy adults were enrolled as the control group. The cross-sectional area (CSA) of paraspinal muscles (multifidus [MF], erector spinae [ES], and psoas [PS]) and the relative CSA of the paraspinal muscles (paraspinal muscle CSA/vertebral CSA) were measured in the IS group, DLS group, and control group. The degree of fat infiltration was simultaneously observed. RESULTS: There was no significant difference in age or sex among the three groups. The relative CSA of the MF and PS was higher in control group than in IS and DLS groups (p < 0.05). The relative CSA of ES was higher in IS and control groups than in DLS group (p < 0.05). The relative CSA of total paraspinal muscles decreased in the order of control group > IS group > DLS group (p < 0.05). Logistic regression analysis showed that the relative CSA of MF, and the degree of fat infiltration of ES were independent protective factors for IS (odds ratio < 1, p < 0.05). The relative CSA of MF was an independent protective factor for DLS (odds ratio < 1, p < 0.05), whereas BMI and the degree of fat infiltration of MF were independent risk factor for DLS (odds ratio > 1, p < 0.05). CONCLUSION: Compared with the control group, patients with IS and DLS showed varying degrees of degeneration, and the degree of degeneration in patients with DLS was more severe at the same age. Lower fat infiltration and higher paraspinal muscle CSA are protective factors for IS and DLS, whereas the higher BMI is risk factor for DLS.