Ultrasound measurement of abdominal and low back muscle symmetry in adult degenerative lumbar scoliosis: A case-control study.

Background: Individuals with adult degenerative lumbar scoliosis (ADLS) have underlying biomechanical alterations along the trunk muscles. However, few studies have evaluated trunk muscles in ADLS.

Objective: To quantify and evaluate the symmetry, thickness, and stiffness (shear modulus) of the abdominal and back muscles in ADLS participants.

Methods: This was a case-control study with participants aged 60-79 years with ADLS (n = 37) and without ADLS (n = 37). Radiographic examination data were collected from the participants. Ultrasound thickness and shear modulus measurements were performed to compare differences in the rectus abdominis, external oblique, internal oblique, transversus abdominis (TrA), multifidus, erector spinae, and quadratus lumborum muscles in the supine, prone and standing positions in the ADLS (n = 37) and control groups (n = 37). Thicknesses and shear modulus were compared.

Results: The absolute thickness of the TrA in ADLS group was significantly greater on the convex side than on the concave side in both the supine (2.978 ± 0.552 vs. 2.556 ± 0.513, p = 0.041) and standing positions (2.671 ± 0.475 vs. 2.054 ± 0.401, p = 0.034). The percentage changes in both sides of the shear modulus of the TrA were significantly greater in the ADLS group than in the control group for the supine position (p = 0.019), and standing position (p = 0.039).

Conclusions: Compared with those in the control group, only the absolute muscle thicknesses and percent change in the shear modulus of the TrA in the ADLS participants were more asymmetric.