The characteristics of lumbar paraspinal muscle degeneration based on the Roussouly classification: a retrospective study

Background: To analyse the characteristics of lumbar paraspinal muscle degeneration in individuals with different Roussouly types. Methods: Eighty patients (20 patients for each Roussouly type) with degenerative lumbar disease were retrospectively enrolled from January 2017 to February 2018. The cross-sectional area (CSA) and percentage of fat infiltration (FI) of the paraspinal muscles at the L1-S1 levels were measured using T2-weighted axial MRI and ImageJ software. The measured data were analysed with independent samples t-tests. Results: Degeneration of the paraspinal muscles of the upper lumbar region was significantly severer in Type 1 than in Type 3, the degrees of paraspinal muscle degeneration of Type 2 appeared to be more evenly distributed in all segments than Type 3, and Type 4 showed severer degeneration in L5-S1 than Type 3. Conclusion: The degree of paraspinal muscle degeneration in each segment was different across the four Roussouly types, but the degrees of degeneration were consistent with the characteristics of degenerative disease within each type.