Sarcopenic obesity is associated with more severe functional impairment and lumbar degeneration in patients with degenerative lumbar spinal stenosis.

BACKGROUND: The intersection of population aging and the obesity epidemic has positioned sarcopenic obesity (SO) as a critical public health challenge. However, its association with clinical characteristics of patients with degenerative lumbar spinal stenosis (DLSS) remains unclear. METHODS: This retrospective cross-sectional study enrolled 408 DLSS patients (age ≥ 50 years). SO was diagnosed according to the ESPEN and EASO consensus statement, integrating handgrip strength, appendicular lean mass, and fat mass percentage (FM%). Clinical characteristics included patient-reported outcomes (VAS, ODI) and comprehensive lumbar imaging assessments (evaluating degeneration of intervertebral discs, facet joints, spinal canal, paraspinal muscles, etc.). Regression and moderation analyses were employed to determine the independent association of SO with clinical characteristics and to assess the moderating effect of FM% on the relationship between sarcopenia and clinical characteristics. RESULTS: 66 patients were diagnosed with SO. After adjusting for confounders, SO was independently associated with greater functional impairment (ODI, β = 7.350, P = 0.010), more severe intervertebral disc degeneration (Pfirrmann grading, OR = 5.025, P < 0.001) and foraminal stenosis (Lee grading, OR = 5.495, P < 0.001), a higher prevalence of Modic change (OR = 2.981, P < 0.001), and increased fat infiltration in the erector spinae (ESFI%, β = 2.658, P = 0.001). Moderation analysis revealed that FM% significantly exacerbated the detrimental effects of sarcopenia on disc degeneration (OR = 1.254, P = 0.001) and foraminal stenosis (OR = 1.127, P = 0.027). CONCLUSION: In patients with DLSS, SO is associated with more severe functional impairment and multifaceted lumbar degeneration. Additionally, obesity significantly amplifies the adverse impact of sarcopenia on intervertebral disc degeneration and foraminal stenosis. Therefore, routine screening for SO should be integrated into preoperative assessments, and comprehensive management strategies targeting both adiposity and muscle preservation are warranted for this population.