For a retrospective observational study, the researchers sought to determine the factors that contributed to the improvement in spinal imbalance after decompression surgery without fusion. Between April 2017 and October 2018, researchers analyzed 92 patients with lumbar spinal stenosis (LSS) with a preoperative sagittal vertical axis (SVA) greater than or equal to 40 mm who had decompression surgery without fusion at a single institution. The status of spinal sarcopenia, defined by the relative cross-sectional area (rCSA) of the paravertebral muscle (PVM) and psoas muscle at the L4 caudal endplate level, was examined using the patients’ background and radiograph information. Patients were separated into 2 groups: those with a postoperative SVA less than 40 mm (balanced group) and those with a postoperative SVA greater than or equal to 40 mm (unbalanced group). The variables were then compared between the 2 groups. After decompression surgery, 29 (31.5%) of patients experienced better sagittal imbalance. The balanced group’s rCSA-PVM was considerably more significant than the imbalanced group’s (P=0.042). The proportion of patients with vertebral compression fracture (P=0.028) and the preoperative pelvic incidence (PI)-lumbar lordosis (LL) mismatch (P=0.048) in the balanced group was considerably lower than those in the unbalanced group. In a multivariate logistic regression study, PI-LL less than or equal to 10 degrees and rCSA-PVM more than or equal to 2.5 were significant related factors for improvement in spinal imbalance after decompression surgery. In individuals with LSS who underwent decompression surgery, a bigger volume of paravertebral muscles and a lower PI-LL were linked to improved sagittal balance.