Laminectomy is a widely used surgical approach in patients with spinal canal stenosis but can result in biomechanical changes leading to iatrogenic spondylolisthesis. While some factors, such as surgical technique and achievement of spinal stability, are key contributors, patient-specific factors remain underexplored. Our study included 64 patients with diagnosed iatrogenic spondylolisthesis following previous spinal surgery. They were stratified into male and female groups, and clinical parameters such as the body mass index (BMI), fatty infiltration of the paraspinal muscles (assessed via Goutallier classification), pain scores (Visual Analogue Scale – VAS), and functional outcomes (Oswestry Disability Index – ODI) were analyzed pre-and postoperatively. The cohort consisted of 19 men and 45 women, with a mean age of 63.7 ± 10.82 years. There was a statistically significant difference in BMI, with higher values in women than men (30.16 ± 2.73 vs. 28.11 ± 2.71, P = 0.0078). Fatty infiltration of the paraspinal muscles was also more pronounced in women, with significant differences observed in Goutallier grades 2 and 3 (P = 0.007). While no differences were noted in surgery duration or hospital stay, males experienced greater intraoperative blood loss (P = 0.0442). Both groups had similar short- and mid-term pain and functional improvement, with no statistically significant differences in the VAS or ODI scores. In conclusion, patients with iatrogenic spondylolisthesis showed sex-based differences in BMI and fatty infiltration of the paraspinal muscles in patients. These factors did not influence short- and mid-term functional recovery but may play a key role in disease progression and surgical outcomes.