Prevalence and Demographic Associations of Ligamentum Flavum Hypertrophy in Lumbar Spinal Stenosis

Background: The ligamentum flavum (LF) is a posterolateral ligament of the spinal canal. Ligamentum flavum hypertrophy (LFH) is a principal degenerative determinant of lumbar spinal stenosis (LSS), causing reduction of canal and foraminal space and thereby promoting nerve roots compression. LFH prevalence and severity increase with advancing age, rendering it a key factor in the clinical presentation and surgical approaches. Objective: This study aims to determine the prevalence of LFH in patients undergoing surgical decompression for LSS. Methods: This cross-sectional study was conducted in the Department of Neurosurgery at Aliabad University Hospital and included all patients diagnosed with LSS (per surgical protocols and/or MRI reports) from January to December 2025. The association between age, gender, and LFH was also tested using a chi-square test in SPSS 26.0. Results: Of 239 patients with LSS, 128 (53.6%) were males and 111 (46.4%) were females. LFH was present in 102 (42.7%) patients, including 64 (50.0%) males and 38 (34.2%) females; with a significant association between LFH and male sex (p = 0.014). LFH prevalence increases markedly with age (21– 30 years: 18.5%; 61– 70 years: 93.9%; p=0.001). Anatomically, LFH was most frequent at L4–L5 (40.2%) and L3–L4 (18.6%). Conclusion: LFH represents a major pathological component of LSS, with prevalence increasing progressively with age. LFH was more frequent in male patients and was most commonly localized to L3 to L5. Accordingly, standardized preoperative cautions for LFH should be considered to support the selection of the surgical approach. Keywords: ligamentum flavum hypertrophy, low back pain, lumbar disc herniation, lumbar spine stenosis