Study of Vertebral Foramen Dimensions in Lumbar Spine and their Correlation with the Low Back Pain

Background: Low back pain is a common musculoskeletal problem and an important cause of functional disability in adults. As the lumbar spine changes its structure, such as a narrowing of the vertebral foramen and spinal canal, this can compress neural structures and cause pain to get worse. The assessment of the dimensions of the vertebral foramen may thus be of value in patients with low back pain. Objective: To study the dimensions of the vertebral foramen in the lumbar spine and determine their correlation with the severity of low back pain. Methods: This descriptive cross sectional study was carried out in Orthopedic Department Khyber Teaching Hospital (KTH) Peshawar from 1st January 2022 to 1st June 2022. The patients included in the study were 82 patients with LBP who were obtained by consecutive non-probability sampling. Demographic and clinical information, such as age, gender, BMI, duration of pain, pain radiation, numbness, difficulty of walking, VAS score and ODI score were collected. The radiological evaluation of the lumbar spine was done to assess the size of the vertebral foramen in terms of its anteroposterior diameter, transverse diameter and the cross-sectional area from L1 to L5. Other associated findings included disc bulge, facet joint hypertrophy, ligamentum flavum hypertrophy, spondylolisthesis and canal stenosis. The data were analysed with SPSS version 25 and a p-value of <0.05 was determined as statistically significant. Results: The mean age of the patients was 43.8 ± 12.6 years. Out of 82 patients, 46 (56.1%) were males and 36 (43.9%) were females. Most patients had moderate low back pain, followed by severe pain. A gradual reduction in vertebral foramen dimensions was observed from upper to lower lumbar levels, with the smallest dimensions noted at L4 and L5. Patients with severe pain had significantly reduced mean cross-sectional area compared with those having mild and moderate pain. The mean cross-sectional area was 249.6 ± 31.4 mm² in mild pain, 226.3 ± 34.2 mm² in moderate pain, and 196.8 ± 29.7 mm² in severe pain, with a statistically significant association (p = 0.001). A significant negative correlation was observed between vertebral foramen dimensions and VAS/ODI scores. Conclusion: Reduced vertebral foramen dimensions in the lumbar spine were significantly associated with increased severity of low back pain and functional disability. The lower lumbar levels, particularly L4–L5 and L5–S1, were more commonly affected. Measurement of vertebral foramen dimensions may be useful in the radiological evaluation and clinical assessment of patients with low back pain.