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Effects of laminectomy on active-passive spine loads: a musculoskeletal finite element modeling investigation

Authors :

Aida Ahmadi¹ Navid Arjmand² Parisa Azimi³

1- Sharif University of Technology 2- Sharif University of Technology 3- Alborz University of Medical Sciences

Keywords :

Lumbar spinal stenosis،Spinal surgery،Laminectomy،Finite element modeling،Spinal load distribution

Abstract :

Lumbar spine pain and disorders, including stenosis, are significant causes of disability, particularly among the elderly. often leading to surgical interventions such as laminectomy with or without facetectomy. It involves the removal of the lamina, spinous process, posterior ligaments, and, in some cases, facet joints, thereby disrupting the normal load-sharing among active and passive spine elements. In the absence of viable in vivo approaches, advanced computational modeling offers insights into the biomechanical mechanisms underlying postoperative complications. This study investigates the biomechanical effects of three surgical procedures, i.e., unilateral laminectomy, full laminectomy, and laminectomy with facetectomy, on active-passive spine load distributions using our validated musculoskeletal–finite element (MS–FE) model. The analysis focuses on preoperative (intact condition) and postoperative simulations of the L4–L5 motion segment during static upright standing posture and forward trunk flexion at 80° (deep flexion). Results show that in the upright standing, negligible differences were observed between intact and postoperative models since ligaments were not tensioned. In contrast, deep flexion induced substantial changes across surgical procedures. Total muscle force increased from 1730 N in the intact model to 1893 N, 2019 N, and 2019 N after unilateral laminectomy, full laminectomy, and laminectomy with facetectomy. Joint compression at L4–L5 increased from 1724 N to 1860 N, 2118 N, and 2118 N across the three procedures. Ligament forces decreased dramatically at L3–L4 and L4–L5 (e.g., 404 N to 12 N, and 399 N to 66 N, respectively) after full laminectomy and facetectomy. Surgical resection of posterior elements had the most pronounced effects on joint compression, ligament forces, and total muscle forces, particularly during deep flexion. Full laminectomy and facetectomy caused greater biomechanical alterations compared to unilateral laminectomy, which led to relatively smaller changes. Unilateral laminectomy should therefore be the preferred approach whenever sufficient decompression can be achieved, especially in cases with unilateral lateral recess stenosis, foraminal stenosis, or focal disc herniation without bilateral symptoms. Understanding these biomechanical changes is essential for optimizing surgical planning, minimizing anatomical disruption, and reducing the risk of postoperative complications.