Related Experiment Video
Updated: Jul 5, 2026
11:30
Multilevel Oblique Lumbar Interbody Fusion in Degenerative Lumbar Disc Disease with Instability
Published on: July 25, 2025
Stepwise reduction of functional spinal structures increase disc bulge and surface strains
Frank Heuer1, Hendrik Schmidt, Hans-Joachim Wilke
1Institute of Orthopaedic Research and Biomechanics, University of Ulm, Helmholtzstr. 14, 89081 Ulm, Germany.
Journal of Biomechanics
|May 27, 2008
Summary
This study reveals complex lumbar disc strains and bulging under compression. Understanding these biomechanical responses is crucial for developing accurate finite element models of the spine.
Area of Science:
- Biomechanics
- Spinal Research
- Orthopedics
Background:
- Lumbar intervertebral disc (LID) axial compression induces complex annulus strains, not fully characterized by uniaxial tensile strain studies.
- Accurate biomechanical data is needed for validating advanced finite element models (FEM) of the spine.
Purpose of the Study:
- To investigate surface strains and disc bulging in lumbar intervertebral discs under various loading conditions.
- To analyze the impact of anatomical structure removal on these biomechanical parameters.
- To provide data for the development and validation of finite element models.
Main Methods:
- In vitro study of six human lumbar spine specimens (L2-3, median age 51).
- Application of pure moments (2.5-7.5 Nm) in principal directions.
- Sequential removal of posterior structures, ligaments, and nucleus, measuring range of motion, 3D disc bulging, and outer annulus surface strains.
Main Results:
- Lateral bending caused the highest axial strains (9.7% intact, 15.1% post-posterior structure removal).
- Flexion resulted in maximal disc bulging (1.56mm intact, 2.06mm post-step 1).
- Ligament removal significantly increased strains (22.6% flexion) and bulging (2.17mm flexion). Nucleotomy altered inward bulging.
Conclusions:
- Anatomical structure removal significantly alters lumbar disc biomechanics, increasing strains and bulging.
- Ligamentous structures exert a constrictive effect on the annulus.
- This study provides essential in vitro data for refining and validating complex finite element models of the lumbar spine.
Related Concept Videos
01:27Degenerative Disc Disease I: Introduction
Degenerative disc disease is a chronic condition in which intervertebral discs gradually lose structure and function. It is not infectious or autoimmune; rather, it results from age-related biochemical and mechanical changes, influenced by genetic, metabolic, and environmental factors.Structure and Function of DiscsThe spine contains 23 intervertebral discs that absorb load, distribute forces, maintain spacing, and allow flexibility. Each disc consists of a nucleus pulposus, a gel-like core...
01:23Degenerative Disc Disease ll: Pathophysiology
The symptoms of degenerative disc disease arise from a combination of mechanical compression, vascular compromise, and biochemical inflammation, which together disrupt nerve function and produce pain.Mechanical CompressionDisc degeneration reduces height and elasticity, predisposing to herniation of the nucleus pulposus, a major cause of radicular pain. Herniations may be protrusion (bulging with intact annulus), extrusion (nucleus extends beyond disc but remains connected), or sequestration...
01:29Herniated Intervertebral Disc l: Introduction
Intervertebral disc herniation refers to the displacement of the nucleus pulposus (the gel-like inner core of the disc) through a tear or weakened area in the annulus fibrosus (the outer fibrous ring). The displaced disc material extends beyond the normal boundaries of the disc space and may compress or irritate nearby spinal nerve roots or, less commonly, the spinal cord.Etiology and Risk FactorsHerniation commonly results from degeneration, in which aging reduces disc hydration and...