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Mechanical response of the lumbar intervertebral joint under physiological (complex) loading.
The Journal of Bone and Joint Surgery. American Volume
|January 1, 1978
Summary
This study on lumbar intervertebral joints found that vertebral bodies, not the disc annulus fibrosus, yield under complex physiological loading. Posterior elements significantly transmit force during simulated spinal movements.
Area of Science:
- Biomechanics
- Orthopedics
- Spinal Mechanics
Background:
- Lumbar intervertebral joints are crucial for spinal stability and function.
- Understanding their mechanical behavior under physiological loads is essential for diagnosing and treating spinal disorders.
Purpose of the Study:
- To investigate the mechanical behavior of fresh, intact lumbar intervertebral joints under various loading conditions.
- To determine the force transmission through posterior elements and identify failure sites during complex loading.
Main Methods:
- Nineteen lumbar intervertebral joints from twelve spines were tested using a materials testing machine.
- Pure axial compression and complex loading simulating physiological states were applied.
- Measurements included load deflection, disc bulge, and strain in vertebral bodies and laminae.
Main Results:
- Posterior elements transmit substantial force during quasistatic complex loading, especially in extension and frontal shear.
- Under complex loading, healthy lumbar specimens exhibited yielding or failure within the vertebral body.
- The annulus fibrosus of the intervertebral disc did not show yielding or failure.
Conclusions:
- The vertebral body is a critical structure for load bearing and failure initiation in the lumbar spine under complex physiological loading.
- Posterior spinal elements play a significant role in force transmission during dynamic spinal movements.
- These findings have implications for understanding spinal injury mechanisms and designing effective treatments.