Loads on the lumbar spine. Validation of a biomechanical analysis by measurements of intradiscal pressures and myoelectric signals
Schultz, A.; Andersson, G.; Ortengren, R.; Haderspeck, K.; Nachemson, A.
Journal of Bone and Joint Surgery. American Volume 64(5): 713-720
1982
ISSN/ISBN: 0021-9355 PMID: 7085696 Document Number: 186133
The validity of predictions of compressive loads on the lumbar spine and contraction forces in lumbar trunk muscles based on a biomechanical model were studied. The predictions were validated by quantitative measurements of myoelectric activities at 12 locations on the trunk and of the pressure in the 3rd lumbar disc. Tasks (25) were performed isometrically by 4 healthy volunteers. The model predicted that the tasks imposed mean compressive loads on the spine of as much as 2400 N and required contraction forces of the posterior muscles of the back of as much as 1800 N. Intradiscal pressures of as much as 1600 kpascals were measured. The predicted and measured quantities were well correlated. Apparently, the model adequately predicted the compressive loads on the lumbar spine and the tensions in the back muscles. Patients with low-back disorders limit their physical activities, which indicates that loading on the spine must be a factor in those disorders. The loads imposed on the spine by physical activities need not be measured; they can easily be calculated. This will significantly accelerate biomechanics research on low-back disorders. The calculation techniques for predicting loads on the spine can be used to calculate the loads on any skeletal structure. Those loads are largely determined not by the externally applied loads, but by the moments of those applied loads and by the moments of the weights of the body segments that the structure must support.