PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 9855668

Low back pain: current physiologic concepts.

S Haldeman
View original source ↗Export metadata ↓

Abstract

It is clear that low back pain is not a simple process that can be explained on purely anatomic, biomechanical, or neurophysiologic theories. The intimate relationship of these processes have to be considered. Each of the potential biomechanical stresses influence the different spinal structures in different ways, depending on the forces applied and the structure being affected. The biomechanical response to the trauma caused by these forces may be immunologic, inflammatory, or neurochemical, depending on the structures being traumatized. Once a nociceptive process is underway, it is greatly influenced by the spinal cord and the brain. Only by following this process through its various steps can a clinician begin to formulate an understanding of the mechanisms involved in the genesis of low back pain.

Explore related subjects

Biomechanical PhenomenaHumansLow Back PainLumbar VertebraeOccupational DiseasesSpinal DiseasesJournal ArticleReview

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

S Haldeman. 1999. Low back pain: current physiologic concepts.. https://doi.org/10.1016/s0733-8619(05)70111-0

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed1999

Single-molecule biomechanics with optical methods.

Single-molecule observation and manipulation have come of age. With the advent of optical tweezers and other methods for probing and imaging single molecules, investigators have circumvented the model-dependent extrapolation from ensemble assays that has been the hallmark of classical biochemistry and biophysics. In recent years, there have been important advances in the understanding of how motor proteins work. The range of these technologies has also started to expand into areas such as DNA transcription and protein folding. Here, recent experiments with rotary motors, linear motors, RNA polymerase, and titin are described.

Biomechanical Phenomena↗
PubMed1999

Biomechanical comparison of spondylolysis fixation techniques.

STUDY DESIGN: A load-controlled biomechanical analysis of flexion, extension, and torsional stiffness in instrumented calf spines. OBJECTIVES: To compare biomechanically the performance of various fixation techniques for the repair of spondylolytic defects in the pars interarticularis. SUMMARY OF BACKGROUND DATA: Several techniques have been developed to stabilize a spondylolytic defect in the lumbar spine. There are, however, no comprehensive biomechanical studies in which these techniques are compared. METHODS: Nine fresh-frozen and thawed calf cadaveric lumbar L2-L6 spines were used for mechanical testing. Scott's technique, Buck's technique (screw fixation in the lamina across the defects), modified Scott's technique (wire loops around cortical screws placed into both pedicles and tightened under the spinous process), and screw-rod-hook fixation were applied on the calf lumbar spines in which bilateral spondylolytic defects were created in the L4 vertebra. Motion across the defects for each direction of loading in flexion, extension, and rotation was measured using extensometers. The intervertebral rotations and the strain at the site of the spondylolytic defect were computed from the acquired load-displacement data. RESULTS: Each fixation technique significantly increased stiffness and returned the intervertebral rotational stiffness to nearly intact levels. Displacement across the defect under flexion loading was significantly suppressed by each instrumentation technique, but the least motion (P < 0.05) was allowed with the screw-rod-hook fixation or Buck's technique. CONCLUSIONS: All four fixation techniques restored the intervertebral rotational displacements under flexion and torsional loading to the intact condition. The screw-rod-hook fixation allowed the least amount of motion across the defect during flexion.

Biomechanical Phenomena↗
PubMed1999

A nanomechanical device based on the B-Z transition of DNA.

The assembly of synthetic, controllable molecular mechanical systems is one of the goals of nanotechnology. Protein-based molecular machines, often driven by an energy source such as ATP, are abundant in biology. It has been shown previously that branched motifs of DNA can provide components for the assembly of nanoscale objects, links and arrays. Here we show that such structures can also provide the basis for dynamic assemblies: switchable molecular machines. We have constructed a supramolecular device consisting of two rigid DNA 'double-crossover' (DX) molecules connected by 4.5 double-helical turns. One domain of each DX molecule is attached to the connecting helix. To effect switchable motion in this assembly, we use the transition between the B and Z forms of DNA. In conditions that favour B-DNA, the two unconnected domains of the DX molecules lie on the same side of the central helix. In Z-DNA-promoting conditions, however, these domains switch to opposite sides of the helix. This relative repositioning is detected by means of fluorescence resonance energy transfer spectroscopy, which measures the relative proximity of two dye molecules attached to the free ends of the DX molecules. The switching event induces atomic displacements of 20-60 A.

Biomechanical Phenomena↗