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The ligamento-muscular stabilizing
system of the spine. |
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AUTHORS: |
Solomonow M; Zhou BH; Harris M; Lu Y; Baratta
RV |
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AUTHOR AFFILIATION: |
Department of Orthopaedic
Surgery, Louisiana State University Medical Center, New Orleans. |
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SOURCE: |
Spine 1998 Dec
1;23(23):2552-62 |
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CITATION IDS: |
PMID: 9854754 UI: 99071918 |
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ABSTRACT: |
STUDY DESIGN: Electrical and
mechanical stimulation of the lumbar supraspinous ligament of three patients with L4-L5
spinal deficits and of the feline model, respectively, was applied while recording
electromyography on the multifidus muscles. OBJECTIVES: To determine if mechanoreceptors
in the human spine can reflexively recruit muscle force to stabilize the lumbar spine, and
to demonstrate, in the feline model, that such ligamento-muscular synergy is elicited by
mechanical deformation of the lumbar supraspinous ligament (and possibly of other spinal
ligaments), the facet joint capsule, and the disc. SUMMARY OF BACKGROUND DATA: The
literature repeatedly confirms that ligaments have only a minor mechanical role in
maintaining spine stability, and that muscular co-contraction of anterior and posterior
muscles is the major stabilizing mechanism of the spine. The literature also points out
that various sensory receptors are present in spinal ligaments, and that the ligaments are
innervated by spinal and autonomic nerves. Data that describe how ligaments and muscles
interact to provide stability to the spine were not found. METHODS: The supraspinous
ligament at L2-L3 and L3-L4 was electrically stimulated in three patients undergoing
surgery to correct deficits at L4-L5. Electromyography was performed from the multifidus
muscles at L2-L3 and L3-L4, bilaterally. In 12 cats, the supraspinous ligaments from L1-L2
to L6-L7 were mechanically deformed, sequentially, while electromyography was performed
from the multifidus muscles of the six levels. Loading of the ligament was applied before
and after each of the two vertebrae were externally fixed to prevent motion. RESULTS:
Electromyograms were recorded from the multifidus muscles, bilaterally, in the two of the
three patients, demonstrating a direct relationship to receptors in the supraspinous
ligament. Electromyograms were recorded from the feline multifidus muscle with mechanical
loading of the supraspinal ligament at each of the L1-L2 to L6-L7 motion segments. In the
free-spine condition the largest electromyographic discharge was present in the level of
ligament deformation, and lower electromyographic discharge was recorded in two rostral
and caudal segments. After immobilizing any two vertebrae, loading of the ligament
resulted in electromyographic discharge in the muscles of the same level and at least one
level above and/or below. CONCLUSIONS: Deformation or stress in the supraspinous ligament,
and possibly in other spinal ligaments, recruits multifidus muscle force to stiffen one to
three lumbar motion segments and prevent instability. Strong muscular activity is seen
when loads that can cause permanent damage to the ligament are applied, indicating that
spastic muscle activity and possibly pain can be caused by ligament overloading. |
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MAIN MESH HEADINGS: |
Ligaments/*physiology
Lumbosacral Region/*physiology
Mechanoreceptors/*physiology
Muscle, Skeletal/*physiology
Reflex/*physiology |
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ADDITIONAL MESH HEADINGS: |
Animal
Cats
Electric Stimulation
Electromyography
Female
Human
Ligaments/innervation
Lumbar Vertebrae/physiology
Lumbar Vertebrae/surgery
Male
Middle Age
Muscle, Skeletal/innervation
Support, Non-U.S. Gov't |
