Wolf's Law - PGOcclusion

Wolf's Law
Dr. Matthew McCoy
editor@jvsr.com
Editor - Journal of Vertebral Subluxation Research www.jvsr.com
It would be pretty hard to get out of chiropractic college without having
heard of Wolf's law though I'm uncertain as to the emphasis placed on it at
our various schools. I'm especially uncertain about the emphasis in
relation to subluxation theories and models.
Let's remember that its Wolf's Law, not Wolf's Opinion and its one of the
basic building blocks of the subluxation hypothesis.
Wolf's Law states:
As bones are subjected to stress demands in weightbearing posture, they
will model or alter their shape accordingly.
Wolf's Law has a less well-known corollary for soft tissue called: Davis'
Law, that states:
Soft tissue will model according to imposed demands
While one could argue against these laws, just as one could argue that the
sun won't rise tomorrow, no one would take them seriously. These two Laws
form the foundation of the rheology associated with subluxation and these
rheological properties are essential elements in the epidemiology of
vertebral subluxation.
Rheology is the study of the change in form and the flow of matter
including elasticity, viscosity and plasticity and epidemiology is the
study of the elements contributing to the occurrence of disease.
No matter which of the various models of vertebral subluxation one chooses
to discuss there are two components that are common to all models. These
components are Kinesiopathology and Neuropathology. The following is a step-
by-step overview of the changes that take place secondary to abnormal
movement and alignment of vertebrae (kinesiopathology). It's not the most
exciting reading but these concepts are essential if one is to understand
the nature and character of vertebral subluxation.
1. Physiologic loads of tension cause increased aggregation of collagen.
Compression has the opposite effect
2. Collagen fibers are laid down in response to stress lines of
mechanical loads
3. The metabolic activity of connective tissue cells is (increased) also
affected by mechanical forces/stress
4. Collagen under compressive and tension creates different distributions
of electrical charge
5. There is increased attachment of proteoglycans, attachment of new
collagen fibers, loss of water and unattached proteoglycans.
6. Fibers are shortened by remodeling
7. An increase in stress causes an increase in collagen production and
organization
8. A decrease in stress causes a decrease and disorganization of collagen
fibers
9. Collagen is permanently lengthened only by denaturing and weakening
the fibers, which occurs when the tissue is subjected to excessive
strain.
10. The development of fibrosis is preceded by an accumulation of
inflammatory cells within a tissue.
11. Tissues that are compressed tend to fold upon one another. This
folding may be the critical factor that promotes interfibrillary
adhesions
12. Any alteration in the degree or type of physiologic loading is
followed by changes in cellular metabolism, matrix morphology, and
functional capacity.
13. Cells, Glycosaminoglycans, and collagen type and architecture are all
affected by the direction and magnitude of physical stress applied to
a tissue.
14. The degeneration of the articular cartilage begins with mild fraying
of the tangential collagen fibers (fibrillation) followed by
cavitation (blistering) between the tangential collagen bundles.
15. Blistering is succeeded by vertical splits (clefting) that penetrate
the superficial layer and then the deep layers.
16. The clefted cartilage is gradually worn away leading to a complete
denuding of affected regions of the articular surface.
17. This process leads to a marked alteration in the porosity of cartilage
and alteration of fluid flow through it.
18. Immunocompetent cells and immunoglobulins obtain access to normally
protected deeper cartilage layers
19. According to Wolff's law, bones remodel to resist an applied stress
20. As a bone is stressed, regions subjected to compression become more
electronegative while areas subjected to tension become more
electropositive.
21. The osteophytes respond by manufacturing additional bone on the
electronegative surface and removing it on the electropositve surface.


22. These mechanically generated electrical signals are monitored and
averaged to influence osteocyte metabolism.
23. A bioelectric signal is generated via a piezoelectric effect and
transduced by the osteocytes, which remodel the bone to resist the
stress.
Further Reading
1. Functional Progressions for Sport Rehabilitation by Steven R. Tippett,
MS,PT,SCS,ATC, and Michael L. Voight, MED,PT,SCS,OCS,ATC. Published by
Human Kinetics, Champlain, IL. Copyright 1995.
2. Lantz, C.A. The Subluxation Complex in: Foundations of Chiropractic:
Subluxation. Meridel Gatterman, Editor. Mosby Year Book. January 1995.


3. Wolf's Law
4. Lantz, C.A. Immobilization Degeneration and the Fixation Hypothesis of
the Chiropractic Subluxation. Chiropractic Research Journal. Vol. 1
No. 1. 1988.
[pic]
Dr. Matthew McCoy editor@jvsr.com
Editor - Journal of Vertebral Subluxation Research
Subscribe and Support Chiropractic Research
http://www.jvsr.com
1: J Musculoskelet Neuronal Interact. 2002 Mar;2(3):277-80. [pic][pic]Links


Mechanical effects on skeletal growth.

. Stokes IA.

Department of Orthopaedics and Rehabilitation, University of Vermont,
Burlington 05405, USA. ian.stokes@uvm.edu


The growth (i.e. increase of external dimensions) of long bones and
vertebrae occurs longitudinally by endochondral ossification at the
growth plates, and radially by apposition of bone at the periosteum.
It is thought that mechanical loading influences the rate of
longitudinal growth. The 'Hueter-Volkmann Law' proposes that growth
is retarded by increased mechanical compression, and accelerated by
reduced loading in comparison with normal values. The present
understanding of this mechanism of bone growth modulation comes from
a combination of clinical observation (where altered loading and
growth is implicated in some skeletal deformities) and animal
experiments in which growth plates of growing animals have been
loaded. The gross effect of growth modulation has been demonstrated
qualitatively and semi-quantitatively. Sustained compression of
physiological magnitude inhibits growth by 40% or more. Distraction
increases growth rate by a much smaller amount. Experimental studies
are underway to determine how data from animal studies can be scaled
to other growth plates. Variables include: differing sizes of growth
plate, different anatomical locations, different species and variable
growth rate at different stages of skeletal maturity. The two major
determinants of longitudinal growth are the rate of chondrocytic
proliferation and the amount of chondrocytic enlargement
(hypertrophy) in the growth direction. It is largely unknown what are
the relative changes in these key variables in mechanically modulated
growth, and what are the signaling pathways that produce these
changes.

PMID: 15758453 [PubMed]



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