Stiffness: a key mechanical factor in normal, degenerate and artificial lumbar intervertebral discs
Abstract
This thesis describes the development of artificial disc technology for the replacement of intervertebral discs in the human lumbar spine. The clinical
problem is back pain. There may be a relationship between certain forms of
back pain and disc degeneration. The mechanical properties of human intervertebral discs are examined in detail. The genetic basis of disc degeneration is
presented. The hypothesis is that such degeneration leads to a loss of normal
stiffness in the segments affected leading to abnormal mechanical behaviour
which in turn leads to pain. The evidence for this is presented. The development of surgical solutions to relieve back pain, from fusion through first
generation mechanical artificial discs to elastomeric designs, is traced. The
author‘s personal contributions to this area of knowledge are set out. The
appreciation of the requirement for a restoration of physiological stiffness is
argued throughout, showing where fusion and first generation discs have not
met the clinical aim of pain relief, because they have not restored physiological stiffness. The path to an elastomeric, viscoelastic, polyhydrocarbon, rubber
solution in the form of the “Freedom“ disc has filled 17 years of the author‘s
academic pursuits. It will be shown that this technology may represent a possible solution to the clinical problem. Failure is part of all new advancement
and this too is presented, to show how that has influenced thinking, producing
original ideas to overcome these failures. Providing lessons are learned from
these failures then our patients in the future will benefit.
Type
Thesis, MD Doctor of Medicine
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