Article

Cumulative lumbar disorder is common in individuals engaged in long term
performance of repetitive and static occupational/sports activities with the
spine. The triggering source and of the disorder, the tissues involved in the
failure and the biomechanical, neuromuscular, and biological processes active in
the initiation and development of the disorder are not known. The hypothesis is
forwarded that static and repetitive (cyclic) lumbar flexion-extension and the
associated repeated stretch of the various viscoelastic tissues (ligaments,
fascia, facet capsule, discs, etc.) causes micro-damage in their collagen fibers
followed by an acute inflammation, triggering pain and reflexive muscle
spasms/hyper-excitability. Continued exposure to activities, over time, converts
the acute inflammation into a chronic one, viscoelastic tissues
remodeling/degeneration, modified motor control strategy and permanent
disability. Changes in lumbar stability are expected during the development of
the disorder. A series of experimental data from in-vivo feline is reviewed and
integrated with supporting evidence from the literature to gain a valuable
insight into the multi-factorial development of the disorder. Prolonged cyclic
lumbar flexion-extension at high loads, high velocities, many repetitions and
short in between rest periods induced transient creep/laxity in the spine, muscle
spasms and reduced stability followed, several hours later, by an acute
inflammation/tissue degradation, muscular hyper-excitability and increased
stability. The major findings assert that viscoelastic tissues sub-failure damage
is the source and inflammation is the process which governs the mechanical and
neuromuscular characteristic symptoms of the disorder. A comprehensive model of
the disorder is presented. The experimental data validates the hypothesis as well
as provide insights into the development of potential treatment and prevention of
the disorder.
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Langue : ANGLAIS