Intervertebral Disc Degeneration Degradation and Herniation Jim Meadows

Intervertebral Disc Degeneration, Degradation and Herniation Jim Meadows BSc. PT. , FCAMT

Degeneration Degradation A set of almost universal changes related to aging and not demonstrated to be associated with pain or impairment A variety of pathological changes only partly related to aging and associated with pain and impairment

Functions of the Disc • increase mobility of spine • limit mobility of the spine • lighten the spine • assist in attenuation of compression loads • assist in the attenuation of torque • assist in the attenuation of shear

Lumbar Disc Degeneration “The Telephone Book Model”

Lumbar Disc Degeneration Events • • • decreased proteoglycan content decreased hydrophilia decreased water content increased compressibility compromised stress dispersal randomized circumferential tearing (clefting) increased type 1 and decreased type 2 collagen content increased disc stiffness and decreased mobility increased height

Mechanism of Disc Height Increase • relative reduction in horizontal trabeculae • loss of lateral bracing of vertical trabeculae • collapse of vertical trabeculae in weight bearing area • increased concavity of the end plate • expansion of the disc into the increased • concavity

Causes of Degradation Lack of exercise Injury to the disc Injury to the joint Sustained loading (driving) Heavy occupations and those requiring prolonged flexion Spondylolysis (thinning of transverse process) Vascularization of the disc Genetics Facet tropism (asymmetry)

Disc Degradation Events

Cervical Disc Degeneration • • Uncinate processes form and extend upwards uncovertebral joint capsular forms disc splits to form articular surface disc splits progress medially and meet nucleus disappears posterior disc becomes bi-valved disc and vertebral height loss