Lecture 5 - finished Flashcards
IVD degeneration epidemiology
Common in adults, esp those 50+
Most common in the L4-L5 and L5-S1 regions
Pathology of IVD degeneration
Biochemical changes: - With aging, several biochemical changes are observed in the IVD - The IVD progressively becomes more desiccated, stiff and less able to resist mechanical forces = reduced proteoglycan synthesis = reduction in proteoglycan size = reduced water content = increased collagen content = reduced elastin content
Degeneration:
- Decreased ability to resist shear forces
= fissures in annulus fibrosis
- Increased forces on endplates
= Endplate micro-fractures may occur
** as a result of annulus fibrosis and end plate microfractures there is acute inflammation and healing
Fissures:
- Causes hernitations of nucleus pulposus, which can happen either in the
- vertebral end plate = schmorls nodes
OR
- CNS = Spinal nerve impingement or spinal cord impingement
What biochemical changes occur in IVD degeneration?`
= reduced proteoglycan synthesis = reduction in proteoglycan size = reduced water content = increased collagen content = reduced elastin content
What does a decrease in water content do to discs? What does this eventually lead to?
Decreased disc hydrostatic pressure
Decreased nucleus pulposus elasticity
Decreased disc height (i.e. flattening)
This eventually leads to altered biomechanical properties
What can fissures in the annulus fibrosis lead to?
Herniation of nuclear material into:
- the spinal cord
- the spinal nerves
Herniation into the intervertebral endplates causes:
- Schmorls nodes
- Reactive bone growth
When herniations into the intervertebral end plates cause reactive bone growth, how does this manifest?
What do these manifestations result in?
Osteophytes
Lipping
They result in spondylosis (= spinal degeneration)
How does disc degeneration result in facet joint spondylosis?
IVD degenerates and flattens
The facet joint becomes misaligned
The facet develops secondary OA
The facet develops spondylosis
How does spondyolsis worsen?
Increases osteophyte production Narrowing of spinal canal Narrowing of IV foramina Nucleus pulposus becomes fibrocartilage Fibrosis of affected structures
What is the main manifestation of chronic disc degeneration?
Pain
What can cause pain from chronic disc degeneration?
Facet misalignment Facet joint arthritis Vertebral instability Root canal stenosis Spinal canal stenosis PLL tension and ossification
Is spinal spondylosis associated with back/neck pain?
No
Describe a partial herniation:
Fibrocartilagenous material extrudes/bulges posteriorly
The annulus usually bulges to one side of the PLL
The degree of the partial herniation gradually increases with successive injuries
Describe a posterolateral rupture:
May press on a nerve root proximal to its point of exit through the IV foramen
- e.g. L4/L5 herniation causes compression of the 5th lumbar root
Describe a large central herniation
Herniation of both the capsule (annulus fibrosis) and the nucleus pulposus
- may result in compression of the spinal cord or cauda equina.
Describe a complete herniation
Herniation where part of the nucleus may:
- break free and lie free in the spinal canal
- break loose and work its way into the IVF
