Spinal Pathology & Clinical Patterns

Question 1

What is the MOI for a lumbar muscle strain?

Answer 1

Often overexertion. Direction dependent.

Note: isolated strain not common in the low back.

Question 2

What is the MOI for a herniated lumbar disc?

Answer 2

i) Traumatic onset: flexion and rotation.

ii) Insidious onset: prolonged or repetitive flexed posture.

Question 3

What is the source of pain in the case of a disc herniation?

Answer 3

The outer 1/3 fibres of the annulus as this is the only neurally innervated components of the disc OR muscle loading imbalances from resultant instability.

Question 4

What are the functions of the intervertebral disc?

Answer 4

i) transmit forces
ii) resist compression, torsion and shear
iii) allow spinal movement

Question 5

What is the biochemical composition of nucleus pulposus?

Answer 5

i) some elastin & collagen
ii) high concentration of proteoglycans (therefore high water content - 85/90% but decreases w/ age)
- The result is an incompressible semi-fluid.

Question 6

What are the functions of the nucleus pulposus?

Answer 6

i) shock absorption
ii) transmit mechanical stresses
iii) fulcrum for movement
iv) weight bearing: resists compression
v) nutrition

Question 7

What are two age-related changes that occur within the nucleus pulposus?

Answer 7

i) decreased proteoglycan (# and effectiveness) and water content
ii) increased collagen
- Grows more similar to annulus.

Question 8

What is the biochemical composition of the annulus fibrosis?

Answer 8

i) 50-60% collagen content

ii) small # of proteoglycans and water content

Question 9

Describe the orientation of layers of lamellae in the annulus fibrosis.

Answer 9

i) Concentric lamellae in which each layer is perpendicular to the adjacent
ii) 65’ from vertical
iii) thick anterolaterally and thin posteriorly

Question 10

What are the functions of the annulus fibrosis?

Answer 10

i) contain nucleus pulposus
ii) enhance mobility
iii) weight bearing
iv) shock absorption
v) resist shear and torsion
vi) vertebral stability (holds VBs together)

Question 11

What is the composition of the vertebral end plate?

Answer 11

1 mm of cartilage. Hyaline cartilage closer to the vertebral body and fibrocartilage closer to the disc.

Question 12

What is the coverage of the vertebral end plate relative to the IV disc?

Answer 12

i) covers NP entirely
ii) does not fully cover AF
ii) covers area encircled by ring apophysis

Question 13

Is the vertebral end plate more strongly bound to the disc or vertebral body?

Answer 13

Disc.

Question 14

What are the functions of the vertebral end plate?

Answer 14

i) growth plate
ii) nutrition for IVD
iii) protection

Question 15

Upon axial compression, which part of the intervertebral system is most likely to fail?

Answer 15

The vertebral end plate. Upon axial compression:

i) hydostatic pressure of NP rises
ii) tensile force in AF rises allowing radial NP expansion
iii) compressive forces exerted upward and downward from NP onto end plate to redistribute force.
iv) trabeculae fracture first, followed by end plate fracture

Question 16

Which nerve root would a posterolateral herniation at L4/5 impact? L5/S1? Large central L4/5 herniation?

Answer 16

i) L5 (often the lower VB)
ii) L5 and S1
iii) cauda equina

Question 17

Is disc herniation a mobility or stability issue?

Answer 17

Stability. Disc injury restributes forces to other structures (esp. facets).

Question 18

Which structures reinforce the z-joint capsules anteriorly and posteriorly?

Answer 18

i) anterior: ligamentum flavum

ii) posterior: multifidus

Question 19

What special intra-articular features to z-joints possess?

Answer 19

i) subcapsular pockets (superior and inferior)
ii) fat pads
iii) meniscoid structures
- these structures can cause locking

Question 20

What is spondylolithesis pathology?

Answer 20

Anterior displacement of one vertebra or the vertebral column relative the vertebra below. Often secondary to a fracture of the pars interarticularis following repetitive trauma or increased training.

Question 21

What is the MOI for a pars interarticularis fracture?

Answer 21

Flexion/distraction.

Question 22

Describe the grading system for spondylolithesis.

Answer 22

I: <25% slippage
II: 25%-50% slippage
III: 50% -75% slippage
IV: >75% slippage
Note: Grade III, IV and high level IIs require surgical stabilization prior to therapy.

Question 23

Define clinical instability.

Answer 23

Pathological increase in translatory movement that interferes with joint function. It is NOT synonymous with hypermobility or joint laxity.

Question 24

What are the expected subjective reports associated with clinical instability?

Answer 24

i) catching/clunking and positive physical exam
ii) history of dislocation/joint slipping
iii) apprehension loading the region or with movement

Question 25

What is the source for pain in DDD?

Answer 25

i) circumferential tears through the outer 1/3 of annular fibres.
ii) inflammation

Question 26

What is degenerative spondylolithesis pathology?

Answer 26

Development of laxity in capsule and disc due to early degeneration which allow for anterior translation of superior vertebra (<30%) often resulting in stenosis.

Question 27

What is the pattern of stenosis that often develops from degenerative spondylolithesis?

Answer 27

Lateral +/- central (often L4/5 causing L5 nerve root compression). This pathology is not likely to progress.

Question 28

What symptoms would arise from lateral stenosis?

Answer 28

Nerve root signs (myotomes, dermatomes, reflexes).

Question 29

What symptoms would arise from central stenosis?

Answer 29

Cord signs (cauda equina, hyperreflexivity, spasticity etc.)

Question 30

What symptoms would arise from foraminal stenosis?

Answer 30

May affect movement if z-joint articular surface implemented.

Question 31

What are the three components of the Panjabi model of stability?

Answer 31

i) passive: vertebrae, discs, ligaments, capsules etc.
ii) active: muscles & tendons.
iii) neural/control: proprioception, descending control, motor coordination etc.

Question 32

What is Panjabi’s neutral position?

Answer 32

Position of the spine that requires minimal internal stress and muscular effort to hold (high laxity).

Question 33

What is Panjabi’s neutral zone?

Answer 33

The part of spinal ROM in which motion is produces with minimal internal resistance.

Question 34

What is Panjabi’s elastic zone?

Answer 34

The part of spinal ROM from the end of the neutral zone into up to physiological limit characterized by significant degree of internal resistance (high stiffness).

Question 35

What is Panjabi’s definition of clinical instability?

Answer 35

A decrease in the ability of the spinal stabilization system to maintain the neutral zone within the physiological limit such that no pathology occurs.

Question 36

What are the components of Hertel’s model of instability?

Answer 36

i) mechanical insufficiencies: ligamentous, articular, degeneration, synovial changes etc.
ii) functional insufficiences: weakness, neuromuscular control, proprioception, postural control etc.
- The result is RECURRENT episodes of pain secondary to instability.