80% of the population affected at some time in life
40% also has sciatica
most frequent claim for disability in USA (1990) involved back disorders
approximately 19%
enormous financial costs
loss of productivity
Nachemson (1993) - cost of LBP was 5% of Sweden’s GNP
clear correlation between welfare benefits & stay away from work
Causes Mechanical Failure
Gross
i.e. plain X ray diagnosis
spondylolisthesis
scoliosis with facet joint arthritis
trauma #’s & dislocations
spinal osteoporosis
Subtle
instability - like to rest
disc pathology - discogram or MRI diagnosis
ligament & facet joint capsule sprains & strains
facet arthrosis - like to move
diagnosed on facet arthrography, CT
Nerve root compression
disc prolapse
stenosis
Rarer causes
inflammation
i.e. ankylosing spondylitis
infection
metabolic
neoplastic
malignant - primary or secondaries
benign
Non-orthopaedic
gynae
intra-abdominal
vascular
Natural history of lumbar disc disease
natural history of the disc sy. is towards resolution
Holmes & Rothman - 90% resolve spontaneously within 3 months
Singer - similar findings
Weber (Spine 1983) - results of disc dx treated operatively at 1 year was far better than those treated non-operatively BUT, at 4 & 10 year follow-up, the results were the same
neurological results improved just as well in the conservatively treated group as the operative group
natural course of herniated discs - decrease in size (serial CT scans) - Thelander & others
Theory of spinal degeneration
all spines degenerate
present methods of treatment are for symptomatic relief, not for a cure
degenerative process divided into three separate stages
1st stage - dysfunction
age group - 15-45 years
tears in the disc anulus & localized synovitis of the facet joints
familial predisposition to lumbar disc herniation in patients who had herniation before age 21 years
2nd stage - instability
35-70-year-old patients
internal disruption of the disc progressive disc resorption, degeneration of the facet joints with capsular laxity, subluxation & joint erosion
Final stage - stabilization
patients older than 60 years
development of hypertrophic bone about the disc and facet joints
leads to segmental stiffening or frank ankylosis
each spinal segment degenerates at a different rate
one level is in dysfunction, another may be entering stabilization stage
disc herniation a complication of disc degeneration in dysfunction & instability stages
spinal stenosis from degenerative arthritis is a complication of bony overgrowth compromising neural tissue in the late instability & early stabilization stages
males were found to have more degeneration than females
L4-5 & L3-4 disc levels showed the greatest degree of disc degeneration
Pain transmitting structures
at the level of the intervertebral foramen is the dorsal root ganglion
distal to the ganglion three distinct branches arise from the dorsal root
Ventral ramus
supplies all structures ventral to the neural canal