Incidence

• 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

1^st 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

2^nd 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

Sinu-vertebral nerve

• originates from the ventral ramus
• innervating posterior aspect of disc, vertebral bodies & posterior longitudinal ligament

Dorsal ramus

• three branches
• innervate the structures dorsal to the neural canal
• posterior musculature and skin
• facet joint

Results of surgery

• failure rate of surgery for pain relief d/t disc herniation is high (reported by several authors)
• significant morbidity also present post-op

Why surgery often fails

• main cause of surgical failure = poor patient selection
• inaccurate diagnosis
• back pain & sciatica can originate from a number of sites

• X rays, CT scans & MRI’s are only of relevance if the findings are supported by clinical findings
• to operate on the basis of special investigations only is unacceptable
• must also remember:
• diabetes can mimic a herniated disc
• ischaemia of the cauda equina & nerve roots are a cause of intermittent claudication
• psychogenic factors

Investigations

• straight x-ray
• blood tests
• myelogram
• CT scan
• MRI scan
• bone scan

Special investigations

• CT & MRI
• low specificity: 30% of the N population have positive scans which are of no importance
• EMG
• has a very high accuracy: helpful test when surgery is considered
• fibrinolytic activity test
• a low fibrinolytic response favours a bad surgical result
• the plasminogen activator inhibitor 1 test is sufficient to assess this
• discogram
• valuable pre-operative examination

Treatment modalities

• manipulation
• if it has a role
• traction
• no proof that it has a beneficial role
• chemonucleolysis
• unpopular because of severe complications:
• transverse myelitis
• allergic reactions
• persisting attacks of muscle spasm
• facet joint infiltration
• useful, may exclude a facet joint arthropathy as a cause of pain
• epidural injections (cortisone)
• recommended
• spinal corsets
• have a place in the treatment of low backache

Indications for surgery in discogenic disease

• all compatible
• symptom complex
• clinical signs
• investigations
• advanced neuro deficit
• progressive neuro deficit
• sphincter involvement
• incapacitating pain
• failed conservative management

Lumbar Spinal Stenosis

• elderly patients
• smaller than normal spinal canal + spondylosis
• local pain in back
• relief by flexion
• claudication of the cauda equina
• random neurological signs in legs
• good surgical outcome

Ankylosing spondylitis

• young males
• non-specific “lumbago” symptoms
• morning stiffness
• typical radiological signs
• later signs
• poker spine
• respiratory difficulty
• cardiac and other systems

Non-specific (mechanical) low back pain

• site
• discomfort across lower back
• central pain, usually over L5
• leg pain or paraesthesia within “sciatic” distribution
• unilateral or bilateral buttock or lateral back pain
• character
• episodic or cyclical pain in the middle years of life
• arises from L3-S 1
• early morning stiffness or pain eases when patient is up and about
• relation to posture
• often aggravated by sitting or standing still
• eased by walking normally
• pain that is greatly aggravated by walking raises the possibility of vascular claudication or spinal or lateral canal stenosis