mechanical lower back pain

Question 1

What do we mean by mechanical

Answer 1

Mechanical means that the source of the pain may be in your spinal joints, discs, vertebrae, or soft tissues.

Question 2

Epidemiology of mechanical back pain

Answer 2

Common in young people: 20-55 years

Question 3

Aetiology of mechanical back pain

Answer 3

• Strain
• Heavy manual handling
• Stooping and twisting whilst lifting
• Pregnancy
• Trauma
• Lumbar disc prolapse
• Spondylolisthesis (one vertebrae slips out of place causing back pain)
• Osteoarthritis
• Fractures
• Exposure to whole body vibration

Question 4

RF for mechanical back pain

Answer 4

• Female
• Increasing age
• Pre-existing chronic widespread pain - fibromyalgia
• Psychosocial factors e.g. high levels of psychological distress, poor self-rated health, smoking and dissatisfaction with work

Question 5

Physiology of mechanical back pain

Answer 5

Spinal movement occurs at the disc and the posterior facet joints - stability is normally achieved by a complex mechanism of spinal ligaments and muscles. Any of these structures may be a source of pain.

Question 6

Where do the main lesions occur

Answer 6

in an intervertebral disc - a fibrous structure whose tough capsule inserts into the the rime of the adjacent vertebra. This capsule encloses a fibrous outer zone and a gel-like inner zone

Disc allows rotation and bending

Question 7

When do changes in discs start?

Answer 7

• occasionally start in teenage years or early twenties and often increase with age
• The gel changes chemically, breaks up, shrinks and loses its compliance
• The surrounding fibrous zone develop circumferential or radial issues

Question 8

What happens when discs become thinner and less compliant

Answer 8

• These changes cause circumferential bulging of the intervertebral ligaments
• Reactive changes develop in adjacent vertebrae; the bone becomes sclerotic and osteophytes form around the rim of the vertebra

Question 9

Most common site for lumbar spondylosis

Answer 9

L5/S1 & L4/L5

Question 10

Spondylosis (mostly symptomless) but can cause

Answer 10

• Episodic spinal pain
• Progressive spinal stiffening
• Facet joint pain
• Acute disc prolapse, with or without nerve irritation
• Spinal stenosis

Question 11

Facet Joint Syndrome

Answer 11

• Lumbar spondylosis causes secondary osteoarthritis of the misaligned facet joints
• Pain is typically worse on bending backwards and when straightening from flexion - it is lumbar in site, unilateral or bilateral and radiates to the buttock
• Facet joints are well seen on MRI and may show osteoarthritis, an effusion or a ganglion cyst
  
  • Treatment consists of direct corticosteroid injections under imaging
  • Physiotherapy and help to reduce weight may also be offered

Question 12

Fibrositic nodulosis

Answer 12

• There are tender nodules in the upper buttock and along the iliac crest
• This condition causes unilateral or bilateral lower back and buttock pain
  
  • Local intralesional corticosteroid injections may help

Question 13

Clinical manifestations of mechanical lower back pain

Answer 13

Stiff back
Scoliosis
Muscular spasm
Pain worse in the evening

Question 14

Investigations for mechanical lower back pain

Answer 14

• MRI - imagine modality of choice. Can see disc prolapse, cord compression, cancer, infection or inflammation.
• Bone scans
• Examine patient to exclude pathologies e.g. nerve root lesions affecting reflexes
• Spinal X-rays

Question 15

Differential diagnossi for mechanical lower back pain

Answer 15

• Polymyalgia rheumatica (PMR): in elderly, ESR and CRP will distinguish this from mechanical back pain
• Sinister causes of back pain e.g. malignancy, infection or inflammatory causes. Must be excluded with spinal x-ray.

Question 16

Management for mechanical lower back pain

Answer 16

Analgesics - NSAIDs paracetamol, codeine
Acupuncture
Avoid excessive rest
Comfortable sleeping postions

Question 17

What is intervertebral disc disease?

Answer 17

common condition characterised by the breakdown (degeneration) of one or more of the discs that separate the bones of the spine (vertebrae), causing pain in the back or neck and frequently in the legs and arms.

Question 18

Which discs are most commonly affected

Answer 18

Discs in the lower lumbar spine

Question 19

What is acute disc diseae

Answer 19

Progressive intervertebral disc breakdown leading to prolapse of the intervertebral disc resulting in acute back pain (lumbago)

Question 20

Epidemiology of Acute disc disease

Answer 20

• Disease of younger people (20-40 yrs) - the disc degenerates with age
  and in the elderly it is no longer able to prolapse
  
  • In older patients, sciatica is more likely to result (as opposed to prolapse) - due to compression of the nerve root by osteophytes in the lateral recess of
    the spinal canal

Question 21

Aetiology of Acute disc disease

Answer 21

• Accumulation of natural stress, minor injury throughout life
• Genetic predisposition

Question 22

RF for acute disc disease

Answer 22

– Genetic predisposition
- Advanced age
- Menopause
- Repeated spinal trauma

Question 23

Pathophysiology of acute disc disease

Answer 23

Intervertebral disc’s nucleus pulposus (mostly water) dehydration → decreased proteoglycan and collagen → decreased padding between vertebrae → unable to absorb shock → disc collapse → annular tears, herniation of disc contents into spinal canal → nerve impingement → pain

Question 24

Clinical manifestations acute disc injury

Answer 24

• Sudden onset of severe back pain - often following a strenuous activity
• Decreased range of motion
• Tingling, paresthesia and numbness
• Muscle weakness and atrophy
• Muscle spasm leads to a sideways tilt when standing
• Decreased tendon reflexes
• The radiation of the pain and the clinical findings depend on the disc
  affected - the lower three disks are more commonly affected

Question 25

Investigation of acute disc

Answer 25

• X-rays are often normal - can detect fracture
• MRI
  
  • Evaluates spinal canal
  • Detects annular tears
  • Increased signal may indicate disc dehydration
  • If surgery is being considered

Question 26

Management for acute disc disease

Answer 26

Bed rest on firm mattress
Analgesics - NSAIDs
Surgery only for severe or increasing neurological impairment
- Nerve root injection
- Corpectomy