What do we mean by mechanical
Mechanical means that the source of the pain may be in your spinal joints, discs, vertebrae, or soft tissues.
Epidemiology of mechanical back pain
Common in young people: 20-55 years
Aetiology of mechanical back pain
- 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
RF for mechanical back pain
- 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
Physiology of mechanical back pain
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.
Where do the main lesions occur
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
When do changes in discs start?
- 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
What happens when discs become thinner and less compliant
- 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
Most common site for lumbar spondylosis
L5/S1 & L4/L5
Spondylosis (mostly symptomless) but can cause
- Episodic spinal pain
- Progressive spinal stiffening
- Facet joint pain
- Acute disc prolapse, with or without nerve irritation
- Spinal stenosis
Facet Joint Syndrome
- 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
Fibrositic nodulosis
- 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
Clinical manifestations of mechanical lower back pain
Stiff back
Scoliosis
Muscular spasm
Pain worse in the evening
Investigations for mechanical lower back pain
- 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
Differential diagnossi for mechanical lower back pain
- 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.
Management for mechanical lower back pain
Analgesics - NSAIDs paracetamol, codeine
Acupuncture
Avoid excessive rest
Comfortable sleeping postions
What is intervertebral disc disease?
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.
Which discs are most commonly affected
Discs in the lower lumbar spine
What is acute disc diseae
Progressive intervertebral disc breakdown leading to prolapse of the intervertebral disc resulting in acute back pain (lumbago)
Epidemiology of Acute disc disease
- 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
- 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
Aetiology of Acute disc disease
- Accumulation of natural stress, minor injury throughout life
- Genetic predisposition
RF for acute disc disease
– Genetic predisposition
- Advanced age
- Menopause
- Repeated spinal trauma
Pathophysiology of acute disc disease
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
Clinical manifestations acute disc injury
- 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
