What are various causes for Lower Back Pain?
  1. Introduction to Lower Back Pain
  2. Anatomical Origin of Lower Back Pain
  3. Back Pain due to Muscle Spasm
  4. Back Pain due to compression of Nerve roots 
  5. Back pain due to Facet joint problem
  6. Back pain due to Narrowing of Spinal Canal (Lumbar Canal Stenosis)
  7. Back pain due to Disc degeneration (Discogenic Pain)
  8. Back pain due to Sacroiliac joint problems 

Introduction to Lower Back Pain 

  • Due to adoption of more sedentary lifestyles the incidence of lower back pain has doubled in the last decade
  • It is said to be chronic when it is continuing for more than 3 months
  • The most important question that everyone who has lower back pain wants an answer to is "What is the cause of lower back pain?"

Anatomical Origin of Lower Back Pain

  • Your back pain may have its origin form any of these potential anatomic targets:
    1. Back Muscles
    2. Nerve roots
    3. Fascial structures
    4. Bones
    5. Joints
    6. Intervertebral discs (IVDs)
    7. Organs within the abdominal cavity 

Back Pain due to Muscle Spasm

  • Muscle tension and spasm is the most common reasons for the lower back pain
  • It happens due to sudden involuntary contraction or tensing of the muscles in the lower back
  • The pain becomes worse with moving and taking a deep breath
  • Usually it is away from midline
  • There is usually a myofascial trigger point which is hard, palpable nodule in a tight band of muscle that is hyperirritable and painful. Such trigger points often have multiple contraction knots within the muscle, and are tender on examination.

Back Pain due to compression of Nerve roots 

  • Pain due to compression of Nerve roots arising from from spinal cord. 
  • It is called as Radicular pain since it radiates from the back and buttock into the leg in a specific distribution based on the level of nerve root involved. 
  • Disc herniation is the most common cause of this type of pain.

Back pain due to Facet joint problem

  • It has been estimated to account for up to 30% of chronic low back pain cases.
  • Pain originates from the synovial membrane, hyaline cartilage, bone, or fibrous capsule of the facet joint
  • Features suggesting back pain due to Facet joint problem:
    • Back pain tends to be off-center 
    • Back pain is worse than the leg pain (or leg pain/ radiating pain component may be absent)
    • Pain increases with hyperextension, rotation, lateral bending, and walking uphill
    • It is exacerbated when waking up from bed or trying to stand after prolonged sitting. 
    • Patients often complain of back stiffness, which is typically more evident in the morning
    • CT spine and Dynamic Flexion Extension Xray are the preferred imaging modalities in this type of pain

Back pain due to Narrowing of Spinal Canal (Lumbar Canal Stenosis)

  • It is due to degenerative changes in spine due to aging
  • This happens due to thickening of ligaments, calcification of ligaments, hypertrophy of bones and joints of the spine and associated disc herniations
  • Normal lumbar spinal canal diameter varies from 15 to 27 mm. It is usually defined as anrrowing of spinal canl with a diameter of less than 10 mm
  • Degenerative lumbar canal stenosis is the most common indication for spinal surgery in people older than 65 years of age
  • Symptoms due to Lumbar canal stenosis can be:
    • midline back pain
    • radiculopathy with neurogenic claudication
    • motor weakness
    • paresthesia
    • impairment of sensory nerves
    • Neurogenic claudication pain is the classical symptom of lumbar canal stenosis 
      • It is caused by venous congestion and hypertension around nerve roots. 
      • This pain is increased by standing erect and by downhill ambulation 
      • This pain is reduced with lying supine more than prone, sitting, squatting, and lumbar flexion
    • The diagnosis is confirmed by doing MRI of lumbar spine

Back pain due to Disc degeneration (Discogenic Pain)

  • Back pain due to disc degeneration is estimated to be associated with 39% cases with chronic low back pain.
  • Due to inflammation of the disc (The radicular pain in disc prolapse is due to compression and irritation of the nerve root)
  • Axial, and without radicular radiation

Back pain due to Sacroiliac joint problems 

  • could be generated by tension in ligaments, altered joint mechanics, and inflammation
  • this could be due to overbearing of weight due to bad posture, osteoarthritis and Rheumatoid arthritis
  • Back pain due to Sacroiliac joint problems, patient feels pain during movement of the joint,  pressing down on the iliac crest (pelvis) or upper thigh