Low back pain is an integral part of most human lives and causes different degrees of suffering and disability. The exact cause of pain cannot be identified in most instances. Approximately 90% of back pain have no identifiable cause.
 

PATHOPHYSIOLOGY

The pathophysiology of low back pain is usually indeterminate. In fact, one of the defining features of this disorder is its non-specific etiology. Pain may arise from a number of sites, including the vertebral column, surrounding muscles, tendons, ligaments, and fascia. Stretching, tearing or contusion of these tissues may occur after sudden unaccustomed force applied to the spine from events such as heavy lifting, torsion of the spine, and whiplash injury. Compression may directly stretch nociceptors (pain receptors) in dura or nerve root sleeve tissues but ischemia from compression of vascular structures, inflammation and secondary edema are also likely to play a role in some cases.

CLINICAL FEATURES

The common physical signs especially of mechanical low back pain are local tenderness over the spine, loss of lumbar lordosis and postural changes, lateral tilting with or without neurological involvement. History and physical examination are critical to diagnosis and thus to the formulation of a rational approach to management. The following briefly summarizes the major points.

A. History
Onset of pain (e.g., time of day, activity)
Location of pain (e.g., specific site, radiation of pain)
Type and character of pain (sharp, dull, etc.)
Aggravating and relieving factors
Medical history, including previous injuries
Psychosocial stressors at home or work Red flags: age greater than 50 years, fever, weight loss

B. Physical exam
Informal observation (e.g., patient's posture, expressions, pain behavior).
Comprehensive general physical examination, with attention to specific areas as indicated by the history.
Neurologic evaluation.
Back examination Palpation, Range of motion or painful arc, Stance, Gait, Mobility, Straight leg raise test.
Careful history taking and examination suffices to uncover the mystery in most of the cases. Mechanical low back pain is predominantly acute in onset and is frequently associated with a history of lifting or bending. The pain may radiate to the lower limbs and can be associated with heaviness, tingling and paraesthesia in the thighs and legs. The pain of prolapsed lumbar intervertebral disc (PLID) can be aggravated by coughing, sneezing and straining during defaecation and radiates down to the back of the leg beyond the knee. Spinal stenosis may be presented with spinal claudication that means pain, numbness, paraesthiesia, weakness, etc. come after standing upright or walking for 5-10 minutes and are relieved by sitting, squatting or leaning against a wall to flex the spine. Intermittent postural low back pain, back pain after exertion and pseudo claudication are often due to degenerative changes like, Spondylosis, Spondylolisthesis, etc. Back pain due to inflammatory causes are frequently associated with prolonged early morning and inactivity stiffness. Severe and constant back pain localized to a particular site suggests local bone pathology, like Neoplasm, Paget's disease, compression fracture, Pott's disease and other chronic infections, etc. Systemic enquiry may give important clues for diagnosis of local neoplasm and other rare causes. A healthy adult of 20-45 years are more prone to develop PLID. Lumbar Spondylosis is related to middle age and is common in the 5th decade. Spinal stenosis occurs commonly in people over 50 years. Unduly protruding abdomen and peculiar stance are often noticed by the mother of the child suffering from Dysplastic Spondylolisthesis. Patient with chronic back pain may often develop affective and psycho somatic ailments & their illness behavior is often self perpetuating & self justifying.