Low Back Pain: Conditions with a Definitive Diagnosis

Low back pain is among the most frequent musculoskeletal complaints, yet only a small fraction - less than 10% of all cases, can be attributed to a clearly defined pathology. The majority of individuals experience non-specific or somatic low back pain, where the source is multifactorial and difficult to localize. However, in certain conditions, the anatomical structure responsible for pain can be confidently identified. Understanding these conditions conceptually helps clinicians differentiate specific spinal pathologies from general mechanical pain.

 

1. Fractures of the Lumbar Vertebrae

Fractures represent structural disruption of the vertebral elements, leading to localized mechanical pain.

Pathophysiology:

Lumbar fractures whether transverse process or compression types are typically caused by direct trauma or high mechanical load. These injuries result in acute pain due to both bony damage and associated soft tissue injury.

Clinical Implication:

Pain is focal, movement-dependent, and often accompanied by muscle guarding. Imaging confirms diagnosis.

 

2. Nerve Root Compression (Radiculopathy)

Pain arises from mechanical or chemical irritation of the spinal nerve root, resulting in neuropathic symptoms.

Pathophysiology:

The most common cause is herniation of the nucleus pulposus through the annulus fibrosus, compressing the nerve root. This generates radiating (lancinating) leg pain following a dermatomal distribution, often termed radicular pain.

Clinical Features:

• Sharp, shooting pain radiating below the knee.
• Sensory loss, muscle weakness, and altered reflexes may occur.
• Pain is aggravated by actions increasing intraspinal pressure (e.g., coughing, sneezing).

 

3. Spondylolysis

A stress fracture occurring in the pars interarticularis, typically due to repetitive overload in extension and rotation.

Pathophysiology:

This lesion develops from chronic microtrauma, commonly seen in athletes performing repetitive hyperextension such as gymnasts, cricketers, and weightlifters. If bilateral, it may compromise spinal stability.

Clinical Insight:

Pain intensifies with extension movements and may reduce with flexion. Early detection allows healing with activity modification.

 

4. Spondylolisthesis

Represents anterior slippage of one vertebra over another, often secondary to bilateral pars defects.

Pathophysiology:

Loss of integrity in the posterior vertebral elements allows forward displacement. This can alter spinal alignment and, in severe cases, compress neural structures.

Clinical Insight:

Patients experience mechanical back pain, stiffness, and occasionally radicular symptoms. Palpable “step-off” deformity may be noted in advanced cases.

 

5. Spinal Canal Stenosis

Pain arises from narrowing of the spinal canal, leading to compression of neural tissue during movement.

Pathophysiology:

Degenerative changes such as ligamentum flavum thickening or facet joint hypertrophy reduce canal diameter. In older athletes, this results in neurogenic claudication pain, heaviness, or numbness in the legs during walking, relieved by sitting or flexion.

Clinical Insight:

Symptoms reflect positional compression rather than acute trauma. Flexion-based exercises are often relieving.

 

6. Hip Joint Pathology Presenting as Low Back Pain

Pain perceived in the low back may originate from structures sharing neural referral patterns, such as the hip joint.

Pathophysiology:

Lesions like acetabular labral tears or rim lesions can refer pain to the posterior pelvis or low back region due to overlapping innervation.

Clinical Insight:

A comprehensive assessment must include hip range, special tests, and gait analysis to rule out extra-spinal causes of back pain.

Understanding these mechanisms conceptually aids physiotherapists and clinicians in identifying the origin of pain, guiding targeted investigations, and designing condition-specific management strategies.