Lower back pain

Lower back pain is one of the most common musculoskeletal complaints worldwide, affecting people of all ages. It can result from a variety of mechanical, inflammatory, or pathological causes and significantly impacts daily activities and quality of life. Accurate evaluation and management are essential for effective treatment and prevention of chronic disability.

Etiology and Risk Factors

Mechanical Causes

Mechanical factors are the most frequent causes of lower back pain, usually resulting from strain or degeneration of spinal structures.

• Muscle strain and ligament sprain: Overuse, poor posture, or sudden movements can injure paraspinal muscles and supporting ligaments.
• Intervertebral disc degeneration and herniation: Age-related disc changes or trauma can lead to nerve compression and pain.
• Facet joint arthropathy: Degeneration of the facet joints can contribute to localized pain and stiffness.

Non-Mechanical Causes

Non-mechanical causes involve systemic or pathological conditions affecting the spine and surrounding tissues.

• Inflammatory conditions: Diseases such as ankylosing spondylitis and other spondyloarthropathies can cause chronic inflammatory back pain.
• Osteoporosis and vertebral fractures: Weakening of vertebrae increases the risk of fractures, leading to acute pain.
• Infections: Discitis, osteomyelitis, or epidural abscesses can present with severe back pain and systemic symptoms.
• Neoplasms: Primary spinal tumors or metastatic lesions may produce progressive back pain and neurological deficits.

Risk Factors

Several factors increase the likelihood of developing lower back pain.

• Age and degenerative changes: Disc degeneration and spinal arthritis are more common with advancing age.
• Obesity and sedentary lifestyle: Excess weight and inactivity place additional stress on the spine.
• Occupational factors: Jobs involving heavy lifting, prolonged sitting, or repetitive movements increase risk.
• Genetic predisposition and comorbidities: Family history and conditions such as diabetes may contribute to susceptibility.

Anatomy Relevant to Lower Back Pain

Spinal Structures

Understanding the anatomy of the lumbar spine and surrounding tissues is essential for diagnosing and managing lower back pain.

• Vertebrae and intervertebral discs: Provide structural support and flexibility; disc degeneration can lead to nerve compression.
• Facet joints and ligaments: Facilitate movement and stability; degeneration or injury can cause pain and stiffness.
• Paraspinal muscles and fascia: Support the spine and maintain posture; muscle strain is a common source of pain.

Nervous System Components

Nerve structures in the lower back are critical in the development of pain and neurological symptoms.

• Spinal cord and nerve roots: Compression or irritation of lumbar nerve roots can result in radicular pain.
• Peripheral nerves: Lumbar plexus and associated nerves transmit sensory and motor signals to the lower extremities.

Pathophysiology

Lower back pain arises from a combination of structural, inflammatory, and biomechanical factors that disrupt normal spinal function.

• Inflammatory processes: Chronic inflammation in spinal tissues, including facet joints and intervertebral discs, can generate persistent pain and stiffness.
• Degenerative changes: Age-related disc dehydration, disc herniation, and osteoarthritis of facet joints can lead to nerve root compression and chronic discomfort.
• Biomechanical alterations: Postural abnormalities, muscle imbalances, and repetitive strain contribute to abnormal loading of spinal structures, aggravating pain.

Clinical Features

Symptoms

Lower back pain presents with a range of musculoskeletal and neurological symptoms depending on the underlying cause.

• Localized low back pain: Pain confined to the lumbar region, often exacerbated by movement or prolonged sitting.
• Radiating pain: Sciatica or radicular pain extending into the buttocks, thighs, or lower legs due to nerve root compression.
• Stiffness and restricted range of motion: Difficulty bending, twisting, or performing routine activities.
• Neurological deficits: Numbness, tingling, or weakness in the lower limbs in severe or chronic cases.

Red Flags

Certain features suggest serious underlying pathology and require urgent evaluation.

• Severe or progressive neurological deficits such as foot drop
• History of trauma, malignancy, or unexplained weight loss
• Signs of infection including fever or systemic illness
• Bowel or bladder dysfunction indicating possible cauda equina syndrome

Diagnosis

History and Physical Examination

Accurate diagnosis of lower back pain begins with a detailed history and thorough physical examination.

• Onset, duration, and character of pain: Helps differentiate acute versus chronic pain and identify potential causes.
• Aggravating and relieving factors: Activities or positions that worsen or relieve pain provide diagnostic clues.
• Physical tests: Straight leg raise, range of motion assessment, and palpation of spinal and paraspinal structures aid in localizing pain and detecting nerve involvement.

Laboratory Investigations

Laboratory tests assist in identifying inflammatory, infectious, or systemic causes of lower back pain.

• Inflammatory markers: Elevated ESR and CRP may indicate infection or inflammatory spondyloarthropathy.
• Complete blood count and metabolic panel: Helpful in cases of suspected infection, neoplasm, or systemic illness.

Imaging Studies

Imaging is essential for assessing structural abnormalities, nerve compression, and early degenerative changes.

• X-rays: Useful for evaluating vertebral alignment, fractures, and degenerative changes in chronic cases.
• MRI: Preferred modality for detecting disc herniation, nerve root compression, spinal infections, and soft tissue abnormalities.
• CT scan: Provides detailed bony anatomy and is useful in complex fractures or when MRI is contraindicated.

Differential Diagnosis

Several conditions can mimic lower back pain. Identifying these is crucial to avoid misdiagnosis and ensure appropriate treatment.

• Herniated intervertebral disc causing lumbar radiculopathy
• Spinal stenosis leading to neurogenic claudication
• Osteoarthritis of lumbar facet joints
• Vertebral fractures due to trauma or osteoporosis
• Spinal infections such as discitis or osteomyelitis
• Primary or metastatic spinal tumors
• Referred pain from abdominal or pelvic organs, including renal or gynecological conditions

Management

Non-Pharmacological Treatment

Conservative measures are the first line of management for most patients with lower back pain.

• Physical therapy and exercise programs: Stretching, strengthening, and core stabilization exercises improve spinal support and reduce recurrence.
• Ergonomic modifications and posture correction: Proper seating, lifting techniques, and workplace adjustments prevent further injury.
• Heat/cold therapy and lifestyle adjustments: Ice or heat application can alleviate acute pain, while maintaining healthy weight and activity levels supports recovery.

Pharmacological Treatment

Medications are used to relieve pain, reduce inflammation, and manage associated symptoms.

• Analgesics: Acetaminophen for mild pain relief.
• Nonsteroidal anti-inflammatory drugs (NSAIDs): Reduce inflammation and provide stronger pain control.
• Muscle relaxants: Used for muscle spasm and associated discomfort.
• Opioids: Reserved for short-term use in severe, refractory cases under strict supervision.
• Adjuvant therapies: Antidepressants or anticonvulsants may help with chronic neuropathic pain.

Interventional and Surgical Options

In selected cases, invasive procedures may be necessary when conservative management fails or serious pathology is present.

• Epidural steroid injections: Reduce inflammation around nerve roots and relieve radicular pain.
• Facet joint injections or nerve blocks: Target localized joint-related pain.
• Spinal decompression or fusion surgery: Indicated for severe structural abnormalities, persistent neurological deficits, or spinal instability.

Prevention

Preventive strategies focus on reducing risk factors and maintaining spinal health to minimize episodes of lower back pain.

• Regular exercise and core strengthening to support spinal stability.
• Proper lifting techniques and body mechanics during daily activities and work.
• Weight management to reduce mechanical stress on the lumbar spine.
• Ergonomic adjustments at work and home to maintain neutral spinal posture.

Prognosis

The prognosis of lower back pain depends on its underlying cause, severity, and response to treatment. Most acute cases resolve within weeks, while chronic or recurrent pain can significantly affect function and quality of life.

• Acute vs chronic course: Acute pain often resolves with conservative management, whereas chronic pain may persist beyond 12 weeks.
• Factors influencing recovery: Early intervention, adherence to exercise programs, absence of neurological deficits, and management of comorbidities improve outcomes.
• Impact on daily activities: Chronic lower back pain can reduce mobility, limit work participation, and affect social and recreational activities.

Complications

Untreated or poorly managed lower back pain can lead to a range of musculoskeletal, neurological, and psychological complications.

• Chronic pain and disability: Persistent pain can limit daily function and lead to long-term disability.
• Neurological deficits: Compression of nerve roots may result in radiculopathy, sensory loss, or cauda equina syndrome.
• Psychological impact: Chronic pain often contributes to anxiety, depression, and reduced quality of life.
• Reduced social and occupational participation: Pain and mobility limitations can interfere with work, leisure activities, and social interactions.

References

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