A 38-year-old man with chronic low back pain is referred to the pain management clinic. Among patients with chronic non-cancer pain, which is the most common site of origin?

Explanation

## Most Common Site of Chronic Non-Cancer Pain **Key Point:** The lumbar spine is the most common source of chronic pain in the general population, accounting for the majority of chronic pain presentations in primary care and pain clinics. ### Epidemiology of Chronic Pain by Site | Site | Prevalence in Population | Prevalence in Pain Clinics | Common Diagnoses | |------|--------------------------|----------------------------|------------------| | Lumbar spine | 30–40% | 40–50% | Disc herniation, spondylosis, facet syndrome | | Cervical spine | 10–15% | 15–20% | Cervical spondylosis, whiplash, radiculopathy | | Thoracic spine | 5–10% | 5–10% | Myofascial pain, costochondritis | | Sacroiliac joint | 10–15% | 10–15% | SI joint dysfunction, referred pain | **High-Yield:** Low back pain (LBP) is the leading cause of disability worldwide and the most common reason for pain clinic referrals. Approximately 80% of the population experiences LBP at some point in their lifetime. ### Why the Lumbar Spine? 1. **Biomechanical factors**: The lumbar spine bears the most load during daily activities 2. **Degenerative changes**: Lumbar discs are most prone to herniation and degeneration 3. **Occupational stress**: Prolonged sitting and heavy lifting affect the lumbar region 4. **Age-related changes**: Spondylosis and facet joint arthropathy are most common in the lumbar region ### Common Lumbar Pain Syndromes - **Lumbar radiculopathy**: Nerve root compression (L4, L5, S1 most common) - **Lumbar facet syndrome**: Osteoarthritis of facet joints - **Discogenic pain**: Internal disc disruption - **Myofascial pain**: Paraspinal muscle dysfunction - **Spinal stenosis**: Central or lateral canal narrowing **Clinical Pearl:** Most chronic low back pain is non-specific (no clear structural cause identified on imaging). Management focuses on physical therapy, core strengthening, and behavioral modification rather than imaging-based diagnosis. **Mnemonic: LUMBAGO** — **L**umbar **U**nder **M**ost **B**urden **A**lways **G**enerates **O**utcomes (most common pain site).