A 47-year-old with 6-month back pain worsened by sitting and rising, focal L4-5 tenderness, normal rest. Most likely diagnosis?

• A. Acute lumbar strain
• B. Degenerative disc disease
• C. Spinal stenosis
• D. Osteomyelitis

Answer: (B)

A pattern of chronic axial low back pain in a middle-aged patient that is worsened by sitting or bending forward and with focal tenderness at a specific level points to degenerative disc disease. As discs degenerate with aging, the loading standard changes; sitting and flexion increase intradiscal pressure and stress on the affected disc, causing persistent, activity-related pain. The localized tenderness at L4-5 supports a problem at that level, such as disc degeneration or facet arthropathy, rather than a generalized muscular strain. Pain at rest is usually not prominent in degenerative disc disease, which is a mechanical pain pattern rather than inflammatory.

Acute lumbar strain would typically present with sudden onset after a specific ergonomic or lifting incident and diffuse paraspinal muscle tenderness, with pain often improving with rest. Spinal stenosis would more commonly involve leg symptoms with walking (neurogenic claudication) and relief with bending forward or sitting, rather than a focal spinal level tenderness. Osteomyelitis would usually include systemic signs such as fever and constitutional symptoms and has a more acute or subacute course with elevated inflammatory markers.