Lower Back Pain Triage: Disc, Facet, Neural — and Red Flags

Effective triage of mechanical lower back pain hinges on directional preference and symptom distribution. Discogenic patterns (most commonly L4–L5 or L5–S1) are flexion-intolerant: pain worsens with sitting, forward bending, and lifting, and improves with extension or walking; radicular leg pain in a dermatomal distribution suggests root involvement. Facet-mediated pain is extension-intolerant and rotation-provocative: standing prolonged, walking downhill, or arching aggravates; flexion offers relief; pain is typically localized to within a hand's-width of the spine and does not radiate below the knee. Neural-tension presentations (nerve root sensitization without frank disc herniation) reproduce on slump test or straight-leg raise at 30–60° and respond to neural glides rather than disc-directed McKenzie extension protocols. Absolute red flags requiring immediate medical referral (not rehabilitation): saddle anesthesia, urinary retention or incontinence, progressive lower-extremity weakness, unexplained weight loss, night pain unrelated to position, history of cancer, or post-traumatic deformity. The single most common rehabilitation error is applying a flexion-based protocol to a flexion-intolerant disc presentation; misdirecting the loading strategy by one axis can drive symptoms backward for weeks.