Low back pain — KFP-style written assessment

KFP 1 (10 marks)

A 44-year-old warehouse worker presents on day three of severe low back pain after shifting pallets. He has no leg pain, no neurological symptoms, no fever, no cancer history, no steroid use, and no significant trauma beyond the lift. He wants an MRI "to see what's torn" and a sick certificate for four weeks off work. ^[1]

1. State your diagnostic triage for this presentation with approximate proportions, naming what must be actively excluded. (3) ^[1]
2. He asks why you will not order an MRI. Give the trial-based justification. (3) ^[4]
3. Outline first-line management, including one trial result that supports each element. (4) ^[2][3]

Model answers

1. Triage allocates presentations to nonspecific low back pain (90–95% of cases), radicular syndrome (about 5–10%), or specific spinal pathology (below 1% — fracture, malignancy, infection, axial spondyloarthritis, cauda equina). His presentation — mechanical pattern, no deficit, no systemic features — sits in the nonspecific category after excluding non-spinal causes; back pain is a symptom, not a diagnosis. ^[1]
2. A systematic review of six randomised trials (n = 1804) found no significant difference in pain or function between immediate lumbar imaging and usual care without immediate imaging at short- or long-term follow-up; clinicians should refrain from routine immediate lumbar imaging without features suggesting serious underlying condition. Imaging also risks cascades: rapid-MRI strategies produced identical outcomes but more spine operations than radiography. ^[4]
3. Advice to stay active (small but real gains in pain relief and function versus bed rest), heat wrap (moderate-quality first-line nonpharmacologic therapy per ACP), and an NSAID at lowest effective dose if needed — NSAIDs beat placebo across 35 trials, though with clinically unimportant average effect (NNT 6) and 2.5-fold more gastrointestinal reactions; paracetamol is not indicated (PACE: median recovery 17 vs 17 vs 16 days versus placebo, HR 0.99). Encourage early return to modified duties. ^[2][3]