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Five progressive clues
These are the case findings in their original reveal order, moving from the broader presentation to the most discriminating evidence.
Clue 1
A 34-year-old woman comes to the chiropractic clinic frustrated that she can no longer sit through her daughter's hour-long dance recitals without constantly shifting in her seat. Her complaint is a nagging pain at the very lowest part of her spine that flares whenever she stays seated too long.
Clue 2
The pain began about three months ago after she slipped on an icy driveway and landed hard on her backside. It is sharp and tightly localized to the base of her spine, worse on hard chairs and when she leans back or rises from sitting, and eased by standing or by perching forward on the edge of a seat. There is no pain radiating into her legs and no numbness.
Clue 3
On examination, firm palpation directly over the terminal bony segment at the base of the spine reproduces her exact pain, while the sacroiliac joints, sciatic notch, and gluteal muscles are all non-tender. Straight-leg raise and neurologic testing of both lower limbs are normal.
Clue 4
Comparative lateral radiographs taken standing and then seated show that the last mobile segment tips forward abnormally, its angulation increasing by more than 25 degrees when she sits — movement well beyond the normal range for that segment.
Diagnosis
Coccydynia
Why the diagnosis fits
A direct fall onto the buttocks, focal pain reproduced only by palpation of the terminal bony segment, position-dependent symptoms (worse on hard seats and leaning back, relieved by leaning forward or offloading the tip), and dynamic sit-versus-stand radiographs showing abnormal forward tipping (>25 degrees) of the last mobile segment together localize the pain generator to the terminal spinal segment itself. The key discriminator from sacroiliac joint dysfunction is that tenderness and provocation are exactly midline over the terminal segment with entirely non-tender sacroiliac joints, sciatic notch, and gluteal muscles, and no referred leg pain or positive SIJ stress tests. Complete abolition of pain when the segment is offloaded on a cut-out wedge cushion clinches a mechanical, segment-specific source rather than a pelvic-floor or soft-tissue cause.
Educational reference
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Open the clinical referenceFor education and entertainment only. This fictional case is not medical advice and does not replace supervised clinical training, diagnosis, or treatment.