Spinal Anaesthesia Landmarks — FRCA Final MCQ

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EasyRegional AnaesthesiaSpinal Anaesthesia LandmarksFRCA Final

A 48-year-old woman with a BMI of 36 is scheduled for a right total knee replacement under spinal anaesthesia. Using surface anatomy alone, which named landmark is conventionally used as the reference from which the L3/4 interspinous space is estimated?

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Correct answer: C — Tuffier's line (intercristal line)

Tuffier's line is the line joining the highest points of the iliac crests. It is conventionally used to orientate the lower lumbar interspaces: it is classically associated with the L4 spinous process or L4/5 interspace, with L3/4 then estimated immediately cephalad. Palpation does not determine an exact vertebral level reliably; studies show substantial variation, especially in women and patients with a higher BMI. Preprocedural ultrasound is therefore more accurate when landmarks are difficult. The inferior scapular angle is a thoracic landmark, C7 identifies the cervicothoracic region, the posterior superior iliac spine lies near the upper sacrum, and the sacral hiatus is used for caudal rather than lumbar neuraxial access.

Reference: Chakraverty R et al. Which spinal levels are identified by palpation of the iliac crests and the posterior superior iliac spines? Journal of Anatomy, 2007. https://pubmed.ncbi.nlm.nih.gov/17261142/