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Experimental study demonstrates that bevelled spinal needles deflect away from the bevel during tissue travel, indicating that introducers or pencil-point tips improve targeting accuracy.
Bevelled spinal needles sizes 22 and 25 gauge were passed through tough meat to assess the influence of bevel orientation on the path of the needle. The needle bent away from the bevel surface by about 1 mm for each centimetre of needle travel through the tissue. With an introducer, the deviation was reduced by a reduction of the distance of unsupported travel. Pencil-point needles were less deviated.
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Drummond et al. (1980) studied this question.
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