Deflection of spinal needles by the bevel.

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.