• Roderick J Finlayson, Atikun Thonnagith, Maria Francisca Elgueta, Jordi Perez, Etheridge John-Paul B JB, and Tran De Q H DQ.
• From the *Department of Anesthesiology, Alan Edwards Pain Management Unit, McGill University Health Centre, Montreal, Quebec, Canada; †Department of Anesthesiology, Chulalongkorn University, Bangkok, Thailand; ‡Department of Anesthesiology, Pontifical Catholic University of Chile, Santiago, Chile; §Kelowna General Hospital, Kelowna, British Columbia, Canada and University of British Columbia, Kelowna, British Columbia, Canada.
• Reg Anesth Pain Med. 2017 Jan 1; 42 (1): 45-51.

Background And ObjectivesNovel multitined cannulae constitute an attractive option for ultrasound-guided radiofrequency neurotomy of cervical medial branches. The deployment tines increase the cannula's active area, thus altering its lesion size. Despite their theoretical benefits, multitined cannulae have not been assessed. In this bench study, we sought to investigate the lesions produced by a standard 18-gauge and 2 commercially available multitined deployment cannulae. We created ex vivo models to evaluate lesion morphology at a periosteal interface using approach angles likely to be encountered during an ultrasound-guided technique.MethodsTwo ex vivo models were assembled using chicken breast tissue and bovine tibia. Monopolar lesions were carried out with 3 commercially available cannulae (18-gauge curved [S], 17-gauge with laterally deploying tines [N], and 18-gauge with distally deploying tines [T]). All cannulae were positioned at 0, 25, 45, and 90 degrees to the periosteal plane. For each angulation and cannula, 2 series of measurements were recorded to document lesion morphology in the axial and sagittal planes. Data collected included the lesion's surface area, shape, and dimensions relative to the needle tip.ResultsA total of 240 lesions were analyzed. The performances of S and N cannulae were significantly affected by approach angle, with lesion size decreasing as the angle increased. In contrast, T cannulae displayed similar lesion surface areas at 0 and 90 degrees. The multitined N and T cannulae produced the largest lesions at 0/25 and 90 degrees, respectively. Lesion height varied inversely according to approach angle for S and N cannulae, whereas T cannulae displayed stable characteristics.ConclusionsUnlike their S and N counterparts, T cannulae demonstrated stable lesion characteristics at varying approach angles.

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