Hydro-jet cutting: a method for selective surgical dissection of nerve tissue. An experimental study on the sciatic nerve of rats.

The aim of this study was to answer the question: is it possible to save motor nerves when dissecting tissue with the hydro-jet dissector? In order to study the influence of the hydro-jet on motor nerves the function of the sciatic nerves of 10 Wistar rats was evaluated. The sciatic nerves were dissected bilaterally and only the left one was exposed to the hydro-jet. The water-jet emerged from a nozzle with a diameter of 0.1 mm and was applied to the nerve for 2, 5 or 10 s and with jet pressures of 80, 85 and 90 bar, respectively. After the operation the animals were observed for 5 months in order to monitor the degree of limping using a scale with 10 clinical grades of function. Five months postoperatively the animals were sacrificed and the sciatic nerves were studied by light and electron microscopy. It was found that hydro-jet pressures of 80 bar and exposure times of 2 s had already lead to irreversible damage to the sciatic nerve. Therefore further studies with lower pressures or shorter exposure times are required before considering hydro-jet cutting for parotid gland surgery. It must be confirmed as harmless to motor nerves before applying this method in humans.