Applicant's invention is of apparatuses and associated methods in the use of high pressure, sterile water jets in effecting surgical incisions, including those of hard tissues such as bone. The combination of high pressure and sterility is achieved by enclosing a collapsible bag of sterile water within an implosion chamber itself filled with fluid. The collapsible bag is sealingly ported through an orifice in the implosion chamber. As pressure is applied to the fluid within the implosion chamber, by way of a hydraulic ram, the sterile water exits the collapsible bag under extremely high pressure through its port and is directed through a hand-held cutting nozzle to an incision site. Unintended, collateral tissue trauma is minimized in one embodiment though use of a water shroud projected about the high pressure water jet during cutting operations.