Experimental approach to study arthroscopic irrigation

The view during arthroscopic operations is kept clear by means of irrigation. The purpose was to determine dominant parameters on irrigation performance from which design considerations were formulated for optimization of joint irrigation. An experimental approach was chosen. The set up consisted of a human joint phantom with normal operative equipment for irrigation. Disturbances of the view were simulated with blue colored ink. With this, an objective and quantitative outcome measure was defined as the time from ink injection till complete clear view (irrigation time). The irrigation times for varying parameters were evaluated: pressure and flow, configuration of in- and outflow portals, location of bleeding, two- versus three-dimensionally shaped joint space, direction and location of inflow, and presence of an instrument. Apart from the level of pressure and flow (F(5,34)=245, p<0.05), the configuration of in- and outflow portals had a dominant significant influence on the irrigation time (F(2,23)=69, p<0.05) achieving a decrease of up to 64% and 77%, respectively. The experimental approach resulted in formulation of design criteria for new sheaths: cross-sectional area as large as possible, and stimulation of a turbulent inflow. The method can be used as a standard testing protocol for new arthroscopic devices and instruments.