The kinematics and kinetics of slipknots for arthroscopic Bankart repair

An apparatus has been developed to enable the in vitro measurement of the k inematics and kinetics of a slipknot, both while the knot is being tightene d and with the knot in place and the tension removed. During tightening, th e apparatus provides a linearly increasing resistance, which may be conside red analogous to the resistance experienced when the labrum is drawn toward and apposed to the edge of the glenoid cavity during a Bankart repair. The tension to close the knot is measured with a tensiometer, in tandem with t he closure of the capsule model onto the bone anchor, which is measured wit h a datalogger. The tightening tension was limited to 25 N and intraoperato r and interoperator comparisons were made for four knots tied by six partic ipants. Failure of a knot was taken to be reverse slippage of 2 mm. A secon d criterion of ease of slide was used to assess each knot. We found wide in teroperator variability with regard to slipknot tying. A methodology for qu ality control of slipknot tying is presented.