A comparison of ultrasonic suture welding and traditional knot tying

The slippage of knots and the technical challenge of tying them securely ar e potential impediments to certain arthroscopic procedures. Ultrasonic ener gy delivered at 70 kHz can be used to weld No. 2 polypropylene suture, This method was compared with a traditional knot (surgeon's knot with four alte rnating half hitches) tied with an open technique to determine whether weld ing of sutures is comparable, in mechanical properties, to hand-tied knots. Both loops were fashioned around a 0.25-inch mandrel and then tested. The load to reach 3-mm elongation (point of likely biologic failure of a repair ) was significantly greater for welded sutures than for knots. The elongati on at ultimate failure was significantly less for welded sutures than for k nots. The number of cycles to failure and the creep after initial displacem ent were similar for both welded and knotted suture loops. The ultimate loa d to failure was significantly greater for the knotted than for the welded suture. The welding of suture for the repair of musculoskeletal soft tissue presents an attractive alternative to traditional knot tying, particularly for arthroscopic applications.