Research On Assessment Method Of Interface Design Of Minimally Invasive Grasping Forceps

Minimally invasive surgical (MIS) technique is a revolutionary change of the modern medical technology. Its development depends on the support of new-type high-tech MIS instruments. It is urgent to realize the breakthrough of basic theory and key technology in the field of MIS instruments. The interaction between medical instruments and target tissue during the surgery occurs in instrument-tissue interface. And the reliability research on the interface is directly related to the safety and effectiveness of medical instruments in the clinical application.Laparoscopic surgery has advantages of small incision, quick recovery and few complications and so on. However, comparing with traditional surgery, there are some deficiencies such as tactile deficits, poor force feedback and visual dimension reduction and so on.Because of separation between surgeon and target tissue by the natural barrier of abdominal wall, surgical instruments become the only way to delivery and realize intended operation including incision, separation, hemostasis and suture and so on by interaction between mechanical rigid body and biological tissue. Except realizing these intended operations, there occurred tissue slipping because of too small pinch force for pull force or tissue damage because of excessive pinch force during the surgery. Therefore, from the angle of medical instrument-tissue interface, it is significant to establish reliability assessment method of MIS forceps jaw surface design for promoting jaw surface reliability by making interface safety performance specific and identifying damage types caused by surgical instruments.This research took frequently used MIS grasping forceps as research object and analyzed their configuration and then designed and machined jaw prototype. And further test the different machined removable jaw by in vitro and in vivo biomechanics tests using self-refitted both pinch force and pull force adjustable testing machine. The obtained conclusions were as follows.(1) Established in vitro assessment method, and identified evaluation indicators and determination method of safety performance. Indicators included slipping index, minimum pinch force without tissue slipping, maximum pinch force without damage, safety region and safety factor. The results of in vitro test proved that teeth and wave surface had good safety performance and could be used as reference of new-type surface design.(2) Established in vivo assessment method. And the results of in vivo test revealed that categories of the damage to small intestine at instrument-tissue interface included inflammatory reaction, intestinal wall structure fracture, mucosa injury and blood vessel rupture.This work initially built reliability assessment method of the interface between surgical instruments and soft tissue, and formed a corresponding surface database, and provided some reference for designing new-type surface of MIS. Moreover, this research laid the foundation for studying the relationship between damage at instrument-tissue interface and postoperative functional recovery.