z-bio 2025-12-01 3692

　　Chinese experts have made a major breakthrough in solving the "dead knot" problem in surgery.

　　On November 27, Beijing time, the team of Academician Yang Wei from the Center for Cross Mechanics of Zhejiang University and the team of Academician Cai Xiujun of Shaw Hospital Affiliated to Zhejiang University School of Medicine jointly published a paper in the top international journal "Nature", innovatively proposing "Sliputure" - a slipknot smart suture, and successfully applied it to surgical sutures.

　　In surgery, the "surgical knot" used to suture a wound is a dead knot used to close tissue. Once this knot is tight, it is difficult to adjust.

　　Generally speaking, if the knot is tied too loosely, the wound may crack and affect tissue healing; if the knot is tied too tight, the local blood supply may be blocked, which can easily lead to tissue ischemia and necrosis.

　　For a long time, this "tightness" has largely relied on the surgical experience of the surgeon. However, due to the lack of quantitative standards for strength, there are many uncertainties. On the one hand, the operations of young doctors may be unstable. On the other hand, for surgeries using surgical robots, the robotic arm is "not very important".

　　To this end, the team of Academicians Yang Wei and Cai Xiujun proposed an unexpected solution - using "slipknots" to encode and transmit force.

　　Generally speaking, this method is to tie a slip knot next to the dead knot in advance. When the dead knot is tied and the suture is tightened, the slip knot is untied, which indicates that the dead knot is finished.

　　To realize this process, Li Tiefeng, a professor at the Cross Mechanics Center of the School of Aeronautics and Astronautics of Zhejiang University, explained the principle: first, during the process of making a slip knot, accurate peak force information must be stored in the knot; second, during the process of untying the slip knot, the force information can be transmitted to the series connected system; finally, the mechanical model depicts the transmission of information and force, and is connected to the robot or human control system to complete the dead knot.

　　One of the biggest technical difficulties is that since the force of the knot is determined by the force at the moment when the slipknot is untied, the slipknot must be stable and controllable and maintain a consistent force. In other words, it is necessary to ensure that each slipknot can be opened at a preset, unique, and precise force.

　　To this end, the joint team carried out a series of technical research, with interdisciplinary cooperation conducted by many teachers and students from different disciplines such as mechanics, medicine, mathematics, materials, machinery, and control.

　　The team used high-speed cameras and Micro-CT to capture the subtle sliding trajectory of the slipknot. Subsequently, through mechanical modeling, finite element simulation and other means, we discovered the orderly rules contained in the slip knot - the force to untie the slip knot is related to the force (pre-tightening force) that tightens the knot when knitting the slip knot, the number of knots, diameter, friction coefficient, and modulus.

　　Therefore, you only need to change the above parameters to obtain the slipknot corresponding to the opening force. Experiments show that for a specific slipknot, the force at the last moment of untying them (peak force) is highly consistent.

　　Since then, the research team has repeatedly improved and gone through a large number of design iterations. By testing and collecting knotting data from surgeons with different seniority and the mechanical indicators of different materials and styles of slip knots, and using computer modeling, they prefabricated a large number of slip knots and finally completed a set of "slip knot-based mechanical transmission mechanism" program.

　　The team created hundreds of special sutures - each with a slip knot of a different knot method, and the force to untie them is also different, achieving accurate control of the "slip knot" and the "dead knot" in different surgical scenarios.

　　Studies have shown that in animal intestinal repair surgery experiments, this system made the anastomosed intestine neither leaky nor tearing. From open rat intestinal repair, to laparoscopic live pig intestinal repair, to robotic operation, good results have been achieved.

　　At present, endoscopes and surgical robots using this technology can increase the accuracy of suturing and knotting force by relatively inexperienced surgeons by 121%, which is close to or even comparable to experienced surgeons. At the same time, it can also empower surgical robots to achieve real-time and reliable force control without sensors.

　　Academician Cai Xiujun is one of the pioneers in the field of minimally invasive surgery and intelligent medicine in my country. He has won the 4th Medical Value Healthcare Taishan Award-Medical Innovation Award. He personally witnessed and promoted the iteration of surgical procedures from large opening and closing to precise minimally invasive surgery, and also deeply felt the current dilemma of "power blindness" faced by surgeons on the operating table.

　　"Technology is advancing, but the surgeon's touch is constantly disappearing." Academician Cai Xiujun said that in traditional open surgery, the doctor's hands can directly sense the softness and hardness of the tissue and accurately control the suturing force, but the price is large trauma and slow recovery for the patient; in minimally invasive surgery, this direct force feedback is greatly weakened, making the control of knotting force very dependent on the doctor's personal experience.

　　Although the solution principle provided by the "Slipknot Mechanical Transmission Mechanism" developed this time may seem primitive, it is a generalized application of the essential laws contained in its structure by researchers. It does not require electronic equipment such as sensors to make instant judgments, and avoids the problem of surgical operations or robots being unable to work accurately in environments where there is a lack of power or a power outage.

　　Looking forward to the future, in addition to clinical applications, this method principle that does not rely on complex electronic device construction operations can also meet the deep cavity environment in routine surgery, and is expected to show application prospects in other extreme conditions (special operations such as deep sea, deep space, deep earth) and extreme size research (extremely microscopic system construction or regulation).

　　This is a vivid epitome of Zhejiang University’s “medical-engineering, clinical-driven” innovation ecosystem. The success of "Sliputure" has verified the "mathematical intelligence" and "Mechano-Intelligence" paradigms in cross-mechanics research.

　　It is understood that the research team is currently building a force value database for different tissues and is committed to developing a series of products suitable for various types of robotic surgery and high-precision suture fields such as digestive tract, cardiovascular, and neurosurgery.