The Safe Suture – Mechatronic Instruments for complex stitch-guidance in minimally invasive surgical procedures
The joining of soft tissue in surgical therapies is based primarily on conventional stitching and stapling techniques. Next to the preparation of the tissue, the suture itself is a crucial factor in achieving successful treatment. The application of the two techniques is especially challenging in minimally invasive surgical procedures, a generic term describing surgical interventions with minimal trauma that was introduced about 15 years ago.
In minimally invasive procedures, surgery is performed under endoscopic visual control with the help of sophisticated instruments, so that big incisions are no longer required. At the beginning this technique mainly concentrated on abdominal surgery. After its benefits over open surgery – a quicker recovery with little postoperative pain, as well as better cosmetic results due to less scarring - were acknowledged, its application expanded to other surgical disciplines. By now minimally invasive interventions are also performed in the chest cavity (thoracoscopy) and during hip joint replacement (hip joint endoprosthesis). There are additional tendencies towards a minimally invasive approach during thyroid surgery or cosmetic surgery.
In addition to the technical and/or manual difficulties surgeons face while joining tissue in a distance of approx. 20cm from the abdominal wall through two 10mm- to 12mm-trocars (a means of introduction for surgical instruments), there are some typical problems persisting at every hand-sutured or mechanically-stapled unification of tissue that must be resolved. High suture tension may result in ischemia (reduced blood flow) or even necrosis (death of tissue), whereas a loose structure holds the risk of haemorrhage of the wound edges, causing postoperative complications and a potential necessity for re-operation.
So far, the adjustment of suture tension is based on the personal estimation as well as on the experience of the surgeon, so that the resulting suture properties can not be reproduced in a standardized way. Consequently, the demand for a joining technique and for a suitable device that allows for quick, secure and reproducible joining of human tissue under the extremely difficult conditions in narrow and deep surgical cavities arises.
The aim of this project was to develop an automated suturing-device for minimally invasive application that allows a defined setting of the suture tension, as well as a control over blood flow during the tightening of each stitch. Integrated sensors are to give the surgeon feedback on the surgical conditions. This way an optimized joining technique, adequate to the respective tissue, can be realized with regard to wound healing and secure sealing of the suture.
This project tends to the needs, wishes and targets of the field of minimally invasive surgery and of the companies supplying this medical branch. The project partners are faced with challenging technological demands due to the considerable complexity of the instruments, so that the consortium is characterized by a high degree of interdisciplinary collaboration. This ensures the development of highly efficient products in keeping with the latest findings in research, as well as an active transfer of knowledge to the industry.
Project partners from the fields of research (Fraunhofer Institute for Production Technology and Institute of Applied Medical Engineering of the RWTH Aachen) and medical device manufacturers (Medi-Globe, SOPRO-COMEG), manufacturers of medical sensors and measurement technology (LEA), specialists in medical suture material (FEG, Ethicon), as well as end users from different surgical fields (University Hospital Aachen) work together on reaching the set targets.
The Fraunhofer IPT has essential know-how in the areas of development and production of miniaturized mechatronic systems. The Institute of Applied Medical Engineering functions as an interface between engineering and medicine through its special experience in the technical implementation of medical requirements as well as in the testing of medical systems. With the help of surgeons from the University Hospital Aachen, consumer oriented requirements can be set and tested appropriately. The industrial partners will assist in developing a recyclable and market-oriented product.
The optimal suture parameters for an improved wound healing determined in this project can be standardized and can be applied in a reproducible way on patients, so that postoperative complications can be reduced. The shortened duration of the surgery, the reduction of necessary re-operations and the shortened hospitalization time can reduce costs in healthcare significantly.
In the field of heart surgery alone expenses can be reduced considerably. In Germany 100.000 heart surgeries are performed with the use of a heart-lung-machine in 78 cardiac centers every year. With an average cost of 5 Euros per surgical minute, a duration of 3-5 minutes for each simple interrupted stitch and an average number of 20 stitches in each heart surgery, the suturing alone causes a cost of approx. 400 Euros plus suture material. If this process can be accelerated to 2 minutes per stitch, yearly savings of 20 million Euros are possible in the long run.
Due to the trend of minimally invasive procedures expanding to more surgical fields, the development of special instruments that satisfy the respective requirements is necessary. Therefore it is to be expected that the assembled consortium will continue using its combined knowledge beyond the end of this project to develop more surgical instruments and will make an important contribution to the expansion of minimally invasive surgical procedures.Furthermore a collaboration in the development of products deriving directly from partial solutions achieved in this project, in innovative joining technology for instance, is possible.
 Fatikow, S., Rembold, U.: Microsystem Technology and Microrobotics, Springer Verlag, Berlin Heidelberg, 1997