Marie Curie Action

Training Material

ROBOTICS IN SURGERY

Andrea Ranftl1, Sergio Casciaro2

1The Katholieke Universiteit Leuven

Andrea.Ranftl@mech.kuleuven.be

2 Institute of Clinical Physiology - National Council of Research

casciaro@ifc.cnr.it

Abstract

The first application of a robotic device in surgery has been realised in the 1980s as a passive tool-holder in neurosurgery. Thence forward outstanding developments have been achieved in almost all fields of surgical intervention in the last two decades. The improvement of the surgical outcome by providing the surgeon with enhanced tools forms the main interest of ongoing research. Robot-assisted surgery as a part of computer-integrated surgery has become a topic of high interest in science, media and public discussion.

In this lecture a short overview of robot-assisted surgery is given. The integration of this field in computer-integrated surgery is shown. The different applications are classified in a specific way and the typical procedure of a robot-assisted intervention is explained. Systems of different application areas which are subject to research as well as industry are introduced.

The lecture will be concluded with the presentation of two main projects at the Katholieke Universiteit in Leuven. Firstly the enhanced sensitivity approach in minimal-invasive surgery is explained and secondly the application of an industrial robot in orthopaedic surgery is shown.  Hybrid force velocity control is combined with the integration of vision sensors for dynamic compensation or target movements.

Introduction

Robotic systems for surgery are computer-integrated surgery (CIS) systems first, and medical robots second. In other words, the robot itself is just one element of a lager system designed to assist a surgeon in carrying out a surgical procedure that may include preoperative planning, intraoperative registration to presurgical plans, use of a combination of robotic assist and manually controlled tools for carrying out the plan, and postoperative verification and follow-up. Medical robots may be classified in many ways: by manipulator design (e.g., kinematics, actuation); by level of autonomy (e.g., preprogrammed versus teleoperation versus constrained cooperative control), by targeted anatomy or technique (e.g., cardiac, intravascular, percutaneous, laparoscopic, microsurgical); intended operating environment [e.g., in-scanner, conventional operating room (OR)], etc. As with industrial robots, the first consideration in design of medical robots is identifying the advantages provided by the robot that would justify its incorporation into a clinical system.

Surgical CAD/CAM

The basic information flow of CIS systems is illustrated in Fig. 1. Preoperative planning typically starts with two-dimensional (2-D) or three-dimensional (3-D) medical images, together with information about the patient. These images can be combined with general information about human anatomy and variability to produce a computer model of the individual patient, which is then used in surgical planning. In the operating room, this information is registered to the actual patient using intraoperative sensing, which typically involves the use of a 3-D localization, X-ray or ultrasound images, or the use of the robot itself. If necessary, the surgical plan can be updated, and then one or more key steps in the procedure are carried out with the help of the robot. Additional images or sensing can be used to verify that the surgical plan is successfully executed and to assist in postsurgical follow-up. The coupling of imaging, patient-specific models, and computer-controlled delivery devices can significantly improve both the consistency of therapy delivery and the data available for patient follow up and statistical studies required to develop and validate new therapies. We refer to the process of building a model of the patient, planning, registration, execution, and follow-up as surgical CAD/CAM, stressing the analogy with computer-integrated manufacturing. The advantages provided by robotic execution in surgical CAD/CAM depend somewhat on the individual application, but include: 1) accurate registration to medical images; 2) consistency; 3) the ability to work in imaging environments that are not friendly to human surgeons; and 4) the ability to quickly and accurately reposition instruments through complex trajectories or onto multiple targets. In addition to the technical issues inherent in constructing systems that can provide these advantages, one of biggest challenger is finding ways to reduce the setup overhead associated with robotic interventions. A second challenge is to provide a modular family of low-cost robots and therapy delivery devices that can be quickly configured into fully integrated and optimized interventional systems for use with appropriate interventional imaging devices for a broad spectrum of clinical conditions with convenience comparable to current outpatient diagnostic procedures.

Figure 1

Surgical Assistants

Surgery is a highly interactive process and many surgical decisions are made in the operating room. The goal of surgical robotics is not to replace the surgeon with a robot, but to provide the surgeon with a new set of very versatile tools that extend his or her ability to treat patients. We thus often speak of medical robot systems as surgical assistants that work cooperatively with surgeons. A special subclass of these systems are often used for remote surgery. Currently, there are two main varieties of surgical assistant robot. The first variety, surgeon extenders, are operated directly by the surgeon and augment or supplement the surgeon's ability to manipulate surgical instruments in surgery. The promise of these systems, broadly, is that they can give even average surgeons superhuman capabilities such as elimination of hand tremor or ability to perform dexterous operations inside the patient's body. The value is measured in: 1) ability to treat otherwise untreatable conditions; 2) reduced morbidity or error rates; and 3) shortened operative times. The second variety, auxiliary surgical supports, generally work side-by-side with the surgeon and perform such functions as endoscope holding or retraction. These systems typically provide one or more direct control interfaces such as joysticks, head trackers, voice control, or the like. However, there have been some efforts to make these systems "smarter"" so as to require less of the surgeon's attention during use, for example by using computer vision to keep the endoscope aimed at an anatomic target or to track a surgical instrument. Their value is assessed using the same measures as for surgeon extenders, though often with greater emphasis on surgical efficiency.

Robot-assisted procedure: an example

Robot-assisted surgery consists of three consecutive phases: the pre-operative planning phase, the registration phase and the phase of the surgical action. The authors have developed a robot-assisted procedure for machining the tibia in total knee arthroplasty (TKA) [1]. In the planning phase, the surgeon chooses a tibial prosthesis and decides upon the ideal position and orientation of this prosthesis. Then, surgery starts with clamping the tibia in a bone holder. Before the planning of the operation can be transformed into robot motions, a registration procedure needs to be performed to determine the spatial relationship between the coordinate frames of the robot, of the anatomic object and of the pre-operative planning. After the tibia is located in the robot working space, the tibial condyles are removed conventionally. In the phase of surgical action the surgeon prepares the proximal tibia with the aid of the robot. At the same time the machining parameters can be monitored as additional information about the bone quality of the implantation bed [2]. Finally, the surgeon fixes the tibial component of the prosthesis on the obtained tibia plateau with the chosen fixation technique.

Robotic Orthopaedic Surgery

Geometric precision is often an important consideration in orthopaedic surgery. For example, orthopaedic implants used in joint replacement surgery must fit properly and must be accurately positioned relative to each other and to the patient's bones. Osteotomies (procedures involving cutting and reassembly of bones) require that the cuts be made accurately and that bone fragments be repositioned accurately before they are refastened together. Spine surgery often requires screws and other hardware to be placed into vertebrae in close proximity to the spinal cord, nerves, and important blood vessels. Further, bone is rigid and relatively easy to image in computed X-ray tomography (CT) and X-ray fluoroscopy. These factors have made orthopaedics an important application domain in the development of surgical CAD/CAM. One of the first successful surgical CAD/CAM robots was the ROBODOC system [3], [4], [5] for joint replacement surgery, which was developed clinically by Integrated Surgical Systems from a prototype developed at IBM Research in the late 1980's (see Fig. 2).

Figure 2

Since this system has a number of features found in other surgical CAD/CAM robots, we will discuss it in some detail. In ROBODOC joint replacement surgery, the surgeon selects an implant model and size based on an analysis of preoperative CT images and interactively specifies the desired position of each component relative to CT coordinates. In the operating room, surgery proceeds normally up to the point where the patient's bones are to be prepared to receive the implant. The robot is moved up to the operating table, the patient's bones are attached rigidly to the robot's base through a specially designed fixation device, and the transformation between robot and CT coordinates is determined either by touching multiple points on the surface of the patient's bones or by touching preimplanted fiducial markers whose CT coordinates have been determined by image processing. The surgeon's hand guides the robot to an approximate initial position using a force sensor mounted between the robot's tool holder and the surgical cutter held by the tool holder. The robot then cuts the desired shape while monitoring cutting forces, bone motion, and other safety sensors. The surgeon also monitors progress and can interrupt the robot at any time. If the procedure is paused for any reason, there are a number of error-recovery procedures available to permit the procedure to be resumed or restarted at one of several defined checkpoints. Once the desired shape has been cut, surgery proceeds manually in the normal manner. After preclinical testing demonstrated an order-of-magnitude improvement in precision over manual surgery, the system was applied clinically in 1992 for the femoral implant component in primary total hip replacement (THR) surgery. Subsequently, it has been applied successfully to both primary and revision THR surgery [6], [7]. As of 2002, approximately 70 systems had been deployed in hospitals, and something over 10 000 procedures had been performed without a fracture or other serious complication due to the robot [8]. An interesting approach [9] uses constrained hand guiding to perform the bone machining operation. The surgeon moves the robot by pulling on a force-sensing handle in a manner resembling that used to preposition ROBODOC prior to bone cutting. In this case, the cutter is turned on and the robot motions are constrained by software so that the cutter remains within a volume corresponding to the bone to be removed. This approach may be appealing to some surgeons, because the surgeon remains more directly "in the loop"" during bone shaping. However, crucial factors affecting outcome, such as the registration accuracy between robot and patient, are the same whether the robot is machining bone autonomously under surgeon supervision or is being hand guided. A number of other robotic systems for use in joint replacement surgery have subsequently been proposed. The system most closely resembling ROBODOC is the CASPAR system [10]. Kwon et al. [17] have proposed an alternative approach, in which a small robot is mounted directly onto the patient's femur. In this system, the surgeon uses a mechanical device to determine the desired position and orientation of the implant hole manually, and the robot machines the desired shape. Both ROBODOC and CASPAR have been applied to knee surgery [10], [11]. Other robotic systems have been proposed or (in a few cases) applied in knee surgery. For example, Garbini [12] and Kienzle [13] separately proposed using a robot to position passive saw guides for TKR. There has also been some interest in using robotic systems to assist in placing pedicle screws in spine surgery. One very interesting approach proposed by Shoham et al. [14] uses a small (5 cm x 3.5 cm x 3.7 cm, 150 grams) parallel link robot mounted directly on the vertebral body. The same group has also proposed a similar, though somewhat larger, robot for intramedulary nailing. Other uses of parallel link robots for a variety of orthopaedic procedures include [15] and [16].

References

  1. G. Van Ham et al., A force controlled robot as a surgical tool in total knee athroplasty. In 12th Computer assisted radiology and surgery congress, pages 699-704, Elsevier, 1998.
  2. G. Van Ham et al. Machining and accuracy studies for a tibial knee implant, using a force controlled robot. Computer aided surgery, 3: 123-133, 1998.
  3. P. Kazanzides, B. D. Mittelstadt, B. L. Musits, W. L. Bargar, and J. F. Zuhars et al., An    integrated system for cementless hip replacement,"" IEEE Eng. Med. Biol. Mag., vol. 14, pp. 307-313, May-June 1995.
  4. R. H. Taylor,H.A. Paul, P. Kazandzides, B. D. Mittelstadt,W. Hanson, J. F. Zuhars,    B.Williamson, B. L. Musits, E. Glassman, andW. L. Bargar, "An image-directed robotic system for precise orthopaedic surgery,"" IEEE Trans. Robot. Automat., vol. 10, pp. 261-275, Apr. 1994.
  5. B. Mittelstadt, P. Kazanzides, J. Zuhars, B. Williamson, P. Cain, F. Smith, andW. Bargar, "The  evolution of a surgical robot from prototype to human clinical use,"" in Computer-Integrated Surgery R. H. Taylor, S. Lavallee, G. Burdea, and R. Mosges, Eds. Cambridge, MA: MIT Press, 1996, pp. 397-407.
  6. M. Boerner and U. Wiesel, "European experience with an operative robot for primary and revision total hip—A summary of more than 3800 cases at BGU Frankfurt,"" in Proc. CAOS USA 2001, Pittsburgh, PA, 2001, pp. 95-98.
  7. F. Gossé, K.Wenger,K. Knabe, and C.Wirth, "Efficacy of robot-assisted hip stem implantation: a rediographic comparison of matched-pair femurs prepared manually and with the robodoc system using an anatomic prosthesis,"" in Proc. Medical Image Computing and Computer-Assisted Intervention (MICCAI 2000), Pittsburgh, PA, 2000, pp. 1180-1187.
  8. L. Witherspoon, Personal Communication, 2002.
  9. M. Jakopec, S. J. Harris, F. R. Y. Baena, P. Gomes, J. Cobb, and B. L. Davies, "The first clinical application of a hands-on robotic knee surgery system,"" Comput. Aided Surgery, vol. 6, pp. 329-339, 2001.
  10. W. Siebert and S. Mai, "One year clinical experience using the robot system CASPAR for TKR,"" in Proc. CAOS USA 2001, Pittsburgh, PA, 2001, pp. 141-142.
  11. U.Wiesel, A. Lahmer,M. Tenbusch, and M. Borner, "Total knee replacement using the ROBODOC system,"" in Proc. 1st Annu. Meeting CAOS Int., Davos, Switzerland, 2001, p. 88.
  12. J. L. Garbini, R. G. Kaiura, J. A. Sidles, R. V. Larson, and F. A. Matson, "Robotic instrumentation in total knee arthroplasty,"" in Proc. 33rd Annu. Meeting, Orthopaedic Research Society, San Francisco, CA, 1987, p. 413.
  13. T. C. Kienzle, S. D. Stulberg, A. Peshkin, A. Quaid, and C. H. Wu, "An integrated CAD-robotics system for total knee   replacement surgery,"" in Proc. IEEE Int. Conf. Robotics and Automation, Atlanta, GA, 1993, pp. 889-894.
  14. M. Shoham, M. Burman, E. Zehavi, L. Joskowicz, E. Batkilin, and Y. Kuchiner, "Bone-mounted miniature robot for surgical spinal procedures,"" in Proc. 2nd Annu. Meeting Int. Soc. Computer Assisted Orthopaedic Surgery (CAOS 2002), Santa Fe, NM, 2002, p. 59.
  15. D. S. Kwon, J. J. Lee, Y. S. Yoon, S. Y. Ko, J. Kim, J. H. Chung, C. H. Won, and J. H. Kim, "The mechanism and the registration method of a surgical robot for hip arthroplasty,"" in Proc. IEEE Int. Conf. Robotica and Automation, May 2002, pp. 1889-2949.
  16. G. Brandt, K. Radermacher, S. Lavallee, H.-W. Staudte, and G. Rau, "A compact robot for image- guided orthopaedic surgery: concept and preliminary results,"" in Proc. 1st Joint Conf. CVRMed and MRCAS, Grenoble, France, 1997, p. 767.