Winter 2001 Newsletter

There is an increasing demand for education and training in arthroscopic procedures. Answering this demand presents certain challenges that are specific to arthroscopic surgery, such as orientation, instrument handling, hand-eye coordination, and working in 3-D while looking in 2-D.

Most established surgical training methods are obsolete for different reasons: animals are far from human anatomy, plastic models lack realism, fresh cadavers are available in limited numbers, and in some countries isolated joints are prohibited. Training on patients is open to criticism and incompatible with the quality level asked by third-party payers. Virtual arthroscopy should be considered as an alternate training method for arthroscopic surgery.

Virtual reality for arthroscopic surgery teaching and development allows continuous and repetitive training at a low cost. Surgeons are able to improve their skills on a trainer instead of patients. In the future, we will be able to participate in practice sessions via the Internet, and to organize tele medicine, tele surgery and tele teaching.

The virtual arthroscopic trainers also allow evaluation ­ evaluation for the surgical residents in their learning curve and evaluation of practicing orthopaedic surgeons for accreditation purposes.

Virtual reality is a real-time interactive visual simulation developed in 1960 for pilot training and is used now more and more for training and developing surgical techniques and improving skills. With the virtual arthroscopic trainer it is possible to assess progress of the surgeon or the residents, and to bring more experience to the operating table with less cost and less time. Virtual reality technology until now was too expensive and impractical for medical use. New tools and new software are now available and affordable for the medical community.

This technology allows interactive, real-time training in an intelligent 3-D environment. Virtual arthroscopic trainer equipment needs a seamless graphics system, force feedback instruments and virtual arthroscopic instruments. The computer is used as a visual monitor.

Virtual reality will not replace real-life surgical training but will ensure that residents' first experience with a patient is a safe one. The virtual arthroscopic trainer can also be proposed to device manufacturers for device prototyping, evaluation and marketing. The virtual arthrosopic trainer (V.A.T.) minimizes development costs and allows functionality and ergonomics testing. For marketing the V.A.T. can be used for demonstration of new surgical devices and techniques. Universities will be involved in V.A.T. programs for procedure and device education, assessing trainees or monitoring surgeon progress in order to reach the confidence level needed to move on to patients.

Hospitals and clinics can use the V.A.T for three main purposes: pre-operative planning, procedure innovation and patient education. Pre-operative planning will be possible by introducing patient imaging (MRI), in order to simulate the procedure on a virtual patient created with specific data. Procedure innovation includes redesign of procedure, new device development and new approach development. V.A.T. enhances patient awareness about the procedure, informs the patient about risks and benefits, and involves the patient in the decision-making process. All this information could be included in the hospital or clinic Web site.

The first problem is to recreate the anatomy. The University of Colorado investigators have worked on the coronal man project and have developed a visible human male navigator. This project was created from a set of digital images from a frozen cadaver allowing synthesis of a complete volume of anatomy. 1878 axial photographic images of the body were taken with a 1 mm interval. They were numbered from 1001 to 2878, and the computed reformatting of the 1878 axial images was performed creating coronal plane images. Prosolvia Clarus from Sweden has created an anatomical shoulder model including the glenohumeral joint and subacromial bursa. This was fully created in the computer using 3-D graphics software. Another option could be the use of radiological imaging with volume CT acquisition, and 3-D MRI. GE medical system engineers have created a program of virtual endoscopy (bronchoscopy, vascular and neurosurgery).

The main problem is to adapt virtual anatomy to virtual arthroscopy creating a virtual articular cavity model, a virtual endoscope and virtual arthroscopic instruments. Force feedback devices allow the surgeon to get tactile information, but in arthroscopy the surgeon adapts many of his movements in response to tissue deformation seen on the monitor. Reconstruction of an articular cavity model needs 3-D graphics software. Different options can be employed: adapting existing data files (coronal man), creating new data files for articular cavity anatomy, inflating the joint before cryo-section in the position of arthroscopy.

The software has to create a virtual endoscope with variable angles such as 30º and 70º, including rotation of the arthroscope and opening angle of the lens. Virtual instruments are created such as probes, punches, shaver blades, and lasers all having a variety of shape, structure and function. Force feedback devices are available allowing the surgeon to feel the virtual environment. To create tissue deformation, a tissue stress analysis is necessary. Tissue stress analysis is included in a static and dynamic way with a contact stress analysis. This step uses finite element analysis of meniscus, labrum, ligament, cartilage, soft tissues, capsule, cuff.
The V.A.T. is also able to score the trainee's skill. Scoring of the trainee's skill is based on accuracy, ability, capability and learning progression. The training program is organized using virtual reality beginning with normal arthroscopic anatomy, manipulative skills, then presentation of various diseases, diagnostic skills, selection of treatment and surgical procedure performance. The second step is to introduce pathologies using MR, 3-D CT or ultrasound, creating a full virtual patient model allowing one to prepare the procedure (e.g., approach, tools). The training surgeon is able to practice the virtual procedure and then compare the virtual procedure to the real procedure.

In conclusion, in the future, the virtual arthroscopic trainer will play a more prominent role in arthroscopic surgery teaching, device and procedure development, surgeon evaluation and patient information.