The twentieth century was characterized by immense human achievements and remarkable progress in many fields. The last several decades have witnessed the revolution led by computers and microtechnology. When computers first made their appearance during the middle part of the twentieth century, they were room-size and consumed enormous amounts of energy. Microtechnology made it possible for computers to be integrated into many appliances. Cellular phones, global positioning systems, portable computers (notebooks and personal digital assistants), and computer-controlled engines in modern cars are but a few examples. There is probably no aspect of our lives in which computers have not caused great advancement and improvement.
Medicine has also progressed into the digital era. Paper-based medical charts are on their way to becoming obsolete. Imaging has immensely progressed since Wilhelm Conrad Röntgen discovered x-rays in 1895. Today, digital reconstruction of skeletal imaging enables us to perform advanced preoperative planning.
However, the rapid progress of modern computerized capabilities has not been paralleled by a similar progress in the operating-room setting and in surgical techniques. A surgeon transported by time machine from 1950 into our time would feel more comfortable in an operating room than he or she would in a current-model car or a household living room. The major advance in orthopaedic surgery during the past fifty years has been the introduction of intraoperative fluoroscopic imaging, while surgical techniques have remained mostly unchanged.
Orthopaedic procedures dealing with bones—a nondeformable tissue—are suitable for computerized guidance based on preoperatively and intraoperatively obtained images. Computer-assisted surgery progressed from the first-generation systems of the 1990s to the present third-generation systems, enabling us to implant a knee or hip prosthesis. However, only 3% of all knee replacements done in the United States are done with the help of computer-assisted surgery. This number is lower than that in other countries, such as Germany, where acceptance of this technology runs between 30% and 40%. All of those percentages indicate that the majority of orthopaedic surgeons avoid using computer-navigation surgical techniques. Why has the implementation of computer-assisted surgery procedures met with so many hurdles and obstacles?
A wide variety of computer-assisted navigation systems exist. This article will not discuss systems used for preoperative planning but rather will concentrate on systems used for the performance of orthopaedic procedures. Navigation systems rely on the interface between markers in the operative field, a tracking sensor, a computer for data processing, and a screen display of the processed data for the surgeon's feedback.
Navigation is performed on a digitally displayed model of the operative field. This model can be obtained by preoperative image data (computed tomography or magnetic resonance imaging), intraoperative image data (fluoroscopy or ISO-C-3D [intraoperative three-dimensional imaging with a motorized mobile C-arm]), or a model built intraoperatively with use of bone-morphing technology. The most commonly used tracking methods in orthopaedic surgery are optic sensors that detect infrared light and magnetic sensors for electromagnetic markers.
Several factors are usually considered as the main obstacles for the integration of computer-assisted surgery in orthopaedic departments. Although computer-assisted surgery systems are less sophisticated than regular household computers, they come with a more expensive price tag. In addition to price, certain technical issues limit the use of computer-assisted surgery: optic sensors require unhindered lines of sight between the markers and the tracker, and magnetic sensors may fail in proximity to metallic instruments and require the use of special magnetically inert instruments. In addition, the operation of the system may be cumbersome and the system itself may become unstable, requiring a resetting of the entire process in the middle of an operation.
Are these the only factors preventing computer-assisted surgery from becoming a common and basic tool in the orthopaedic armamentarium? We believe that other factors play a major role in delaying the progress of computer-assisted surgery. These factors can be divided into three groups: human factors, technological factors, and financial factors.
Human Factors
Psychological Impact
Most orthopaedic surgeons have received classic training with little or no exposure to computerized techniques. A senior orthopaedic surgeon who is confident in his or her operative techniques and results tends to be more hesitant in accepting a new technique to replace the previous successful one. Furthermore, a senior surgeon has self-confidence in his or her capabilities and will not easily accept the help of a computer in performing surgery.
"User-Friendliness"
Operating with the aid of computer-assisted surgery navigation entails specific coordination. The task of moving a trajectory on the screen by positioning a guide tool in the operative field may seem simple to a young boy who is accustomed to playing video games but may be difficult for an older person who was raised with less exposure to computers. These capabilities can be enhanced by practice and special training aids1,2. Basic computer knowledge is also necessary for handling these systems, a prerequisite that is met by the growing number of personal computers in the general population.
Evidence-Based Medicine
Objective scientific data should be available before the large-scale integration of new techniques and systems. With regard to trauma and orthopaedic surgery, published results are available for navigated cannulated screw fixation, navigated anterior cruciate ligament tunnel-positioning, and navigated total knee replacement3-6. Studies in these areas have shown both improved accuracy and repeatability. Variance of operating results with regard to the targeted goal decreases when computer-assisted surgery is used, with the results being more pronounced with less experienced surgeons. Computer-assisted surgery helps decrease the number of outlying results, meaning that fewer patients will be exposed to a malpositioned screw, anterior cruciate ligament tunnel, or prosthesis. These data (radiographic measurements of outcomes, alignment, and positioning), even when published, have not sufficed in convincing orthopaedic surgeons to use the new technology.
Learning Curve
Inherent to the implementation of a new technique is the learning curve. In computer-assisted surgery, the learning curve affects all members of the surgical team. It affects the surgeons who perform the operation, the nurses who have to cope with new tools, the anesthesiologists who need to adjust the anesthesia time to the expected operation time, and the radiology technicians who sometimes need to operate fluoroscopy-based navigation systems. The entire team should be aware that there is a "new partner" in the operating theater (i.e., the computer), and sometimes a computer technician will need to be part of the team as well. The learning curve should be accepted as part of the integration and not as an excuse for delaying implementation. King et al. demonstrated that the implementation of mini-incision total knee replacement has a learning curve even for the most experienced surgeon7. Bové showed that experience with one navigation system shortens the learning curve when moving to a different navigation system8.
Ergonomic Factors
Most operating rooms were not designed with the new technology in mind in terms of size or placement of the computer, the computer screen, and the connecting cables. A surgeon who is experienced with computer-assisted surgery can appreciate the advanced ease of use that is inherent in newer generations of navigation systems. However, the insertion of a navigation system into the operating room still warrants special consideration. The machine occupies space. Its positioning is dictated by lines of sight between the tracker sensor and the markers. This adds obvious technological and economic factors to the human factors that must be considered.
Technological Factors
There are two major partners in the implementation of computer-assisted surgery technology: academia and industry.
Academia
The science of computer engineering should merge with orthopaedic sciences. An understanding of the logic (algorithms) behind each procedure is mandatory in order to develop new solutions. The solutions may be categorized as either enablers or improvers. While enablers refer to procedures that are not possible without computer-assisted surgery (i.e., the introduction of a new concept or ability rather than a translation of a current technique into computer-assisted surgery), improvers yield mainly improved accuracy and not the creation of an entirely new concept. For example, the insertion of screws for fixation of a hip fracture is currently performed with use of cannulated screws and guidewires. These wires can be inserted with greater accuracy with the use of a fluoroscopic navigation system4. This is actually a translation of the current method into another technology. The creation of a new technology, for example, would be direct insertion of noncannulated screws, since guidance is an inherent character of the technology and there is no need for a guidewire.
Industry
There is no doubt that industry greatly contributes to the field of computer-assisted surgery. However, some of the development of sophisticated computerized tools by commercial companies is led by the desire to make a profit. The end result of the development is a product that can be sold to hospitals.
There are two main product groups: closed systems and open systems. Closed systems are composed of both hardware and software designed for only one procedure, and "open systems" are designed such that common hardware may be fitted with different software, each of which is suitable for a different surgical procedure. Additionally, there are some information technology companies that introduce universal "open systems" with linkage to orthopaedic implant companies. This linkage may lead to a second phase, in which the contract between the companies will turn it into a "closed system."
Obviously, commercial companies welcome closed systems, which hospitals cannot afford. The future lies in open systems—open both to different procedures as well as to software upgrades. The challenge is to create a technology that will become mandatory in the operating room, similar to that of current basic tools, such as the image intensifier in the orthopaedic operating room. These systems will require a preliminary financial investment in hardware but will allow for future software additions and system upgrades. It is not clear as to whether the final product will be the computerized tool, the disposable parts, or both. Anyone involved in the development of such systems must bear in mind that a brilliant idea with no marketable end product will not be endorsed by commercial companies.
Financial Factors
Finally, it will be necessary to deal with the financing of these navigation systems. The purchase of a complete navigation system may result in a considerable investment on the part of the hospital, and ongoing maintenance and upgrading must be taken into account. There are three main financing sources that may invest in sponsoring this technology: research grants, hospital budgets, and patient payments. Research grants, either academic or from industry research and development investments, are usually used in the initial phases of computer-assisted surgery integration. However, widespread and continuous integration and implementation are not feasible with research grants alone. Therefore, the burden of financing this new technology will be shouldered by the health system, by patients themselves, or by a combination of the two.
For health-system and hospital financing, computer-assisted surgery will have to demonstrate not only better positioning, alignment, and longevity but also financial savings. These savings can derive from shorter hospital stays through the use of minimally invasive surgery, savings on conventional equipment (e.g., fewer tools being required for a navigated knee replacement procedure), fewer complications, and lower litigation expenditures. In addition, more revenues can be generated through the development of a referral pattern to the hospital that offers computer-assisted surgery.
Will patients carry the financial burden? The costs can be borne by patients either directly, through specific pricing of computerized procedures, or indirectly, by repricing procedures.