Extract
The 2008 AAOS/ORS Advanced Imaging and Computer-Assisted Surgery of the Knee and Hip (AICKH) Research Symposium explored avenues for technology integration between advanced imaging and computer-assisted surgery, and it assessed the value of imaging in evaluating the progression of joint disease and the efficacy of therapeutic interventions.
The 2008 AAOS/ORS Advanced Imaging and Computer-Assisted Surgery of the Knee and Hip (AICKH) Research Symposium explored avenues for technology integration between advanced imaging and computer-assisted surgery, and it assessed the value of imaging in evaluating the progression of joint disease and the efficacy of therapeutic interventions.
The four overarching themes that were explored during the symposium and the consensus statements for future research are detailed below.
The concept of technical specifications and standards for computer-assisted surgery procedures and imaging protocols was highlighted. For example, most computer-assisted surgery procedures rely on the use of quantitative data rather than surgeon feel and intuition to inform clinical decision-making. As this quantitative feedback becomes more important in surgical decision-making, we must establish appropriate specifications for various operations. These specifications must be clinically relevant and must have known target values and tolerances. In addition, we must understand the reliability of our computer-assisted tools in achieving the desired specifications.
Navigated total knee replacement is an excellent example of the use of quantitative data to affect surgical technique. The first-generation navigated total knee replacement protocols focused on achieving neutral alignment in the coronal plane. The relevant specification for the navigation system is therefore coronal plane alignment. The target is well established as 0°; the tolerance has also been established as ±3°. Many authors have demonstrated the reliability of navigation in achieving neutral alignment of the lower limb within this specification. However, while navigated total knee replacement has been shown to reduce the number of outliers in terms of alignment, it has not been shown to improve short-term results. This is likely because the chosen specification (knee alignment) for this procedure in fact has no effect on short-term results. Newer iterations of navigation for total knee replacement have addressed soft-tissue balancing in addition to alignment; however, the specifications, tolerances, and reliability of navigation for knee-balancing are not well established. Finally, the relative importance of these specifications in relation to other surgical considerations (such as fixation and implant design) has not been clearly delineated.
Consensus
To make effective use of computer-assisted surgery, we must identify technical specifications for the various procedures. These specifications must be clinically relevant, be associated with known target values and tolerances, and have the capability of being reliably measured by computer-assisted surgery tools. These target values and tolerances are likely to be established only with the development of imaging and diagnostic modalities that can correlate the target value with the outcome.
The assessment and treatment of chondral lesions is an excellent example of refining surgical care through advanced imaging. As magnetic resonance imaging technology allows for more sophisticated noninvasive evaluation of cartilage morphology and health, biologic and nonbiologic treatment strategies can be employed at earlier stages of chondral disease. In addition, objective assessment of the efficacy of these treatments can be performed. As a result, treatment options such as microfracture, autologous chondrocyte implantation, and osteochondral autograft transfers can be compared. It is clear that magnetic resonance imaging modalities will have an essential role in defining optimal treatment options for chondral lesions.
While magnetic resonance imaging can distinguish the relative success of various biologic chondral resurfacing procedures, there is a paucity of imaging modalities that are sensitive enough to refine the surgical technique for total knee replacement. While plain radiographs can demonstrate alignment, document progressive loosening, and reveal mechanical failure, imaging tools are often unable to detect a difference between a knee replacement that is causing pain and one that is well functioning. As a result of the poor correlation between standard radiographic endpoints and clinical functions, the primary outcome for total knee replacement remains survivorship. This outcome, although supported by current radiographic criteria, does not take into consideration other parameters, such as midflexion stability, which can have a profound effect on knee function.
Consensus
Precise, repeatable, and objective outcome tools are necessary to refine surgical procedures so that both short-term and long-term knee function and patient satisfaction are improved. These outcome tools are the critical link that will be necessary to document the efficacy and hone the techniques for computer-assisted surgery procedures. Dynamic joint imaging may provide more insight into joint kinematics and may help refine surgical target values. In this way, the data that result from advances in imaging could be used to better direct computer-assisted surgery techniques.
Computer-assisted surgery tools can be conceptualized as enabling or improving technologies. For the most part, computer-assisted surgery procedures have, to date, been improving rather than enabling. In total knee replacement, navigated procedures have been used in an attempt to reduce the number of malaligned outliers. Clearly, the procedure can be done well without the aid of navigation, but navigation may improve the reliability of the technique. This strategy of using computer-assisted surgery tools to improve a procedure that is widely performed and has good clinical results may limit the impact of the technology.
Few computer-assisted surgery procedures are truly enabling at this time. However, navigation and robotic tools as well as custom jigs and implant strategies are being employed for more technically challenging surgical tasks. These technologies, for example, may allow for more bone-sparing total and partial knee replacements, new fixation strategies, or custom recontouring of the head-neck junction of the hip.
Consensus
Improving computer-assisted surgery technologies must be fast, reliable, and cost-efficient. They should have clear target values and tolerances and should enhance standard surgical techniques. Enabling computer-assisted surgery technologies should be developed for challenging surgical procedures, with the goal being to make the performance of these procedures safe and reliable. These enabling computer-assisted surgery tools, which may include navigation, robotics, and custom implants or jigs, may considerably alter standard surgical workflows.
The development of computer-assisted surgery tools has been dominated by industry rather than by surgeons. At present, most of the navigation companies are owned by implant companies; navigation is often developed solely to facilitate the implantation of a particular prosthesis. While these applications may be clinically relevant, they remain "improving" strategies that are likely to demonstrate only a modest impact on patient outcome.
The cost of computer-assisted surgery tools can be prohibitive for many centers; this limits the ability of the surgeon to participate in the development of computer-assisted surgery technologies. Efforts should be made to establish networks of computer-assisted surgery pioneers who can collaborate on basic-science and clinical research. This research should focus not only on improving the computer-assisted surgery technology but also on developing appropriate specifications for various procedures.
Finally, standards should be applied to the technologies to ensure that various computer-assisted surgery systems measure the same quantitative data. The application of standards to the computer-assisted surgery systems will mean that these tools can be compared and combined in longitudinal studies, thus permitting the technology to mature.
Consensus
The development and implementation of computer-assisted surgery technologies should be surgeon-driven. This will require partnerships between industry and surgeons as well as the establishment of networks of computer-assisted surgery pioneers. The development of a shared lexicon and framework will permit computer-assisted surgery technologies to be systematically applied to surgical procedures. Ultimately, to promote consistent implementation of these tools, surgeons should help establish standards for computer-assisted surgery procedures.
The classic analogy for computer-assisted surgery technologies is that they are a global positioning system for the operating room. To extend the analogy, a global positioning system is only useful when a discrete address (i.e., a precise target) is known. At present, using computer-assisted surgery techniques is like entering a zip code but not a street address into a global positioning system. This limits the applicability of the technology. To define the targets (i.e., the street address) for these guidance systems, basic-science research as well as objective imaging and postoperative diagnostic modalities are needed. 