Authors' objectives:

To determine whether computer-assisted navigation improves the accuracy of implant alignment for TKA, and whether the amount of improvement in alignment results in meaningful improvements in health outcomes, such as pain, function, or revision surgery.

Authors' recommendations: The RCTs allow conclusions on postoperative alignment outcomes. These RCTs are relatively consistent in demonstrating a reduction in alignment outliers for the computer-assisted navigation group across different studies and different measures of alignment. It is possible to conclude that approximately 15.5% of patients may avoid malalignment of more than 3 degrees in overall limb alignment when computer-assisted navigation is used. It is also possible to conclude that computer-assisted navigation is associated with longer operating times. The evidence on blood loss is less certain, in that some studies report a small reduction in blood loss, but others do not. There is no direct evidence to evaluate whether long-term functional outcomes are improved by computer-assisted navigation. The RCTs that report on short- to intermediate-term functional outcomes do not report improvements associated with computer-assisted navigation. This establishes that there is not a large difference in functional outcomes associated with computer-assisted navigation over a 2- to 3-year follow-up period. However, these small RCTs are inadequately powered and have an insufficient length of follow-up to detect the smaller differences in functional status scores that might be expected from computer-assisted navigation when evaluating the entire population of patients undergoing the procedure. Since the vast majority of patients do well following TKA and only a small minority has poor outcomes, larger RCTs with longer follow-up will be required to demonstrate improved outcomes as measured by standardized knee rating scores. The available evidence on the relationship between malalignment and clinical outcomes consists of observational studies of various designs. Only one of these observational studies was a prospective cohort study that used postoperative alignment as a predictor of future poor outcomes in a multivariate analysis, and this study had only a relatively small number of outcomes (n=41). This study did show a strong relationship between malalignment and poor outcomes. Four other cohort studies, which were generally much older studies, reported that outcomes were worse for patients who had postoperative varus alignment. The case-control studies and case series that evaluated the association of alignment with outcomes represent weak study designs to answer the specific questions. These studies did not use postoperative malalignment to predict outcomes, but rather evaluated alignment at the time of the poor outcomes. The case-control studies did report an association between rotational malalignment and clinical outcomes, and the case series suggested that approximately 10% of patients undergoing TKA revision surgery have malalignment at the time of revision surgery. Thus, while RCTs suggest that approximately 15.5% of patients may avoid malalignment of greater than 3 degrees by this analysis, it is not possible to conclude that all these patients benefit from computer-assisted navigation. The threshold definition for malalignment is derived from older studies. It is not certain that this threshold is the most clinically relevant definition of malalignment in the current era of TKA. There have been many advances in TKA that might mitigate the impact of malalignment seen in earlier studies. In addition, there is a lack of clinical studies that define the threshold for malalignment, and there may be an interaction between alignment and other risks for poor outcome, such as obesity. The positive associations reported across different types of observational studies suggest that there is a relationship between malalignment and poor outcomes. However, as a result of deficiencies in the available evidence, it is not possible to test this hypothesis or to determine whether the degree of improvement in alignment reported in the RCTs leads to meaningful improvements in health outcomes, such as pain, function, or revision surgery. Therefore, it is not possible to conclude that the use of computer-assisted navigation with TKA leads to improved health outcomes. Based on the available evidence, the Blue Cross and Blue Shield Association Medical Advisory Panel made the following judgments about whether the use of computer-assisted navigation for total knee arthroplasty (TKA) meets the Blue Cross and Blue Shield Association’s Technology Evaluation Center (TEC) criteria. 1. The technology must have final approval from the appropriate governmental regulatory bodies. TKA is a surgical procedure that is not subject to U.S. Food and Drug Administration (FDA) regulations. Several systems for computer-assisted navigation have been cleared for marketing by the FDA via the 510(k) process (e.g., PiGalileo™ Computer-Assisted Orthopedic Surgery System, PLUS Orthopedics; OrthoPilot® Navigation System, Braun; Navitrack® Navigation System, ORTHOsoft). 2. The scientific evidence must permit conclusions concerning the effect of the technology on health outcomes. The evidence is sufficient to conclude that the use of computer-assisted navigation with TKA results in more accurate implant alignment. This conclusion is derived from RCT evidence comparing TKA using computer-assisted navigation with conventional TKA and reporting on the number of patients in each group with malalignment. Approximately 15.5% of patients may avoid malalignment of greater than 3 degrees in overall limb alignment with the use of computer-assisted navigation. The evidence is not sufficient to conclude that the improvement in alignment associated with computer-assisted navigation leads to meaningful differences in health outcomes, such as pain, function, and revision surgery. Long-term evidence from RCTs is not available to answer this question. Observational studies that evaluate the association between alignment and clinical outcomes consistently report an association between malalignment and poor outcomes. However, these studies have a variety of methodologic limitations and, by their nature, are hypothesis generating. Thus, the evidence is not sufficient to determine that the degree of improvement in alignment reported in the RCTs leads to a meaningful benefit in health outcome. 3. The technology must improve the net health outcome; and4. The technology must be as beneficial as any established alternatives. Evidence is not sufficient to permit conclusions as to whether computer-assisted navigation improves the net health outcome or is as beneficial as conventional alignment techniques. 5. The improvement must be attainable outside the investigational settings. It cannot be determined whether any improvement is attainable outside the investigational setting since the evidence is not sufficient to permit conclusions on the effect of computer-assisted navigation on health outcomes. For the above reasons, the use of computer-assisted navigation for total knee arthroplasty does not meet the TEC criteria.

Project Status: Completed

URL for project: http://www.bcbs.com/blueresources/tec/contact-tec.html

Year Published: 2007

English language abstract: An English language summary is available

Publication Type: Not Assigned

Country: United States

Organisation Name: BlueCross BlueShield Association

Contact Address: BlueCross BlueShield Association, Technology Evaluation Center, 225 North Michigan Ave, Chicago, Illinois, USA. Tel: 888 832 4321

Contact Name: tec@bcbsa.com

Contact Email: tec@bcbsa.com

Copyright: BlueCross BlueShield Association (BCBS)