CORR Insights®: Is Spinal Anesthesia Safer than General Anesthesia for Patients Undergoing Revision THA? Analysis of the ACS-NSQIP Database

Where Are We Now? During the past decade, joint replacement specialists have focused on improving the safety and predictability of total hip and total knee replacement. The type of anesthesia chosen plays a role in this effort, with a substantial body of evidence suggesting neuraxial techniques are associated with a lower risk of death, thromboembolic events, transfusion usage, and prolonged hospital stay compared to general anesthesia [1-3]. The benefits of neuraxial anesthesia are realized in all categories of patients, from those considered low risk to those who are high risk for surgery as judged from their comorbidity profiles [1-3]. In the current study, Wilson and colleagues [5] used the American College of Surgeons National Surgical Quality Improvement Program database to determine whether the benefits associated with spinal anesthesia can also be demonstrated in revision THA. The authors found that spinal anesthesia is associated with a reduced risk of mortality, readmission, reoperation, thromboembolic events, incidence of transfusion and risk of unplanned intubation or failure to be weaned off intubation. Where Do We Need To Go? Despite the strong body of evidence suggesting neuraxial anesthesia [1-3] is associated with fewer complications after arthroplasty surgery, [1-3] the topic remains somewhat controversial. For example, current data suggest that more than 70% of THAs in the United States are performed using general anesthesia [3], but the rationale for favoring general anesthesia in most US hospitals performing THA and revision THA is not well known. We do know that neuraxial anesthesia requires a specific skillset for anesthesia providers that is enhanced by anesthetists that are dedicated to orthopaedic anesthesia. There is also a perception that prolonged or complex procedures such as revision THA may require more anesthesia duration than can be expected from spinal anesthesia. High-volume joint replacement centers often provide the opportunity for fellowship or other training to develop the skills and experience necessary for routine avoidance of general anesthesia in arthroplasty. This added training should be considered for anesthesiologists that are interested in dedicated practice in orthopedic anesthesia. Because the current study is also limited to a 30-day follow-up period, future studies should address longer-term benefits in functional recovery that may be associated with avoiding general anesthesia. Researchers should also compare the risk and benefits of epidural as opposed to spinal anesthesia, as they may differ. Furthermore, it seems as though the choice of anesthesia does play a role in managing post-operative pain. A recent study [4] found that multi-modal pain management strategies that combine spinal anesthesia with peripheral nerve blocks and systemically administered analgesics enhance early recovery, reduce the dependence on opioid analgesia leading to shorter hospital stays, fewer opioid-related complications, and perhaps better long-term functional recovery. As length of hospital stay decreases and ambulatory joint replacement is adopted, the importance of the anesthetic and analgesic strategies become more critical. Studies that report on new approaches to regional anesthesia and analgesia in the fast tract setting will clarify best practices for the future. How Do We Get There? The studies that provide the strong support for use of neuraxial anesthesia both in primary [1-3] (and in the current study, revision total hip replacement [5]) rely on large databases to provide the data; studies of this design can identify associations, but they are silent on causation. The next step would be to confirm causation, but this is not easy. Prospective, comparative trials robust enough to support inferences about cause and effect will call for large numbers of participants in order to have sufficient statistical power to resolve between-group differences in complications, because the serious complications—the ones we’re most interested in—are quite rare. It is going to be near impossible to perform studies that provide the leap from association to confirmation of direct causation. In order to confirm that neuraxial anesthesia provides best practice compared to general anesthesia, we would need randomized controlled trials conducted on a national scale funded through agencies that have proper financial resources such as NIH/NIAMS or Agency for Healthcare Research and Quality. These studies would have to directly compare novel modalities for general anesthesia combined with peripheral nerve blockade and neuraxial anesthesia combined with peripheral nerve blockade. Further comparative population studies may fill in some gaps, but they will never provide the proof we are looking for. It is hard to accept that we are unable to resolve so fundamental an issue.