Postoperative Analgesia Following Total Knee Arthroplasty: In Response

Abstract

We appreciate the interest Drs. Lang and Rooney have shown in our work and their implicit endorsement of our conclusion that sciatic blockade is usually necessary after TKA to provide satisfactory conduction analgesia. It is particularly gratifying to see that the nature of discussion has shifted to a plane of how best, rather than whether, to provide continuous peripheral neural blockade for postoperative analgesia. Certainly production pressures are a reality and, sadly, one can expect little patience for pain management practices that delay case flow. Yet it is hard to compare the situation today with that of only 10 years ago. Little dedicated equipment was then available for continuous peripheral neural blockade (CPNB) which usually required a fair amount of effort and jerry-rigging. Today multiple manufacturers market prepackaged CPNB sets, which greatly simplifies matters. Even more important than equipment advances has been the development of greater organizational sophistication. Production pressure becomes much more manageable if one is doing the blocks, as we are, in a properly equipped preoperative area, and if they are in the hands of a dedicated acute interventional pain service (AIPS). If blocks must be done by each individual anesthesiologist in the OR, then in all likelihood they will not be done at all. In our practice, the solution has been formation of a dedicated AIPS team whose sole function is to manage postoperative pain. The assigned attending will spend a week at a time on the service. His duties include both placing the blocks (single and/or continuous) and having primary responsibility for managing the patient’s pain postoperatively. Clearly, the economics and logistics of a dedicated acute pain service will vary for each institution and will require a certain amount of creative adaptation. However, over the years it has become clear to us that 1) a separate dedicated AIPS team with a consistent approach and 2) the continuity of patient care provided by at least weekly assignment of one of the team are critical elements of a successful acute pain program. A situation where each attending does or does not manage postoperative pain as time and inclination allow is a prescription for both problems and failure. While the technique suggested by Drs. Lang and Rooney is interesting and may indeed prove useful, it raises several issues. Use of a single shot block provides time-limited relief and, in fact, will create the very situation postoperatively that we wish to avoid—the inability to distinguish nerve injury from neural blockade. Our method has evolved to the point where we now place the sciatic catheter using saline injectate only. No local anesthetic (LA) is administered via the catheter until, after surgery, the patient has demonstrated intact sciatic function and is complaining of posterior pain. As for use of a catheter passing through or in close proximity to the wound, in our experience, orthopedic surgeons are wary of placing infusion catheters in or about the wound when prosthetic implants are used. Since as many as 1% of implants may suffer from infection, then regardless of whether or not a surgical wound-sited LA catheter predisposes to infection, it will certainly predispose to medicolegal liability (as the catheter will doubtless be blamed for introducing infection). There are several companies currently marketing wound infusion catheters and pumps, and this seems to be a common theme of concern. There are, to our knowledge, no published direct comparisons of CPNB and LA wound infusions, but our impression remains consistent with that of Chelly et al. (1), who found superior analgesia from CPNB versus intraarticular LA infusion. Nevertheless, such an approach to the use of local anesthetic as part of a multimodal analgesic plan may be the most practical in many locales. Bruce Ben-David, MD Clinical Associate Professor of Anesthesiology, University of Pittsburgh Medical Centers-Shadyside Hospital Jacques Chelly, MD, PhD Professor of Anesthesiology and Orthopedic Surgery, University of Pittsburgh Medical Centers, Pittsburgh, PA