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Peripheral Nerve Blocks for Postoperative Pain Relief After Total Knee Replacement: More Questions Than Answers

Ben-David, Bruce MD; Chelly, Jacques E. MD, PhD, MBA

doi: 10.1213/01.ANE.0000151472.37849.81
Letters to the Editor: Letters & Announcements

Department of Anesthesiology; University of Pittsburgh Medical Centers; Pittsburgh, PA; bendbx@anes.upmc.edu

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In Response:

Dr. Guay’s recent paper on analgesia following total knee replacement (1) demonstrated (a) approximately a 50% reduction in opiate consumption with both CFNB and CPCP, (b) a small but statistically insignificant further reduction in opiate consumption with CPCB versus CFNB, (c) a significant reduction in VAS score at rest with both techniques, (d) a small but statistically insignificant further reduction in VAS with CPCB versus CFNB, and (e) no reduction in VAS with physical therapy. We accept these data as valid and feel they support our own experience and published work (2). That is, we agree with and accept the conclusion that beyond the analgesia of femoral blockade, obturator blockade makes only a limited contribution to analgesia following TKR.

However, Dr. Guay would have been wise to limit her conclusions to the question posed by their study—as to the relative analgesic contribution of obturator blockade. We believe that their patients’ opiate needs would have been much further reduced and the analgesia during PT far more effective had they added continuous sciatic blockade to their protocol. Furthermore, neural blockade does not alter the inflammatory response and sensitization (central or peripheral) and will be far more effective if combined with COX-2 inhibition (3). Where Dr. Guay sees a failed technique (neural blockade) we see a failure to use the technique properly. One may not be able to travel far in a car with one wheel, but that does not leave walking as the only option. One might try attaching the other wheels.

More disturbing than extrapolating beyond the limits of her work is Dr. Guay’s use of dubious retrospective “outcome data.” This is worse than meaningless. It is misleading. For example, how do we know that the physical therapists didn’t actually measure but simply approximated flexion? Would that not lead to fairly routinized charting, thus making any comparative data worthless? The extremely long hospitalizations of 7 days suggests that hospital stay was dictated by standard practice rather than by a set of discharge criteria, thus debasing any conclusion as to the influence of analgesia technique on hospital length of stay. As she herself noted, their study was not designed to assess rehabilitation. That was correct. She should have heeded her own caution.

On the basis of false extrapolation, meaningless data, and supposition (as to complications), Dr. Guay would admonish us to reconsider the use of neural blockade as a postoperative analgesic technique. We would admonish her to be more careful with such baseless, sweeping, and hubristic commentary.

Bruce Ben-David, MD

Jacques E. Chelly, MD, PhD, MBA

Department of Anesthesiology; University of Pittsburgh Medical Centers; Pittsburgh, PA; bendbx@anes.upmc.edu

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References

1. Kaloul I, Guay J, Côté C, Fallaha M. The posterior lumbar plexus (psoas compartment) and the three-in-one femoral nerve block provide similar postoperative analgesia after total knee replacement. Can J Anaesth 2004;51:45–51.
2. Ben-David B, Schmalenberger K, Chelly JE. Analgesia after total knee arthroplasty: is continuous sciatic blockade needed in addition to continuous femoral blockade: Anesth Analg 2004;98:747–9.
3. Buvanendran A, Kroin JS, Tuman KJ, et al. Effects of perioperative administration of a selective cyclooxygenase 2 inhibitor on pain management and recovery of function after knee replacement: a randomized controlled trial. JAMA 2003;290:2411–8.
© 2005 International Anesthesia Research Society