Copyright © 2009 by The Journal of Bone and Joint Surgery, Inc.
Commentary & Perspective
Commentary & Perspective by
Nigel E. Sharrock, BMedSci, MB, ChB*,
Hospital for Special Surgery, New York, NY
Posted January 2009
The amount of pain experienced by a patient after total hip
arthroplasty is generally perceived by caregivers to be "not that bad" in
comparison with the pain that may be experienced after total knee arthroplasty,
and thus the early pain-control regimen following total hip arthroplasty often consists
primarily of systemic narcotics. This excellent paper involving an extensive
amount of work effectively refutes this misconception. By randomizing 225
patients into three groups, the authors showed with good statistical power that
a continuous lumbar plexus block provided far superior pain relief with less
narcotic-related side effects than patient-controlled intravenous analgesia
with hydromorphone. Furthermore, this study shows that optimal local analgesia
improves early rehabilitation after total hip arthroplasty similarly to the way
in which it affects rehabilitation after total knee arthroplasty.
A number of important aspects of perioperative pain control
not covered in the paper are worth discussing. First, this paper demonstrates
that femoral blocks do not work effectively for total hip arthroplasty. As the
authors point out, the nerve supply to the hip includes the obturator nerve, and
the nerves supplying the hip no doubt exit proximal to where a femoral block is
achieved. For this reason, the most effective block is a lumbar plexus block.
In this regard, the type of block used to achieve pain relief following a hip
fracture should be a lumbar plexus rather than a femoral block1. The
potential therapeutic benefits of this are substantial. If a patient with a hip
fracture were to receive a lumbar plexus block upon arrival in the emergency
room, then he or she might avoid the adverse effects of narcotics or surgical
delay.
Second, the continuous nerve blocks that were administered
to patients in this study were preceded by administration of a very large
single injection (approximate average, 45 mL) of a long-acting local
anesthestic, ropivacaine. This may explain why these results were better than those
in a recent trial of continuous lumbar plexus block following total hip
arthroplasty2. Such a substantial initial block may, in fact, have
provided most of the postoperative analgesia. If this is the case, it raises
the possibility that a single injection technique with a smaller and less
traumatic needle (not requiring a catheter) could be almost as effective and much
simpler than the continuous catheter technique.
Finally, and perhaps most importantly, the authors
demonstrate that the block provided two very important secondary outcome
advantages. They describe less fever in patients receiving lumbar plexus block.
This suggests that the metabolic injury following surgery may have been blunted
by the lumbar plexus block, as has been found recently with use of lumbar
plexus block and sciatic block following total knee arthroplasty3.
Not only do patients have less pain and less narcotic side effects, but they
may also be less metabolically injured, which would be a huge advantage. In the
discussion section of the paper, the authors also note that postoperative
confusion developed in eight octogenarians in the patient-controlled
intravenous analgesia group, whereas no confusion was observed in the lumbar
plexus block group. They did not do a subset analysis, but it is possible that
elderly patients might do better with lumbar plexus block for this reason
alone.
In conclusion, this excellent study clearly shows that lumbar
plexus block provides multiple benefits following total hip arthroplasty. It is
possible that this study could stimulate interest in using lumbar plexus block
to improve outcome following not only total hip arthroplasty but also femoral neck
fractures.
*The author did not receive any outside funding or grants in support of his research for or preparation of this work. Neither he nor a member of his immediate family received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity.
References
1. Foss NB, Kristensen BB, Bundgaard M, Bak M, Heiring C, Virkelyst C, Hougaard S, Kehlet H. Fascia iliaca compartment blockade for acute pain control in hip fracture patients: a randomized, placebo-controlled trial. Anesthesiology. 2007;106:773-8.
2. Ilfeld BM, Ball ST, Gearen PF, Le LT, Mariano ER, Vandenborne K, Duncan PW, Sessler DI, Enneking FK, Shuster JJ, Theriaque DW, Meyer RS. Ambulatory continuous posterior lumbar plexus nerve blocks after hip arthroplasty: a dual-center, randomized, triple-masked, placebo-controlled trial. Anesthesiology. 2008;109:491-501.
3. Bagry H, de la Cuadra Fontaine JC, Asenjo JF, Bracco D, Carli F. Effect of a continuous peripheral nerve block on the inflammatory response in knee arthroplasty. Reg Anesth Pain Med. 2008;33:17-23.
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