Copyright © 2007 by The Journal of Bone and Joint Surgery, Inc.
Commentary & Perspective
Commentary & Perspective by
Richard Laskin, MD*,
Hospital for Special Surgery, New York, NY
Posted January 2007
In this issue of The
Journal, Patel et al. address the problem of drainage after total joint
replacement and try to assess which preoperative and intraoperative factors
might be associated with this complication. In addition, they investigate
whether drainage is a real problem and whether it is related to the development
of infection. To answer this, the authors reviewed the hospital records of
almost 2500 patients who had undergone either a primary unilateral hip or knee
replacement.
The authors are to be commended for their diligent effort in
amassing these data from this large cohort of patients. They have shown that
prolonged wound drainage is a real problem. It can increase the risk of
infection and can lead to a longer hospital stay.
They have answered some questions but, like all good
scientists, have found new ones to stimulate our interest. For example, the
authors limited their analysis to patients in whom a closed suction drain had
been used. There is ongoing controversy as to whether a drain is necessary after
a primary joint replacement. Why did the authors not analyze those patients in
whom a drain was not used? Were there sufficient numbers of these patients? If
so, knowledge as to whether these patients had more or less wound drainage would
be of great interest. Possibly, this could be an area for future research for
the authors.
The diagnosis of active wound drainage was made if "a ≥2 × 2-cm area of gauze covering the wound
was wet or if fluid was noted to be originating from the surgical site" on any
day postoperatively. Who determined this? Since this study was a retrospective
review of more than 2000 charts, one would assume that such careful documentation
of drainage was a mandatory routine chart entry for all patients who underwent total
joint arthroplasty at the authors' institution. If so, the authors and their
institution are to be commended.
I cannot understand, however, why they excluded patients whose
wounds were draining secondary to "poorly approximated wound edges or
ulceration." If the premise is that an open wound is a portal for ingress of bacteria
into the incision, why not include all incisions?
The authors have shown that increased drain output was a
risk factor for prolonged wound drainage. They state that for each 100-mL
increase in postoperative drain output, there was a 0.2-day (4.8-hour) increase
in wound drainage time. However, since the assessment of wound drainage was
made on a daily basis, reporting drain output on a four-hour basis is not
helpful and weakens quantification of a possible association of drain output
and wound drainage.
More importantly, the use of closed suction drainage as a "measure"
is fraught with possible inaccuracies. For example, if the drain is occluded,
then the drain output would be small, yet there might be subsequent drainage
from a large hemarthrosis. One could therefore hypothesize that, in
some patients, decreased drain output would be associated with increased
(albeit delayed) wound drainage. This might explain why some of the outcomes of
infection or drainage as related to the amount of blood in the closed suction
drain were so variable in this study.
The drain output statistics suggest to me that the authors should
consider eliminating this parameter in further studies and should instead concentrate
on the other areas in which their data have shown real power.
The authors' reported infection rate for hips seems somewhat high (approximately 1.25%), whereas it was not this high for knees.
Likewise they found multiple factors that were correlated with infection in
hips (morbid obesity, higher drain output, and the use of low molecular weight
heparin) while only higher drain output for knees seemed to be important. I am
not sure why this occurred and am at a loss to understand why obese patients
with wound drainage were not at a higher risk for infection, especially since
the knee joint is so superficial. In another published study, knee infection and
obesity appeared to be statistically related1.
After reading this paper, I believe that some valuable
conclusions can be drawn on the basis of the data. For hip replacement,
prolonged wound drainage was a real predictor of the development of a wound
infection. Morbid obesity and the use of low molecular weight heparin both were
related to increased drainage after hip replacement. Although, as a surgeon, I
cannot effectively control the obesity of a patient, I would seriously consider
the possibly of not using low molecular weight heparin for deep venous
thrombosis prophylaxis in morbidly obese patients, at least with regard to hip
replacement. I would appreciate hearing from the authors as to how the data in
this study have affected their practice of joint replacement, especially as
related to anticoagulation.
*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. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the author, or a member of his immediate family, is affiliated or associated.
Reference
1. Peersman G, Laskin R, Davis J, Peterson M. Infection in total knee replacement: a retrospective review of 6489 total knee replacements. Clin Orthop Rel Res. 2001;392:15-23.
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