Copyright © 2009 by The Journal of Bone and Joint Surgery, Inc.
Commentary & Perspective
Commentary & Perspective by
Thomas Parker Vail, MD*,
University of California at San Francisco, San Francisco, California
Posted June 2009
The authors of this study have performed a carefully
constructed prospective and blinded comparison of total knee replacement performed
with and without eversion of the patella and subluxation of the tibia. This
type of focused clinical research is very important for the orthopaedic
community as we try to differentiate between the marketing claims and anecdotal
assertions and the true improvements in surgical technique.
Classical training in surgical technique for total knee
replacement has emphasized the importance of adequate exposure1. At
the same time, minimizing damage to soft tissues by limiting surgical exposure is
considered to be an advantage to patients2. It is a logical and
intuitive assertion that a well-executed operation performed through an
approach that is less injurious to soft tissues is superior to one with more
soft-tissue damage. So-called less-invasive or less-injurious surgical
techniques, smaller incisions, or tissue-sparing approaches often do not meet
the burden of proof that the proposed method is either protective of the soft
tissues or an advantage to a patient for some other reason (e.g., a lower
prevalence of complications or faster rehabilitation)3. Critical
analysis of these so-called less-invasive approaches is very important so that
we may ensure that patients and their surgeons are not being exposed to potentially
increased risk without an accompanying incremental increase in advantage. Any
change in surgical technique that is associated with an elevated level of
difficulty introduces the potential for an incremental increase in the risk of having
a poor outcome.
One might argue that the focus of this study is on a
technique that is not associated with enough clinical differentiation in complexity
to really matter. Is there actually any difference in surgical complexity when
performing total knee arthroplasty by subluxating rather than everting the
patella and by subluxating or not subluxating the tibia? For this study to
impact clinical practice, one must accept the premise that, for some surgeons
performing total knee arthroplasty in certain knees, exposure may be more difficult
if the patella is not everted and if the tibia is not adequately subluxated to
allow proper bone preparation and component insertion.
The strength of this analysis is that the study was
carefully designed, was prospective, and that the assessment was blinded even
to the patients who were asked to assess their level of satisfaction with
regard to the knee. The lack of statistical power is an issue that the authors
acknowledge as a weakness. However, the data clearly demonstrate no clinically
relevant differences even if the statistical power falls short of statistical
significance. The lack of any clinically relevant difference is enough to help
refute the claim that these differences in technique (i.e., whether the patella
was everted or not, and whether the tibia was subluxated or not) are associated
with a difference in outcome.
There are potential confounders that must be considered. The
experimental model of comparing two knees in one patient may not provide a consistently
appropriate comparison if the knees are not exactly the same with regard to the
severity of osteoarthritis. In particular, the objective clinical measurement
tools may not be sensitive enough to detect patient perceptions that impact judgment
regarding satisfaction before and after an operation, making it difficult to
determine whether comparing one knee with another is actually a fair comparison
in the domain of patient perception.
In conclusion, I believe that the authors have successfully
tested a hypothesis with use of a safe and controlled prospective clinical
protocol. We need more of this type of investigation in orthopaedic surgery.
*The author did not receive any outside funding or grants in support of his research for or preparation of this work. The author, or a member of his immediate family, received, in any one year, payments or other benefits in excess of $10,000 or a commitment or agreement to provide such benefits from a commercial entity (DePuy).
References
1. Insall JN. Surgical approaches to the knee. In: Insall JN, editor. Surgery of the knee. New York: Churchill Livingstone; 1984. p 41-54.
2. Laskin RS. Minimally invasive total knee arthroplasty: the results justify its use. Clin Orthop Relat Res. 2005;440:54-9.
3. Pagnano MW, Leone J, Lewallen DG, Hanssen A. Two-incision THA had modest outcomes and some substantial complications. Clin Orthop Relat Res. 2005;441:86-90.
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