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Dialogue on Evidence in Practice |
University of South Florida
School of Physical Therapy
12901 Bruce B Downs Blvd
MDC 077
Tampa, FL 33612-4766
mmaitlan{at}hsc.usf.edu
In their March 2004 Evidence in Practice article,1 Wetherbee and Pellecchia do not appear to follow a systematic approach or a comprehensive method to gather and synthesize information to answer their question. The articles they present to support their clinical decision are from completely different perspectives: muscle activation patterns,2 injury incidence,3 a review article focusing on performance tests,4 and a comparison of 2 braces.5 The authors do not present a scientific or theoretical rationale for discussing these articles other than statements that the articles were appealing or interesting.
From the case description, there is no doubt that the patient can "resume" downhill skiing, but Wetherbee and Pellecchia may not have intended this to be their outcome of interest. The term "stability" during skiing might be interpreted to mean "prevention of injury" or "motion of the tibiofemoral joint." Therefore, I would suggest that their clinical question should read: Do knee braces prevent excessive motions of the tibiofemoral joint that might cause injury for a skier with a deficient anterior cruciate ligament (ACL)?
In my opinion, attempting to answer such a complex question with so little foundational knowledge as presented by Wetherbee and Pellecchia seems presumptuous. The approach that the authors used in synthesizing the information contributed to what I believe was their inability to gather important information.
The effectiveness of bracing the ACL-deficient knee is controversial, but the authors' approach did nothing to help clinicians understand the controversies. For example, Wetherbee and Pellecchia might have cited a recent study that used bone pins in the lower extremities of subjects with ACL-deficient knees who were randomized to braced and unbraced conditions to investigate joint motion during activities.6 Ramsey et al6 did not find consistent reductions in anterior tibial translations as a function of the knee brace that they tested. In this same article, Ramsey et al6 state that other investigations have reported that knee braces fail when high loads are encountered or when load is applied in an unpredictable manner. A more recent paper by Ramsey et al7 provides citations to show that functional braces do not mechanically stabilize the anterior cruciate ligament deficient knee. In addition, there are controlled experiments using cadavers. Erikson et al8 applied a lateral impact force to the cadaver knee to measure ACL elongation in braced and unbraced conditions. They did not find a statistically significant protective effect from bracing. Beynnon et al,9 on the other hand, found braces had a protective effect when they studied ACL strains by direct measurement during sit to stand and other activities.
The fact that Wetherbee and Pellecchia felt they "had sufficient information" about the effectiveness of functional knee braces from the 4 cited papers intimated that they did not understand the complexity of the issues they were presenting. For example, they interpret the study by Wojtys and Huston5 to mean that knee braces reduce anterior tibial translation. To be more precise, Wojtys and Huston5 stated that the braces control anterior tibial translation when the knee muscles were contracted. The relative importance of the knee muscles in knee stability cannot be understated. The effectiveness of the quadriceps and hamstring muscles in controlling anterior tibial translation depends on knee joint angle.10 The quadriceps muscles alter their arthrokinematic function at about 70 degrees of knee flexion and become very important protectors of the ACL. Also, muscle stiffness of the thighs and calves may directly affect the interface between the brace and the lower extremity, affecting the anterior tibial displacement.11
Wetherbee and Pellecchia might have examined the mechanism by which skiers are injured to decide whether a brace is warranted or whether other interventions might be advisable. Ettlinger et al12 identified 2 common mechanisms of anterior cruciate injury in skiers by examining data from 1,400 injuries over 22 years. Ettlinger et al12 found that the most common scenario involves a situation where the skier falls backward and the hips move below the knees. They also describe a scenario where the skier looses balance to the rear during a hard landing. Ettlinger et al12 studied the effect of an educational intervention on the rates of ACL injury. Serious knee sprains were reduced by 62% in the intervention group compared with historical rates, but rates of knee injuries were not reduced in the control group. Wetherbee and Pellecchia might provide their skiing patient with some insight into how he should avoid injury.
It is well known that noncontact mechanisms of ACL are important for both male and female athletes in a variety of sports.13 The mechanism of noncontact injury remains speculative. The importance of this issue for skiers remains controversial. In my own examination of ski injuries, patients report no untoward, sudden forces but that their knees "give way." Braces may—or may not—be effective for these injury mechanisms.
In addition to the mechanism of injury, Wetherbee and Pellecchia might have mentioned the quantity of motion that the braces must limit in order to be effective. Woo et al14 studied the ultimate failure of cadaver ACLs. Failure of the ACL occurred between 7 mm and 13 mm of tibial displacement relative to the femur. Can external support affixed to muscles above and below the knee prevent such small tibiofemoral movements?
Wetherbee and Pellecchia distilled the entire literature on the effectiveness of knee braces to maintain knee stability to a meager 4 papers. In keeping with an "evidence-based practice" approach (à la Sackett and colleagues15), Wetherbee and Pellecchia distill out much of the information that can be used to make clinical judgments and to inform our patients. In following the linear 5-step process propounded by Sackett et al15 in a literal fashion, Wetherbee and Pellecchia may have degraded forms of information despite potential value to the patient, and they state that they simply did not read information that does not appear to meet a presumed set of criteria. On the other hand, Sackett et al15 never suggested that reviewers like Wetherbee and Pellecchia subjectively discard papers because of time constraints. Wanting a "quick" answer cannot be adequate justification for the content of an evidence-based practice review published in a professional journal. The authors have a responsibility to provide more comprehensive insight into this controversial topic.
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Department of Physical Therapy
University of Hartford
West Hartford, Conn
Physical Therapy Department
University of Connecticut
Storrs, Conn
We appreciate Dr Maitland's comments on our Evidence in Practice (EiP) article.1 We acknowledge his expertise related to biomechanics of the knee and his comprehensive knowledge of the literature related to our topic. The purpose of EiP articles is to demonstrate the process of retrieving literature from pertinent databases and applying research findings to clinical practice. As stated at the beginning of every EiP article and in the Journal's Information for Authors (http://www.ptjournal.org/info/aut_info.cfm), EiP articles are not intended to be comprehensive case reports or extensive reviews of the literature.
When we conducted our literature search, we found ourselves in a typical situation in clinical practice—the patient wanted a reasonable answer to his question within a limited amount of time. We decided to explore a variety of literature in which living subjects with anterior cruciate ligament (ACL) insufficiency were subjected to conditions similar to those that our patient would experience while skiing. Dr Maitland stated that we supported our decision by presenting articles from completely different perspectives. We are uncertain why he criticized this. We wanted evidence about bracing from different and relevant perspectives that were available in the literature.
Maitland states that we "did nothing to help clinicians understand the controversies" surrounding the effectiveness of knee braces. In presenting the rationale for our clinical decision, we stated that the findings from the research that we explored were equivocal, thereby conceding that the evidence to support use of a knee brace to enhance the stability of the ACL-deficient knee was not overwhelming. It was beyond the scope of this EiP article to explore fully all of the issues related to effectiveness of bracing.
Maitland implored us to provide our "skiing patient with some insight into how he should avoid injury." We concluded our article with a brief description of our instructions to the patient, which included continuation of an exercise program and caution against developing a false sense of security from the knee brace. Once again, this article was not a comprehensive case report, and, therefore, our discussion of interventions other than bracing was not all-inclusive.
Maitland falsely asserts that we followed "the linear 5-step process propounded by Sackett et al in a literal fashion," and "simply did not read information that does not appear to meet a presumed set of criteria." Contrary to Maitland's assertion, we considered the advantages as well as the limitations of traditional literature reviews and decided to read the review article by Kramer et al2 even though it did not meet the standards of a systematic review as defined by Sackett.3 Maitland appears to misunderstand the purpose of EiP papers. To reiterate, our paper was never intended to provide a comprehensive review of the literature on bracing people with ACL injuries, but rather our aim was to illustrate the process of searching the literature to find evidence that can be used to guide clinical decision making.
In summary, we found no evidence to indicate that this patient's use of a knee brace would increase his chance of reinjuring his knee, and there was modest evidence to indicate that this patient might benefit from wearing a brace. Although Maitland raised many issues related to bracing and people with ACL deficiency, he did not offer additional insight into making the clinical decision to brace or not to brace the knee. We note that Maitland has reported that many skiers choose to wear a knee brace following ACL injury.4
We certainly understand that questions regarding bracing patients with ACL insufficiency still exist and that further research is required to elucidate the answers. We would encourage any physical therapist to continue examining the literature and critically appraising the research in an effort to better understand the controversies regarding bracing and ACL injury.
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