Using Evidence-Based Medicine in Orthopaedic Clinical Practice: The Why, When, and How-To Approach

Mary Beth Nierengarten, MA Medical WriterHost Orthopaedic Surgeon: Kelly Vince, MD, FRCS Associate Professor of Orthopaedic Surgery Center for Arthritis and Joint Implant Surgery USC University Hospital Los Angeles, CaliforniaGuest Speaker: Aaron G. Rosenberg, MD Professor, Department of Orthopaedic Surgery Rush Presbyterian Medical College Chicago, Illinois

Medscape Orthopedics. 2001;5(1) 

Using Evidence-Based Medicine in Orthopaedic Clinical Practice: The Why, When, and How-To Approach

At most major medical centers, Orthopaedic Grand Rounds are lectures given by orthopaedic surgeons of national and international prominence, providing opportunities for faculty, residents, and fellows to present difficult clinical case studies and original basic science research, and to engage in discussions on timely and controversial topics.

Medscape Orthopaedics is pleased to make these valuable educational programs available online to an ever increasing segment of the orthopaedic community. Visitors to the Medscape Grand Rounds programs are encouraged to interact with the discussions and provide commentary on the topics presented.

Introduction

Physicians are under pressure, increasingly, to provide quality healthcare in the most cost-effective way possible. The high costs of medical care, in terms of both morbidity and money, are driving the need to base clinical decision making on standardized guidelines that can help physicians provide the best care to all patients at the lowest cost to the individual and to society.[1]

Evidence-based medicine (EBM) is the term used to describe the approach to clinical decision making that is based on the consensus development, within a specialty, of standards of clinical practice that lead to diagnostic and treatment guidelines that may be used across disciplines. First developed in the 1980s at McMaster University School of Health Sciences in Ontario, Canada, evidence-based medicine is a clinical learning strategy that teaches physicians to turn a clinical problem into a question that can be answered by a systematic review and evaluation of the most current results from published studies and then applied to a particular clinical problem.[2]

Application of evidence-based medicine comes under several names, some of which are as follows:

Clinical Practice Guidelines Directory
Standardized Plans of Care
Clinical Algorithms
Clinical Policies
Clinical Pathways

The process of using scientific studies to form clinical guidelines that direct clinical decision making and patient care is still evolving.[3]

A discussion of evidence-based medicine as applied to current clinical care, and to orthopaedic surgery in particular, was presented at a Grand Rounds at the University of Southern California (USC) University Hospital, on November 3, 2000. The session was hosted by Dr. Kelly Vince, with the presentation by guest speaker Dr. Aaron Rosenberg. Dr. Vince and Dr. Michael Malo provided the case study.

The Rationale for Evidence-Based Medicine

Using evidence-based medicine in clinical practice requires some changes in physician behavior. For years, clinical decision making was based, primarily, on physician knowledge base and expert opinion. Accountability was centered on patient outcomes, with success determined by meeting the agreed-upon treatment goals, rather than having accountability rest with the healthcare insurance companies. State medical boards provided the "final" accountability, if a patient brought legal action. Now physicians are expected to create, maintain, and improve on standards of care that have measurable outcomes and can be applied with a high degree of quality control and accountability. Increased patient sophistication, brought about, largely, by mass media coverage of medical advances and by information accessibility on the Internet, and globalization require that physicians provide evidence validating the treatments or testing procedures they choose. Soaring medical costs have prompted healthcare insurance companies to establish formularies and treatment guidelines that further affect physicians' choices.

Discussion of Steps to Practicing Evidence-Based Medicine

Five major steps are involved in teaching and practicing evidence-based medicine:

  1. Formation of a clear clinical question that defines a patient's problem.

  2. Search of the medical literature for the most current and relevant study results on that problem.

  3. Critical appraisal of the selected study results for validity and clinical usefulness.

  4. Application of the relevant data to form an answer to the clinical question.

  5. Outcome assessment: follow-up evaluation of the efficacy of the first 4 steps, making improvements as necessary.[2,4,5]

All 5 steps involve an active learning process. Students of evidence-based medicine need well-developed skills of observation and application that enable the execution of these steps.

Forming an Answerable Question

Isolating and identifying the problem is the first step to forming relevant diagnostic or therapeutic questions, and requires training in good history taking and the ability to perform a thorough physical exam. This step is critical, because all 4 of the following steps flow from this initial question.[4,6]

Searching the Literature

Even though many medical specialty professional associations have begun the process of providing evidence-based practice guidelines, accessible through their Web sites, that may be used as reference, questions of patient care may arise that are not answered in those guidelines. A literature search may then be the next step. This step requires a familiarity with and some skill in selecting accurate, appropriate cross-referencing terms to provide useful literature searches. Online medical databases, such as MEDLINE or PubMed, are commonly used sources.[7] In MEDLINE, http://www.nlm.nih.gov/medlineplus/ searchers may now use "best evidence" or "evidence-based medicine" as a main subject heading, to combine with other subject headings. PubMed, http://www.ncbi.nlm.nih.gov:80/entrez/query/static/clinical.html a version of MEDLINE sponsored by the National Library of Medicine, provides excellent access to relevant articles through an option called "clinical queries."

A hierarchy of types of studies that provide the "best evidence" is shown in Table 1. Students need to learn the advantages and disadvantages of each type of study design.[4,6,7]

Table 1. Quality of Evidence

[8]

Randomized, controlled, clinical trials Grade I
Well-designed, controlled, nonrandomized studies Grade II-1
Well-designed case-control or cohort studies (preferably multicenter studies) Grade II-2
Evidence compared across time or place, with or without the intervention under study Grade II-3
Expert opinion (based on clinical experience, descriptive study, or expert committee reports) Grade III

Adapted from Canadian Task Force on Periodic Health Examination. The Canadian guide to clinical preventive health care. Ottawa: Ministry of Supply and Services; 1994.

Critical Appraisal of Studies

Several Internet sites that appraise the research literature for readers have now been developed. Physicians may go directly to these sites to find the evidence they are seeking. Several sites offer "best evidence" on a number of specialties. Many of these sites are geared to use by either primary caregivers or specific specialties; however, few target orthopaedic surgery as subject matter or as an audience. The following are a few of the more established sites:

National Guideline Clearinghouse (Clinical Guidelines for Orthopaedic Surgery)

Cochrane Database of Systematic Reviews

Clinical Evidence (New journal published by the British Medical Journal)

Although these sites make it easier to access pre-evaluated evidence, several specialties, such as orthopaedic surgery, are not yet well represented on these sites. Physicians still need to become familiar with epidemiologic and biostatistical methods of assessing the evidence.

Applying Evidence-Based Data to the Clinical Problem

This step requires physicians to apply the validated evidence to the particular situation of the patient, including the relevance of objective and subjective findings in the patient to the findings of the subjects in the studies. The physician needs to ask questions such as the following:[4]

Is the diagnostic test or treatment procedure based on evidence available from the literature and accurate for this particular patient at this particular institution? Do patient capabilities, preferences, and values permit the accurate or appropriate use of the diagnostic test or treatment procedure deemed valid by the evidence? Do the treatments or procedures used provide answers to the clinical questions, and, if not, how may the process be improved?

Special Issues for Orthopaedic Surgeons

Although evidence-based medicine is now widely accepted and used in primary care as well as in many specialties, surgical disciplines such as orthopaedic surgery have been slow to adopt this clinical practice learning strategy. This is, in part, because of the difficulty of conducting randomized controlled clinical trials in surgery. However, other types of studies such as case control studies, which are applicable to orthopaedic surgery, are also good sources of evidence and can provide clinically relevant results on which to develop clinical practice guidelines.[6,9]

Several studies in orthopaedics show the need for standardizing care in orthopaedic surgery by showing the wide variation in outcomes based on geography, patient demand, and physician availability.[10,11,12,13] A recently published article proposes ways in which orthopaedic surgeons may improve patient outcomes by applying evidence-based medicine approaches.[14]

Following is a case showing a possible clinical guideline to treat bilateral hip avascular necrosis (AVN) of the femoral heads.

Case Report: Bilateral Idiopathic Avascular Necrosis of the Femoral Heads: An Evidence-Based Medicine Approach to Treatment

Patient Description

35-year-old African American woman.
Complaint of hip pain in both hips, with worse pain in the left hip.
Spontaneous development of pain in the left and, to a lesser extent, right groin region that radiates down the anteromedial thigh, with a duration of 3 months.
Patient's level of disability necessitates using a cane to walk.
Conservative management, including crutches and medications, failed to provide adequate relief or restore function.
No pertinent medical history or risk factors.

Objective Findings

Pain in left hip on reflexion, extension, abduction, and adduction; pain worsens with internal rotation.
Mild discomfort in right hip at extremes of flexion, extension, abduction, adduction, and rotation.
No other relevant physical findings.
Anteroposterior (AP) and lateral radiographs of both hips showed altered bone density in both femoral heads; subchondral collapse on the left femoral head.
The right hip has an intact cortex on both AP and lateral views.

Preliminary Diagnosis

Bilateral idiopathic AVN of the femoral heads.

Points of Consideration -- Staging and Subsequent Differential Diagnosis

Diagnosis of bilateral AVN, without apparent risk factors
Key clinical decision: define the stage of the disease (radiographs and magnetic resonance imaging [MRI] as needed)
Questions to ask: is there structural change to the articular surface? Has the femoral head collapsed?
If AVN exists in 1 hip, there is a risk for development in the contralateral hip.[15]
MRI is defensible to determine presence of AVN in the contralateral hip.
The initial classification system for AVN of the femoral head, based on radiographic changes, was developed by Ficat (Table 2).[16] Based on this classification system, the patient in this case report has the differential diagnosis of stage 3 AVN disease in her left hip, and stage 2 AVN disease in her right hip.

Table 2. Classification System for Avascular Necrosis of the Femoral Head Based On Radiographic Findings

[16]

Stage 0 - Preclinical. No clinical or radiographic signs.
Stage 1 - Preradiographic. No apparent significant change on x-ray. With advances in MRI techniques, this stage is also referred to when early changes can be identified on MRI.
Stage 2 - Precollapse. Diffuse porosis, sclerosis, and cyst formation.
Transition into stage 3 - crescent sign (subchondral fracture) and segmental flattening.
Stage 3 - Collapse. Break in the articular contour of the femoral head, sequestrum.
Stage 4 - Osteoarthritis. Terminal phase. Collapse and flattening of femoral head, articular joint space narrowing.

Adapted from Ficat RP. Idiopathic bone necrosis of the femoral head: early diagnosis and treatment. J Bone Joint Surg. 1985;67(suppl B):3-9.

Apply the Evidence to Treatment Selection

The importance of early diagnosis in the treatment and prognosis of osteonecrosis of the femoral head is universally recognized and emphasized. Diagnosis of AVN in an early stage, prior to structural change in the femur, allows time for the patient and surgeon to consider less aggressive treatment options. However, when a patient presents with later-stage AVN, as this patient does, treatment selection is more controversial. To apply the principles of evidence-based medicine practice to treatment selection for this patient, the following are considered:

The question. What is a good treatment approach for a middle-aged woman with no known risk factors, a differential diagnosis of bilateral AVN, and 1 hip showing a collapsed femoral head and the contralateral hip showing a hip progressing toward collapse?

Literature search.Controversy exists in the literature regarding the most advantageous treatment for patients with stage 2 and stage 3 AVN, as follows:

No single treatment method has yet proved to be 100% effective in stopping the disease process before subchondral collapse, or in preventing the progression of femoral-head destruction after subchondral collapse.
Based on prospective, randomized trials and review studies, core decompression, if performed in early stages of the disease (stages 1 or 2), has generally resulted in significant improvement compared with nonoperative treatment.[17,18]
As soon as a crescent sign is present, most surgeons should be hesitant to perform core decompression because results are less predictable.
Once subchondral collapse has occurred, progressive degenerative changes are usually inevitable. At this stage, a total hip arthroplasty is the best treatment clearly recommended for these more advanced stages.[19]
Other surgical options, which are very specialized and technically demanding (ie, structural bone grafting, osteotomy) have also been proposed, with good results, when performed in the early stages,[20,21] but their superiority over simpler surgical techniques has not been established.

Applying evidence to the clinical problem.In this case, the clinical decision was surgical treatment, using uncemented total hip arthroplasty of the left hip and core decompression of the right hip

Based on the diagnosis and staging of this patient, a general clinical guideline was formulated using the evidence suggested in the literature and surgical experience.

This illustrates that general guidelines can be proposed for clinical decision making based on the evidence, but it remains difficult to entirely define a straightforward clinical pathway.

Follow-up evaluation.Long-term, prospective, randomized, and multicenter studies for better standardization are still required to establish a more definitive clinical pathway for this orthopaedic problem.

Conclusion

Many areas of medicine have now adopted clinical pathways in an effort to standardize care for patients. Orthopaedic surgery lags behind in adopting clinical pathways, largely because of the difficulty of conducting randomized controlled trials that provide the "best" nonbiased source of evidence. However, an attempt to standardize orthopaedic procedures is becoming necessary, given the pressures of cost constraints and accountability.

The case example highlights both the possibility for and the difficulty of creating a standard clinical pathway for a specific orthopaedic diagnosis. It illustrates that algorithms can be created and used as a guideline, but that standardization will depend on evidence from future trials that minimize bias.

Question-and-Answer Session With Dr. Vince and Grand Rounds Participants

Q. Do clinical practice guidelines improve clinical outcomes?
A. Since clinical practice guidelines are relatively new, their effects on clinical outcomes are not yet completely established. Similar to the length of time it takes for randomized clinical trials to prove a diagnostic or therapeutic outcome, time is needed for a better understanding of improvements in clinical outcomes based on clinical practice guidelines.

One important effect clinical practice guidelines may have on clinical outcomes is a redefinition of outcomes based on clinical evidence. For example, instead of looking at the 15-year survival rate of knee implants, orthopaedic surgeons may compare the number of quality-adjusted life-years in patients who receive a cemented implant, vs results from those who received an uncemented implant. This redefinition of clinical outcomes creates a new way of evaluating physician and institutional effectiveness. Orthopaedic surgeons will increasingly be evaluated by the outcome quality of their interventions, as compared with the relevant costs.[14]

Q. What are the limitations of evidence-based medicine?
A. Evidence-based medicine is only as good as the evidence on which it is based. Much importance rests on well-conducted studies and on professionals well trained in evaluating those trials. Also needed is an understanding of which study design is the best for evaluating a given outcome.[6,9] Although randomized, controlled clinical trials are considered the "gold standard" of evidence, these trials are difficult to conduct in specialties such as orthopaedic surgery. Other study designs, if well conducted and evaluated, may provide effective evidence.[6,9]

Basing clinical decision making on evidence will always be limited by the uncertainty inherent in clinical practice and delivery of medicine. Medicine is not an exact science, but blends the "art of uncertainty with the science of probability."[22]

Made possible through an unrestricted educational grant from Zimmer.

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