Osteoarthritis (OA) is a disease characterized by the breakdown of articular joint cartilage, and often causes severe pain and disability.1-4 In particular, the knee joint is most commonly affected, with more than 30% of adults over 60 years of age experiencing functional limitations, such as inability to perform Activities of Daily Living (ADL) or Instrumental Activities of Daily Living (IADL) due to OA of the knee.3,5,6 With the decrease in function an individual's quality of life is susceptible to deterioration. By 2020, the number of people with functional limitations due to OA of the knee is expected to rise to 11.6 million.3 Currently, health care costs related to OA of the knee are $60 billion per year.3
There are multiple interventions to treat OA of the knee. Current popular methods of treatment include, but are not limited to physical therapy based on practice pattern 4E; as well as nonsteroidal anti-inflammatory drugs (NSAIDS), surgery, and knee capsule injections, which are commonly followed by physical therapy. It should be noted, however, that NSAIDs though frequently prescribed, often have significant side effects.2,5,7-9 Arthroscopic surgery has not been shown to have a major role in the management of OA of the knee.3 Similarly, knee capsule injections have been shown to be equal to arthroscopy in effective management of the disorder.7 Exercise-based interventions are extensive, and include pool-based strengthening exercise, muscular strengthening, stretching, cardiovascular programs, and mechanical unloading.10,11 Modalities include, but are not limited to, knee bracing, heat, ice massage, cold packs, ultrasound, acupuncture, and taping.
Because the risk of disability due to OA of the knee is greater than that due to any other medical condition in aging adults,11 it is essential for physical therapists to have a thorough understanding of different treatment methods, if they wish to make an impact in the reduction of this risk. Due to a lack of systematic reviews on the effectiveness of physical therapy management of OA of the knee, as well as the conflicting evidence about modalities, the primary aim of this paper is to review current trends for treatment of OA of the knee, and to compare the effectiveness of each intervention. This article explores various methods of treating OA of the knee and makes recommendations for physical therapy management of the disorder.
Several common databases and search engines that the authors were familiar with were used for this review, including PubMed, EBSCO, The Cochrane Library, and Google Scholar.12-15 Articles included were written in English, peer-reviewed, and published from 1996 to 2007. Key search words and phrases for the physical therapy treatment of knee osteoarthritis included “physical therapy or physiotherapy,” “knee osteoarthritis,” and “management or treatment.” Only studies that included a control group or presented a case report (ie, having true experimental design) of physical therapy management of knee osteoarthritis were included. Two additional articles evaluating acupuncture were also included, because they had sufficient scientific rigor, level of evidence, and close connection with rehabilitation. Previously conducted review articles on the subject of physical therapy management of knee osteoarthritis were excluded.
Five first year physical therapy students evaluated the studies selected for inclusion. The student's goals were to identify and classify the studies according to their quality and adherence to scientific rigor. The quality of each study was determined by using the rating system of Sackett's 5 levels of evidence, which then allows for 3 grades of recommendations to be made.16 The procedural rigor of each study was graded according to the list of criteria created previously by Megens and Harris.17
Sackett's levels of evidence include 5 hierarchal categories: Studies classified at Level I studies are randomized controlled trials with a sample size of 100 or more subjects, with a low incidence of false-positive and false-negative errors. Level II studies consist of randomized, controlled trials with a sample size of less than 100 subjects, with a high incidence of false-positive and false-negative errors. Level III studies consist of nonrandomized, concurrent, cohort comparisons between subjects that did and did not receive treatment. Level IV studies consist of nonrandomized, historical cohort comparisons between current subjects, who did receive treatment and former subjects who did not receive treatment. Level V studies consist of case series without control16
The grades of recommendations will be assigned in the following manner: a grade A recommendation is supported by at least one level I study, a grade B recommendation is supported by at least one level II study, and a grade C recommendation is supported by any combination of levels III, IV, or V studies.16,17 The grading of the recommendations is based purely on the level of scientific study. Scientific studies with higher levels should be considered as having increased validity, and therefore should be considered weighted higher by a physical therapist as a treatment option.
The scientific rigor of each study was evaluated using the following 6 criteria developed by Megens and Harris: (1) inclusion and exclusion criteria noted for the subjects and an operational definition of the clinical condition provided; (2) treatment methodology described adequately enough to allow replication; (3) outcome measures assessed for reliability; (4) validity of outcome measure's assessed; (5) blind assessment of outcome; and (6) accounting for attrition.17 Each study was assigned a “Y” for “yes” if it met the specific criteria and an “N” for “no” if it failed to meet the criteria. The scientific rigor is a broader spectrum of analysis of each article as compared to Sackett's levels of evidence and therefore gives the reader a more through inspection about specific aspects of each article. An increase in an article's scientific rigor should increase the confidence of the treating therapist in the validity of the article. Each article was independently evaluated by all 5 reviewers and graded according to Sackett's levels of evidence and Megens and Harris' criteria for scientific rigor to establish inter-rater reliability. Any discrepancies between rater's grades were decided by a round-table discussion over the articles. A rating was determined from the discussion or majority vote. Inter-rater reliability was determined using an Intraclass Correlation Coefficient (ICC). ICC measures association and agreement for more than two raters.
Twenty-two articles were found pertaining to physical therapy management of osteoarthritis of the knee. Fifteen of these articles met the inclusion criteria and were reviewed and evaluated according to Sackett's levels of evidence.16 A summary of the articles evaluated can be found in Table 1. The inter-rater reliability for grading the articles according to Sackett's levels of evidence was ICC(3,1)=.93.
Studies included in this review either evaluated or described procedures or tools used in PT procedural interventions of OA of the knee. Four studies dealt with analysis or development of a tool to treat knee OA.18-21 Ten studies evaluated the effects of exercise programs.4,5,7,20,22-27 Two studies evaluated the use of acupuncture.2,28
A variety of techniques in physical therapy management of knee osteoarthritis were included in the articles presented in this study. Studies differed in research design, level of evidence, and type of intervention. The research design distribution of the articles consisted of the following: 13 studies2,4,5,7,10,18,20,23-28 were randomized, controlled clinical trials, 2 studies were case studies,19,22 and one was a nonrandomized convenience sample trial.21
In order to determine the weight of evidence, articles were evaluated according to Sackett's levels of evidence. The results of this analysis produced 2 level I trials,2,25 12 level II trials,4,5,7,10,18,20,21,23-28 and 2 level V trials.19,22 Studies were classified as level I or II trials based on randomization, presence of a control group and number of participants in each group. Level III and IV studies were nonrandomized cohort trials with or without a control group. Level V studies consisted of case studies or observational studies.
Grades of recommendation were developed based on these levels of evidence. Grade A recommendations were made according to level I results, Grade B recommendations were made according to level II studies and Grade C recommendations were made according to level III, IV, and V results.
Grade A Recommendations:
- Class based exercise is more effective than home based exercise to decrease the pain associated with OA of the knee.25
- True or electro acupuncture has been shown to relieve pain in patients with OA of the knee when compared to patients that received placebo or “sham” acupuncture.2,28
Grade B Recommendations:
- Mechanical unloading using a Zuni Exercise System of patients with OA of the knee may not help with pain reduction.21
- The use of a neoprene brace and/or therapeutic tape on patients with OA of the knee may help reduce pain and regain function.10,18
- Patients that are treated in a clinic or classroom setting benefit more from exercise and manual therapy, than those patients given instructions for home based exercise.25,27
- Aquatic or hydrotherapy has positive effects on the strengthening of patients with OA of the knee.20,23
- Manual therapy and exercise is shown to increase quadriceps strength, while decreasing disability.4,5,7,26
Grade C Recommendations:
- An evidence-based exercise and health education program to inform patients of OA is useful in patient comprehension of the disease.19
- Stretching, strengthening exercise, and perturbations are all useful interventions for aging adults with OA of the knee.22
The studies were assessed according to Megens and Harris' criteria for scientific rigor and the results are presented in Table 2. The inter-rater reliability for this classification was ICC(3,1) = .93. Overall, the evaluations revealed a moderately strong attention to scientific rigor. All the studies contained inclusion and exclusion criteria as well as operational definitions. Only one study19 did not include enough information for the procedure to be replicated. Many studies did not include blinding.3,9,18,19,21,22,24,25 or accounting for attrition.8,19,21 The reliability2,5,22,24 and validity2,24 of measures used in the study were sometimes absent as well.
After a thorough literature search and filtering of numerous articles on osteoarthritis of the knee, the usefulness of various physical therapy interventions in the treatment of OA of the knee were determined. Sackett's levels of evidence offered a basis on which to categorize and assess various research articles, which led to numerous recommendations for physical therapy management of OA of the knee.
Megens and Harris' criteria for scientific rigor were also used in this review to categorize the articles. According to the criteria (Table 2), very few articles reviewed met each of the scientific rigors and this should be noted when accepting any recommendations from these studies.
While the recommendations of this review are based on varying degrees of scientific levels, it should be noted that none of them should be accepted without caution. The significant clinical recommendations that can be made from this review include:
- Use of either neoprene sleeves or therapeutic tape to supplement the bone loss in patients with knee osteoarthritis;
- Patients that receive therapy in direct contact from the therapist have lower pain and better Western Ontario and McMaster Osteoarthritis Index (WOMAC) scores than those that are given a take home therapeutic plan;
- Class based exercise with instruction from a physical therapist is more effective than a home based exercise program;
- Aquatic or hydrotherapy can be very useful in the treatment of OA;
- Manual therapy has the ability to decrease pain and increase strength in for aging adults with OA of the knee.
A trend that was noted while reading and classifying articles was that patients who received treatment from a physical therapist directly showed better WOMAC scores and had decreased pain when compared to individuals that received no treatment for their knee osteoarthritis. Therefore, physical therapy is recommended to patients with OA of the knee in order to increase their functioning ability. Exercise is shown to be beneficial for patients suffering from OA of the knee, however, it is important that the program be designed properly. Two modalities were directly addressed in the studies reviewed. It should be noted that hot packs have been shown to be of little therapeutic value, while ultrasound, based on 2 studies, has shown contradicting evidence.4,7
Additional studies about the usefulness of physical therapy interventions in the treatment of knee osteoarthritis are needed in order to further support the role of a physical therapist in the recovery and adaptability of patients with OA of the knee. Furthermore, most operational definitions used in these studies relied on physician and radiological diagnosis of knee osteoarthritis. While this is currently acceptable, in the spirit of APTA Vision 2020, there should be an operational definition in place for the physical therapist to objectively determine the presence or absence of knee osteoarthritis. Finally, the base of research needs to be expanded assessing the usefulness of tools, such as neoprene braces and therapeutic tape, in the physical therapist's treatment of OA of the knee based on the preliminary success of these tools.10,18.
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