Arthritis & Rheumatism

Guidelines for the Medical Management of Osteoarthritis

Part II. Osteoarthritis of the Knee

Marc C. Hochberg, Roy D. Altman, Kenneth D. Brandt, Bruce M. Clark, Paul A. Dieppe, Marie R. Griffin, Roland W. Moskowitz, And Thomas J. Schnitzer

Osteoarthritis (OA), previously called degenerative joint disease, is the most prevalent form of arthritis in the United States (1). Clinically, patients with OA of the knee have pain in and around the knee that is typically worse with weight-bearing and improved with rest, morning stiffness, and gel phenomenon, and, on physical examination, often have tenderness to palpation, bony enlargement, crepitus on motion, and/or limitation of joint motion.

Unlike rheumatoid arthritis and other inflammatory arthritides, inflammation, if present, is usually mild. Although the causes of OA of the knee are not always known, biomechanical stresses affecting the articular cartilage and subchondral bone and biochemical changes in the articular cartilage and synovial membrane are important in its pathogenesis (2-4).

Guidelines for the medical management of patients with OA of the hip are reported in an accompanying article (5). Herein, we present guidelines for the medical management of patients with OA of the knee. Because many of the specific approaches are common between these two conditions, the reader is referred to the guidelines for OA of the hip for a detailed discussion (5). Differences in approach and treatment strategies which are unique to OA of the knee, including the role of intraarticular corticosteroid injections, will be discussed.

Specific recommendations for surgical management of OA of the knee, however, are not included.

Goals of management

The goals of management of patients with OA of the knee are identical to those for patients with OA of the hip. Before considering therapeutic options in an individual with OA of the knee, the physician must be certain that the patient's knee pain is indeed attributable to OA. For instance, it is not infrequent for an individual with a periarticular disorder such as anserine, infrapatellar, or prepatellar bursitis to be treated erroneously for knee OA. In some patients with disorders of the spine and hip, pain can be referred to the knee.

Therefore, it is essential that OA of the knee be established as the basis for the patient's signs and symptoms before beginning therapy.

The American College of Rheumatology criteria for the classification of OA of the knee have excellent precision for identification of patients with symptomatic OA of the knee (Table 1) (6). If the physician is in doubt about the diagnosis of OA, consultation with a rheumatologist should be sought.

Table 1. American College of Rheumatology classification criteria for osteoarthritis of the knee*

Traditional format Knee pain and radiographic osteophytes and at least 1 of the following 3 items: Age >50 years Morning stiffness <=30 minutes in duration Crepitus on motion

Classification tree Knee pain and radiographic osteophytes or Knee pain and age >=40 years and morning stiffness <=30 minutes in duration and crepitus on motion * Modified from ref. 6.

The treatment modalities currently available in the United States for the medical management of patients with OA of the knee are listed in Table 2. As with OA of the hip, the treatment plan must be individualized and should be based on numerous factors, including the presence of such comorbid conditions as hypertension, heart disease, peptic ulcer disease, or kidney disease, which influence decisions about drug therapy.

Table 2. Medical management of patients with osteoarthritis of the knee*

Nonpharmacologic therapy Patient education Self management programs (e.g., Arthritis Self-Help Course) Health professional social support via telephone contact Weight loss (if overweight) Physical therapy Range of motion exercises Quadriceps strengthening exercises Assistive devices for ambulation Occupational therapy Joint protection and energy conservation Assistive devices for ADLs and IADLs Aerobic exercise programs

Pharmacologic therapy Intraarticular steroid injections Non-opioid analgesics (e.g., acetaminophen) Topical analgesics (e.g., capsaicin and methylsalicylate creams) Nonsteroidal antiinflammatory drugs Opioid analgesics (e.g., propoxyphene, codeine, oxycodone) * ADLs = activities of daily living; IADLs = instrumental ADLs.

Nonpharmacologic therapy

The components of nonpharmacologic therapy and the central role of the physical and occupational therapist in the management of patients with OA of the knee are identical to those used in patients with OA of the hip (5). The role of exercise in the management of OA of the knee has been reviewed by others (7-9). Three randomized controlled trials in patients with knee OA demonstrated that strengthening of quadriceps musculature with either isometric or isotonic, resistive exercises was associated with significant improvement in quadriceps strength, knee pain, and function, when compared with controls (10-12). If the patient cannot participate in an organized exercise program, the primary care physician should ensure that all patients with OA of the knee are instructed in quadriceps strengthening exercises.

Proper use of a cane (in the hand contralateral to the affected knee) reduces loading forces on the joint and is associated with decreased pain and improved function (13). In addition, patients may benefit from shoe inserts to correct abnormal biomechanics due to angular deformities of the knees (14). Although no trial data are available, the wearing of shock-absorbing shoes with insoles is believed to be of benefit. Another useful maneuver for patients with OA of the knee who have symptomatic patellofemoral compartment involvement is medial taping of the patella (15). Finally, the use of light-weight knee braces may also be helpful in patients with tibiofemoral disease, especially if complicated by lateral instability (16).

Aerobic conditioning exercises have been found to be feasible and efficacious in individuals with OA of the knee (17). In addition, a supervised fitness walking program combined with patient education was shown to be of benefit in patients with knee OA (18). A program of aerobic activity, particularly an aquatic program such as that sponsored by the Arthritis Foundation, should be suggested to all patients with OA of the knee to improve functional status and reduce pain. These exercise programs, however, require a commitment of time and effort on the part of the patient.

Several epidemiologic studies have found that obesity is a major risk factor for the development and progression of knee OA (for review, see ref. 19), and, in one study, weight loss was associated with lower odds of developing symptomatic knee OA in women (20). Whether weight loss will slow the progression of or alleviate symptoms in patients with existing OA of the knee is not known. Nonetheless, overweight patients with OA of the knee, especially if they are being considered as candidates for total knee arthroplasty (see below) should be encouraged to participate in a comprehensive weight management program including dietary counseling and aerobic exercise. Specific dietary therapy and other unproven therapies are not recommended in the management of patients with OA of the knee (21).

Pharmacologic therapy

The principles of pharmacologic therapy for relieving pain and other symptoms in patients with OA of the knee are similar to those for patients with OA of the hip (5). Areas covered in those guidelines which are not discussed in this paper include the possible adverse effects of acetaminophen, use of other oral analgesics, use of nonsteroidal antiinflammatory drugs (NSAIDs), and strategies for the prevention of NSAID-associated ulcer disease and gastrointestinal bleeding.

In patients with OA of the knee who have an effusion and local signs of inflammation, judicious use of intraarticular corticosteroid injections is appropriate (Figure 1) (22). When joints are painful and swollen, aspiration of fluid, followed by intraarticular injection of a corticosteroid preparation (e.g., triamcinolone acetonide or hexacetonide at a dose of 40 mg) is an effective short-term method of decreasing pain (23) and increasing quadriceps strength (24). Injection can be used as monotherapy in selected patients or as an adjunct to systemic therapy (see below). Joints should be aspirated/injected using aseptic technique, and fluid should be sent for cell counts and Gram stain and culture if infection is suspected (25). On occasion, patients may experience a mild flare of synovitis related to a reaction to the crystalline suspensions; however, these postinjection flares are short-lived. The risk of introducing infection into an osteoarthritic joint using standard aseptic technique is exceedingly small.

It is generally recommended, although not well supported by published data, that injection of corticosteroids in a given joint not be performed more than 3-4 times in a given year because of concern about the possible development of progressive cartilage damage through repeated injection in the weight-bearing joints (22). Most individuals who require more than 3-4 intraarticular injections per year to control symptoms are probably candidates for joint lavage or surgical intervention.

The non-opioid, simple analgesic, acetaminophen, is the initial drug of choice for systemic treatment of symptomatic OA of the knee (Figure 1).

Several short- and long-term studies have shown that acetaminophen, in doses up to 4,000 mg/day, is superior to placebo and comparable in efficacy to both ibuprofen and naproxen in the management of patients with OA of the knee (26-29). Since other NSAIDs have not been shown to have superior effectiveness compared with ibuprofen or naproxen in the treatment of patients with OA of the knee, acetaminophen should be considered the preferred first-line therapy for patients with symptomatic OA of the knee.

In individuals with OA of the knee who do not respond to oral analgesics or do not wish to take systemic therapy, the use of topical analgesics, e.g., methylsalicylate or capsaicin cream, is appropriate as either adjunctive or monotherapy, respectively (30, 31). Capsaicin cream must be applied to the symptomatic joint 4 times daily; a local burning sensation is common, but this rarely leads to discontinuation of therapy.

If the patient fails to respond to acetaminophen or other oral or topical analgesics, the use of an NSAID is indicated. The clinical pharmacology of NSAIDs in OA is reviewed elsewhere (32).

In individuals with OA of the knee who have not responded satisfactorily to the nonpharmacologic and pharmacologic modalities outlined above, and in whom surgery is to be avoided or is medically contraindicated, consultation with a rheumatologist should be sought. In such patients, other modalities may be appropriate, but cannot be routinely recommended. Closed tidal knee irrigation with saline can be performed in an ambulatory setting under local anesthesia. This procedure mimics the lavage affect of arthroscopy. Saline is infused into the knee to distend the capsule, and the fluid is then withdrawn.

This process is repeated several times until a total volume of 2 liters has been infused and removed. Theoretically, such tidal irrigation disrupts intraarticular adhesions and mobilizes debris and inflammatory cytokines from the entire joint. Ike et al performed a randomized single-blind 14-week parallel trial of tidal irrigation compared with standard medical therapy in 77 patients with OA of the knee (33). Tidal irrigation resulted in statistically significant improvement in patients' assessment of joint stiffness and pain after a 50-foot walk. The lack of a comparable control group in that study, however, makes it difficult to determine the role of a possible placebo effect.

Arthroscopic lavage, with or without debridement, may also be useful in certain patients with OA of the knee, especially those individuals who have concomitant meniscal disease or symptoms of locking of the knee (34). Chang and colleagues randomized 32 patients with OA of the knee to either arthroscopic surgery or closed-needle tidal irrigation (35). Overall, arthroscopic lavage and debridement was no better than tidal irrigation alone in the relief of pain and dysfunction in the knees of these patients. Improvement after arthroscopy was more likely, however, in those patients who had a meniscal tear than in those who had no internal derangement.

Investigational therapy

Several experimental therapies that are not currently approved by the US Food and Drug Administration for use in patients with OA of the knee have been studied by rheumatologists and others in recent years, and some have shown promise as either slow-acting symptomatic drugs or disease-modifying anti-OA drugs (36). A discussion of these agents is beyond the scope of the present guidelines (for a review of these agents, see ref. 37); however, based on the results of ongoing clinical trials, it is recognized that these guidelines may require revision if one or more of these agents is approved for marketing.

Surgical treatment

Patients with severe symptomatic OA of the knee who have pain that has failed to respond to medical therapy and progressive limitation in ADLs should be referred to orthopedic surgeons for evaluation (2,38). Osteotomy, in appropriately selected individuals, provides pain relief and may prevent progression of disease in patients who are not yet considered to be candidates for total joint arthroplasty. Total joint arthroplasty provides marked pain relief and functional improvement in the vast majority of patients with OA of the knee. Outcomes are dependent on the timing of the surgery, the number of procedures that the surgeon and the hospital have performed, and the patient's preoperative medical status, peri- and postoperative management, and rehabilitation (39,40).

Summary

Treatment of patients with OA of the knee should be individualized and tailored to the severity of the symptoms. In individuals with mild symptomatic OA, treatment may be limited to patient education, physical and occupational therapy and other nonpharmacologic modalities, and pharmacologic therapy including non-opioid oral and topical analgesics.

In patients who are unresponsive to this treatment regimen, the use of NSAIDs in addition to nonpharmacologic therapy is appropriate unless medically contraindicated. Judicious use of intraarticular steroid injections has a role either as monotherapy or an adjunct to systemic therapy in patients with knee OA who have symptomatic effusions. The role of joint lavage and arthroscopic debridement in patients with OA of the knee who are unresponsive to conservative medical therapy needs further study, and these procedures cannot be routinely recommended for all patients at this time. Patients with severe symptomatic OA of the knee require an aggressive approach to decreasing pain, increasing mobility, and decreasing functional impairment; such patients may benefit from orthopedic consultation and evaluation for osteotomy or total joint arthroplasty.

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Supported by a grant from the Arthritis Foundation. The Arthritis Foundation received an unrestricted grant from McNeil Consumer Products Company. Approved by the Board of Directors, American College of Rheumatology, July 8, 1995.

Marc C. Hochberg, MD, MPH: the University of Maryland School of Medicine and Baltimore Veterans Affairs Medical Center, Baltimore, Maryland; Roy D. Altman, MD: the University of Miami School of Medicine and Miami Veterans Affairs Medical Center, Miami, Florida; Kennenth D. Brandt, MD: Indiana University School of Medicine, Indianapolis, Indiana; Bruce M. Clark, CPT: The Mary Pack Arthritis Centre, Vancouver, BC, Canada; Paul A. Dieppe, MD: the Bristol Royal Infirmary, University of Bristol, Bristol, UK; Marie R. Griffin, MD, MPH: Vanderbilt University School of Medicine, Nashville, Tennessee; Roland W. Moskowitz, MD: Case Western Reserve University School of Medicine, Cleveland, Ohio; Thomas J. Schnitzer, MD, PhD: Rush Medical College, Chicago, Illinois.

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