Since osteoarthritis is by definition a progressive disease, there is a misconception that treatment is not likely to result in any real benefit to the patient. While it is true that there are currently no treatments available that are capable of achieving structural modification or disease modification, the currently available treatments aimed at symptom modification have been shown to be effective in decreasing pain, impairment, and functional limitations (14). Prevention of osteoarthritis and educating patients in its prevention are important roles for the clinician treating these patients. Osteoarthritis has been linked to increased mortality in a number of studies, and seems to be related to the functional decline that is often a consequence of reduced mobility (4).

Treatment for the patient with osteoarthritis should be individualized for each patient and should consist of a combination of interventions to be most effective (14). Nonpharmacologic treatment options include patient education, weight loss, modalities, exercise, orthoses, and activity modification (14). The 2012 ACR guidelines strongly recommend exercise and weight loss if necessary for patient with knee or hip osteoarthritis (16). There are multiple pharmacological options available including topical, systemic, and intraarticular agents. The risks and benefits of each must be explored in collaboration with the patient (14). The 2012 ACR guidelines do not have strong recommendations for any particular agent, except for the use of opioid analgesics in the treatment of refractory osteoarthritis of the knee in patients who are unable or unwilling to consider joint replacement (16). Surgical intervention should be considered when pain is refractory to nonsurgical treatment and the impairments from the osteoarthritis have resulted in significant functional and activity limitations (14).

ETHICAL ISSUES

The basic principles of medical ethics apply to the evaluation and treatment of patients with osteoarthritis. To preserve autonomy, a patient with the diagnosis of osteoarthritis should be given a complete set of appropriate treatment options by his or her physician, which includes discussion of the risks and benefits of the proposed treatments and the risks and benefits of refusing those treatments. Patients have the right to choose all, some, or none of the proposed treatments, and the physician must accept those choices even if he or she disagrees with the patient’s choice. Since osteoarthritis is a chronic disease process, the physician can continue to offer previously refused treatment options, or if there are changes in the patient’s condition he or she may offer additional treatment options during subsequent encounters. The principle of beneficence requires that the clinician individualize treatment options for each patient based on clinical presentation and examination findings. Physicians must consider religious and cultural differences that may affect understanding of the diagnosis and treatment options, and potentially the choice of treatment options. Nonmaleficence refers to the concept of “do no harm,” and requires the clinician to discuss the diagnosis and treatment options in the context of its effects on the whole person. Certain treatments may have increased risks for individuals with certain comorbid conditions and these increased risks need to be anticipated and discussed with the patient. Lastly, the principle of justice requires the clinician to discuss all relevant treatment options, the role of diagnostic testing, and the opportunities and risks of participation in medical research conducted for osteoarthritis, as well as provide referral for expensive and high-level interventions whenever clinically indicated.

MEDICAL KNOWLEDGE

GOALS

Demonstrate knowledge of established evidence-based and evolving biomedical, clinical epidemiological, and sociobehavioral sciences pertaining to osteoarthritis, as well as the application of this knowledge to guide holistic patient care.

OBJECTIVES

1.  Discuss the epidemiology of osteoarthritis, its risk factors, and its morbidity and mortality.

2.  Describe the relevant normal anatomy and physiology of the synovial joint.

3.  Review the pathogenesis and pathophysiology of osteoarthritis.

4.  Assess the appropriate role of diagnostic testing.

5.  Evaluate the treatment and management options for osteoarthritis and the evidence behind those recommendations.

6.  Educate patients on making patient-centered decisions regarding their plans of care.

EPIDEMIOLOGY

According to CDC data from 2005, approximately 26.9 million U.S. adults are affected by osteoarthritis (17). These data have been obtained largely from population-based studies and have been shown to be increasing in both prevalence and incidence. Most of the increase has been attributed to the increased longevity, resulting in aging of the population and also to the increasing prevalence of obesity to epidemic proportions (4). The prevalence of the most common forms of symptomatic osteoarthritis is the following: knee (9.5%–16%), hand (8%), and hip (4.4%). The incidence of the development of these most common forms of osteoarthritis is as follows, expressed per 100,000 person years: knee (240), hand (100), and hip (88) (17).

The incidence of the development of osteoarthritis is based on systemic and local risk factors that result in the development of osteoarthritis and ultimately its progression. Once symptomatic, osteoarthritis is associated with functional decline and is the most common cause of walking-related disability and a leading cause of upper limb disability (4).

Local risk factors for the development of osteoarthritis include joint injury, occupational exposure, physical activity, leg-length discrepancy, neuromuscular factors, joint alignment and force abnormalities, and joint bony characteristics. Especially at the knee joint, a history of joint injury is correlated with the subsequent development of osteoarthritis of that joint. Exposure to repetitive joint motion at work has long been thought to play a pivotal role in the development of osteoarthritis, but study limitations have called this into question, because most studies did not adjust for joint injury. Similarly, exercise and participation in specific sports have also been hypothesized to result in the increased likelihood of developing osteoarthritis. Proving a direct correlation has been difficult due to the association of increased injury rates in participating individuals. Leg-length discrepancies can be present before or can occur as the result of osteoarthritis of the lower limb joints. Some studies have shown knee osteoarthritis and its progression to correlate to a leg-length discrepancy, but similar findings have not been seen in other joints of the lower limb. Muscle weakness has been implicated in affecting the development of osteoarthritis; however, only one study found knee extensor weakness to correlate with the radiographic development of knee osteoarthritis in women. Sensation and proprioception have not been proven to be independent risk factors for the development of osteoarthritis. Joint malalignment, whether primary or secondary, has been shown to correlate with a greater risk of radiographic development and progression of osteoarthritis of the knee. Bony characteristics, such as hip joint dysplasias, have been shown to correlate with the development of osteoarthritis of the hip in young adults; however, this does not account for the prevalence of hip osteoarthritis in the general population (4).

Once symptomatic, osteoarthritis contributes to functional decline; however, this has not been as well studied. Like in most painful conditions, advancing age, increasing pain, obesity, depression, anxiety, and reduced physical activity are risk factors for the development of functional decline in patients with osteoarthritis. There is limited evidence that joint laxity, impaired proprioception, and reduced balance are osteoarthritis-specific factors that can contribute to functional decline and that cognitive decline and visual decline are independent predictors of functional decline in patients with osteoarthritis (17).

RELEVANT ANATOMY AND PATHOPHYSIOLOGY

Normal joint function is dependent upon the smooth articulation of the involved bones to facilitate motion when force is applied to that joint. Articular cartilage is a thin, shock-absorbing interface that, combined with the effects of synovial fluid, provides an essentially frictionless surface on which joint motion can occur. The loads to articular cartilage are primarily imposed by muscle contraction and are further increased by weight bearing during motion. Subchondral bone is highly elastic and serves as a major shock absorber during the application of higher loads. Further joint protection is offered by the periarticular muscles, which provide dynamic shock absorption by adjusting muscle length and force generation to absorb large amounts of energy (18).

Normal chondrocytes produce the collagen and ground substance that become cartilage and function to maintain the cartilage matrix. In normal cartilage, these cells do not divide. In the development of osteoarthritis, cartilage damage and degradation stimulates an inflammatory response with the proliferation of chondrocytes in an attempt to repair. Unfortunately, these proliferative cells also release matrix-degrading enzymes, growth factors, and inflammatory cytokines, which lead to further cartilage degradation. Changes in the synovial fluid, water content of the cartilage, and changes in the collagen matrix produce an inferior matrix, which leads to further cartilage loss. Destruction of articular cartilage damages the underlying bone, and attempts to repair this damage result in new bone formation. These are seen as osteophytes at the joint margins at the interface of the cartilage and periosteum and as subchondral sclerosis at the base of cartilage lesions. The progression of cartilage breakdown can result in cartilage fragments, capsular thickening, joint effusion, and bone cyst formation. Muscle weakness and atrophy near the involved joint occur via a variety of mechanisms including muscle inhibition due to pain, decreased activity levels due to pain, and altered joint biomechanics. Loss of the muscular support needed for joint protection during activities results in increased forces distributed to the already compromised articular surface and contributes to progression (14,19).

DIAGNOSTIC TESTING

Imaging studies and laboratory testing are of limited use in the diagnosis of osteoarthritis, and are more frequently used to rule out other conditions that present similar to osteoarthritis, such as rheumatoid arthritis. Several techniques are available for imaging of synovial joints, but none are useful without correlation of the clinical presentation and findings.

MRI can visualize and provide excellent detail of articular cartilage, subchondral bone, and soft tissues of the joint. Its clinical utility in the diagnosis and management of osteoarthritis is limited due to its relatively high cost and lack of clear correlation between MRI findings and clinical presentation. Again, it is useful to rule out other causes of joint pain that can mimic osteoarthritis, such as avascular necrosis or osteochondritis dissecans. Its greatest value at present is in the research setting, where it is a useful tool in the monitoring of disease progression. This may make it useful in demonstrating the potential effectiveness of disease-modifying treatments as they are developed (20).

Musculoskeletal ultrasound may play a role in imaging the joints of patients suspected to have osteoarthritis. It is relatively inexpensive, does not expose the patient to ionizing radiation, and does not require the use of any contrast agents. It can be used to assess synovial blood flow and can therefore assess patients for synovial pathology. Its major limitation is that its utility is user dependent (20).

CT is a superior method for imaging bony morphology, but its use in the assessment of osteoarthritis is limited by several factors. It is a high-cost modality that requires relatively high radiation exposure compared to the other techniques. Additionally, soft-tissue visualization requires the use of contrast and is still inferior to MRI in many ways (20).

TREATMENT OPTIONS

Treatment options for osteoarthritis are broadly categorized as nonpharmacological interventions, medications, and surgery. Often a combination of treatment options offers a comprehensive plan for the patient that is individualized and incorporates the patient into the treatment team.

Nonpharmacologic Interventions

Patient education should be considered an important part of the treatment of osteoarthritis; it should be provided starting at the first visit and refined throughout the treatment course of this chronic condition. Reassurance and access to information detailing the expected outcomes for specific interventions will assist the patient in choosing and complying with treatment guidelines. Patients should be referred to reputable organizations and websites as alternate sources of information. Screening and discussion of the potential for associated mood disturbances should be part of this process and referral for psychiatric intervention should be pursued when necessary (14).

Obesity is a major risk factor for the development of osteoarthritis and its progression. This has been consistently demonstrated in knee osteoarthritis and is often attributed to excess forces during weight-bearing activity. However, there is also evidence that obesity contributes to the systemic development of osteoarthritis, such as in the hand (21). Weight loss is considered a major intervention in the treatment of osteoarthritis and has been shown to reduce both development and progression in knee osteoarthritis (4). Patients with osteoarthritis and obesity have several options for treatment of the obesity; these include weight-loss medications, exercise, dietary changes, and bariatric surgery. The choices again need to be individualized for each patient (22).

Exercise in the treatment of osteoarthritis has several benefits. Exercise increases caloric expenditure and can assist in weight reduction. It also strengthens muscles supporting and acting on the involved joints, which helps to further reduce joint stresses. Many patients with osteoarthritis have pain with certain activities and develop kinesiophobia, which is the fear of movement in response to the pain. Supervised programs, including physical therapy interventions, can be cost effective and useful in patients with kinesiophobia. Additionally, when exercise is combined with other weight-loss strategies, the combination is more effective than either intervention alone. Lastly, exercise has been shown to reduce pain over time and results in the reduction of self-reported disability (22).

Pain-relieving modalities can be a useful adjunct in the treatment of osteoarthritis. No one modality has been proven to have any long-term benefit, as the primary purpose of modality use is to reduce pain and enhance the patient’s ability to participate in exercise. Each of the modalities has specific contraindications, and recommendations for usage must take these into account. Cold and heat modalities can be applied to painful joints, as long as the patient is aware of the purpose, safe usage, and risks and benefits of thermal agents. The use of transcutaneous electrical nerve stimulation (TENS) has not been studied extensively in the osteoarthritis population, but has been shown to be of some benefit in the short term in one study (14). Recent systemic review has not shown TENS to be of any benefit over sham stimulation (23). Pulsed electromagnetic fields and magnets have not been shown to be effective in randomized controlled studies (14).

Orthoses can be used in osteoarthritis to limit painful range of motion, allow relative rest, adjust joint alignment, reduce abnormal joint forces, accommodate deformities, and provide shock absorption. While some studies have shown benefit of specific orthoses in the treatment of osteoarthritis (14), systematic review of the evidence for their use is a conditional recommendation in the 2012 ACR guidelines (16). The use of durable medical equipment may play a role in the treatment of osteoarthritis. The cane has been demonstrated to be useful in decreasing forces across the hip and knee, when used in the contralateral hand (14). No other ambulatory devices have been studied effectively in the treatment of osteoarthritis.

Medications

Pharmacological options in the treatment of osteoarthritis include topical medications, systemic medications, and injectable medications. All of the available agents are used for symptomatic relief. There are currently no available agents that prevent the development or progression of osteoarthritis (24).

There are several topical analgesics available for the treatment of pain related to osteoarthritis. Topical nonsteroidal anti-inflammatory drugs (NSAIDs) have been shown to have similar efficacy to oral NSAIDs, but have reduced GI and renal toxicity. Diclofenac is available in gel form, and specifically has an FDA indication for the treatment of osteoarthritis. It is also available in a patch form; however, it only has an FDA indication for acute pain related to sprains, strains, and contusions (24). Topical lidocaine is available in gel and patch forms as well, and has been used in the treatment of osteoarthritis; however, neither form has an FDA indication for pain secondary to osteoarthritis (14). Capsaicin is derived from chili peppers and is used topically in the treatment of pain. Its effectiveness in osteoarthritis has been demonstrated in randomized, double-blinded, placebo-controlled studies, but its usage is limited by the local burning sensation associated with its application (24).

Acetaminophen is considered the first-line systemic agent in the treatment of osteoarthritis. Early studies of its efficacy showed that therapeutic doses ranging from 2,600 to 4,000 mg/day were effective in decreasing pain at rest and with motion, and had the analgesic equivalence to 1,200 mg/day of ibuprofen. Acetaminophen at these doses had reduced GI side effects compared to oral NSAIDs. Patients using this medication regularly must be cautioned about the potential for accidental overdose, due to the abundance of over-the-counter products that include acetaminophen as an ingredient, as well as opioid combination preparations with acetaminophen.

The second-line systemic agents used in the treatment of osteoarthritis are the nonselective NSAIDs, which inhibit both cyclooxygenase (COX) 1 and 2. The inhibition of COX-2 results in the analgesia of osteoarthritis pain (24), but this is also partially responsible for potential renal toxicity, as COX-2 is also expressed in the kidney (14). Inhibition of COX-1 decreases platelet aggregation, increases GI vulnerability to gastritis and ulceration, and alters renal vascular regulation that can result in toxicity. Medications in this group can be prescribed as part of a daily regimen or can be prescribed as needed. In general, the lowest effective dose should be prescribed, as GI side effects are largely dose dependent. To avoid the renal complications of chronic use, the clinician should attempt to use intermittent, short courses of nonselective NSAIDs to manage flare-ups of osteoarthritis pain. Well-designed studies have shown the efficacy of nonselective NSAIDs in reducing pain and improving function using objective measures. There are numerous available NSAIDs, and none have been shown to be superior to any other. Therefore, choice of a particular agent is essentially up to the clinician, and failure of, or intolerance to, one agent should not preclude trial of other agents (24). The clinician should consider the concomitant prescription of misoprostol, proton pump inhibitors, or H2 blockers to reduce toxicity to the GI tract (14).

COX-2-selective NSAIDs preferentially inhibit COX-2 over COX-1 and have similar efficacy to nonselective NSAIDs for the reduction of osteoarthritis-related pain and improvements in function. These agents have considerably less GI toxicity, but still have the potential for significant renal toxicity. Additionally, these agents increase the risk of cardiothrombic events and should be used with caution in patients with cardiac risk factors. COX-2-selective NSAIDs are considered second-line treatment for patients with osteoarthritis that have increased GI risk factors and low cardiac risk factors (24).

Opioid analgesics are indicated in the treatment of osteoarthritic pain in patients who have failed treatment with acetaminophen and NSAIDs, have contraindications to the use of these agents, or have inadequate pain relief with these agents alone. Tramadol is a weak mu opioid agonist and also inhibits norepinephrine and serotonin reuptake. It is a good first-line opioid for patients without increased seizure risk or epilepsy and who are not taking any medications with significant potential for interaction (24). Other, more potent opioids can be considered for patients who have failed treatment with tramadol or have contraindications to its usage. No one agent or preparation is specifically recommended, nor is there any consensus on the use of extended-release or immediate-release opioid preparations. Patients should be maintained on the lowest effective dose and should be followed up frequently during dose adjustment. Due to the potential risks of addiction and diversion (14), responsible prescribers must screen patients for potential for abuse and diversion, discuss risks and benefits of opioid usage, provide close follow-up, and clarify patient responsibilities when using these medications. Additionally, due to the potential side effects of sedation, confusion, and constipation, these agents should be used with caution in the geriatric population (24).

Intraarticular injections should be considered in patients who have failed or could not tolerate less invasive treatment and in patients who are potentially considering surgical intervention. Because of the invasive nature of injections, these types of treatments have risks associated with the medication injected and risks that are independent of the agent injected. Joint injections are associated with the risk of injury to the skin and other soft tissues, bleeding, and infection. Injections are specifically contraindicated in patients with systemic infections, local skin infections, high risk of bleeding, and symptomatic prosthetic joints.

Corticosteroid injections have historically been used in the treatment of osteoarthritis, despite the lack of clear research to warrant their widespread use (14). Most studies have looked at the efficacy of intraarticular steroid injections of the knee and found them to be effective in relieving pain for 2 to 3 weeks. There are concerns about potential harm of repeated injections, including the possibility of causing disease progression and direct cartilage damage, but this has not been clearly demonstrated in research either (25). In general, no more than four steroid injections per year are recommended in a particular joint (14).

Surgery

Surgical options for the treatment of osteoarthritis should be considered only for patients who have failed nonsurgical treatment. For younger patients, osteotomies are done to improve alignment and redistribute joint forces with the goal of delaying the need for joint replacement surgery. In older patients, joint arthroplasty is appropriate for the treatment of refractory osteoarthritis. The timing of the surgery is largely patient-driven and based on the severity of the pain and its impact on the patient’s quality of life. The primary purposes of these procedures are to reduce pain and increase function. Operative candidates must be willing and able to participate in postoperative rehabilitation to maximize attainment of these goals (14). Total hip arthroplasty and total knee arthroplasty are the most common joint replacement procedures performed. Both procedures have high rates of success with predictable and proven long-term results. Total shoulder arthroplasty is also associated with good outcomes for reduction of pain and resultant improvements in functional status (26).