Degenerative Joint Disease (Osteoarthritis)

Osteoarthritis, the most common form of joint disease, is chiefly a disease of aging. Ninety percent of all people have radiographic features of osteoarthritis in weight-bearing joints by age 40. Symptomatic disease increases with age.

Sex is also a risk factor; osteoarthritis develops in women more frequently than in men.

This arthropathy is characterized by degeneration of cartilage and by hypertrophy of bone at the articular margins.

Inflammation is usually minimal.

Hereditary and mechanical factors may be involved in the pathogenesis.

Obesity is a risk factor for osteoarthritis of the knee, hand, and probably of the hip.

Recreational running does not increase the incidence of osteoarthritis, but participation in competitive contact sports (eg, football) does.

Jobs requiring frequent bending and carrying increase the risk of knee osteoarthritis.

Diagnostic Essentials

• A degenerative disorder with minimal articular inflammation.
• No systemic symptoms.
• Pain relieved by rest; morning stiffness brief.
• Radiographic findings: narrowed joint space, osteophytes, increased subchondral bone density, bony cysts.

Clinical Findings

Symptoms and Signs

Degenerative joint disease is divided into two types:

• (1) primary, which most commonly affects some or all of the following: the DIP and the proximal interphalangeal (PIP) joints of the fingers, the carpometacarpal joint of the thumb, the hip, the knee, the metatarsophalangeal (MTP) joint of the big toe, and the cervical and lumbar spine;
• and (2) secondary, which may occur in any joint as a sequela to articular injury. The injury may be acute, as in a fracture; or chronic, as from occupational overuse of a joint or metabolic disease (eg, hyperparathyroidism, hemochromatosis, ochronosis) or joint inflammation (eg, rheumatoid arthritis).

The onset is insidious.

Initially, there is articular stiffness, seldom lasting > 15 minutes; this develops later into pain on motion of the affected joint and is made worse by activity or weight bearing and relieved by rest.

Flexion contracture or varus deformity of the knee is not unusual, and bony enlargements of the DIP (Heberden nodes) and PIP (Bouchard nodes) are occasionally prominent.

There is no ankylosis, but limitation of motion of the affected joint or joints is common.

Crepitus may often be felt over the knee.

Joint effusion and other articular signs of inflammation are mild.

However, in some cases a one-way valve effect between the knee joint and gastrocnemius-semimembranosus bursa can lead to accumulation of synovial fluid, called a popliteal (Baker) cyst.

There are no systemic manifestations.

Laboratory Findings

ESR or other laboratory signs of inflammation are not elevated or increased due to osteoarthritis.

Synovial fluid is noninflammatory.

Imaging

Radiographs may reveal narrowing of the joint space; osteophyte formation and lipping of marginal bone; and thickened, dense subchondral bone.

Bone cysts may also be present.

Differential Diagnosis

Because articular inflammation is minimal and systemic manifestations are absent, degenerative joint disease should seldom be confused with other arthritides.

The distribution of joint involvement in the hands also helps distinguish osteoarthritis from rheumatoid arthritis. Osteoarthritis chiefly affects the DIP and PIP joints and spares the wrist and metacarpophalangeal (MCP) joints; rheumatoid arthritis involves the wrists and MCP joints and spares the DIP joints.

Furthermore, the joint enlargement is bony-hard and cool in osteoarthritis but spongy and warm in rheumatoid arthritis.

Skeletal symptoms due to degenerative changes in joints—especially in the spine—may cause coexistent metastatic neoplasia, osteoporosis, plasma cell myeloma, or other bone disease to be overlooked.

Prevention

Weight reduction reduces the risk of developing symptomatic knee, hip and hand osteoarthritis.

Correcting leg length discrepancy of > 1 cm with shoe modification may prevent knee osteoarthritis from developing in the shorter leg.

Treatment

General Measures

Patients with osteoarthritis of the hand may benefit from assistive devices and instruction on techniques for joint protection; splinting is beneficial for those with symptomatic osteoarthritis of the first carpometacarpal joint.

Patients with mild to moderate osteoarthritis of the knee or hip should participate in a regular exercise program (eg, a supervised walking program, hydrotherapy classes) and, if overweight, should lose weight.

A randomized, controlled trial of 156 individuals with knee osteoarthritis found that physical therapy was more effective at reducing pain and disability at 1 year than intra-articular glucocorticoid injections.

Reduction in pain with weight loss can be significant; one study showed that loss of 10% or more of body weight resulted in a 50% reduction in pain scores of knee osteoarthritis.

Using assistive devices (eg, a cane on the contralateral side) can improve functional status.

Medical Management

Oral NSAIDs

NSAIDs (see Table) are more effective than acetaminophen for osteoarthritis but have greater toxicity. NSAIDs inhibit cyclooxygenase (COX), the enzyme that converts arachidonic acid to prostaglandins. COX exists in two isomers—COX-1, which is expressed continuously in many cells and is responsible for the homeostatic effects of prostaglandins, and COX-2, which is induced by cytokines and expressed in inflammatory tissues. Most NSAIDs inhibit both isomers. Celecoxib is the only selective COX-2 inhibitor available in the United States.

GI toxicity, such as gastric ulceration, perforation, and GI hemorrhage, are the most common serious side effects of NSAIDs.

The overall rate of bleeding with NSAID use in the general population is low (1:6000 users or less) but is increased by the risk factors of long-term use, higher NSAID dose, concomitant corticosteroids or anticoagulants, SSRIs, the presence of rheumatoid arthritis, history of peptic ulcer disease or alcoholism, and age over 70.

PPIs (eg, esomeprazole 20–40 mg orally daily) reduce the incidence of serious GI toxicity and should be used for patients with risk factors for NSAID-induced GI toxicity.

Patients who have recently recovered from an NSAID-induced bleeding gastric ulcer appear to be at high risk for rebleeding (about 5% in 6 months) when an NSAID is reintroduced, even if prophylactic measures (such as PPIs) are used. Compared with nonselective NSAIDs, celecoxib is less likely to cause upper GI tract adverse events, including bleeding.

All of the NSAIDs, including aspirin and celecoxib, can produce renal toxicity, including interstitial nephritis, nephrotic syndrome, prerenal azotemia, and aggravation of hypertension. Hyperkalemia due to hyporeninemic hypoaldosteronism is seen rarely.

Renal toxicity is uncommon but is increased by the following risk factors: CKD, volume depletion from diuretic use or GI loss, HF, cirrhosis, or use of ACE inhibitors or ARBs.

All NSAIDs, except the nonacetylated salicylates and celecoxib, interfere with platelet function and prolong bleeding time.

Aspirin irreversibly inhibits platelet function, so the bleeding time effect resolves only as new platelets are made.

In contrast, the effect of nonselective NSAIDs on platelet function is reversible and resolves as the drug is cleared.

Concomitant administration of a nonselective NSAID can interfere with the ability of aspirin to acetylate platelets and thus may interfere with the cardioprotective effects of low-dose aspirin.

All NSAIDs are associated with a small increase in the absolute risk of MI and stroke in patients with or without risk factors for heart disease or known heart disease. While the cardiovascular risk is related to the dose and duration of treatment, stroke and MI can occur within the first week of treatment. Cardiovascular risks associated with naproxen, ibuprofen, and moderate dose celecoxib (200 mg orally daily) are comparable.

Topical Therapies

Topical NSAIDs (eg, 4 g of diclofenac gel 1% applied to the affected joint four times daily) appear more effective than placebo for knee and hand osteoarthritis.

Because they have lower rates of systemic side effects than with oral NSAIDs, topical NSAIDs are preferable for patients with risk factors for NSAID-induced GI toxicity. Topical NSAIDs are preferred for patients 75 years of age or older.

Topical capsaicin may be of benefit for osteoarthritis of the hand or the knee.

Acetaminophen, Opioids, Chondroitin, and Glucosamine

Acetaminophen is not recommended given that its impact on pain is frequently negligible and hepatotoxicity can occur from high doses.

Opioids are generally not appropriate for the long-term management of pain due to osteoarthritis.

Chondroitin sulfate and glucosamine, alone or in combination, are no better than placebo in reducing the pain of knee or hip osteoarthritis.

Intra-Articular Injections

Intra-articular injections of corticosteroids, hyaluronate, or platelet-rich plasma have not convincingly produced long-term benefits in reducing pain or preserving function in osteoarthritis.

A 2-year controlled trial demonstrated that injecting the knee with triamcinolone every 12 weeks was no more effective than injecting saline in reducing knee pain and resulted in more cartilage volume loss.

Similarly, platelet-rich plasma injections were no better than saline injections in improving knee pain or slowing disease progression in a randomized, controlled trial of patients with knee osteoarthritis.

Duloxetine

For patients with osteoarthritis in multiple joints who either have not responded to or cannot use NSAIDs, the selective serotonin and norepinephrine reuptake inhibitor duloxetine, 30–60 mg orally daily, can reduce pain.

Nausea occurs in 6–15% of patients.

Physical Therapy

Physical therapy is beneficial for knee osteoarthritis.

A randomized, controlled trial of 156 patients with knee osteoarthritis compared intra-articular glucocorticoid injections to physical therapy; those receiving physical therapy had less pain and functional disability after 1 year compared to those receiving injections.

Surgical Measures

Total hip and knee replacements provide excellent symptomatic and functional improvement when involvement of that joint severely restricts walking or causes pain at rest, particularly at night.

Arthroscopic surgery for knee osteoarthritis is ineffective.

Severe first carpometacarpal osteoarthritis can be treated surgically when other treatments are inadequate.

Prognosis

Symptoms may be severe and limit activity considerably (especially with involvement of the hips, knees, and cervical spine).

When to Refer

Refer patients to an orthopedic surgeon when recalcitrant symptoms or functional impairment, or both, warrant consideration of joint replacement surgery of the hip, knee, or thumb.