Osteoarthritis: Diagnosis and Treatment

Diagnosis

The diagnosis of idiopathic OA is based on history, as well as physical, laboratory, and radiologic findings. An atypical presentation warrants inquiry into a secondary cause.

OA is usually asymmetrical, but can be bilateral in small joints. The following findings may be present on physical exam:

• Tender joint.
• Crepitus during flexion and extension.
• Bony enlargements, especially of the distal interphalangeal joints (Heberden’s nodes), and proximal interphalangeal joints (Bouchard’s nodes).
• Flexion contracture or varus deformity of the knee.

Joint effusion, if present, is mild and is not typically inflammatory; usually no other signs of inflammation are present. However, a variant of OA termed “inflammatory osteoarthritis” may present with effusion, redness, warmth to palpation, and morning stiffness.

No lab test is specific for osteoarthritis. The presence of an abnormal erythrocyte sedimentation rate, rheumatoid factor, or >2000 WBC/mm³ in joint aspirate suggests an inflammatory arthritis, such as rheumatoid or infectious arthritis.

Treatment

The choice of treatment depends partly on whether inflammation is present. Options include a supervised exercise/muscle strengthening program, medication, or surgical intervention. In some cases, isometric exercises may be emphasized. Arthroscopy and joint replacement are usually reserved for patients with severe, functionally limiting disease.

Nonpharmacologic Treatments

Nonpharmacologic treatments should generally be attempted first in mild cases. Depending on the affected joint, treatments can include weight loss, exercise (low–impact, individualized programs), physical therapy; and shoe inserts/braces/splints.

Pharmacologic Therapy

Capsaicin cream significantly reduces pain, possibly by depleting substance P.⁴

Glucosamine and chondroitin sulfate are oral cartilage–enhancers and can be safely used with other treatments. Although such supplementation may improve symptoms, no convincing evidence has shown that the underlying disease process is ameliorated.

Acetaminophen dosing up to 4 grams per day is helpful in noninflammatory mild OA. However, chronic use may lead to renal or liver impairment.

Nonsteroidal anti–inflammatory drugs (NSAIDs) are the most effective treatment in inflammatory OA, moderate to severe noninflammatory OA, knee/hip OA, or after a failed acetaminophen trial. Careful monitoring of blood pressure is necessary when employing NSAIDs owing to the potential for aggravating or causing hypertension, and a 2 to 4 week trial should be completed before increasing the dose. If analgesia is suboptimal after 2 to 4 weeks at the maximum dose, a different NSAID or a nonacetylated salicylate should be used.

There is no preferred NSAID.

Chronic use may lead to gastrointestinal ulceration or kidney disease, especially if it is combined with aspirin. Some evidence suggests less toxicity occurs with salsalate and nabumetone (nonacetylated salicylates).

COX–2 inhibitors require further study to determine whether the benefits outweigh the potential cardiovascular risks.

Tramadol, another type of analgesic, may be combined with the above drugs.

Narcotics should be reserved for short–term severe pain or for nonsurgical candidates unresponsive to the above therapeutics.

Intra–articular glucocorticoid injection should be reserved for noninflammatory OA that is refractory to NSAID treatment, or inflammatory OA when NSAIDs are contraindicated. Adequate evidence for efficacy exists only for the knee joint, and injections should be limited to 3 or 4 times a year per joint. Infection should be ruled out prior to injection.

Injections of hyaluronic acid derivatives (hyalgan or hylan GF–20) may be beneficial when noninvasive treatments achieve suboptimal results.

Surgical Therapy

Joint replacement (arthroplasty) should be reserved for severe refractory cases when the disease limits activities of daily living. However, significant improvement in symptoms and function may occur after surgery.

Arthroscopic debridement and synovectomy for OA have not yet gained acceptance.