Medications

Hyaluronic Acid Injections (Viscosupplementation)

Injections of hyaluronic acid (Hyalgan, Synvisc, Artzal, Nuflexxa) into the joint -- a procedure called viscosupplementation -- is now recommended as one of the treatments for osteoarthritis. Hyaluronic acid is a naturally occurring substance in joints that acts as a lubricant for slow movements and a shock absorber for fast motions. In high amounts, it also may have anti-inflammatory effects.

• Patients receive a series of three to five injections once a week.
• The drug is injected into the joint.
• A health care worker will apply local anesthetic because these viscous (sticky) injections require a large needle.
• Patients need to avoid weight-bearing activities for about 48 hours after each shot.

Hyaluronic injections appear to be about as effective as NSAIDs and corticosteroid injections for relieving pain, at least in men, and they have no adverse effects in the stomach or intestines. One study reported that between 39 - 56% of patients were at least nearly free of weight-bearing pain up to 24 weeks after the final injection. In another study, response was judged better or much better for 87% of knees after a second course, which was administered about 8 months later. Nevertheless, a number of studies on viscosupplementation have shown little or no benefits, particularly in women, and more research is needed to determine if they are useful. Injections are also expensive. Accurate placement of the needle directly into the knee joint space is important and may be difficult, even for experienced doctors, if there is no fluid build-up in the joint. Best success rates are with a specific approach into the kneecap called the lateral midpatellar.

Side Effects. Serious adverse reactions are rare. The most common side effects, pain at the injection site and knee pain and swelling, are usually mild and temporary. More research is needed to confirm benefits and long-term risks.

Experimental Therapies

Bisphosphonates. Bisphosphonates such as alendronate (Fosamax) and risedronate (Actonel) help prevent bone loss in people with osteoporosis. They are currently being investigated for osteoarthritis as well. A 2005 study reported that risedronate may delay joint destruction in patients with knee osteoarthritis.

Lidocaine Patch. Lidocaine, a local anesthetic, is available in patch form (Lidoderm) and has been used specifically for herpes zoster pain. Early studies are suggesting that it may provide significant relief for people who suffer from osteoarthritis with very few adverse effects, even with continuous use of four patches a day. If further studies support its benefits, the patch could prove to be an important treatment.

Additional Investigative Therapies. Other therapies under investigation include drugs that aim at stopping the disease process itself.

• Tetracycline antibiotics, such as doxycycline, may have a role to play in treating osteoarthritis. At low concentrations, the drug reduces the production of collagenases, which are enzymes critical to disease development and progression. Initial results from clinical trials suggest that doxycycline may help delay joint space narrowing.
• Licofelone is a drug that inhibits both the COX enzyme plus an inflammatory substance called lipoxygenase 5. Early trials indicate it may be effective and safer than either NSAIDs or COX-2 inhibitors.
• Nitric oxide increases blood flow in the mucous lining and secretions of mucus and bicarbonate. Combining nitric oxide with NSAIDs may reduce the adverse effects on the gastrointestinal tract.
• Diacerein inhibits an inflammatory substance in arthritic joints called interleukin-1b. It has shown some promise in clinical trials.
• Trials of gene therapies that either fight joint degradation or strengthen cartilage are underway.