Erosive OA is one of the most vexing problems in rheumatology. It often affects middle-aged women, can be very disabling, and there’s no specific evidence-based intervention that’s truly effective. It’s necessary to rule out other inflammatory arthropathies, not least because most others are easier to treat. It’s particularly key to rule out psoriatic arthritis, but this isn’t always easy. X-rays, lab tests and a careful examination of the skin, scalp and nails for psoriasis is very important. Psoriatic arthritis can be effectively treated.

Crystal arthropathies, such as gout, can also masquerade as erosive OA, particularly in the older female. Blood levels of uric acid, calcium, phosphorus and ferritin are easy to obtain, and gout, of course, is also very treatable. Synovial fluid aspirate and crystal exam are helpful in making this diagnosis. A number of these patients may present with low-titre serology (antinuclear antibodies, rheumatoid factor) adding further confusion as to whether this process represents a localized autoimmune disorder. Invariably they have no systemic features of a condition such as rheumatoid arthritis, and the joints involved — PIPs (proximal interphalangeal) and particularly DIPs (distal interphalangeal) are rarely involved in classic RA.

When all studies combine to paint a picture of true erosive OA, treatment is unfortunately symptomatic — NSAIDs, if tolerated, or topicals, as well as non-medicinal treatments such as the old hot wax or warming gloves, or ice. In the past, controlled trials of Plaquenil (hydroxychloroquine) and other DMARDs have failed to show consistent benefit. Neutraceuticals (chondriotin sulphate, glucoasmine, rose hip oil) have been assessed in standard OA, but not specifically in erosive OA. There have been claims that they protect against progression to erosive disease, but this
is uncertain. A recent presentation at the American College of Rheumatology suggested that a subset of erosive OA patients may be candidates in controlled trials for biologic therapy similar to that used in RA. The overall outcome of these trials is still indeterminate, and the cost-benefit and risk-benefit ratios need to be defined.

Lastly, I will often inject the most inflamed joints with Depo-Medrol to relieve symptoms and reduce the swelling. In some cases this can be quite helpful, but it requires a little skill. If helpful, it can be repeated at an appropriate interval (> 3 months).

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