Osteoarthritis of the knee

Sir—Our statement about the efficacy of hyaluronic acid versus intra-articular steroids was made on the basis of Jones’ and colleagues’ randomised, double-blind comparative study

that compared hyaluronic acid with 20 mg triamcinolone hexacetonide. Although there was a high drop-out rate in both groups, intention-to-treat analysis showed a greater reduction in pain in the hyaluronic acid group, over a 6-month period.

We agree with Margaret-Mary Gordan and colleagues that the older published research on this treatment is confused by several short-term, poorly designed, or uncontrolled studies. Nevertheless, since 1993 studies have been published that compared hyaluronic acid with placebo,

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as well as studies comparing hyaluronic acid with intra-articular triamcinolone hexacetonide and non-steroidal anti-inflammatory drugs (NSAIDs).

All but one

of these large, well-designed studies showed a slight but significant benefit for hyaluronic acid, at least in some subgroups.

We agree that hyaluronic acid has not, as yet, been accepted as a standard or routine treatment for knee osteoarthritis and that optimum guidelines for its use have yet to be established. However, we believe that the product may have a role in a small group of patients: for example, older individuals in whom surgery is not contemplated and whose pain is uncontrolled by other measures, or patients with isolated knee osteoarthritis with contraindications to NSAIDs. Two preparations of hyaluronic acid have been approved by the US Food and Drug Administration for use in the treatment of knee osteoarthritis.

We thank Madhur Bhattaral for sharing his experience of the bicycle ergometer as a means to provide exercise for patients with knee osteoarthritis. Most intervention studies focus on strengthening the quadriceps, since that is believed to be the muscle which contributes most to functional loss in knee osteoarthritis. Bicycling involves many other muscles and also requires greater degrees of knee flexion than are used in everyday activities. However, compliance is likely to be an issue with any exercise programme and, if bicycling is well tolerated, we see no reason why it should not be encouraged, if only as an adjunct to weight reduction.