THERAPEUTIC SYNERGISM BETWEEN HYALURONIC-ACID AND DEXAMETHASONE IN THE INTRAARTICULAR TREATMENT OF OSTEOARTHRITIS OF THE KNEE - A PRELIMINARY OPEN STUDY

In vitro studies on the effects of dexamethasone on human synovial cells have shown that with high concentrations of the steroid in the culture medium cellular activity was completely blocked whereas with low concentrations (10(-6)M), cellular density decreased but there was an increase in the synthesis of RNA, DNA, protein, and hyaluronic acid. These data, coupled with clinical experience of using intra-articular hyaluronic acid to treat patients with osteoarthritis of the knee, prompted the investigators to carry out an open, randomized study of the use of very small doses of dexamethasone in association with hyaluronic acid in 40 osteoarhritic patients. Twenty patients received a weekly intra-articular injection of 20 mg sodium hyaluronate in 2 ml phosphate buffer for 5 weeks; the other 20 patients followed a similar treatment regimen, the only difference being the addition of 0.4 mg dexamethasone phosphate to the first injection. Clinical examination of the knee was made before each injection, 7 days after the fifth injection and 60 days after the start of the trial. Rating scale assessments were made at each visit of spontaneous pain, pain during the day, at night, weight bearing and whilst walking. The results showed that whilst a progressive decrease in all pain parameters was evident and persisted after the end of treatment in both patient groups, pain intensity decreased more rapidly and to lower levels in all but weight-bearing pain, as did improvement in joint mobility, in the combined treatment group. Local tolerance was good with both treatment regimens, with no untoward signs or symptoms at any time. These data suggest a very effective therapeutic synergism between hyaluronic acid and the steroid but further studies are needed to confirm the preliminary findings.