Terapia hialurónica intraarticular. Efectividad en pacientes con osteoartritis.

Intraarticular (IA) hyaluronan (HA) therapy is safe and effective in patients with mild to moderate, predominant unilateral knee osteoarthritis (OA), with pain relief persisting 13 weeks after a series of 5 injections, a new study shows.

Although recognized as a therapeutic approach to OA, the injection of HA (formerly called hyaluronic acid) into the knee remains controversial due to variable outcomes in clinical trials and an unclear mechanism of action.

To further evaluate the efficacy and safety of IA HA, Richard Day, MD, FRACP, and colleagues of the Department of Clinical Pharmacology and Toxicology, University of New South Wales, Sydney, Australia, performed a double blind, randomised, parallel group, multicentre, saline vehicle-controlled study in patients with symptomatic knee OA using the Western Ontario McMaster (WOMAC) Osteoarthritis Scale as the primary outcome measure.

A total of 240 patients were randomised to receive a course of 5 injections of either HA 25 mg or a phosphate buffered solution given at 1 week intervals, after which all subjects were followed up for a period of 13 weeks. Secondary efficacy variables included the Lequesne Index, knee examination, physician and patient global assessments, and reported acetaminophen consumption.

Among study subjects, 223 were evaluable for the modified intention to treat analysis (subjects receiving a dose of study medication with at least one efficacy observation recorded after treatment).

The researchers found that overall, scores for the WOMAC pain and stiffness subscales were modestly but significantly lower in the HA-treated group (P < .05). These results were confirmed by the same analysis of the Lequesne Index, which revealed a difference of 0.91 (P < .05). Adjusted mean scores were 15?18% lower in the HA group for all WOMAC variables and 11% lower for the Lequesne Index score.

Furthermore, tolerability was found to be good, with 95% of patients receiving the full course of injections and over 90% of patients completing the study. Approximately 10% of patients experienced local pain and inflammation at the injection site, which was usually considered mild and of short duration.

The researchers note that in contrast to previous studies with HA products, the onset of the treatment effect was slow, with a significant difference from the control group not being observed until 6 weeks after treatment initiation.

"Significant clinical uncertainties on the use of HA remain," they concluded. "Further studies on mechanism of action are required that might lead to more rational use."