Abstract #617 Structure Modifying Study of Hyaluronan (500-730 Kda, Hyalgan) on Osteoarthritis of the Knee.
RW Jubb, S. Piva, I. Beinat, J. Dacre, P. Gishen. UK and Italy.

Hyaluronan (HA) injections in patients with knee OA have been reported to reduce pain. The purpose of this study was to determine whether HA treatment is also associated with structure modification - that is, decrease in cartilage destruction assessed by a decreased rate of radiographic joint space narrowing.

Methods: This was a 17 center, UK, randomized placebo-controlled, double-blind study. Patients were assigned to receive 3 courses of 3 intra-articular injections of HA or saline during the one year study. The primary endpoint was the change in joint space width (JSW) over one year, using standard weight-bearing radiographs. Uncontrolled use of analgesics and NSAIDs was permitted.

Results: 408 patients were enrolled, 319 completed, and complete data were available on 273. Baseline characteristics of the two groups were similar at baseline (mean age 64.2 yrs, 68% female). HA reduced the rate of joint space narrowing in those with greater JSW at entry: HA group mean joint space loss of 0.13 mm (sd=1.1), control group mean joint space loss of 0.55 mm (sd=1.0) (p=0.02). NSAID and analgesic use was comparable in the two groups, but the HA group reported greater improvement in pain at multiple time points compared to the control group.

Conclusion: HA may represent a disease-modifying treatment for knee OA.

Editorial comments: This study suffers from the problem discussed above (see editorial comment for abstract 614) - that is, that standard extended knee radiographs were used to assess the primary outcome. Semi-flex radiographs with radioanatomic positioning by fluoroscopy is probably a more reliable instrument for long term studies of progression of knee OA, especially where pain is relatively marked, than standard extended views. Thus, while the results of this study are interesting, they bear repetition and confirmation using this radiographic technique. Also, the amount of missing data is of concern in that it may skew the results.

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