Hyaluronate Injections May Reduce Movement Pain in OA

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Hyaluronate Injections May Reduce Movement Pain in OA

NEW YORK (Reuters Health) Feb 11 - Intra-articular injections of

hyaluronate sodium appear to provide more relief of pain associated with

physical activity due to osteoarthritis of the knee than treatment with

nonsteroidal anti-inflammatory drugs (NSAIDs) or placebo.

In the Archives of Internal Medicine for February 11, Canadian

investigators report the results of a placebo-controlled trial involving

120 patients with osteoarthritis of the knee.

Dr. Petrella, of the University of Western Ontario in

London, Canada, and associates randomly assigned patients to treatment

with hyaluronate sodium, 2 mL of a 10 mg/mL solution, administered at

baseline and weeks 1 and 2; oral diclofenac 75 mg plus misoprostol 200

g; hyaluronate, NSAIDs and placebo; or placebo only.

As assessed by the Western Ontario McMaster Universities Index, all

three treatment groups reported significantly reduced pain and physical

disability at 4 weeks. Only the group treated with hyaluronate plus

NSAIDs exhibited significantly more pain relief at week 12 than at week

4. Both groups treated with hyaluronate improved in terms of physical

disability between weeks 4 and 12.

Dr. Petrella's group assessed patient physical functioning using

self-paced walking and stepping tests. Patients were asked to walk for

40 meters or step up and down 20 times at a " normal " or comfortable pace.

The two viscosupplementation groups walked faster and exhibited greater

oxygen uptake at week 4 than the other two groups. At week 12, pain

after the walking test was significantly lower than at week 4 in those

treated with hyaluronate alone and unchanged among those treated with

hyaluronate plus NSAIDs. Patients that did not receive intra-articular

injections experienced significantly more pain after the walking test at

week 12 than at week 4.

Thus, the investigators write, " The effect of hyaluronate sodium on

activity-related pain and functional performance seems to improve with

time from intervention compared with the effect of NSAIDs, which does

not show continued improvement after 4 weeks of treatment. "

However, Drs. T. Felson and J. , of the Boston

Medical Center, disagree with the statistical analysis put forward by

Dr. Petrella and his associates, who used repeated-measures analysis of

covariance to determine the effects of treatments. Analyses were

adjusted for prerandomization baseline factors.

In contrast, when Drs. Felson and used a factorial design

analysis and within-group sums of squares, " neither the main effects of

hyaluronate sodium or NSAIDs nor their interaction were statistically

significant. "

The editorialists back up their comments by referring to three

previously published trials, each containing more than 200 subjects,

which compared hyaluronate sodium treatment with placebo injection. Drs.

Felson and report that none of these three trials showed

significant differences between treatment and placebo.

" This was not a large enough cohort to be analyzed in that way, " Dr.

Petrella told Reuters Health in defense of his findings. Rather, it was

intended as a within-group analysis, he said.

" I do believe that hyaluronate sodium does make a clinically significant

difference in pain and function, " he emphasized. Osteoarthritis patients

are " willing to undergo repeated injections, and most have to pay for

the treatment themselves, so they must feel that something good is

happening. "

Dr. Petrella discussed the three types of patient responses he typically

sees. " For 10% to 20% of patients, injection therapy makes no

difference " in their symptoms, he said.

In contrast, " 60% to 75% will come in and get more relief than they've

experienced with any other product at that point. " He added that some of

these patients even report complete relief, though it usually only lasts

about 6 months to 1 year.

About 5% of patients never return for treatment. " Whether it's because

it relieved all their symptoms or did not help at all, I don't know. "

He added that patient response tends to reflect how advanced their

condition is. " If their x-ray shows severe changes, or they describe

significant symptoms, a lot of pain medication use and restricted

mobility, " they tend not to respond well to hyaluronate.

Arch Intern Med 2002;162:292-298.