Nancy A. Melville

May 31, 2013

INDIANAPOLIS, Indiana — For patients with shoulder impingement syndrome, a twice-daily heated lidocaine tetracaine patch (Synera, ZARS Pharma) reduces pain to the same extent as a single steroid injection, a new study shows.

"Based on this small study, it appears that in the short term, both the lidocaine tetracaine patch and injections are helpful in reducing pain and restoring more normal range of motion for shoulder impingement syndrome," said lead investigator Richard Radnovich, DO, from the Injury Care Medical Center in Boise, Idaho.

He presented the results here at the American College of Sports Medicine 60th Annual Meeting.

The study involved patients reporting symptoms of shoulder impingement syndrome for at least 14 days and an average pain score of at least 4 on a 10-point scale. They were randomized to treatment with the lidocaine 70 mg tetracaine 70 mg patch (n = 29) or a single subacromial corticosteroid injection (n = 31).

After an initial 2-week treatment period, patients in the patch group continued with treatment on an as-needed basis for another 2 weeks. During that period, the patients averaged 1 patch per day. Twenty-three patients in each group completed the study.

After 6 weeks, more patients in the patch group than in the injection group achieved a clinically important reduction, defined as 30% or more, in average pain score (83% vs 74%). Similar patterns of improvement were seen in the 2 groups for measures of worse pain and pain interference with general activity, work, or sleep.

At baseline, average pain scores were similar in the patch and injection groups (6.0 vs 5.6). Decreases in pain during the first 2 weeks of treatment were significant in the 2 groups (44% vs 57%; < .001). Improvements continued out to 6 weeks.

Table. Range of Motion for Internal Rotation

Treatment Baseline 6 Weeks
Patch 36.4° 64.0°
Injection 28.9° 52.3°

 

Improvement in abduction was similar in the 2 groups.

The most common adverse event in the patch group was erythema, reported by 22 patients, but all cases were mild or moderate in severity. No adverse events in the injection group were deemed to be related to the treatment.

"Frankly, I was surprised at the efficacy in both groups," Dr. Radnovich said. "But what was more unexpected were the improvements in range of motion in the patch cohort. These results were comparable to the injection."

"I have been doing shoulder injections for a long time, but to actually get the data on results in a controlled way is striking," he noted.

There is generally not a major difference between the cost of 2 patches per day for 2 weeks and the cost of a single steroid injection, he added. "The real saving comes if you can avoid referral to another provider or to physical therapy."

These results will be important for patients and clinicians who would like an effective alternative to steroid injections, Dr. Radnovich said.

The noninvasive patch treatment will be a "significant advantage for patients who may be apprehensive about getting an injection or do not tolerate steroids," he said. "In addition, it is an advantage for providers who may not feel comfortable performing an injection."

Sports medicine specialist Joseph Chorley, MD, from the Baylor College Medicine, in Houston, Texas, said he was also surprised by some of the study's results. However, he explained that issues such as the sustainability of improvement need to be answered before he recommends the patch over injections to his patients.

"The product uses 2 anesthetic agents that provide decreased pain for minutes (in the case of tetracaine) and hours (in the case lidocaine), but what changed in the patient's pathology that gave them impingement?" Dr. Chorley asked. "If you do not treat the cause of the problem, there is no reason to believe that there will be sustained improvement."

Steroid injections for the subacromial bursa, which are half the usual 20 mg dose of triamcinolone, can typically address cause, Dr. Chorley noted.

"Steroid injections can treat the cause in patients with specific overuse-related inflammation, such as a younger swimmer with too much yardage or a younger pitcher with too much throwing," he explained.

"In more degenerative patients, it is treating a symptom that allows you to do your rehab more effectively, but rehab is not mentioned in the study."

Dr. Chorley added that his patients typically tolerate the steroid injections relatively well.

"I think that patients would like to avoid an injection if possible," he said, "although the pain is relatively minimal for this injection, risk for infection is extremely low, and I find that most patients have a good response if they are appropriately selected."

This study was investigator-sponsored and paid for by a grant from Nuvo Research. Dr. Radnovich reports being a consultant for and receiving research funding from Nuvo Research. Dr. Chorley has disclosed no relevant financial relationships.

American College of Sports Medicine (ACSM) 60th Annual Meeting: Abstract 1244. Presented May 30, 2013.

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