Extracorporeal Shock Wave Therapy without Local Anesthesia for Chronic Lateral Epicondylitis

Author(s): Pettrone FA, McCall BR

Source: JBJS 87(A): 1297-1304, 2005.

Summary:

This study is a double-blind, placebo controlled, multi-center trial of shock wave therapy for the treatment of chronic refractory lateral epicondylitis without local anesthesia. One-hundred fourteen patients were treated with a minimum of a 6-month history of lateral epicondylitis that was unresponsive to at least 2 of 3 conventional therapies including physical therapy, non-steroidal anti-inflammatory medications, and corticosteroid injections. Exclusion criteria included age less than 18 years, a steroid injection within the prior 6 weeks, therapy within the prior 4 weeks and the use of non-steroidal anti-inflammatory medications within 1 week prior to treatment.  Diagnosis was made by tenderness to palpation over the lateral epicondyle and reducible pain provoked by resisted wrist extension.  The study population included 60 women and 54 men with a mean duration of symptoms of 21 months prior to participation.  The average age was 47 years and the right arm was affected in 67%. Active treatment consisted of 1 treatment each week with 2000 impulses at 0.06 mJ/mm2 with use of the Sonocur extracorporeal shock wave system (Siemens Medical Solutions USA, Iselin New Jersey) for 3 weeks.  The placebo group consisted of sham treatments of 2000 impulses at 0.06 mJ/mm2 with use of a sound reflecting pad between the patient and the application head of the machine.  Only the technician was aware of the treatment group.  Follow-up examinations were at 1,4, 8 and 12 weeks as well as at 6 and 12 months after completion of treatment.  In the active treatment group, 53 patients concluded a 12-week protocol and 2 withdrew due to intolerance of the treatment.  At 12 weeks, a significant difference between treatment groups was observed with respect to pain reduction during resisted wrist extension, with reduction of pain to at least 50% in 60% of the patients compared with only 30% of the placebo group.  The average pain scored decreased from 74 at baseline to 38 at 12 weeks, 24 at 6 months and 10 at 1-year.  The mean improvement in the upper extremity functional score at 12 weeks was 2.4 for the active treatment group compared with 1.4 for the placebo group.  There was no significant improvement with respect to grip strength.  By 6 months, most patients in the placebo group had been lost to cross-over and were therefore not available for comparison.  Of the 16 remaining placebo patients who had not crossed over which were seen at 6 months, 13 had received a 50% reduction in pain but only represented 22% of the original 58 patients in the intent to treat placebo cohort.

Thirty-four patients from the placebo group crossed over after 12 weeks to receive active treatment.  During the placebo phase, the mean pain score changed from 78 before placebo treatment to 70 before active treatment whereas during active treatment, the mean pain score decreased from 70 to 28 at 12 weeks and the mean functional score improved from 4.7 to 4.0 during the placebo period but ultimately improved to 1.98 after 12 weeks of active treatment.  There was no serious adverse affects.  Fifty percent in the active treatment group compared with 22% in the placebo group experienced moderate treatment-related pain that was transient.  Eighteen percent in the active treatment group experienced nausea during treatment.

This is the first double-blind, placebo-controlled, multi-center trial of extracorporeal shock wave therapy for recalcitrant lateral epicondylitis.  There have been many previous studies in the literature suggesting only questionable efficacy of extracorporeal shock wave therapy for lateral epicondylitis.  Many of the previous studies varied in their indications as well as their concomitant treatments, length of follow up, etc.  This study provides evidence for the possible use of extracorporeal shock wave therapy for recalcitrant chronic lateral epicondylitis, considering that both the active treatment group and the cross-over group achieved reasonable success.  Further studies may be necessary to clarify these results considering the marginal previous results recorded in the literature.  The study must be read with caution, due to the difficulty in truly blinding patients in the placebo group and the fact that lateral epicondylitis is a self-limiting in the vast majority of patients, resolving in over 90% of patients over time.
 
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