Objective: To describe the outcomes of a cohort of individuals involved in a randomized control trial of extracorporeal shockwave therapy (ESWT) in the treatment of lateral epicondylitis (LE) not previously treated.
Design: Prospective cohort.
Setting: General population.
Patients: Sixty subjects (23 female, 37 male) who participated in a double-blind randomized control trial on the effectiveness of ESWT in the treatment of LE. All subjects had previously not received therapy for their LE.
Intervention: At the 8-week follow-up of a randomized control trial comparing ESWT with a stretching protocol for treatment of LE, all subjects were unblinded to their treatment allocation, and subjects initially allocated to sham therapy were offered active therapy.
Main Outcome Measures: Overall elbow pain (10-cm visual analogue scale [VAS]) and maximum pain-free grip strength were evaluated at 0, 4, and 8 weeks and 3, 6, and 9 to 12 months postinitiation of therapy. Time to pain-free status (less than 1 cm on the VAS) was calculated from time of onset of symptoms, time of inclusion into the trial, and time from initiation of active therapy.
Main Results: A statistically significant difference in time to pain-free status was not detected between groups. Duration of symptoms was identified to be an effect modifier of early response to therapy (at least 50% improvement on the VAS at 8-week postinitiation of therapy). A higher proportion of subjects treated within 16 weeks of onset of LE symptoms showed a response to ESWT than subjects treated after 16 weeks of onset of their LE symptoms.
Conclusions: The use of ESWT with a stretching program is not supported by this study, with the possible exception of the possible interaction effect of time of ESWT initiation from the time of onset of symptoms, which requires further investigation.