Background: Lateral epicondylitis may cause pain and functional disability in many daily activities. Steroid injection or phonophoresis are the recommended treatments in this regard. In this study, we aim to compare the effect of ultrasound guided local injection of dexamethasone with dexamethasone phonophoresis for treatment of lateral epicondylitis.

Materials and Methods: In this clinical trial, patients with lateral epicondylitis were randomely assigned to injection (n=18) and phonophoresis (n=18) groups. Three patients in phonophoresis group dropped out from the study. In injection group, dexamethasone with lidocaine was injected once with the guide of sonography at the base of common extensor tendon. Phonophoresis group received 5 minutes treatment with ultrasound using dexamethasone gel for 10 sessions. Patients’ pain in total and in specific and usual activities according to PRTEE questionnaire before, one and three months after treatment was calculated.

Results: Injection group compared to phonophoresis had significantly better improvement in pain (p=0.04), but there was no significant difference in serial changes of functional subscale and total score of PRTEE between groups. Injection group compared to phonophoresis had also better pain and total score one month after treatment (p=0.003 and p=0.01, respectively).

Conclusion: Dexamethasone injection compared to phonophoresis had significant improvement in patients’ pain which was more apparent one month after treatment, but the results were similar between groups three months after treatment.