The effect of interferential current therapy on patients with subacromial impingement syndrome: a randomized, double-blind, sham-controlled study.

BACKGROUND: Although interferential current (IFC) is a common electrotherapeutic modality used to treat musculoskeletal pain, there is not any randomized controlled trial investigating its clinical efficacy in subacromial impingement syndrome (SAIS).

AIM: Investigation of effectiveness of IFC treatment in patients with SAIS.

DESIGN: Randomized, double-blind, sham-controlled study.

SETTING: Physical medicine and rehabilitation outpatient clinic.

POPULATION: Patients (N.=65) between 25 and 65 years of age, with a diagnosis of SAIS according to clinical evaluation and subacromial injection test.

METHODS: Patients were randomly distributed into two groups: 1) active IFC group (N.=33); 2) sham IFC group (N.=32). Exercise, cryotherapy, and a non-steroidal anti-inflammatory drug (NSAID) were given to both groups. Ten sessions of IFC with bipolar method were applied to the active IFC group daily 20 minutes per session, 5 days per week, for 2 weeks while sham IFC was applied to the sham IFC group with the same protocol. Visual Analog Scale (VAS), Constant scores, and Shoulder Disability Questionnaire (SDQ) were used for evaluation at baseline, immediately post-treatment, and 1 month post-treatment. Both the patients and the researcher who assessed the outcomes were blinded to the treatment protocol throughout the study period.

RESULTS: Sixty of the 65 patients (active IFC group N.=30, sham IFC group N.=30) completed the study, 3 patients from active IFC, 2 from sham IFC group dropped during the follow up period. Statistically significant improvement was observed in all parameters of both groups immediately and 1 month post-treatment (P<0.01). There were no statistical differences between the active IFC group and sham IFC group in all outcome parameters (P>0.05).

CONCLUSIONS: Our results demonstrated that IFC therapy does not provide additional benefit to NSAID, cryotherapy, and exercise program in treatment of SAIS.

CLINICAL REHABILITATION IMPACT: Our study responds to the needs of the lack of evidence in the field of rehabilitation. IFC therapy does not provide additional benefit for the treatment of SAIS.