Interferential Phototherapy

Clin Rehabil.  2012 May 29. [Epub ahead of print]

Interferential light therapy in the treatment of shoulder tendinopathies: a randomized controlled pilot study.

Montes-Molina R, Martinez-Rodriguez ME, Rodriguez AB, Martinez-Ruiz F, Prieto-Baquero A.


Unit of Physiotherapy and Clinical Electrotherapy, Hospital University Ramon y Cajal, IRICYS, Madrid, Spain.


Objectives: To test the safety of the diode light therapy and evaluate the advantages of the interferential effect of two light probes versus a conventional light probe in the relief of shoulder pain and disability caused by shoulder tendinopathies.

Design: Randomized single-blind pilot study.Setting: Clinical electrotherapy unit.Participants: A total of 30 patients with shoulder pain from tendinopathies.Interventions: The patients were randomly assigned into two groups. Group 1 (n = 15) received interferential light therapy generated by two independent and identical cluster probes composed of light emitting and superluminescent diodes. Similarly, two applicators were applied in group 2 (n = 15), but only one was active, as in conventional clinical therapy. Each multi-diode cluster probe was composed of seven light-emitting diodes at 600 nm and 12 superluminescent diodes at 950 nm.Main outcome measures: Pain was evaluated by visual analogue scale (VAS) at day, at night and during several shoulder movements. Shoulder functional status was measured by means of the University California Los Angeles scale (UCLA).

Results: Comparison between both treatments using the Mann-Whitney U-test showed better results for the interferential treatment. There were significant differences in pain reduction during abduction (P < 0.05) and external rotation (P < 0.05), with pain reductions in abduction and external rotation of 1.5 (± 1.3) and 0.5 (± 1.0) respectively.

Conclusion: Interferential light therapy was safe and effective regarding the shoulder pain reduction during abduction and external rotation movements. The estimated size sample needed for future two-treatment parallel-design studies will require about 60 patients.

Photomed Laser Surg.  2009 Jun;27(3):467-71.

Efficacy of interferential low-level laser therapy using two independent sources in the treatment of knee pain.

Montes-Molina R, Madroñero-Agreda MA, Romojaro-Rodríguez AB, Gallego-Mendez V, Prados-Cabiedas C, Marques-Lucas C, Pérez-Ferreiro M, Martinez-Ruiz F.


Unit of Physiotherapy, Hospital Ramón y Cajal, Madrid, Spain.



The aim of this study was to evaluate the effectiveness of an interferential pattern generated by two identical and independent lasers in the relief of knee pain.


Low-level laser therapy (LLLT) is generally applied by a single probe.


A double-blind controlled clinical trial was performed on 152 patients with knee pain who were randomly assigned into two different groups. Group I patients (n = 76) received interferential laser therapy generated by two identical laser probes located opposite each other on the knee joint. Group II patients (n = 76) received one live probe in conventional laser therapy and one dummy probe. The device used in both groups was an AlGaAs laser (wavelength 810 nm, power 100 mW, in continuous mode). Fifteen laser sessions were applied transcutaneously on 5 knee points (6 J/point) per session. In addition, patients in both groups received a quadriceps strength program based on isometric exercises. A visual analogue scale (VAS) was used for pain evaluation in different situations, such as in standing, in knee flexion/extension, and when going up and down stairs. VAS pain scores were evaluated before, in the middle of, and after treatment.


ANOVA results showed no significant differences between groups for all VAS scores or in the interaction with the sessions (p > 0.05). The VAS score results showed a statistically significant pain reduction throughout all sessions (p = 0.000).


Interferential laser therapy is safe and effective in reducing knee pain. However, the results of the study indicate that it is not superior to the use of a single conventional laser.