Efficacy of High-Power Laser in Alleviating Pain and Improving Function of Patients With Patellofemoral Pain Syndrome: A Single-Blind Randomized Controlled Trial

Abstract Introduction: In this study, a single-blind and randomized controlled trial (RCT) for assessing the effectiveness of high-power (up to ۱۲ W) laser therapy (HPLT) on patients with patellofemoral pain syndrome (PFPS) was carried out.Methods: Forty-four patients were randomly assigned to two treatment groups by generating random numbers with MATLAB ۲۰۱۴b software, where odd and even numbers were attributed to sham laser group (group A) and actual laser group (group B), respectively. Group B patients underwent HPLT with total dose of ۳۰۰ J/session for ۵ consecutive sessions separated by a ۲-day interval. On the other hand, sham laser was applied to group A patients. Both groups had the same exercise therapy programs during the study period (۳ months). The exercise therapy program included isometric knee exercise for ۳ sets per day and ۱۰ times in each set, with duration of ۱۰ seconds per time and straight leg raise for ۱۵ seconds ۱۰ times a day. The group codes of patients were not revealed to subjects and data analyzer until completion of the study. Kujala, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and visual analog scale (VAS) questionnaires were chosen as outcome measures. These questionnaires were completed at three points during the study; at the beginning of the study to obtain the pre-therapy conditions and one month and three months after the start of the study to evaluate post-therapy conditions.Results: Two main analyses were conducted: within-group and between-group analyses. Within-group analyses indicated significant improvements in respect to all measurements where pre-therapy and post-therapy comparisons were conducted in both groups (P < ۰.۰۵). On the other hand, between-group comparisons did not reveal any statistically significant functional difference between group A and group B regarding the evaluative criteria (P > ۰.۰۵) except for pain VAS (P < ۰.۰۵).Conclusion: This study indicated that short-term HPLT accompanied by appropriate exercise regimen significantly decreased pain in patients with PFPS. But it was not recommended as an efficient modality in functional improvement. Also, it was observed that, in the short-term period of study, HPLT was a safe modality. Keywords: High-power laser Patellar chondromalacia Patellofemoral pain syndrome Exercise