Objectives: To conduct a double-blinded randomized controlled trial study of the efficacy of high-intensity laser in patellofemoral pain syndrome patients in Ramathibodi Hospital, Thailand.

Study design: A double-blinded randomized controlled trial.

Setting: Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.

Subjects: A total of 18 patients with patellofemoral pain syndrome for at least three months were studied.

Methods: Subjects were randomly allocated into two groups. The treatment group received high-intensity laser therapy (frequency 20 Hz, energy 1,530 mJ/cm2, total energy 3,000 joules per session (6 sessions, 2-3 sessions per week) at an average power of 10.5 W). The control group received sham laser therapy (6 sessions, 2-3 sessions per week). In both groups, the patients were advised to exercise and to make lifestyle modifications. Pain (assessed by the VAS pain scale), functional ability of the lower extremity (assessed by the Thai version of the Kujala scoring questionnaire), and quality of life (assessed by Short Form-36 health survey version 2.0, SF-36V2) were collected before and at 3, 6, and 12 weeks after treatment.

Results: At baseline, demographic data as well as pain, function, and quality of life were similar between the groups. The differences in VAS decrement from baseline in the treatment and control groups after 3 weeks were 44.0 (28.0) and 34.0 (24.8), after 6 weeks were 44.0 (28.0) and 38.0 (37.3), and after 12 weeks were 47.0 (35.0) and 35.0 (41.3), respectively. There was statistically signifi-cant improvement in pain (VAS score), functional ability (Kujala score), and quality of life (SF-36V2) within both groups compared to before treatment (p <0.05), but there was no statistically signifi-cant difference in those values between the treatment and control groups at 3, 6, and 12 weeks.

Conclusions: The efficacy of high-intensity laser therapy (HILT) combined with effective exercise was not significantly different from exercise alone in improving pain, function, or QOL.