Design of a Clinical Trial to Determine the Effects of Low Level Laser on Pain and Function in Patellofemoral Pain Syndrome: Protocol for a Triple-Blinded Randomized Clinical Trial

We aimed to design a triple-blinded randomized clinical trial study to asssess the effect of low-level laser (LLL) on pain and function in patients with patellofemoral pain syndrome (PFPS).

This designed study will involve 60 patientswith PFP syndrome. Eligible subjects will be divided randomly into control (physical therapy), physical therapy plus active LLL, and physical therapy plus placebo laser. The physical therapy program will be exactly the same for all groups including exercise and education for ten sessions, every other day. The LLL group will receive 808 nm, 200 mW, 4 J Ga-Al-As laser over 5 points for 20 seconds per point. The laser will be deactivated in placebo group, and for the control group, the laser will not be used. The outcomes include pain and function, which will be measured using visual analogue scale (VAS), the Persian version of the Kujala patellofemoral questionnaire, and the step down test. Following Shapiro-Wilk test, the paired t and one-way ANOVA tests, if data distribution followed normal distribution, or the Kruskal-Wallis and Mann Whitney tests, if data distribution did not follow normal distribution, will be administered at the significance level of less than 0.05.

Therapeutic exercises is the treatment of choice for PFP syndrome. LLL is a commonly favorable modality prescribed as a part of physical therapy program for musculoskeletal disorders. However, the effect of laser in subjects with PFPS has not been thoroughly investigated. In designed study, it will be examined whether adding LLL to standard physical therapy has a clinical benefit in subjects with PFPS.