Low-Level Laser Therapy for Osgood-Schlatter or Sever Pain in Youth Athletes

This pilot randomized, placebo-controlled, double-masked clinical trial evaluates the feasibility and preliminary clinical signal of laser photobiomodulation (low-level laser therapy; LLLT) in youth athletes (10-17 years) with symptomatic lower-extremity apophyseal pathology, primarily consistent with Osgood-Schlatter disease and/or calcaneal apophysitis (Sever disease) confirmed clinically and by ultrasound. Participants will be randomized 1:1 to active LLLT or sham LLLT. The intervention consists of 10 sessions over 2 weeks (5 sessions/week) delivered with a class 3B GaAlAs (Gallium-Aluminum-Arsenide) laser device using standardized parameters (near-infrared wavelength range; continuous mode; preset energy density; contact application over the symptomatic apophyseal region). Sham procedures are identical in appearance, session duration, and device operation but deliver 0 mW output. The primary objective is feasibility (recruitment, retention, adherence, data completeness, safety). Secondary objectives are estimate-only between-group differences in pain and function at post-intervention and follow-up. Mechanistic measures (biomarkers and ultrasound features) are exploratory and used to inform the design of a future full-scale trial.