Comparative Efficacy of Low-Level Laser Therapy and Platelet-Rich Plasma Injection on Pain, Tendon Thickness, and Functional Outcomes in Athletes with Patellar Tendinopathy: A 12-Week Randomized Controlled Trial

Abstract

Background: Patellar tendinopathy is a prevalent overuse injury among athletes, characterized by anterior knee pain, tendon thickening, and impaired function. Conventional treatments often yield inconsistent outcomes, prompting interest in novel regenerative and photobiomodulation therapies. Platelet-Rich Plasma (PRP) injections and Low-Level Laser Therapy (LLLT) are two non-invasive modalities with distinct biological mechanisms, but their comparative efficacy in athletic patellar tendinopathy remains inadequately defined. Objective: To compare the clinical effectiveness of LLLT and PRP injection in reducing pain, improving tendon morphology, and enhancing functional outcomes over 12 weeks in athletes with patellar tendinopathy. Methods: In this randomized controlled trial, 60 athletes aged 18–40 years with ultrasonographically confirmed patellar tendinopathy were allocated to receive either LLLT (n=30; 810 nm, 100 mW/cm², thrice weekly for 12 weeks) or a single-dose PRP injection (n=30; 3 mL, under aseptic ultrasound-guided technique). Pain (Visual Analog Scale), tendon thickness (ultrasound), and function (Lequesne Index) were assessed at baseline and 12 weeks. Independent and paired t-tests evaluated within- and between-group differences. Results: Both groups showed significant improvements in all outcomes (p < 0.001). However, the LLLT group demonstrated superior reductions in pain (ΔVAS: 5.4 vs 4.3, p = 0.02), tendon thickness (Δ: 1.8 mm vs 1.0 mm, p = 0.001), and Lequesne Index (Δ: 6.1 vs 5.2, p = 0.04). Effect sizes were consistently larger for LLLT. Conclusion: LLLT offers significantly greater clinical benefits than PRP for managing patellar tendinopathy in athletes, supporting its use as a preferred non-invasive intervention in sports rehabilitation.