Therapeutic Effect of Photobiomodulation and Single Intratendinous Injection at the Lesion Site of Platelet-Rich Fibrin in Inducted Tendinopathy.

Tendinopathy is a multifactorial condition characterized by collagen disorganization, inflammation, and impaired tendon function. Photobiomodulation (PBM) and platelet-rich fibrin (PRF) have emerged as therapeutic approaches due to their regenerative potential, although their mechanisms during tendon healing remain unclear. This study compared the effects of PBM and PRF, alone or combined, on experimentally induced calcaneal tendinopathy in rats. A total of 75 animals were divided into five groups: control, injury, PRF, PBM, and PRF + PBM. Treatments began 48 h after injury. Functional performance, nociception, and histological features were evaluated up to 21 days. Combined PRF and PBM promoted superior early functional recovery, enhanced collagen synthesis, and increased angiogenesis, despite greater initial inflammation. PBM alone resulted in gradual recovery with better fiber organization, while PRF accelerated function but sustained inflammation. Combined therapy shows promise for tendon repair, supporting stage-specific treatment strategies.