Toward Standardized Platelet-Rich Plasma Therapy in Tendon Healing: Integrating Biological Characterization with Clinical Translation.

Platelet-rich plasma (PRP) has emerged as one of the most extensively investigated orthobiologic therapies for tendon disorders because of its potential to modulate inflammation, enhance extracellular matrix remodeling, and promote tissue regeneration through the delivery of concentrated platelets and bioactive molecules. However, despite compelling biological rationale and encouraging preclinical evidence, clinical outcomes remain inconsistent across different tendon pathologies. This narrative review critically examines the principal biological and methodological factors underlying this variability, including differences in cellular composition, growth factor and cytokine profiles, activation strategies, and current PRP classification systems. We further synthesize the available clinical evidence across major tendon disorders, highlighting the influence of disease-specific biology, product heterogeneity, and procedural variability on treatment response. In addition, the emerging role of quantitative imaging biomarkers in objectively evaluating tendon regeneration is discussed as a complementary tool for biological outcome assessment. Based on the evidence reviewed, we propose the quantifiable platelet-rich plasma (Q-PRP) framework, a practical reporting model that integrates cellular, molecular, procedural, and clinical variables into a standardized approach for biologically meaningful PRP characterization. Rather than replacing existing classification systems, the proposed framework aims to improve reproducibility, facilitate cross-study comparison, and support the transition toward precision regenerative medicine. Standardized biological characterization, combined with objective outcome assessment, may represent a critical step toward optimizing PRP research and clinical application in tendon healing.