Biologic Therapies for Knee Osteoarthritis: A Structured Narrative Review of Joint Preservation Strategies and Clinical Outcomes.

Knee osteoarthritis (KOA) is among the leading causes of chronic pain and physical disability worldwide, representing a major clinical challenge as currently available treatments primarily address symptoms rather than the biological mechanisms driving disease progression. As interest in joint preservation strategies has grown, biologic therapies have emerged as promising approaches capable of modulating the intra-articular environment and potentially delaying invasive interventions. This structured narrative review critically synthesizes contemporary evidence retrieved from PubMed, the Cochrane Library, and Google Scholar to evaluate the biological rationale, clinical applications, therapeutic outcomes, and current limitations of biologic therapies for KOA. Collectively, the available literature suggests that platelet-rich plasma, mesenchymal stromal cell-based therapies, and bone marrow aspirate concentrate are associated with meaningful improvements in pain, physical function, and patient-reported outcomes, particularly in appropriately selected patients and when incorporated into individualized treatment strategies. However, substantial heterogeneity in product composition, preparation techniques, and patient selection continues to limit reproducibility and hamper standardized clinical recommendations. Although the available evidence supports symptomatic improvements with selected biologic therapies, their long-term structural effects and disease-modifying potential remain uncertain. Current evidence therefore supports their consideration as adjunctive options within individualized joint-preservation strategies rather than as replacements for established surgical treatment. Further high-quality comparative studies and greater standardization of treatment protocols and patient selection are needed to define their long-term clinical role.