Introduction Platelet rich plasma (PRP) consists of plasma sample from one's own blood enriched with autologous platelets indications controversially used in orthopaedics for possible stimulation of bone and soft tissue healing preparation technique PRP is created by centrifugation of blood to separate platelet rich plasma layer from a sample of whole blood calcium chloride used to initiate platelet activation in the prepared sample of PRP optimal concentration 3-5x that of whole blood >5x inhibits healing Platelet function plays an important role in the inflammatory cascade response after injury growth factors released from platelets include PDGF TGF-B VEGF IGF-1 EGF (epidermal growth factor) CTGF (connective tissue growth factor) FGF-2 Proposed function of PRP increase ECM deposition reduce pro-apoptotic signals minimize joint inflammation Clinical Application PRP efficacy is controversial due to small amount of high level studies in literature soft tissue injury healing no consensus for acute ligamentous, tendon and muscle injuries or chronic tendonopathies osteoarthritis no consensus in evidence, lack of studies with long term followup purportedly downregulates COX-2 and nuclear factor-kappa B (NF-κB) pathways while increasing hyaluronic acid production by synoviocytes, decreasing cartilage degradation, and increasing chondrocyte proliferation in knee OA fracture healing / fusion limited evidence for bone formation (some studies show detrimental effects) ACL reconstruction literature does NOT support PRP for ligamentization/graft maturation, patient reported outcomes direct application to patellar and tibial plug donor sites (BPTB) linked to improved patient-reported outcomes of knee function and decreased patellar tendon gap meniscal repair no clear evidence to support use in meniscal repair rotator cuff repair no benefit in augmenting RC repair (possible detrimental effects) tendon healing lateral epicondylar tendinosis (tennis elbow) potential benefit (improved patient reported outcomes and pain scores) midsubstance/insertional Achilles tendinopathy current literature does NOT support Summary Potential benefits for BPTB donor sites and tennis elbow