Autologous blood product concentrated for growth factors, used therapeutically.
Platelet-rich plasma is an autologous blood product made by centrifuging a patient's own blood to concentrate platelets above baseline levels, then usually injecting this concentrate into or around an injured tissue. The platelets degranulate and release growth factors and cytokines that are thought to influence local healing, angiogenesis and pain pathways. Critically, PRP is not one standardised product — it's a broad family of preparations that differ in platelet concentration, leukocyte content and whether the sample is activated before injection.
On the clinic floor this matters because a patient asking 'does PRP work for my Achilles/patellar tendinopathy or knee OA' cannot be answered with a single yes or no — the answer depends on which formulation, for which condition, and evidence quality varies accordingly. It shapes the informed-consent conversation: clinicians should be explicit that outcomes reported in one trial may not generalise to a different PRP system, and that leukocyte-rich versus leukocyte-poor preparations may behave differently, particularly in intra-articular use where leukocytes may provoke more inflammatory response. It also affects how you counsel on cost and expectations, since PRP is frequently offered as a self-funded adjunct with variable evidence support depending on indication.
In practice, a venous blood sample is drawn and processed through a commercial or in-house centrifugation kit, producing a plasma fraction enriched in platelets that is then injected under clinical or image guidance into the target tissue (e.g., tendon, joint). Some protocols add an activating agent (such as calcium chloride or thrombin) before injection, while others rely on endogenous activation from contact with collagen at the injection site. Outcome tracking typically uses patient-reported measures (pain scores, validated tendinopathy or joint-specific questionnaires) and functional return-to-activity milestones over weeks to months, since PRP's proposed mechanism is biological modulation of healing rather than an immediate mechanical or analgesic effect.
The major limitation is heterogeneity: platelet dose, leukocyte content, activation method and injection technique vary enormously across studies and commercial systems, so pooled meta-analyses and general claims about 'PRP efficacy' should be interpreted cautiously and per formulation and condition. A common misuse is treating PRP as a single generic therapy validated by any positive trial, when a favourable result for one preparation in one condition (e.g., leukocyte-poor PRP in lateral epicondylitis) does not license extrapolation to a different preparation or a different joint or tendon pathology. Clinicians should also flag that reporting of exact preparation parameters is inconsistent in the literature, which limits reproducibility and makes it harder to match a patient to the specific protocol that has actual supporting evidence.
This guide was auto-drafted and is pending editorial review.