The Role of Platelet Rich Plasma Therapy in Treating Athletic Injuries
California University of Pennsylvania
With the increasing speed, size, and strength of today’s athletes, athletic injuries are becoming more prevalent. Due to high demand for athletic competition, the fast rehabilitation and return to play process is crucial. Common athletic injuries such as torn tendons and ligaments are slow healing injuries that sometimes keep athletes out of play for an entire season, but that could all change with the introduction of platelet rich plasma therapy. Platelet rich plasma therapy may be able to reduce healing time by as much as half for injured athletes and, in the future, may become a great tool for certified athletic trainers, doctors, and physical therapists to utilize in returning athletes to the field sooner.
Platelet Rich Plasma
Platelet rich plasma is, quite simply, blood plasma enriched with blood platelets. In fact, the amount of platelets present in platelet rich plasma is as much as ten times greater than that of whole blood.1 There are three types of platelet rich plasma: allogenic, homologous, and the safest and most frequently used, autologous.2 Autologous means that the platelet rich plasma was derived from the same person that it will ultimately be applied to, thus helping to prevent the spread of transmissible diseases such as HIV and hepatitis.2 Whole human blood consists of four major components, erythrocytes (red blood cells), leukocytes (white blood cells), thrombocytes (blood platelets), and blood plasma. Thrombocytes and blood plasma are the two substances utilized in platelet rich plasma therapy.
Platelet rich plasma is derived from whole human blood through the use of a centrifuge. To begin the process, approximately 30 – 60mm of whole human blood is drawn from the patient; most commonly from a vein in the arm.1 The blood is then placed in a centrifuge to separate the blood into separate components. This process allows for the erythrocytes to be removed.1,3 Following that, most systems will require a second centrifugal stage to separate the platelet rich plasma from the platelet poor plasma and extract just the platelet rich layer.1,2 After this process, the substance is complete and ready for use in a patient.
Platelet rich plasma can be applied to the patient in several different ways, the most common being through injection. After the patient’s blood is separated in the centrifuge, and the platelet rich plasma is acquired, it is placed into a syringe and injected back into the patient at the injury site. These injections can be given in both intra-operative and non-operative settings.3 In the intra-operative setting, the platelet rich plasma will usually be injected directly into the newly repaired ligament or tendon, such as a reconstructed ACL. In the non-operative cases, the platelet rich plasma will be injected through the skin into the target site, such as the plantar fascia or a strained muscle. This non-operative application of platelet rich plasma is a very quick procedure that can be done in a normal visit to the doctor. After the injection is given, the patients are able return home or to work with minimal to no pain or swelling.1
Another method used in surgeries, such as ACL reconstructions, involves soaking or coating the tissues for the new ACL in platelet rich plasma before fixing the new ligament in place. Studies have shown other ways to apply platelet rich plasma, such as augmenting the sutures used for a specific surgery, but the primary application processes are injection and soaking.
How Platelet Rich Plasma Therapy Works
In order to fully understand how platelet rich plasma therapy works, the healing process for a musculoskeletal injury must first be understood.3 The repair of damaged musculoskeletal tissue starts with the formation of a blood clot to stop the bleeding, after which degranulation of the platelets begins.3 Degranulation is the release of granules or active substances from the cell itself. When a platelet degranulates, it releases the many different growth factors that it contains.3 The growth factors contained in platelet rich plasma include transforming growth factor beta (TGF-β), which is believed to stimulate collagen synthesis, platelet-derived growth factor (PDGF – AA, BB, and AB), insulin-like growth factor (IGF) which is believed to stimulate osteoblast proliferation and differentiation, vascular endothelial growth factor (VEGF) that is believed to augment early angiogenesis and revascularization, epidermal growth factor (EGF), and fibroblast growth factor-2 (FGF-2) that stimulates proliferation of osteoblastic progenitors as well as affect the division of stem cells and stimulate epidermal cell proliferation. Along with that those important growth factors, platelet rich plasma also includes platelet factor 4 (PF4), interleukin-1 (IL-1), platelet-derived angiogenesis factor (PDAF), platelet-derived endothelial growth factor (PDEGF), epithelial cell growth factor (ECGF), osteocalcin (Oc), osteonectin (On), fibrinogen (Ff), vitronectin (Vn), and thrombosspondin-1 (TSP-1).2,3,4 As a whole, these growth factors released by the blood platelets have been shown to enhance one or more phases of bone and soft tissue repair.2,3
In the case of platelet rich plasma therapy, because the platelets are not acting directly on a musculoskeletal injury, the blood clotting and degranulation will not begin on its own; therefore, the platelet rich plasma solution must be manually activated. There are two substances that can be used to activate platelet rich plasma: thrombin and calcium chloride.2,3 Due to the fact that the treatment being given is comprised of the patient’s own blood, there is a slim chance of the body reacting with any sort of inflammatory or immune response.1
How Platelet Rich Plasma has been Studied
Platelet rich plasma has been studied in three different ways, vitro: a study conducted not in a living organism, such as an animal or human, but in a controlled environment such as a test tube or Petri dish using cells of the tissue being studied; in vivo, a study conducted in a live animal rather than a human being, or in a controlled environment; and in human subjects. Studies have been conducted on platelet rich plasma therapy using many different tissue types with a wide array of results. Studies have been conducted on bone, ligamentous tissue, tendinous tissue, and muscular tissue with conflicting results. An example of this is the in-human study conducted by Silva and Sampio on the effectiveness of platelet rich plasma in enhancing tendon healing after an ACL reconstruction surgery, in vitro, in vivo, and in humans as well. 9-13
Although there is conflicting evidence on the effectiveness of the use of platelet rich plasma therapy, there is not yet a definitive answer on whether or not it truly stimulates the healing process and helps athletes return to play faster after an injury of any kind or magnitude. In athletics, if platelet rich plasma therapies are proven to stimulate and accelerate the healing process, the relevance of this substance can be helpful in assisting athletic trainers, physical therapists, and doctors in safely returning athletes to play more quickly and without compromising their health. But there is a great deal of research to be conducted on many varying aspects of platelet rich plasma therapy to render the necessary information about outcomes.
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