The Blood, Plasma and Platelets – what is their function in the body?
Blood is made up of 55% Plasma, 45% red blood cells and 1% white blood cells and platelets. Plasma is the liquid element of blood and comprises 92% water. Plasma suspends the cells and platelets in our bloodstream, transports waste products to the kidneys, and nutrients, proteins and hormones to our lungs and tissues. The best known function of platelets is in clot formation to control bleeding and in repairing vascular walls (blood vessels) after injury. More recently however, the bioactive growth factors in platelet-rich plasma are being recognized for their importance in the healing process.
How important are Platelets?
The platelets in plasma are critical to our health, healing and injury repair. This includes coagulation (blood clotting), immune response (defense from infection and disease), angiogenesis (the formation of new blood vessels), and in the healing of damaged tissues. Platelets contain an abundance of growth factors (proteins) that activate cellular proliferation (increase the number of cells), and stimulate the body’s natural ability to heal. The cytokines in platelets are a special group of proteins that work in the repair and modulation of inflammation in the process of tissue regeneration. Cytokines are pivotal in soft tissue healing and bone mineralization (Sampson et al, 2008).
What is Platelet-Rich Plasma (PRP)?
PRP is a solution of plasma in which the red and white cells have been removed. It contains a supra-physiological (greater than amounts normally found in the body) platelet concentration – this can be 5 to 10 times greater (or richer) than normal. PRP is a common procedure used in musculoskeletal medicine as an adjunct therapy to traditional rehabilitation.
It is used to great effect in the treatment of sports injuries and degenerative conditions in cartilage, tendons, ligaments, joints and bone tissue. PRP therapy works by accelerating the healing process through tissue regeneration and elicits healing in muscle and connective tissue. PRP has become a therapeutic option in the treatment of tendon injuries that fail to respond to other more traditional rehabilitation therapies. PRP is proven to reduce pain and increase function in the long term.
Concentration of Platelets
Normal blood contains 50,000 – 450,000 platelets per microliter. Whereas in platelet-rich plasma this can vary from 2.5 – 9 times in concentration depending upon the individual’s blood and how much blood is drawn during the centrifuge process used in the separation of blood and plasma.
PRP is autologous (made from the patient’s own blood)
The platelets in PRP are autologous and re-injected into the site of an injury. PRP stimulates healing by delivering a high concentration of platelets to the site of an injury. PRP solutions vary, as blood and plasma content is a little different in each patient. The approach taken by physicians in preparing and formulating the solution may also differ. Therefore it is important to use a specialist practitioner with extensive experience in separating plasma and in obtaining good results.
Tendons have poor healing properties due to an inadequate blood supply and a lack of inflammatory response to promote healing. Without inflammation, the tendon repair system resorts to an abnormal pathological response called ‘angiofibroblastic degeneration’. Tendons heal by scarring, this results in a weakened tendon and increased risk of re-injury. PRP is focused on restoring tissue composition to diminish the risk of further degeneration and re-injury.
Traditional therapies, unfortunately, do not address the poor healing properties of tendons. The use of injected corticosteroids has been commonplace, however, they do not provide
a healing solution. In direct contrast to PRP, they can cause atrophy and permanent structural damage to tendons (Sampson et al, 2008). In addition, corticosteroids are found to provide only short-term pain relief (Coombes et al, 2010). Alternatively, the use of non-steroidal anti-inflammatories can result in gastrointestinal or kidney damage (www.prpinjection.com.au, 2018).
PRP in sports injuries and degenerative conditions
PRP is often used in the treatment of damaged or diseased tendons (referred to as tendonitis or tendinopathy). PRP can alleviate pain and symptoms in conditions such as Tennis elbow (common extensor tendinopathy and lateral epicondylitis), Golfers elbow (common flexor tendinopathy), Knee Tendinopathy, Achilles Tendinopathy, Heel Spurs (Plantar Fascitis), Hamstring tendons and mild to moderate osteoarthritis. Muscle injuries occurring in Hamstrings, Calf and Quadriceps can also be successfully treated with PRP – as well as Trochanteric Bursitis (inflammation of the Bursa affecting joints).
Musculoskeletal injuries – almost at ‘epidemic levels’ in the U.S
Studies in the U.S have found that soft tissue injuries, including tendon and ligament trauma, represent almost half of all musculoskeletal injuries. The cause of this is the increasing popularity of sporting activities and fitness regimes. Musculoskeletal disorders have reached almost epidemic levels – with most attention focused on tendons (Sampson et al, 2008). Tendons account for some 30-50% of all musculoskeletal injuries and often result in a significant restriction in activities. This trend applies not only to elite athletes and active sports participants but to joggers and ‘weekend’ fitness enthusiasts.
Achilles tendon tears and Jumpers knee
Sports or recreational activities that involve running and jumping are particularly susceptible to tendon damage. Running for example generates a force inside the Achilles tendon equal to ten times the body weight (medicinenet.com, 2018). The severity of injuries due to overuse or a degenerative condition can range from acute to chronic. In Achilles tendinopathy partial ruptures (due to micro-tears in collagen fibres) left untreated may lead to complete tendon rupture. Research provides evidence of the effectiveness of PRP in the acceleration of healing and functional recovery following PRP treatment in acute Achilles tendon tears (Alsousou et al, 2012). In other studies, it was found that PRP provides long-term persistence in patellar tendinopathy (over-stress of the patellar tendon resulting in Jumpers Knee) a common cause of premature retirement in the careers of athletes (Jeong et al,2014).
How is PRP treatment administered?
An MRI (magnetic resonance imaging) or musculoskeletal ultrasound may be needed prior to the treatment. This is to ensure proper treatment, pinpoint the injection site, and exclude other treatments that may be more suitable. A typical procedure may take between 45 to 90 minutes. This is because the patient’s blood is first drawn and a solution is prepared in the centrifuge that separates blood from plasma. PRP is injected directly into the damaged area to provide stimulation that causes mild inflammation and triggers the healing cascade. In some injuries, PRP may even be used to improve healing after surgery and stitched into torn tissues.
The number of injections needed will depend upon the specific condition. Patients may require just a single injection, or two or more injections depending upon the injury – these are separated by 2 – 4 weeks. Side effects are uncommon although the procedure may cause some localized soreness and discomfort lasting several days. An over-the-counter analgesic such as Paracetamol can relieve this. (To complement PRP, an eccentric exercise programme is often recommended. This can increase the tensile strength of tendons and speed up recovery).
PRP therapy is effective in both the short and long term with good and stable results in periods of 1 to 4 years (Filardo et al, 2014). Recovery following treatment may take weeks or months, but when successful the effect is long-lasting. Optimal effects are usually seen at 6 to 9 months.
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