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PRP Injections

Patients commonly ask our physiotherapists about Platelet Rich Plasma (PRP) injections, which have come to prominence recently as a strategy for improve healing for certain conditions.

So, what are PRP Injections? Are they safe? What populations are they used on? What are they used for? What does the current research indicate for dosages, applications, and prognosis?

History of PRP Injections

PRP injections were first used in the medical field in 1987 in open heart surgery. Since this time their usage has been widely experimented and has successfully expanded into the musculoskeletal field to treat common problems such as muscle, tendon and ligament injuries.

What is PRP?

PRP injections involve the removal of a small amount of the patient’s own blood, which is then placed in a centrifuge to split the blood into its three major components; red blood cells, white blood cells and platelets. It is these platelets which PRP injections aim to use, as platelets, which have clotting and growth factors known as platelet derived growth factor (contained in granules within the platelets), stimulate the inflammatory cascade to encourage the healing process. Sounds complicated, but basically it is these growth factors which stimulates your healing process, and PRP is basically harvesting your healing cells from your abundant blood supply, concentrating out the good stuff, which is then re-injecting them into your damaged tissue. The theory is that this will increase the healing process available at the damaged tissue.

Blood contains about 6% platelets. PRP injections, depending on the method of preparation and distraction, contain up to four times this amount, also known as a “supra-physiological platelet concentration”.

When are PRP Injections Used?

PRP injections are now widely used to treat a range of musculoskeletal injuries. The most common current uses include conditions such as:

  • Lateral Epicondylalgia (tennis elbow)
  • Medial Epicondyialgia (golfers elbow)
  • Patella Tendinopathy
  • Achilles Tendinopathy
  • Plantar fasciitis
  • Hamstring tendinopathy
  • Adductor tendinopathy
  • Gluteal tendinopathy
  • Hamstring muscle tear
  • Quadriceps muscle tear
  • Calf muscle tear

PRP injections are used commonly in the treatment of tendinopathies with the aim of increasing the growth factors to the area and stimulating healing. Tendons are structures that connect muscles to the bone. They are comprised of a strong weave of proteins that provide a durable anchor to the bone. If tendons are repeatedly placed under excessive strain they can start to form micro-tears in the collagen. These micro-tears heal slowly due to the poor blood supply to the tendon, as this slow healing process occurs, scar tissue is laid down in the tendon, which in turn increases the chance of re-injury. The PRP injection allows the growth factors to stimulate healing by restoring normal tissue function whilst preventing further tendon degeneration.

Does PRP Work? What does the Evidence Say?

Although these days the theory behind these injections is widely accepted, there is little high quality evidence to support their use. There are a number of small scale studies which document the effectiveness of PRP; however the quality of this evidence is poor, mainly due to the inconsistencies in the preparation method.

A Cochrane review (2014) studied 19 trials for different types of musculoskeletal injuries and found that the evidence available was insufficient to support the use of PRP. Fortunately, adverse effects are rare, so the injections are unlikely to do harm. Overall the research suggests the need to standardise the methods in order to improve the quality of the research. This is an emerging field of study, however, and an area to watch in the future for managing chronic tendon and muscle injuries.

As a result of the insufficient evidence to back up their use, these injections are currently not covered by Medicare.


  • Moraes W, Lenza M, Tamaoki M, Faloppa F, Belloti J. Platelet-rich therapies for musculoskeletal soft tissue injuries. Cochrane Database of Systematic Reviews 2014, Issue 4. Art. No.: CD01Q071, DOI: 10.1002/14651858.CDO1007l.pub3
  • Fenwick SA, Hazlelman BL, Riley GP. The yasulature and its role in the damaged and healing tendon. Arthritis Res. 20u2;4: 252-60. i
  • Sampson S, Gerhardt M, Mandelbaum B. Platelet rich plasma injection grafts for musculoskeletal injuries: a review. Curr Rev Musculoskelet Med. 2008 Dec;l(3-4):165-74.
  • Sanchez M, Anitua E, Drive G, Mujika I, Andia I. Platelet-rich therapies in the treatment of orthopaedic sport injuries. Sports Med. 2GG3-33{5):345-54.

Written by Amy Byrnes, Physiotherapist