Platelet rich plasma injections (PRP injections)
Blood contains plasma, red blood cells, white blood cells and platelets. Platelets are small discoid cells with a life span of about 7-10 days. Inside platelets contain granules which contain clotting and growth factors. During the healing process, the platelets are activated and aggregate together. They then release the granules which contain growth factors which stimulate the inflammatory cascade and healing process.
Blood typically contains 6% platelets whereas PRP has a significantly increased supra-physiological platelet concentration. Although this level can vary depending on the method of extraction and equipment, studies have shown that clinical benefit can be obtained if the PRP used has an increased platelet concentration of 4x greater than normal blood.
Platelet rich plasma injections (PRP injections) can be used in the treatment of many musculoskeletal injuries including that of tendons, muscles and joints. Typically 2 or more injections are required, separated by 4-6 weeks apart. This may vary dependant on your injury.
Platelet Rich Plasma (PRP) Injections for Tendons
What is the structure of tendons?
Tendons are made of special cells called tenocytes, water and fibrous collagen protein. These proteins weave together to make a strong durable structure that naturally anchor to bone. Tendons can transfer great force and thus can be injured if they are overused or overwhelmed. If this occurs, micro tears start to form in the collagen.
How do tendons heal after injury?
Injured tendons heal by scarring — this affects their strength and hence increases the risk of re-injury. Also, because tendons do not have a good blood supply, they tend to heal slower than other soft tissues (2-4).
Why is my tendon injury not improving?
As tendons have a poor blood supply, there is only a minimal inflammatory response. Without inflammation, the tendon repair system is limited and an abnormal pathological response occurs called angiofibroblastic degeneration (5-7). This degenerative response to the micro tears in collagen is the essence of tendinopathy or tendinosis. Often pain, localised tenderness, swelling and impaired performance occurs (8).
How have tendons been treated traditionally?
Traditional therapies do not address the inherently poor healing properties of tendons. Corticosteoid is sometimes injected but adverse effects such as atrophy and permanent structural damage to tendons can occur (6). Non steroidal anti-inflammatory medications (NSAIDs) can cause gastrointestinal or kidney damage (1).
How is PRP different?
PRP injections aim to embrace and stimulate the inflammatory process which in turn will encourage the healing process. PRP focuses on restoring normal tissue composition while avoiding further degeneration.
Which tendon injuries can be treated with PRP?
PRP can be injected into:
- Tennis elbow (common extensor tendinosis)
- Golfer’s elbow (medial epicondylitis)
- Jumper’s knee (patellar tendinosis)
- Achilles tendinosis
- Plantar fasciitis
- Hamstring tendons
- Adductor tendons
- Gluteal tendons