PRP Injections

Platelet rich plasma (PRP) has soared in use in the last decade. Many scientific advancements in understanding tendon injury, degenerative disease, and improved imaging with musculoskeletal ultrasound have fostered the use of platelet rich plasma for regenerative therapies.  PRP injections are very useful in repairing injured tissues for many diseases and has helped athletes return to sports at a rapid pace following an injury. It has been proven in scientific studies to accelerate wound healing because PRP treatmentscontain many growth factors for tissue and blood vessels. These are especially significant for damage to tendons, ligaments, and cartilage because normally they have poor blood supply and very slow healing. Theplatelets produce a clot and release growth factors that attract inflammatory cells at the site of injury. PRP contains many components that modulate growth and progression of wound healing from inflammation to proliferation. At the end of the healing process there is increase in blood supply and therefore nutrition to facilitate tissue healing.

Components of PRP.  The main component in PRP is platelets. Platelets contain alpha granules.  Alpha granules contain growth factors and cell signaling molecules that attract cells to repair a damaged area. The platelets form a fibrin matrix that serves as a tissue scaffold and fundamental building block.  The scaffold holds the platelets and will continue to produce signals for growth factors, recruitment, differentiation, and communication with healing cells. Important growth factors include PDGF, TGF-Beta, VEGF, EGF, basic FGF, and IGF-1.

These growth factors have various functions that play a key role in regenerative medicine. For example, PDGF stimulates growth of cells, differentiation, and increased blood vessel formation. Other growth factors are involved in skin development, strength improvement in wounds, matrix secretion, protease inhibition.

Platelet concentration from 4-6 times greater than whole blood have been made. Scientific studies show that 1.5 million platelets (per uL) have been optimal to promote vascular healing. More than that ironically can cause inhibition of vascular healing. In studies involving wound healing of the skin,0.5-1.5 million platelets have been found to be optimal. A platelet rich preparation can enhance hyaluronic acid secretion in fibroblasts from arthritis patients.

Leukocytes are white blood cells contained and PRP. They fight infection, promote inflammation, and promote wound healing. Another name is neutrophils.

Monocytes and macrophages enhance tissue repair by removing the damaged tissues. Macrophages have been shown in studies to aid in bone regeneration. These cells are critical and protecting against infection.  Monocytes and lymphocytes. It is believed that a help in stimulating collagen production and fibroblasts.

Current areas were further study is needed to involve obtaining the exact and optimal concentration of PRP. For example, inclusion of mononuclear cells, neutrophils, and red blood cells have been found to also affect the inflammatory responses after an injection. This will alter the effectiveness.  Red blood cell concentration has been focused significantly for study. Once study found higher concentrations of red blood cells in PRP increases inflammation. It also showed cells in the joint tended to die when high concentrations of red blood cells are in the PRP. This was compared to PRP that had high or low white cells.

Leukocyte (white blood cell) concentration in PRP also seems to affect the outcome. High white cell content in PRP promotes inflammation and includes many signaling molecule called interleukins.  In addition, there are high amounts of proteases that degrade tissue.  There is also higher synovial site death one high white cell content is in PRP. Thus when treating osteoarthritis, low white cell PRP is thought to be more beneficial.

Many companies cell PRP kits with varying concentrations of platelets, white blood cell, and growth factors.

Rotator cuff disease.Rotator cuff disease can be treated with PRP.  Shoulder injury of the soft tissue is very common with prevalence as high as 60%. The majority of these injuries resolved from 6 months to one year. Conservative management with physical therapy and pain control is the preferred initial option after diagnosis.

If conservative options do not improve the symptoms regenerative medicine may be instituted.  Repetitive stress due to high demand activity on the shoulder will lead to collagen fatigue and later on partial rotator cuff tear as. Risk factors such as age, strenuous activity, deconditioning make patient’s prone to injury. Evidence shows PRP treatment promotes normal collagen matrix synthesis and decreases degradation and inflammation by cytokines.  Studies have shown a single ultrasound guided injection into rotator injury resulted in significant and sustained improvement of pain and function compared to conventional steroids or physical therapy. Randomized controlled studies on rotator cuff tears treated with PRP injection resulted in lower recurrence of tears at 2 years follow-up compared to saline injection. Various studies have suggested that PRP positively affects rotator cuff healing.

PRP injection has also been applied to various other joint and orthopedic conditions including hip injury, hip labral tears, ACL injury, knee injury. In meniscal tears, data shows increased rates of healing following ACL repair. With respect to knee arthritis, PRP treatment helps with cartilage growth and proliferation. Cartilage cells called chondrocytes have increased sympathetic capacity following PRP application.  With respect to hip arthritis, PRP injection has helped patients improve their pain and function for patients followed up to one year.

Plantar fasciitis has been studied in randomized controlled trial showing PRP treatment as more effective than steroid to reduce pain with a 3-monthfollow-up. Functional improvement also occurred in patients with chronic plantar fasciitis.

Greater trochanteric pain has also responded well as a safe and effective treatment when applied using ultrasound guidance. One single blinded prospective study shows pain reduction and ultrasound findings improved with PRP injection.