We wish to address the efficacy and safety of Platelet Rich Plasma (blood platelets), a new treatment for lateral epicondylitis (tennis elbow) and compare this new treatment to either injection with steroid or saline solution.

All injections are guided by ultrasonography.

Plate Rich Plasma (PRP) is a new treatment for tendinopathy. A high concentration of blood platelets is made from the patients own blod, and then injected into the tendon. The idea is that the complex mixture of growth factors within the platelets can stimulate the healing process of the tendon. We want to address the efficacy and safety of this new treatment and compare it to either the best documented treatment, Steroid injection, or to a saline solution. We want to make a randomized controlled trial with 60 participants, 20 in each of the 3 groups, and a 12 months follow up. All injections are guided by ultrasonography.

Inclusion Criteria:

• Duration of tennis elbow > 6 months
• Doppler activity on ultrasonography
• Lateral elbow pain that is maximal over the lateral epicondyle, and increases with pressure on the lateral epicondyle, and resisted dorsiflexion and/or middle finger.

Exclusion Criteria:

• Inflammatory disease.
• Fibromyalgia.
• Pain in hand or shoulder/neck in the same arm as being treated.
• Anticoagulation treatment.
• Wounds around the elbow.
• Treatment with steroids within the last 3 months.