This study is a prospective randomized controlled study of different arthroscopic treatments for refractory external humeral epicondylitis combined with platelet rich plasma (PRP) injection. The patients with intractable external humeral epicondylitis were randomly divided into groups before the operation. After the arthroscopic operation was completed, they were divided into a local PRP injection group and a control group (normal saline) to perform additional operations on the damaged tendons, each for up to half a year after the operation. In different time periods, the quantitative and qualitative indicators including pain, functional score, muscle strength, MRI performance, etc. were compared between groups at the same time period to evaluate the difference in the effect of arthroscopic treatment combined with PRP on the treatment of damaged tendons. Determine the effectiveness of PRP. At the same time, in the process of arthroscopic treatment, look for risk factors that affect the curative effect of intractable external humeral epicondylitis, as well as the causes and prevention of common complications.

Inclusion Criteria:

• Clinically diagnosed patients with refractory external humeral epicondylitis (preoperative MRI confirmed loss of ECRB integrity) patients who have received non-surgical treatment with poor efficacy
• Young and middle-aged patients aged 20 to 60, who have not previously received local injection therapy
• Voluntarily accept randomized controlled grouping, cooperate with treatment and follow up patients
• No other comorbidities or medical diseases affect the surgical patients
• Unilateral disease

Exclusion Criteria:

• Early patients who have not received standard non-surgical treatment
• Patients who have received hormone injections or "small needle knife therapy" and other invasive procedures within three months before surgery, poor skin conditions, and local infections
• Elderly people older than 60 years old and patients younger than 20 years old
• Unable to accept randomization, insufficient follow-up time or lost to follow-up
• Bilateral disease
• Combined immune disease