This study is a prospective randomized controlled study of arthroscopic release for primary osteoarthritis of the elbow with stiffness with or without ulnar nerve release. The patients with primary osteoarthritis of the elbow with stiffness, which ulnar neuropathy proven by electromyography without clinical symptoms, were randomly divided into groups before the operation. Before the arthroscopic operation was began, the procedure of ulnar nerve release was performed according to the group(release group or unrelease group). In different time periods postoperatively, the quantitative and qualitative indicators including pain, functional score, muscle strength, etc. were compared between groups at the same time period to evaluate the difference in the effect of arthroscopic treatment combined with ulnar nerve release.

Inclusion Criteria:

1. Age >18 years
2. Primary osteoarthritis of the elbow with stiffness. Osteoarthritis was confirmed on CT-arthrography, by cartilage damage, osteophytes or local or global joint impingement.
3. Ulnar neuropathy proven by electromyography without clinical symptoms
4. Failure at least 6 months of conservative treatment
5. Availability of medical information for >2 years of follow-up

Exclusion Criteria:

1. Severe skin contracture or wound problem that could affect the neurovascular structures or require flap surgery.
2. Revision surgery
3. Ulnar nerve pathology results in clinical symptom such as motion and feeling deficiency
4. Other indication for elbow arthroscopy: synovial or inflammatory rheumatoid pathology, osteochondritis dissecan, acute infection, tumor or pure capsular stiffness.
5. Inadequate or loss of follow-up
6. elbow instability