Previous studies have not addressed the question, whether or not a repeated leeching can supply symptomatic relief of osteoarthritic pain for extended periods of time. We present a randomized study to the effectiveness of single and repeated leech therapy in cases with advanced osteoarthritis of the knee using a large patient group compared to a control group, who were both blinded to the actual treatment modality.

Inclusion Criteria:

• Osteoarthritis of the knee
• Persistent osteoarthritic symptoms for at least 6 months
• Radiographic evidence of late stage osteoarthritis of the knee (stage III-IV)
• History of conservative management including pain medication and physical therapy

Exclusion Criteria:

• Anticoagulant treatment or history of hemophilia
• History or presence of rheumatic diseases leading to secondary osteoarthritis
• Presence of hematological, hepatic, renal or immunological disease
• Insulin-dependant diabetes mellitus
• Intraarticular injections or systemic application of corticosteroids during the 3 preceding months
• History of surgery of the affected knee during the last 3 months or joint replacement
• History of previous leech therapy
• Lack of informed consent