Study: Leeches May Provide Relief from Knee Osteoarthritis Pain and Stiffness

Although the jury is still out among rheumatologists, modern medicine may have found a place for the folkloric treatment of leeches in providing relief from the pain and stiffness caused by knee osteoarthritis.

Leeches have traditionally been used as a treatment for localized pain. Their saliva is thought to contain anti-inflammatory substances. Since osteoarthritis has no cure, an important goal of therapy is to relieve pain and stiffness and maintain or improve physical function.

A team of German researchers evaluated the effectiveness of leech therapy in relieving the pain, stiffness associated with osteoarthritis of the knee in 51 patients who suffered from this condition.

This randomized trial compared a single application of four to six leeches to the affected knee with 28 days of treatment with topical diclofenac, a non-steriodal anti-inflammatory drug.

Patients who underwent leech therapy had less pain through the seventh day of the trial than those receiving diclofenac. Although the difference between group pain scores was no longer significant after day seven, differences for function, stiffness and total symptoms remained significant in favor of leech therapy until the end of the 91-day study and for quality of life until the 28th day of the study.

"Leech therapy helps relieve symptoms in patients with osteoarthritis of the knee," concluded the researchers. "The potential of leech therapy for treating osteoarthritis and the pharmacologic properties of leech saliva remain to be clarified."

In an editorial accompanying the study, Dr. Marc Hochberg, of the University of Maryland School of Medicine, expressed concerns about the study since it was not blinded and patients and researcher assistants knew what treatment they were receiving or administering. This could have led to bias, he added.

Another concern of Hochberg's centered on the short time frame for measuring the primary outcome variable of pain. "Seven days is but a brief moment in the long epic of knee osteoarthritis," he noted. "Indeed, the mean duration of symptoms in this study was 10 years."

If the authors pursue further research on leeches, Hochberg suggested that they attempt to find out what it is about leeches that relieves the symptoms of osteoarthritis in addition to comparing leech therapy with other local treatments, such as intra-articular corticosteroid injections.

"While future studies might demonstrate consistent efficacy of leech therapy, the more exciting aspect of this work is the potential for the discovery of a novel analgesic agent that could be safely administered without the need for a leech bite," said Hochberg. "This could benefit not only patients with osteoarthritis, but also patients with other causes of pain. At the moment, however, on the basis of these data, I am not ready to refer my patients with knee osteoarthritis for leech therapy."

Other sources: Annals of Internal Medicine 139:9; 724-730