Osteoarthritis of the knee is a very common and chronic condition, in particular among people over the age of 55. Caused by a degeneration of knee cartilage, this condition results in pain and stiffness in the joint, leading to decreased knee function and an associated drop in quality of life. Osteoarthritis is commonly treated by physiotherapy, pharmaceuticals (pain-killers and anti-inflammatory drugs), and surgery. Physiotherapy is usually recommended as an effective first-line treatment, typically involving manual therapy to assist with joint stiffness and pain, modalities for additional symptomatic relief, and most importantly, exercise therapy. For more advanced cases of degeneration, in particular where individuals are unable to participate in a rehabilitation program, surgery becomes necessary. Unfortunately, those who don’t want surgery are left to rely primarily on pharmaceuticals… or sometimes leeches.
Last week, the first systematic review of the clinical data regarding the use of leeches for treating Osteoarthritis was published (Lauche R., Cramer H., et al. A Systematic Review and Meta-Analysis of Medical Leech Therapy for Osteoarthritis of the Knee. Clin J Pain. 2013 Feb 26 Epub). The authors of this paper found moderate to strong evidence that medical leech therapy can be effective for decreasing pain, functional impairment and stiffness in patients with Osteoarthritis. Could this be true?
No longer a fringe medical practice relegated to the annals of medical history, leeches are currently used medically in North America and Europe to improve circulation and stimulate tissue reattachment during some types of reconstructive surgery. There are also many less well validated uses of medical leeches, including in Germany where they can be used to treat Osteoarthritis. The saliva of leeches contains both known and as yet unidentified anticoagulation, anti-inflammatory, and anesthetic compounds. So the possibility of an effect in Osteoarthritis is definitely not out of the question.
Although this systematic review is interesting, only four clinical data sets were found suitable to be included in the authors’ final analysis, and these studies only examined effects for up to 6 months following treatment. For these reasons the authors appropriately recommend that additional high-quality randomized controlled trials be performed. Unfortunately, high-quality clinical trials on this subject are difficult. Controlling for the placebo effect by “blinding” the therapist and patient to the treatment type (either leech or sham treatment) would be nearly impossible. One of the studies included in the above analysis actually tried to use fake leeches, but was understandably unsuccessful in fooling participants.
The medical leech hypothesis for treating Osteoarthritis is also missing a mechanistic underpinning for the reported effects. Is it realistic to expect that the act of bloodletting, or the introduction of small amounts of bio-active compounds in leech saliva could actually work for this condition?
So are leeches on their way to a clinic near you? In Germany perhaps, but here in Canada it’s not very likely, at least not without considerable additional clinical validation. Perhaps research into identifying, synthesizing, and testing the active compounds in leech saliva may lead to a more palatable treatment option for Osteoarthritis patients.