Leech therapy in knee osteoarthritis: mechanism and effects

Abstract

Bloodletting is an ancient therapy and is being practiced in terms of leech therapy as well as cupping with scarification for treating various illnesses. According to Unani classics many diseases are the result of imbalance of body humors and that can be brought in equilibrium by releasing blood. Leech therapy has remained a popular option among Unani physicians for this purpose. Hirudo medicinalis has long been used as medicinal leech in European countries, whereas in India, Hirudinaria granulosa is used traditionally for therapeutic purposes. Leech therapy is being practiced in knee osteoarthritis very effectively. Recently, several clinical trials have been conducted in knee osteoarthritis that have showed better outcomes with minimal adverse effects. Earlier it was believed that the beneficial effects of leech therapy are merely due to the bloodletting process, whereas, later on scientists are able to discover various bioactive substances in leech saliva. These bioactive substances are injected in to the body tissues during leech bite. It is the bioactive substances which are responsible for these beneficial effects. At present more than 100 bioactive compounds have been isolated that include anticoagulants, antistasins, protease inhibitors, prostaglandins, histamine-like vasodilators, and poorly characterized anesthetic and analgesic compounds. Therefore, the possible mechanism of action of leech therapy in knee osteoarthritis are due to anti-inflammatory, analgesic and anesthetic action, increasing tissue perfusion, relieving oedema and stiffness by reducing venous congestion, facilitating the nutritive and anabolic substances to reach the knee joint by improving blood circulation, increasing the availability of medicaments by its tissue spreading action.