Introduction: Historically physicians have used leech therapy for various ailments. Hirudo medicinalis is commonly used in western countries for medicinal purpose and in other parts of the world, different species are used. In India, Hirudinaria granulosa species is used traditionally for this purpose. Although this treatment approach has been used for many centuries, there is little scientific data on its effectiveness. The aim of this study was to validate the efficacy of leech therapy in knee osteoarthritis.

Materials and methods: This study was a randomized, parallel group, controlled trial with the approval of Institutional ethics committee. The total of 60 patients, 30 in each group, completed the study. The outcome measures included; Visual Analogue Scale (VAS), Knee injury and Osteoarthritis Outcome Score (KOOS), range of motion, 15-m walking time and knee circumference were used to assess clinical efficacy. The test group received leech therapy along with a Unani formulation. The other group (control) received the Unani formulation only.

Results and discussion: The test group demonstrated highly significant improvements in evaluated parameters when compared with baseline values. Statistically significant differences were observed in KOOS total score and its sub scores (P < 0.0001), VAS (P < 0.0001) at the 4th week when compared with the control group. The reduction in pain, other symptoms and physical function, were observed even 4 weeks after the treatment (P < 0.0001).

Conclusion: The leech therapy seems to be an effective treatment for reducing symptoms of knee osteoarthritis and improving physical function with no major adverse effects.