Subcutaneous botulinum toxin type a injection for chronic medial knee pain with ostheoarthritis

ABSTRACT

BACKGROUND:This study was designed to evaluate the efficacy of subcutaneous Botulinum toxin type A (BoNT-A) injection for treating chronic medial knee pain with osteoarthritis. METHODS:A randomized, double-blind, placebo-controlled clinical trial was conducted at a university hospital in Korea.The subjects suffering from chronic medial knee pain with osteoarthritis were randomly allocated to either the BoNT-A (treatment, n = 23) group or the normal saline (placebo, n = 27) group.Injections were given to 10 points per unilateral knee along the course of the saphenous nerve.A total of 90 units of BoNT-A (60 units at baseline and 30 units after 1 week) was given for treating unilateral knee pain and a total of 180 units of BoNT-A was given for treating bilateral knee pain.The placebo group received the same volume of normal saline. RESULTS:The Visual Analog Scale (VAS) pain score was significantly decreased in both the BoNT-A and normal saline groups 1, 4 and 12 weeks after injection.After adjusting for covariates, BoNT-A had a 0.788 times higher effect to decrease the VAS score than did normal saline, but the effect was marginally significant (P = 0.050). CONCLUSIONS:Subcutaneous injection along the course of the saphenous nerve significantly reduces chronic medial knee pain. The pain reduction effect of BoNT-A is higher than that of placebo, but the effect is marginally significant