Background Mild to moderate osteoarthritis (OA) knee pain is often poorly controlled despite recommendations of efficacious therapy. These are compounding in the fact that many patients are either intolerant to some therapeutic options (NSAIDS) or co-existent morbidity may present high risk further morbidity (total knee joint replacement). Intra-articular therapies with Hyaluronic Acid (HA) have been shown to be efficacious and relatively free of adverse events. Further, limited data support the use of botulinus toxin in off label intra-articular use in patients with OA of the knee, ankle, and shoulder. HA therapeutic effectiveness has been described as the result of alteration of the rheologic properties of the synovial fluid ± analgesic and anti-inflammatory effects. Botulinus toxin has been shown to inhibit release of neuropeptides such as substance P and calcitonin gene-related peptide (CGRP) and hence decreased noci-ceptor function resulting in decreased pain and neurogenic inflammation.
Objectives To describe the efficacy and safety of combined intra-articular HA combined with Botulinus toxin in patients with mild to moderate OA of the knee.
Methods Forty-five patients with Grade 2-3 unilateral knee OA were randomized using a computer generated program to one of two groups to receive: 2.8cc (750- 1300kDa) of intra-articular HA + 100 units botulinus toxin or 2.8cc saline placebo. Double-blind assessments were made at the baseline, 1, 3 and 6 months. Two injections were made within seven days. The primary outcome measure was the WOMAC index pain score and function score. Secondary outcomes included WOMAC walking pain as well as weight bearing pain VAS, patient and physician global assessment of pain and function. Adverse events according to WHO criteria were also collected at each assessment.
Results The 45 patients included 18 males. Six placebo patients withdrew after one month due to lack of efficacy, two patients experienced local pain at the injection site in the HA:Botox group and one patient in the placebo group. No serious adverse events were reported. A significant decrease in WOMAC pain score from 7.1 (standard error 1.0) to 3.2 (standard error 0.9, p < 0.01) and improvement in WOMAC physical function score 8.9 (2.2) to 3.8 (1.3, p < 0.01) after one month in the intervention group while there are no significant improvements in the placebo group. Walking pain VAS decreased from 7.1 to 3.2 (p < 0.01). Similar improvement was observed at 3 months in the intervention group. Improvement was sustained at 6 months.
Conclusions Combined intra-articular HA + Botulinum toxin produced clinically and statistically significant improvements in OA knee pain and physical functioning. These results were persistent to 6 months. There were no significant adverse events in either group. These data provide support for the efficacy of this novel approach to local treatment in OA of the knee.
Disclosure of Interest None Declared
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