Summary

This study shows for the first time the effectiveness of using periarticular injection of Gonyautoxina after TKA without motor block

Abstract

Background

Improvements in pain management in the last decade have had a major impact on total knee arthroplasty (TKA). Gonyautoxin is a phycotoxins, whose molecular mechanism of action is a reversible block of the voltage-gated sodium channels at axonal level, impeding nerve impulse propagation. This study was designed to evaluate the clinical efficacy of Gonyautoxin infiltration as long acting pain blocker in TKA. Methods: Fifteen consecutive patients enrolled for TKA received periarticular injection in different anatomic landmarks for a total dose of 40 µg of Gonyautoxin. All patients received spinal anesthesia alone (2.5 mL. 0.5% bupivacaine). Postoperatively all they received 100 mg intravenous ketoprofen (e.v.) + dipyrone 1gr e.v + paracetamol 1000 mg orally every 8 hours. Visual analogue scale (VAS) for pain and range of motion were recorded 12, 36 and 60 hours post-surgery. The results were compared with the cohort of TKA performed in 2014 at our center. Successful was considered a VAS of 4 or less, full extension and flexion equal or greater than 90°. The data are summarized in median, range and percentage of success. To compare with 2014 cohort, repeated measures logistic regression was performed by Stata v11.2 (StataCorp LP, College Station, Texas, USA).Results: All patients had 4 or less in VAS pain scale at 12, 36 and 60hrs post surgery. All patients achieved full extension, while the median ROM was 100 °, 100 ° and 97 ° at 12, 36 and 60 hrs respectively. No adverse effects were reported. The median hospital stay was 3 days. Gonyautoxina patients had an odds ratio of 22, 12 and 4 for success in VAS pain, full extension and flexion equal or greater than 90° compared to 2014 TKA cohort. Conclusions: This study shows for the first time the effectiveness of using Gonyautoxina in TKA Fifteen patients had successful postoperative analgesia without motor block, more ROM and shorter hospital stay.