Purpose

The goal of this study was to compare the periarticular infiltration of Gonyautoxin 2/3 (GTX 2/3) and of a mixture of levobupivacaine (Chirocaine®), ketorolac, and epinephrine in patients undergoing total knee arthroplasty. The total morphine consumption during hospital stay was selected as the primary outcome.

Methods

Forty-eight patients were randomly allocated to receive periarticular infiltration of 40 µg GTX 2/3 (n = 24) or a combination of 300 mg of levobupivacaine, 1 mg of epinephrine, and 30 mg ketorolac (n = 24). Intraoperative anesthetic and surgical techniques were identical for both groups. Postoperatively, all patients received patient-controlled analgesia (morphine bolus of 1 mg; lockout interval of 8 minutes) as well as acetaminophen (1 g orally every 6 hours) and ketoprofen (100 mg IV every 8 hours) for 72 hours. A blinded investigator recorded morphine consumption. The range of motion and static and dynamic pain were assessed at 6, 12, 36, and 60 hours after surgery. The incidence of adverse events (e.g., postoperative nausea/vomiting, pruritus, somnolence, respiratory depression), time to readiness for discharge, and length of hospital stay were also recorded.

Results

No intergroup differences were found in terms of total cumulative morphine consumption, which was 9 mg (range, 0 to 54 mg) in the Levobupivacaine group and 16 mg (range, 0 to 62 mg) in the Gonyautoxin group. Furthermore, static and dynamic pain scores were similar at all time intervals. GTX 2/3 was inferior in range of motion at 6 and 12 hours; nevertheless, we noted no difference after 36 hours. No intergroup differences were found in terms of complications, side effects, or length of hospital stay.

Conclusions

No significant differences were found between groups in terms of breakthrough morphine requirement. However, the use of local anesthetic resulted in an increased range of motion in the first 12 hours. This study shows that GTX 2/3 is a safe and efficient drug for pain control after TKA.