Intrathecal baclofen for postoperative analgesia after total knee arthroplasty

Abstract

Study objective: To determine whether intrathecal baclofen is an effective adjunctive agent to decrease acute and chronic postoperative pain after total knee arthroplasty.

Design: Prospective, randomized, double-blind controlled trial.

Setting: Operating room and inpatient units of a university hospital.

Patients: 60 adult, ASA physical status I, II, and III patients presenting for total knee arthroplasty.

Interventions: Anesthesia was provided by spinal injection of 15 mg of 0.75% hyperbaric bupivacaine combined with either 100 mcg baclofen or saline. Sedation was provided with intravenous midazolam and propofol.

Measurements: Data were collected on adverse effects, opioid usage, and verbal pain scale (VPS) from 0 to 10. The study period was divided into six discrete time intervals that included the 1(st) 72-hour postoperative period and a three-month post-discharge follow-up telephone call.

Main results: The baclofen group used less morphine in the PACU than the control group (5 mg vs. 9.3 mg; P = 0.04). VPS were lower in the baclofen group than the treatment group, but significant differences could be demonstrated only in the time periods 48-72 hours and three months postoperatively. At three months, fewer patients in the baclofen group reported pain than the control group (8/27 vs. 19/29; P = 0.009). Regression analysis showed that the baclofen group was 4.5 times less likely to report pain at three months (95% CI: 1.5-16.6).

Conclusions: IT baclofen used as an adjuvant to spinal anesthesia for total knee arthroplasty allows for less postoperative opioid usage and less chronic pain at three months.