Posterior versus anterolateral approach interscalene catheter placement: a prospective randomized trial

Two distinctly different approaches to interscalene catheter placement have been in common use for close to a decade. This prospective randomized study tested the hypothesis that interscalene catheters placed using the posterior approach would provide a more effective analgesia after shoulder surgery compared with catheters placed using the anterolateral approach.

A total of 110 patients presenting for elective shoulder surgery were randomly assigned to receive an ultrasound-guided posterior (n=54) or anterolateral (n=56) interscalene catheter with 20 mL of ropivacaine 0.375% administered preoperatively via the catheter before surgery under general anesthesia. Ropivacaine 0.2% at 2 mL/hr with on-demand hourly 5-mL boluses was continued for more than 48 hrs with tramadol available as rescue. Patients were questioned in the recovery room, at 24 and 48 hrs after surgery, for pain, ropivacaine bolus, and tramadol consumption.

Patients were more frequently free of pain in the recovery room in the anterolateral group compared with the posterior group (mean, 91%; 95% confidence interval [CI], 84%-99% versus mean, 61%; 95% CI, 48%-74%; P=0.005). Rescue tramadol consumption was higher for the posterior group during the first but not during the second 24 hrs after surgery (day 1/day 2: 48%versus 27%, P=0.017 / 35% versus 27%, P=0.27). Postoperative pain, ropivacaine bolus consumption, numbness, weakness, neck discomfort, and satisfaction were similar between groups. Catheter threading difficulty was more common (33% versus 13%, P=0.012), and catheter placement time was longer (median, 9 min; interquartile range, 7.5-10 min versus median, 6.5 min; interquartile range, 6-8 min; P<0.0001) in the posterior group.

Anterolateral interscalene catheters perform more effectively and are procedurally more easily placed compared with catheters placed using the posterior approach.