Is There Benefit in Using an Adductor Canal Catheter in Knee Arthroplasty? A Randomized Clinical Trial

Adductor canal catheters (ACCs) are widely used for adjunctive pain control for patients undergoing total knee arthroplasty (TKA), but no fully powered clinical trial of the device has been reported despite the device's cost and potential adverse effects. We conducted a randomized, open-label, non-inferiority trial to assess whether not implanting the ACC was noninferior to implanting an ACC on second-postoperative-day pain levels among patients undergoing elective primary TKA.

Patients undergoing elective primary unilateral TKA in an orthopaedic practice in one medical center were eligible. All participants received intraoperative periarticular injections of long-acting anesthetics and were randomized 1:1 to have an ACC placed preoperatively (standard-of-care control condition) or not have an ACC placed (intervention arm). The primary outcome was the patient-reported 0 to 10 numerical rating scale for pain on the second postoperative day. Secondary outcomes included pain scores and medication use over the 15-day postoperative period, hospital length of stay, and return to care. In all, 126 patients were randomized.

The mean difference in the primary outcome was 1.06 points with a 95% confidence interval of 0.18 to 1.94; since the upper bound did not cross the predetermined noninferiority margin, noninferiority was confirmed. There was no significant difference in mean total opioid tablets consumed over the 15-day postoperative period (46.0 tablets (ACC group) versus 41.9 tablets (non-ACC group), P = 0.55). There were no significant differences in hospital length of stay or frequency of return to care.

We found that not using the ACC was noninferior to using the ACC, suggesting that the incremental benefit of the ACC is small and likely of insufficient magnitude to justify its routine use for patients undergoing TKA. Further trials will be helpful in defining the appropriate use of this costly technology; until such evidence becomes available, the value of the ACC for most patients remains in doubt.