Complication rates and efficacy of single-injection vs. continuous interscalene nerve block: a prospective evaluation following arthroscopic primary rotator cuff repair without a concomitant open procedure.

BACKGROUND: To compare the complications and efficacy of pain relief of the interscalene anesthetic block using either a single-injection (SI) vs. a continuous, indwelling catheter (CIC) for arthroscopic rotator cuff repair surgery.

METHODS: Patients undergoing primary, arthroscopic rotator cuff repair without concomitant open procedure or biceps tenodesis were prospectively enrolled by 4 fellowship-trained sports medicine and shoulder surgeons. Patients received either a SI or CIC preoperatively based on surgeon preference. Patients were contacted by phone to complete a standard questionnaire on postoperative days (PODs) 1, 3, 7, 14, and 28. Patients were asked to rate the efficacy of their subjective pain relief (scale of 0-10), document issues with the catheter, describe analgesic usage, and report pharmacological and medical complications. The primary outcome was measured as complication rate. Postoperative narcotic use, patient satisfaction, and visual analog scale pain scores were measured as secondary outcomes.

RESULTS: Seventy patients were enrolled, 33 CIC patients (13 male, 20 female, mean age 61 ± 8 years) and 37 SI patients (20 male, 17 female, mean age 59 ± 10 years). There were significantly more injection/insertion site complications in the CIC group (48%) vs. the SI group (11%, P  = .001). The incidence of motor weakness was higher in the CIC group on POD 1 ( P  = .034), but not at any subsequent time points. On POD 1, CIC patients had a clinically significantly lower pain score compared to SI (3.2 vs. 5.4; P  = .020). Similar scores were observed at subsequent time points until POD 28, when CIC again had a lower pain score (0.8 vs. 2.7; P  = .005). However, this did not reach clinical significance. All patients in both groups rated a satisfaction of 9 or 10 (scale 0-10) with the anesthesia provided by their nerve block.

CONCLUSION: CIC interscalene nerve blocks had an increased risk for injection site complications and minor complications in the immediate postoperative period when using the CIC for arthroscopic rotator cuff repair without any concomitant open procedures. CIC blocks demonstrated clinically significant superior pain relief on POD 1 but were equal to SI blocks at every time point thereafter. Superior pain relief of CIC at POD 28 was not clinically significant. CIC catheters do not appear to markedly decrease the use of postoperative narcotics. Despite this trend in complication rates and pain scores, all patients in both groups were satisfied with their nerve block.