Background and Aims This retrospective study aims to evaluate the efficacy, safety, and complications associated with two types of interscalene nerve catheters used in shoulder arthroscopy surgeries: the conventional-catheter and the catheter-over-needle.

Methods A comprehensive 7-year retrospective analysis was conducted at a single institution, involving 696 patients who underwent shoulder arthroscopy surgeries after taking an approval from the Local Ethics Committee (2020.023.IRB2.004). Patient characteristics included a mean age of 50.4 years, American Society of Anesthesiologists (ASA) classifications of ASA-1 (53.4%), ASA-2 (33.3%), and ASA-3 (13.2%), and a mean Body Mass Index of

25.34. Various surgery types were included, and the analysis focused on 610 patients with catheters.

Results Dyspnea was observed in 8.6%, while Horner syndrome was present in 13.2% of patients. Early catheter-dislodgement occurred in 5.2% of the conventional-catheter group and 1.9% of the catheter-over-needle group demonstrating a statistically significant difference (p=0.041). Late catheter dislodgement rates were 5.6% in the conventional-catheter group and 2.8% in the catheter-over-needle group, which did not reach statistical significance. Pain scores at 24-hours postoperatively were significantly lower in the catheter-over-needle group (mean NRS-score: 1.98) compared to the conventional-catheter group (mean NRS-score: 2.36).

Conclusions This retrospective evaluation of interscalene nerve catheter types in shoulder arthroscopy surgeries demonstrates that the catheter-over-needle technique yields a lower incidence of early catheter dislodgement, reduced rates of dyspnea and Horner syndrome, and significantly lower pain scores at 24 hours compared to the conventional catheter technique. The increasing utilization of the catheter-over-needle technique over time may have influenced the results due to the operator’s growing expertise.