Enhancing intraoperative visibility: A prospective blinded comparative study on the efficacy of epinephrine injections to the portal site in arthroscopic rotator cuff repair

INTRODUCTION

Arthroscopic shoulder surgeons frequently encounter challenges related to compromised visibility, a concern exacerbated by the inability to employ a tourniquet and the necessity of performing crucial surgical maneuvers in the extra-articular sub-acromial space, particularly in rotator cuff surgery.^[1] The risk of inadvertent damage to vascular structures and ensuing active bleeding is significant when the intricate vascular anatomy in the subacromial space is disregarded.^[2] Despite advancements in arthroscopic instrumentation and the diligent efforts of anesthesiologists, intraoperative bleeding within the subacromial space remains a persistent issue, impeding visibility during shoulder arthroscopy.^[3] Consequently, this hampers the efficiency of the operative technique, prompting surgeons to resort to cautery, thereby heightening the potential for iatrogenic injuries.

Enhancing intraoperative visualization stands paramount in enabling orthopedic surgeons to execute procedures safely and with precision. The degree of visibility is measured based on various outcomes of assessment.^[4] Various evidence-based strategies have been suggested, such as intra-articular or intravenous tranexamic acid (TXA) and the utilization of TXA/epinephrine for irrigation.^[5-7] Furthermore, the efficacy of portal-site injections with epinephrine in improving visualization during knee arthroscopy has been established.^[8] Notably, there is a dearth of comparative studies addressing the specific context of shoulder arthroscopy.

The aim of our study was to examine the potential enhancement of intraoperative visualization through injections of 1:200,000 epinephrine to the portal site during arthroscopically performed rotator cuff repair. The underlying hypothesis suggests that these diluted epinephrine injections may lead to improved visualization and a reduction in operative time for shoulder procedures.

MATERIALS AND METHODS

This was a prospective, blinded comparative study. It was conducted to assess the impact of a 1:200,000 epinephrine solution injection to the portal site on intraoperative visibility during arthroscopically performed rotator cuff repair.

Inclusion criteria were patients having partial-thickness supraspinatus tears, specifically those classified as Neer stage 3 or Ellman Grade 2.

Exclusion criteria comprised a history of cardiovascular disease, coagulative disorders, diabetes mellitus, pre-operative thrombocyte counts below 150,000 platelets per microliter (mL) of blood, those allergic to epinephrine, and excessive use of non-steroidal anti-inflammatory drugs.

Our study employed a single-blinded design. Patients were blinded to group allocation, while the surgical team administering the intervention was aware of the treatment. Epinephrine and placebo (saline) injections were prepared in identical syringes by a third-party nurse not involved in data collection. Allocation was randomized using a computer-generated sequence, and group assignments were concealed in sealed envelopes to ensure allocation concealment. Participants were categorized into two groups after being assigned consecutive numbers: The intervention group (injection) and the control group (no injection). Informed consent, both written and verbal, was obtained upon admission to the hospital.

Under general anesthesia, patients received a pre-operative ultrasound-guided inter-scalene brachial plexus block (IBPB), and a standardized lateral decubitus position was maintained throughout the surgeries. Flow rate and arthroscopic pump pressure were set at 100 mL/min and 70 mmHg, respectively.

The intervention involved administering approximately 30 mL of 1:200,000 epinephrine with 1% lidocaine to every odd-numbered patient at the start of the surgery by the surgeon. The injections, totaling 10 mL each, were applied to the lateral, anterolateral, and anterior portals, reaching both subcutaneous and intramuscular layers. No repeat injections were administered.

Primary outcome assessment focused on intraoperative visibility, utilizing an ordinal, unipolar 5-point Likert scale^[9] [Table 1] and Johnson’s visibility classification.^[10] Secondary outcomes included the need for temporary increases in arthroscopic pump pressure, requests to lower blood pressure from the anesthesiologist, and operative time. The senior surgeon recorded outcome measures digitally on a worksheet, with video confirmation conducted the following working day. Sample size calculation, assuming good visibility in 90% of the control group and 98% of the intervention group, determined that at least 54 individuals per group were required for statistical significance (a = 5% and power of 80%).^[9] Statistical analyses, including independent-samples t-test, Chi-squared test (χ²), and Wilcoxon signed-rank test, were performed using the Statistical Package for the Social Sciences (SPSS) version 14.0 (SPSS, Chicago, IL), considering a P = 0.05 as statistically significant.

RESULTS

A total of 110 patients were enrolled in this study, with 55 participants in the control group and 55 in the intervention group. No statistically significant differences were observed in demographic data between the two groups [Table 1]. The study spanned a 3-year timeframe, from December 2020 to December 2023.

Intraoperative visibility, as assessed by the Likert scale [Table 2], showed significant differences between the intervention and control groups. In the control group (no injection), 34 out of 55 cases (61.8%) were rated as satisfactory (Grade 4 or 5), while 21 out of 55 cases (38.2%) were considered unsatisfactory (Grade 1, 2, or 3). Conversely, the intervention group (injection) demonstrated improved outcomes, with 45 out of 55 cases (81.8%) rated as satisfactory and only 10 out of 55 cases (18.2%) classified as unsatisfactory. This difference was statistically significant (P < 0.05, Chi-square test).

Furthermore, there was a significant shift in surgeon Likert scale scores in the intervention group, with more cases being rated at Grade 2 (Fair) instead of Grade 3 (Neutral). Compared to the intervention group, the control group exhibited fewer instances of Grade 4 (Good) and Grade 5 (Excellent), indicating that optimal visualization was less frequently achieved. This shift in visibility ratings was statistically significant (P = 0.00008, Wilcoxon signed-rank test) [Table 3].

In addition to the Likert scale, Johnson’s visibility classification was also employed to assess intraoperative clarity [Table 4]. In the control group, 35 cases (63.6%) were rated as Grade I (clear visibility), 14 cases (25.5%) as Grade II (moderate bleeding but acceptable visibility), and 6 cases (10.19%) as Grade III (poor visibility due to significant bleeding). In comparison, the intervention group showed improved clarity with 44 cases (80.0%) rated as Grade I, 7 cases (12.7%) as Grade II, and only 4 cases (7.3%) as Grade III. This difference was statistically significant (P = 0.032, chi-square test) [Table 4].

In cases where visibility was rated as poor/unsatisfactory, the need to temporarily increase arthroscopic pump pressure was noted in 5 out of 55 in the intervention group compared to 7 out of 55 patients in the control group (P = 0.76). Similarly, blood pressure adjustments were required in 3 out of 55 cases (intervention group) versus 4 out of 55 cases (control group) (P = 1.00). These results indicate that there is no significant difference between the intervention and control groups regarding the need for arthroscopic pump pressure or blood pressure adjustments.

The mean procedure duration was 80.4 ± 12.2 min in the control group and 78.4 ± 9.4 min in the intervention group. Although the intervention group exhibited a slightly shorter operative time, the difference was not statistically significant (P = 0.338, Student’s t-test). No complications associated with the injection were recorded.

DISCUSSION

The key finding of this study suggests that injections of diluted epinephrine at the portal site significantly enhance intraoperative visibility during arthroscopic rotator cuff repair for patients with supraspinatus tears (Partial-thickness - Neer Stage 3, Ellman Grade 2).

While much of the existing literature focuses on epinephrine irrigation, our study emphasizes the efficacy of portal-site injections. Previous studies have reported improved visual clarity and reduced operative time with epinephrine irrigation during rotator cuff repair, superior labrum anterior to posterior (SLAP), and Bankart repairs.^[8,11,12] These studies utilized varying concentrations of epinephrine, ranging from 0.33 mg/L to 1.5 g/L. Our findings suggest that localized epinephrine injections offer similar benefits without the need for continuous irrigation.

A systematic review and meta-analysis by Kuo et al.^[13] support the use of epinephrine in arthroscopic shoulder surgery, highlighting its favorable role with no significant risks. However, concerns regarding systemic effects persist. For instance, Abdelrahman et al.^[14] reported cases of tachycardia, hypertension, and even cardiomyopathy after epinephrine irrigation. In contrast, our study found no systemic complications associated with epinephrine injections, reinforcing its safety profile as a localized intervention.

Our findings align with the results of Tsenkov et al.,^[15] who also reported improved hemostasis and reduced operative time with portal-site epinephrine injections during shoulder arthroscopy. Beyond replicating these outcomes, our study provides additional insights by assessing secondary measures, such as the need for arthroscopic pump pressure adjustments and intraoperative blood pressure changes, thereby offering a more comprehensive evaluation of the intervention’s safety and efficacy.

The rigorous blinding methodology and prospective comparative design of our study further strengthen the evidence supporting the use of diluted epinephrine in enhancing surgical visualization while minimizing the risk of bias.

CONCLUSION

Our findings suggest that the administration of diluted epinephrine through portal-site injection emerges as a secure and efficacious approach to enhance intraoperative visibility during arthroscopic rotator cuff repair, all without extending the operative time.