Injection Site in Ultrasound-Guided Interscalene Block for Shoulder Arthroscopy (ISB-ROOT)

Does the Injection Site of Local Anesthetic Around the C5-C7 Nerve Roots Affect Block Success and Complication Rates During Ultrasound-Guided Interscalene Block for Shoulder Arthroscopy?

Ultrasound-guided interscalene block is commonly used for postoperative analgesia in patients undergoing shoulder arthroscopy. The location of local anesthetic injection may influence both block efficacy and the incidence of block-related complications. This randomized, double-blind clinical trial compares two different injection sites around the C5-C7 nerve roots using the same local anesthetic dose and volume. The study will assess block success, postoperative analgesia, opioid consumption, diaphragmatic function, and procedure-related complications.

Study Overview

• Status: Not yet recruiting
• Conditions: Postoperative Pain; Shoulder Arthroscopy
• Intervention / Treatment: Procedure: Ultrasound-Guided Interscalene Block

Detailed Description

Patients scheduled for elective shoulder arthroscopy under general anesthesia will be randomly assigned to one of two ultrasound-guided interscalene block techniques. In one group, the local anesthetic will be injected between the C5-C7 nerve roots and the anterior scalene muscle. In the other group, the injection will be performed between the C5-C7 nerve roots and the middle scalene muscle. The same local anesthetic solution, volume, and concentration will be used in both groups.

Block success, postoperative pain control, opioid consumption, diaphragmatic movement assessed by ultrasonography, and block-related complications including vascular puncture, Horner syndrome, hoarseness, dyspnea, nausea, vomiting, and prolonged motor block will be recorded and compared between the groups.

• Study Type: Interventional
• Enrollment (Estimated): 50
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Hakan Emirkadı, MD; Phone Number: +905322609367; Email: hemirkadi@gmail.com

Study Locations

• Turkey (Türkiye)
  • Istanbul
    • Istanbul, Istanbul, Turkey (Türkiye), 34668
      • Sultan Abdulhamid Han Training and Research Hospital
      • Contact: Hakan drhemirkadi; Phone Number: 05322609367; Email: hemirkadi@gmail.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

Adults aged 18 years or older. ASA physical status I-III. Scheduled for shoulder arthroscopy under general anesthesia with a planned ultrasound-guided interscalene block for postoperative analgesia.

Able to provide written informed consent. Normal coagulation parameters and no antithrombotic therapy. No infection or anatomical abnormality at the injection site. No known allergy to local anesthetics. No contralateral diaphragmatic paralysis or pneumothorax. No dyspnea and adequate pulmonary function.

Exclusion Criteria:

Age younger than 18 years or ASA physical status IV. Antithrombotic therapy or abnormal coagulation parameters. Infection or anatomical abnormality at the injection site. Known allergy to local anesthetics. Contralateral diaphragmatic paralysis or history of pneumothorax. Dyspnea. Refusal to undergo interscalene block.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Anterior Interscalene Block; Ultrasound-guided interscalene block with local anesthetic injected between the C5-C7 nerve roots and the anterior scalene muscle.	Procedure: Ultrasound-Guided Interscalene Block; Ultrasound-guided interscalene brachial plexus block performed before induction of general anesthesia. Participants are assigned to one of two injection sites around the C5-C7 nerve roots according to the randomized study protocol.
Experimental: Posterior Interscalene Block; Ultrasound-guided interscalene block with local anesthetic injected between the C5-C7 nerve roots and the middle scalene muscle.	Procedure: Ultrasound-Guided Interscalene Block; Ultrasound-guided interscalene brachial plexus block performed before induction of general anesthesia. Participants are assigned to one of two injection sites around the C5-C7 nerve roots according to the randomized study protocol.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postoperative Analgesic Efficacy	Postoperative analgesic efficacy will be assessed using patient-controlled analgesia demand and delivered dose counts and the need for rescue analgesia.	12 hours after surgery

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time to First Rescue Analgesic	Time from the end of surgery to first rescue analgesic administration.	12 hours after surgery
Hemidiaphragmatic Paralysis	Presence of ipsilateral hemidiaphragmatic paralysis assessed by ultrasonography.	Before block and 2 hours after surgery
Block-Related Complications	Incidence of vascular puncture, intraneural injection, Horner syndrome, dyspnea, hoarseness, nausea, vomiting, recurrent laryngeal nerve block, stellate ganglion block, and prolonged motor block.	During block placement and within 12 hours after surgery
Block Duration	Duration of sensory and motor block recorded during postoperative follow-up.	12 hours after surgery

Collaborators and Investigators

• Sponsor: Sultan Abdulhamid Han Training and Research Hospital, Istanbul, Turkey
• Investigators: Principal Investigator: Tuna Erturk, MD, Sultan Abdulhamid Han Training and Research Hospital, Istanbul, Turkey

Study record dates

Study Major Dates

• Study Start (Estimated): July 15, 2026
• Primary Completion (Estimated): November 10, 2026
• Study Completion (Estimated): November 30, 2026

Study Registration Dates

• First Submitted: July 5, 2026
• First Submitted That Met QC Criteria: July 5, 2026
• First Posted (Actual): July 10, 2026

Study Record Updates

• Last Update Posted (Actual): July 10, 2026
• Last Update Submitted That Met QC Criteria: July 5, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Local Anesthetic; Brachial Plexus Block; Regional Anesthesia; Postoperative Analgesia; Interscalene Block; Shoulder Arthroscopy; Phrenic Nerve; Ultrasound-Guided Interscalene Block
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Postoperative Complications; Pathologic Processes; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Pain, Postoperative
• Other Study ID Numbers: 21-19

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be shared because no data sharing plan has been established for this investigator-initiated study.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No