Analgesic Efficacy of the Infraspinatus-Teres Minor (ITM) Interfascial Plane Block After Shoulder Arthroscopy: A Simon's Two-Stage Design

Significant post-operative pain follows shoulder arthroscopy. Currently the interscalene brachial plexus (ISB) block is recommended as the first-choice regional anaesthesia technique (1). However, interscalene bloc is associated with phrenic nerve paralysis for the duration of the block which can exacerbate pulmonary co-morbidities, as well as motor block of the arm which can decrease patient autonomy. An alternative to the interscalene block is the combined suprascapular nerve and axillary nerve (SSAX) block (2). However, this requires two needle punctures and is more difficult to perform technically. Recently, the Infraspinatus Teres Minor Interfascial Plane (ITM) block was developed by Kim et al (1) to anaesthetise the suprascapular and axillary nerves with a single approach. As a fascial plane block, its high safety profile and ease of performance make it a potentially safer alternative the SSAX block when the ISB is contraindicated.

A monocentric, prospective Simon two-stage trial

Inclusion criteria

• The study population inclusion criteria will be:

• Patients of any sex
• Class ASAI-III
• Patients 18 years of age or older
• Scheduled for elective shoulder arthroscopy
• Able to give written informed consent autonomously
• Sex and gender dimensions are irrelevant for this study as enrolled patients are benefitting from shoulder surgery without reference to gender and our standard care as well as our research disposition is indiscriminately applied to all genders.

Exclusion criteria

• The subject exclusion criteria will be:

• Allergy to any of: ropivacaine, paracetamol, celecoxib, morphine, ondansetron or dexamethasone
• Refusal or inability to give consent
• Bleeding diathesis (according to HEMSTOP score)
• Neurological deficit of the operative side
• Existing preoperative chronic opioid use (greater than or equal to 3 months of use)
• Renal insufficiency (GFR<30ml/min according to the Cockroft-Gault formula)
• Known or suspected non-compliance
• Illicit drug use
• Excessive alcohol use (<8 drinks per week for women, >15 drinks per week for men)
• Inability to follow the procedures of the study, e.g due to language problems, psychiatric disorder, dementia, etc
• Participation in another study with an investigational medicinal product within 30 days preceding the study and during the study
• Hepatic insufficiency (CHILD-Pugh score B or C)
• Enrolment of the investigator, his/her family members, employees and other dependent persons