Combined Shoulder Anterior Capsule and Suprascapular Nerve Block Versus Interscalene Block in Shoulder Surgery: Randomized Controlled Clinical Trial

Significant acute postoperative pain is common in adults after shoulder surgery, with approximately 45% reporting severe pain in the immediate postoperative period. This pain may necessitate opioid use for several days. The opioid requirement may be similar to that following gastrectomy or thoracotomy, and opioid-only analgesic techniques for shoulder surgery are commonly associated with opioid-related adverse effects such as nausea , vomiting, respiratory depression, pruritus, allergic reactions, sleep disturbance and constipation.

With the majority of these procedures being performed in the ambulatory setting, providing effective postoperative analgesia has become paramount in promoting quicker recovery and rehabilitation of these patients. Thus, alternative techniques are preferred. Nowadays, several ultrasound guided regional anesthesia methods are used for postoperative analgesia .

The shoulder is formed by two joints the acromioclavicular joint formed by the acromion process of the scapula and the clavicle, and the glenohumeral joint formed by the glenoid process of the scapula and the humeral head.

The shoulder joint is innervated by branches of the brachial plexus which include the suprascapular nerve, the axillary nerve, the subscapularis and lateral pectoral nerves .

The suprascapular nerve arises from the ventral rami of cervical nerve roots (C5 and C6), and it is a branch of the superior trunk of the brachial plexus. The suprascapular nerve is a mixed motor and sensory nerve providing motor innervation to the supraspinatus and infraspinatus muscles. And sensory innervation to the acromioclavicular joint, glenohumeral joint, and ligaments of the shoulder. The axillary nerve also originates from the ventral rami of C5 and C6 and it is a terminal branch of the brachial plexus. The axillary nerve is a mixed motor and sensory nerve providing motor innervation to the deltoid and sensory contributions to the glenohumeral joint . Other nerves involved in the sensory innervation of the shoulder joint include the nerve to subscapularis and the lateral pectoral nerve both of which arise from ventral rami of C5 and C6.