Shoulder arthroscopic surgeries are one of the most common procedures performed daily in our practice. The arthroscopic techniques offer a less invasive option as Open repair does not offer a significantly better 2-year result in terms of stability, and furthermore, can negatively affect the recovery of the full range of motion of the shoulder. Open techniques Shoulder procedures are performed arthroscopically nowadays with fewer complications compared with open surgery.

Indications of shoulder arthroscopy are expanding and include biceps tears, labral tears, rotator muscle tears, subacromial impingements chondral injuries, loose bodies, early degenerative changes, adhesive capsulitis, shoulder instability and acromioclavicular osteoarthritis.

There are many regional anesthetic techniques used to control perioperative pain during arthroscopic procedures. Interscalene block results in effective shoulder surgery analgesia, but it is associated with various complications such as diaphragmatic paralysis due to the high incidence of phrenic nerve block.

The suprascapular nerve block combined with the axillary nerve block is non-inferior to conventional inter-scalene block except for the early recovery period with the advantage of lower incidence of dyspnea and discomfort.

. In a cadaveric anatomical study that the posterosuperior quadrant and the posteroinferior quadrant of the GHJ were innervated by the suprascapular nerve and the axillary nerve respectively. While the anterosuperior quadrant portion of the joint is sensory supplied by the subscapularis superior branch and the anteroinferior by the main branch of the axillary nerve. These anatomical data the possibility of a new block targeting the GHJ sensory branches. It was suggested that deep pericapsular infiltration of local anesthetic towards the subscapularis may cover the axillary and subscapularis branches that feed the anteroinferior and superior quadrants of the GHJ.

Recently, the pericapsular nerve group block of the shoulder joint as described in a case series including two cases underwent a humeral neck fracture fixation and Bankart arthroscopic repair with promising anesthesia and analgesia in selected shoulder surgeries.

anesthetics Bleeding disorders receiving antiplatelet or anticoagulant drugs local infection at the site of local injection Intra articular infections

Sample size and methodology:

We will enroll 42 patients undergoing elective shoulder arthroscopy. They will be randomized and allocated into two groups; Group A and Group B. Group A will receive an ultrasound-guided PENG block and Group B will receive a shoulder block Sample size justification The sample size was calculated using Power Analysis and Sample Size software program (PASS) version 11.0.4 for Windows (2011) with time to first analgesic request as the primary outcome. Using the results published by Pani et al 2019 (8) with the mean time to first analgesic request in the shoulder block group was (5.9 ± 1.2 hours) Using a two-sided two-sample unequal-variance t-test, a sample size of 42 patients is needed to achieve 95% power to detect 20 % difference in time to a first analgesic request by using a two-sided hypothesis test with a significance level of 0.05.

Anticipated Results The application of pericapsular nerve group block in patients undergoing elective shoulder arthroscopic surgeries may improve the management of their perioperative pain.

Randomization:

The study subjects will be randomized by using block randomization using sealed concealed envelopes into two groups.

Data collection:

The patients will be observed for 24 hours postoperatively by a blinded investigator for the given block. All patients will receive one gram of acetaminophen intravenously every 8 hours as a part of the multimodal analgesia protocol.

The primary outcome will be the duration of analgesia (time to first rescue analgesia after administration of the block). Postoperative pain will be assessed using a 100 mm vertical visual analog score (VAS). The pain score will be recorded at 0, 1, 4, 8, 12, and 24 hours at rest (VASr) and movement (VASm). Morphine will be given intravenously if VASr, VASm, or both exceed 30mm in one milligram allequate with 5 minutes intervals till VAS is less than 30 mm or exceeds the safety dose of 30 mg in 4 hours.

Secondary outcomes:

Total fentanyl consumption as a rescue analgesia intraoperatively. Total morphine consumption in 24 hours postoperatively. Intraoperative hemodynamics mean arterial pressure and mean heart rate. length of stay in hospital Ability to perform physical rehabilitation program in the first 24 hours postoperatively.

postoperative sedation score using the Ramsey score patient satisfaction will be assessed by numerical score (1= very dissatisfied, 2= dissatisfied, 3=neither satisfied or dissatisfied, 4= satisfied, 5=very satisfied) postoperative nausea and vomiting (PONV) will be assessed using a 4 points numerical score (0=no PONV, 1= mild nausea, 2= severe nausea or vomiting once, 3= vomiting more than once)

Endpoint:

The observation of patients will be finished 24 hours postoperatively.

Results:

It will be recorded and analyzed statistically.

Inclusion Criteria:

• ASA I - II
• Age between 18 - 60
• unilateral elective shoulder arthroscopic surgery

Exclusion Criteria:

• Patient refusal
• Altered mental status or un-cooperative patients
• Hypersensitivity to local anesthetics
• Bleeding disorders
• receiving antiplatelet or anticoagulant drugs
• local infection at the site of local injection
• Intra articular infections

The block will be performed by one investigator who is not participating in either data collection or analysis. Also the patient will be blinded .