The use of ISB in patients undergoing total shoulder arthroplasty (TSA) is the gold standard and results in significantly reduced pain scores and opioid use. However, patients still have pain and the majority require opioids postoperatively as the interscalene block (ISB) doesn't cover all of the dermatomes impacted during TSA. A pectoserratus block typically provides coverage to additional dermatomes that are impacted during TSA. Currently ISB is performed for every patient and perform a pectoserratus block to a portion of our patients undergoing TSA. The purpose of the study is to determine if the addition of the pectoserratus block to the ISB will results in improvement in pain control and decrease in opioid use, among patients undergoing TSA. This is a randomized prospective controlled trial. All patients undergoing total shoulder arthroplasty or reverse total shoulder arthroplasty aged 18-85 will be considered eligible for the study. Participants will be randomized to one of 2 treatment groups. Group 1 will receive an ultrasound guided pectoserratus block with 25 mL of 0.25% bupivacaine. Group 2 will be the control and receive an ultrasound guided pectoserratus block with 25 mL of saline. The drug will be administered by the anesthesiologist in-charge of the participant's care or an anesthesiologist who is a part of the study team.

Inclusion Criteria:

• Patients undergoing total shoulder arthroplasty or reverse total shoulder arthroplasty;
• Patients aged 18-85 years old.

Exclusion Criteria:

• Patients who have an exclusion to regional anesthesia such as pre-existing nerve damage to their brachial plexus or infection at the site of injection.
• Patients who have exclusion to interscalene blockade such as severe lung disease.
• Non-English speakers will be excluded because pain scales are not validated in other languages and there is lack of standardization of pain reporting.
• Pregnant patients
• Patients who are currently using opioids and patients with a diagnosis of chronic pain will be excluded.

This will be double blinded. The surgeon performing the surgery and the research team member collecting follow-up pain and opioid data will be blinded to the randomization assigned to the patient. The anesthesiologist performing the block and the medical assistant preparing the drugs for the anesthesiologist will be unblinded.