Arthroscopic shoulder rotator cuff repair and acromioplasty are associated with severe postoperative pain. The interscalene block (ISB) is commonly used for this type of surgery, providing analgesia by anesthetizing the nerves that supply the shoulder. Although the nerve block provides extremely effective analgesia for the first 6-8 hours, patients experience severe pain once its effect has regressed. This study will assess whether a single dose of oral hydromorphone controlled release, given to overlap the waning of the ISB, will improve postoperative pain control and reduce the incidence of rebound pain.

Seventy patients undergoing rotator cuff repair will receive standardized ISB and general anesthesia for the surgery. Six hours (+/- 1 hour) after ISB, the patients will randomly receive either a single oral dose of 2 mg Hydromorphone (immediate release formulation) or placebo. The patient will be then discharged home with a prescription for multimodal analgesia, which is the standard of care. Patients will be given a diary to record their pain scores and track use of analgesic medications for 24 hours. Twenty-four hours after the ISB, the patients will receive a phone call from a nurse as per the standard of care. During this phone call, questions will be asked about their pain control.

If a single dose of pre-emptive hydromorphone is demonstrated to be safe and effective, it will lead to change in practice of how we manage pain after rotator cuff repair. Furthermore, the finding of this study may apply to similar surgical procedures (such as elbow, knee and ankle repairs) that are associated with rebound pain when the nerve block wears off.

Inclusion Criteria:

• Age 18-65
• scheduled to receive ISB and general anesthesia as a day surgery patient for rotator cuff repair and acromioplasty, as a part of planned routine care

Exclusion Criteria:

• Allergy, sensitivity, or absolute contraindications to any of the medications involved in the study
• preexisting CNS depression, or taking regularly medication that cause CNS depression
• preexisting cognitive deficits, dementia, or delirium
• severe respiratory comorbidities (e.g. chronic obstructive pulmonary disease, pneumonia, respiratory failure)
• sleep disordered breathing (diagnosed OSA, obesity hypoventilation syndrome)
• pregnancy and breast feeding
• history of chronic pain or regular (at least once daily) opioid use preoperatively
• renal impairment - CrCl ≤60 mL/minute
• not fluent in English to be able to participate in the study process, including consent and phone interview
• Body Mass Index >35
• inability to take oral medication.