Interscalene Dynamometer Pilot Study

Study Overview
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Brief Summary
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Total shoulder arthroplasty (shoulder replacement) can cause severe postoperative pain. Commonly, patients receive general anesthesia with interscalene block (injection of local anesthetic or numbing medicine near nerves in the shoulder) during surgery. As a result of the interscalene block, patients often experience sensory and motor blockade. The purpose of this study is to determine the effects of the interscalene block on the anterior deltoid muscle and hand grip strength after total shoulder arthroplasty.

Detailed Description
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Total shoulder arthroplasty can cause severe postoperative pain. Pain management includes general anesthesia with interscalene block during surgery and intravenous (IV) hydromorphone patient controlled analgesia (PCA) and oral opioid analgesics given after surgery. Side effects, such as motor blockade, may impair participation in physical therapy and diminish patient satisfaction. In order to prepare for a future study that will examine what mixtures of adjuncts/additives will best prevent recovery room pain and minimize motor blockade, the investigators are conducting this pilot study to collect preliminary data on current practice. The investigators believe the current regimen will provide adequate pain relief, but may cause extensive motor blockade and reduce patients' muscle strength after surgery.

Official Title
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Interscalene Dynamometer Pilot Study

Conditions
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Total Shoulder Arthroplasty

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients scheduled for primary total shoulder arthroplasty Age 18 to 80 years old Planned use of general anesthesia via laryngeal mask airway (LMA) and peripheral nerve block Ability to follow study protocol Patients with American Society of Anesthesiologists (ASA) physical status of I, II or III Exclusion Criteria: Patients younger than 18 years old and older than 80 Patients not intending to receive general anesthesia and peripheral nerve block Allergy or intolerance to one of the study medications Patients with an ASA of IV Hepatic or renal insufficiency Chronic opioid use (taking opioids for longer than 3 months)

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Anterior Deltoid Strength | Anterior deltoid strength as measured by a dynamometer. Percentage change in measure as compared to post-surgery (with post-surgery measure at 0%). | 2 days postoperatively | 
| Hand Grip Strength | Hand grip strength as measured by a dynamometer. Percentage change in measure as compared to post-surgery (with post-surgery measure at 0%). | 2 days postoperatively | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of Participants With Reduced Sensation in a Dermatome | Pin-prick sensation assessed. | 2 days postoperatively | 
| Numeric Rating Scale (NRS) Pain Scores With Movement | NRS pain scores (0-10; 0 = no pain, 10 = worst pain possible) assessed. | 2 days postoperatively | 
| Total Oral Opioid Intake in 48hrs | Opioid Usage | 0-48hrs |