The investigators purpose of this study are to perform a prospective clinical study to determine the following after subscapularis-sparing anatomic total shoulder arthroplasty performed for glenohumeral osteoarthritis:

1. patient-reported outcomes
2. shoulder motion and strength
3. rotator cuff integrity
4. the accuracy of component placement and the completeness of osteophyte removal

Anatomic total shoulder arthroplasty (TSA) provides excellent pain relief and restoration of shoulder function in the setting of glenohumeral osteoarthritis. However, the surgical approach requires the subscapularis to be cut and repaired, via either a lesser tuberosity osteotomy, a subscapularis tenotomy, or a subscapularis peel.This repair must be protected post-operatively, even with a lesser tuberosity osteotomy, or it can displace or fail to heal, which complicates rehabilitation. Failure of the subscapularis repair occurs in 10-25% of patients. Failure of the subscapularis repair is often devastating for shoulder function and often requires revision to a reverse total shoulder arthroplasty. Even when muscle-tendon-bone healing does occur there is post-operative atrophy of the subscapularis that may compromise function and strength. Atrophy of the subscapularis may lead to imbalance of the rotator cuff musculature, leading to subluxation and glenoid loosening. While there have been attempts to develop approaches that do not involve cutting the subscapularis, they have been plagued by osteophyte retention, component malposition, damage to the deltoid, or damage to the supraspinatus.

The principal investigator has spent four years developing a technique for anatomic total shoulder arthroplasty that does not involve cutting any muscles or tendons and has been through the learning curve with this technique by completing >20 cases and at least as many cadaver surgeries during that time period. This technique has been designed to avoid the potential issues with prior attempts and utilizes purpose designed instrumentation and retractors.

Inclusion Criteria:

• Patients undergoing subscapularis-sparing anatomic total shoulder arthroplasty by the principal investigator at the University of Utah.

Exclusion Criteria:

• Patients unwilling to consent and comply with study procedures (i.e. follow up visits).
• Patients under the age of 18.
• Patients with contraindications to an anatomic total shoulder arthroplasty such as active infection, insufficient glenoid bone, damage to the rotator cuff, or a history of instability.
• Patients with known prior shoulder arthroplasty.
• Patients unable to undergo a magnetic resonance imaging study.

Patients undergoing subscapularis-sparing anatomic total shoulder arthroplasty.