Effect of Deltoid Volume on Range of Motion and Patient-Reported Outcomes Following Reverse Total Shoulder Arthroplasty in Rotator Cuff -Intact and Rotator Cuff -Deficient Conditions

S. Gray McClatchy, MD1 Griffi n M. Heise, BS2 William M. Mihalko, MD, PhD1 Frederick M. Azar, MD1 Richard A. Smith, PhD1 Dexter H. Witte, MD3 John G. Stanfi ll, MD3 Thomas W. Throckmorton, MD1 Tyler J. Brolin, MD1

1 University of Tennessee-Campbell Clinic Department of Orthopaedic Surgery & Biomedical Engineering Memphis, Tennessee 2 University of Tennessee

Health Science Center

College of Medicine

Memphis, Tennessee 3 Mid-South Imaging and Therapeutics

Memphis, Tennessee

Corresponding Author

Tyler J. Brolin, MD

1458 W. Poplar Avenue, Suite 100 Collierville, TN 38017 P: 901-759-5522 F: 901-435-5713 tbrolin@campbellclinic.com

Eff ect of Deltoid Volume on Range of Motion and Patient-Reported Outcomes Following Reverse Total Shoulder Arthroplasty in Rotator Cuff -Intact and Rotator Cuff -Defi cient Conditions

Background

Deltoid muscle function is paramount to the success of reverse total shoulder arthroplasty (RTSA). The purpose of this study was to investigate the role of deltoid volume on shoulder range of motion and patient-reported outcomes following RTSA in rotator cu -intact and rotator cu -defi cient conditions.

Methods

Retrospective review of records identifi ed 107 patients who met inclusion criteria. The rotator cu (RC) integrity was evaluated by two musculoskeletal-trained radiologists. Volumetric deltoid measurements were calculated from preoperative CT or MRI scans. Satisfactory outcomes were defi ned as forward elevation (FE) of at least 135 degrees, external rotation of at least 35 degrees, and scores of at least 70 on the American Shoulder and Elbow Surgeons (ASES) and Single Assessment Numerical Evaluation (SANE) patient-reported outcomes.

Results

Mean total deltoid muscle volume was signifi cantly higher in patients with satisfactory FE (57.8 cm³ ± 18.1 cm³) versus unsatisfactory FE (48.6 cm³ ± 19.5 cm³) (p = 0.013). When separated by RC integrity, total deltoid volume was signifi cantly higher (p = 0.030) in patients who achieved satisfactory FE in the RC-defi cient group but not the RC-intact group (p = 0.533).

Discussion

Preoperative deltoid volume directly correlated with achieving satisfactory FE after RTSA in RC-defi cient conditions and may be one factor in determining the ability to achieve satisfactory outcomes in the RC-defi cient patient.

S. GRAY MCCLATCHY, MD

Hometown: Memphis, Tennessee Undergraduate Institution: Mississippi State University Medical School: University of Arkansas for Medical Sciences Dr. McClatchy is the middle child, with an older and a younger sister. He is the fi rst in his family to choose medicine as a career.

Dr. McClatchy and his wife Katie were introduced by a friend while he was in med school and she was about to begin pharmacy school, and they were married in 2018. Katie is a pharmacist at Sam’s Club. When asked why he chose medicine as a career: I’ve always loved science and engineering and understanding how and why diff erent parts work together. Medicine combined those interests with personal interaction and the ability to impact the lives of others in a meaningful way on a daily basis. And why he chose orthopaedics as a specialty: I like that orthopaedics generally involves specifi c problems with abstract solutions. It off ers the ability to greatly improve the quality of life for a wide variety of patients by restoring function and relieving pain. Plans After Campbell: Dr. McClatchy will complete a Sports Medicine Fellowship at Mississippi Sports Medicine and Orthopaedic Center in Jackson, Mississippi. Dr. McClatchy adds: I’m grateful for the opportunity to train at Campbell Clinic for the past fi ve years. It has been an honor to learn from such giants in the fi eld. They set a great example and have taught us much more than just orthopaedics. Their patience and commitment to teaching and developing residents into better people and surgeons is what makes Campbell Clinic such a special place. Finally, I want to thank my fellow residents for their friendship and support throughout residency. I feel honored to have trained alongside the best.