Male patients with a body mass index (BMI) greater than 30 who have had previous shoulder surgeries are at higher risk for early dislocation after reverse total shoulder arthroplasty (RTSA), according to a study presented during the American Shoulder and Elbow Surgeons (ASES) 2013 Specialty Day session on shoulder trauma and arthroplasty.

Presenter Gregory P. Nicholson, MD, of Rush University Medical Center, summarized findings for nine patients (eight male), out of a total of 40 patients who underwent RTSA and experienced early dislocation events unrelated to falls. Six of the nine patients were diagnosed as having a dislocation at the first postoperative visit, and five of these six did not know they had a dislocation.

Patients who experienced early dislocation were treated as follows:

• closed reduction (seven patients)
• open reduction (one patient)
• open reduction with thicker polyethylene (one patient)

All patients were placed in an abduction orthosis. The patient who required thicker polyethylene was the last to experience early dislocation (at 12 weeks postoperative), and the shoulder remained stable after treatment.

Of the other eight patients, four remained stable after the initial reduction. One patient experienced a second dislocation, was treated with open reduction and thicker polyethylene, and remained stable thereafter. In the other three patients, the RTSA was converted to a hemiarthroplasty due to inability to maintain stability. Thus, six of the nine patients (67 percent) retained the RTSA despite early dislocation.

Of the patients who had early dislocation, seven had undergone previous surgery, including four failed rotator cuff repairs (RCRs), one failed RCR with manipulation that led to chronic anterior dislocation, one failed total shoulder arthroplasty, and one open reduction internal fixation of a surgical neck fracture of the humerus. The average BMI of the patients was 32 (range 23–41), and eight patients had a BMI of 30 or greater.

From these finding, Dr. Nicholson said, the authors concluded that “almost all early RTSA dislocations will occur in the first month, and the majority will occur in the first week postoperative.” In view of the risk factors observed in this study, he recommended use of an abduction orthosis postoperatively for four weeks to allow encapsulation and stability in higher-risk patients—those with BMI greater than 30, males, and those with previous surgery.

Dr. Nicholson’s coauthors include Daniel J. Enriquez, MA; Stacy L. Twigg, PA-C; and Anthony A. Romeo, MD.

Disclosure information: Dr. Nicholson—Innomed; Zimmer; Tornier; SLACK Inc. Dr. Romeo—Arthrex; DJO Surgical; Ossur; Smith & Nephew; Saunders/Mosby-Elsevier; Journal of Shoulder and Elbow Surgery; SLACK Inc.; Orthopedics Today; Orthopedics Sports Health; Techniques in Shoulder and Elbow Surgery; Operative Techniques in Sports Medicine; Orthopaedic Journal of Sports Medicine; American Orthopaedic Society for Sports Medicine; ASES; Arthroscopy Association of North America. Mr. Enriquez and Ms. Twigg reported no conflicts.

Terry Stanton is senior science writer for AAOS Now. He can be reached at tstanton@aaos.org

Bottom Line

• This small study sought to identify risk factors for early dislocation following reserve total shoulder arthroplasty.
• Patients who experienced early dislocation were primarily male (eight out of nine patients), had a BMI greater than 30 (eight out of nine), and had had prior surgery (seven out of nine).
• The authors recommend use of an abduction orthosis postoperatively for 4 weeks in patients at high risk of early dislocation.