EMG and Delta Function in Standard RTSA vs Lateralization

Reverse total shoulder arthroplasty (RTSA) is a well-established method to treat patients with irreparable rotator cuff tears and glenohumeral osteoarthritis. The biomechanical principle implies a medialization and distalization of the center of rotation (COR). Deficiencies in internal and external rotation constitute frequently encountered functional problems. Some studies showed reduced activation of the posterior deltoid in EMG measurements, which may explain the inability to compensate these movements. Lateralized prosthetic designs demonstrated increased external rotation through an alteration of the deltoid's lever arm. The aim of the study is to investigate the impact of lateralization on functional outcome and deltoid EMG activity in comparison to a standard implantation technique.

NCT Number	NCT07464977
Lead Sponsor	Vienna Hospital Association
Conditions	Cuff Tear Arthropathy, Omarthrosis, Rotator Cuff Tear Arthropathy
Enrollment	130 participants
Start Date	2026-06
Primary Completion	2027-08 (estimated)
Study Completion	2027-12 (estimated)
Updated on ClinicalTrials.gov	2026-05-07