BackgroundReverse shoulder arthroplasty (RSA) has seen a recent transition from cemented to press-fit humeral stems. Several press-fit designs have focused on proximal fixation, yet there remains a paucity of data on their performance. The purpose of this study is to report early radiographic and clinical results of a third-generation RSA system, featuring metaphyseal porous metal fixation. MethodsA retrospective review was performed on primary RSA patients treated with a single third-generation standard-length implant system incorporating proximal osteointegration features with a minimum 2-year follow-up. Patient-reported outcome measures, including the Simple Shoulder Test, American Shoulder and Elbow Surgeons, Visual Analog Scale for pain, and Single Assessment Numeric Evaluation, as well as measured active motion (forward elevation, external, and internal rotation) were recorded at pre- and postoperative intervals. Immediate postoperative radiographs were used to measure filling ratios at the epiphyseal, metaphyseal, and diaphyseal levels. Most recent radiographs were also reviewed for bone adaptations, acromial fractures, scapular notching, and humeral loosening. ResultsThere were 90 patients included in the study, with an average age of 73 years (± 7.23) and clinical follow-up of 32 months (± 7.25). Indications included osteoarthritis with a rotator cuff tear (51%), osteoarthritis without a cuff tear (40%), fracture sequelae (2%), and locked anterior dislocation (2%). There were significant improvements in all measured motions and patient-reported outcome measures at the most recent follow-up, with good to excellent satisfaction in 91.1% of patients. High mean epiphyseal (0.90 ± 0.06) and metaphyseal (0.83 ± 0.07) filling ratios together with low mean diaphyseal filling ratio (0.48 ± 0.07) represented proximal fixation. There were 6 cases with scapular notching, 5 postoperative acromial fractures, and 2 with temporary postoperative neuropathy. Proximal bone resorption was seen in 18.9% of cases, and there were no cases of humeral loosening, baseplate failure, or need for revision. ConclusionPrimary RSA with a third-generation press-fit humeral component with metaphyseal fixation provides excellent early outcomes with no loosening and low rates of proximal stress-shielding. Results of this study support the use of an inlay humeral component with osteointegration features that facilitate proximal stem fixation. Level of EvidenceTreatment Study