Background: The purpose of this study was to evaluate the use of a custom reverse total shoulder arthroplasty glenoid baseplate for severe glenoid deficiency, with emphasis on the challenges with this approach, including short-term clinical and radiographic outcomes and short-term complications.Methods: This was a single-institution, retrospective case series of 29 patients between January 2017 and December 2022 for whom a custom glenoid component was created for extensive glenoid bone loss. Patients were evaluated preoperatively and at intervals for up to 5 years. All received a preoperative physical examination, plain radiographs, and computed tomography (CT). The custom implant was planned and manufactured by the manufacturer’s engineers. Intra- and postoperative complications are reported. Results: Of the 29 patients, delays resulted in only 25 undergoing surgery, and in three of those 25, the implant did not match the glenoid. For those three, the time from their CT scan to implantation averaged 7.6 months (range, 6.1–10.7 months), compared with 5.5 months (range, 2–8.6 months) for those whose implants fit without difficulty. In patients with at least 2 years of follow-up (n=9), no failures occurred. Significant improvements were observed in all patient-reported outcome measures in those nine patients (American Shoulder and Elbow Score, P<0.01; Simple Shoulder Test, P=0.02; Single Assessment Numeric Evaluation, P<0.01; Western Ontario Osteoarthritis of the Shoulder Index, P<0.01). Range of motion improved significantly for forward flexion and abduction (P=0.03 for both) and internal rotation up the back (P=0.02). Pain and satisfaction were significantly improved (P<0.01 for both). Conclusions: In this study, prolonged time (>6 months) from the CT scan to device implantation resulted in bone loss that rendered the implants unusable. Satisfactory short-term radiographic and clinical follow-up after a minimum of 2 years can be achieved with a well-fitting device.