The patient and seven surgeries: A clinical case of late-diagnosed posterior shoulder dislocations resulting in bilateral arthroplasty using 3D technology.

Background: Posterior shoulder dislocations are rare and frequently misdiagnosed injuries that can lead to significant functional impairment if treatment is delayed. Chronic instability, restricted range of motion, and progressive degenerative changes often develop in neglected cases. Case presentation: We report a clinical case of a patient with bilateral posterior shoulder dislocations diagnosed 12 months after an epileptic seizure. The patient underwent multiple surgical interventions, including bilateral open reduction and defect reconstruction using custom implants. Persistent pain and limited motion after initial surgeries led to right shoulder anatomic total arthroplasty. In the postoperative period, a periprosthetic infection developed, requiring revision surgery and placement of an antibiotic-loaded spacer. During preoperative planning for the second-stage surgery, computed tomography revealed a substantial glenoid bone defect, which required the development and use of patient-specific instrumentation (PSI) and custom 3D-printed glenoid. Subsequently, anatomical total shoulder arthroplasty was performed on the left side, with autograft reconstruction of the humeral head. Results: At the latest follow-up 34 to 43 months postoperatively, the patient demonstrated excellent functional outcomes (Constant Shoulder Score: 94 right, 98 left; ASES: 93 right, 95 left) with minimal residual pain and stable implant positioning on radiographs without evidence of bone resorption or lysis. Conclusion: This case highlights the critical importance of early diagnosis and individualized treatment planning for posterior shoulder dislocations. Advanced 3D technologies, including patient-specific instrumentation and custom implants, can effectively address complex bone defects, enabling restoration of function even after multiple prior surgeries.