*Article* **Temporary Protective Shoulder Implants for Revision Surgery with Bone Glenoid Grafting**

**Daniel Schaffarzick <sup>1</sup> , Karl Entacher <sup>2</sup> , Dietmar Rafolt <sup>3</sup> and Peter Schuller-Götzburg 4,\***

	- <sup>3</sup> Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna General Hospital, Währinger Gürtel 18-20, A-1090 Wien, Austria

**Abstract:** This article describes the development of a temporary protective glenoid prosthesis placed between the augmentation and humeral head prosthesis during the healing phase of shoulder prosthesis revision with necessary reconstruction of the bony structure of the glenoid. The glenoid protection prosthesis ensures the fixation of the augmentation material and protects the screws from contact with the metallic humeral head prosthesis. Another approach of the development is a reduction of the resorption of the augmentation by targeted mechanical stimulation of the tissue. The aim should be to achieve significantly improved conditions for the implantation of a new glenoid component at the end of the healing phase of the augmentation material in comparison to the current standard method. The development of the protective prosthesis was carried out according to specific needs and includes the collection of requirements and boundary conditions, the design and technical detailing of the implant, the verification of the development results as well as the validation of the design. For the verification, FEM simulations (Finite Element Analysis) were performed to estimate the mechanical stability in advance. Mechanical tests to confirm the stability and abrasion behavior have been carried out and confirm the suitability of the protective implant. The result of the present work is the detailed technical design of two variants of a glenoid protective prosthesis "GlenoProtect" for use in revision procedures on shoulder joints—with large-volume defects on the glenoid—treated by arthroplasty and the necessity of augmenting the glenoid, including a description of the surgical procedure for implantation.

**Keywords:** glenoid implant; implant development; finite element analysis; 3D modelling; abrasion test; glenoid defect
