Design of Patient Specific Guides (PSG) for Reverse Shoulder Arthroplasty

Reverse shoulder arthroplasty is a treatment for both non-synthesizable fractures and arthropathy degenerative. This implant is based on two main components: glenosphere and stem. The stem in turn is integrated in its upper part by a polyethylene that reduces the friction torque between the glenosphere and the stem.

Correct positioning of the glenosphere is critical for functionality and survival of the implant. Malpositioning of glenosphere can be related to:

In recent years, given the

• The scapula is a flat bone, without any reference axis;
• Surgical approaches expose only the glenoid cavity, with few bone landmarks;
• The humerus and deltoid make access to the glenoid difficult;
• The morphology of the scapula is very variable.

Preoperative planning even without PSG improves the positioning accuracy of the guide in the glenoid. In glenoids with only a slight deformity, PSGs improve the accuracy of the guide entry point (<1 mm error, compared to > 4 mm under visual control) and orientation (< 3◦ error compared to > 7◦). In glenoids with more significant deformities, planning also showed superiority.

Inclusion criteria

• Patient with proximal humerus fracture candidate for reversed shoulder arthroplasty
• Patient with degenerative arthropathy candidate for reversed shoulder arthroplasty

Exclusion criteria

• Previous surgeries on the proximal humerus or glenoid
• No desire to participate in the study
• Lack of ability to accept the study (tutored patients)
• Open fractures