Tomographic Analysis of Positioning of Reverse Baseplates Positioning

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Radiology

Background:

• Accurate reverse baseplate positioning is crucial for successful reverse shoulder arthroplasty (RSA).
• Intraoperative 3D technology is often used to guide baseplate placement.
• The impact of glenoid bone deformity (GBD) on positioning accuracy is not fully understood.

Purpose of the Study:

• To evaluate the accuracy of reverse baseplate positioning without intraoperative 3D guidance.
• To determine if GBD affects the accuracy of baseplate positioning in RSA.

Main Methods:

• Volumetric CT scans of 69 RSA cases were analyzed by two blinded radiologists.
• Evaluated parameters included baseplate proximity to the inferior glenoid rim, inclination, version, screw positioning, and peg intraosseous placement.
• Patients were stratified based on the presence or absence of GBD.

Main Results:

• High inter-radiologist agreement was observed for baseplate position (95.7-97.1%) and inclination (81.2-82.6%).
• Acceptable positioning was noted for baseplate proximity to the inferior glenoid rim and inferior screw placement.
• Baseplate version (56.5-69.6%) and upper screw positioning (71-79.7%) were less consistently within acceptable parameters.
• GBD did not significantly affect baseplate positioning accuracy.

Conclusions:

• Reverse baseplate positioning without 3D technology is largely within acceptable limits, with exceptions in version and upper screw placement.
• GBD does not appear to compromise the accuracy of reverse baseplate positioning in RSA.
• Further refinement of techniques for version and upper screw placement may be beneficial.