Reverse total shoulder glenoid baseplate stability with superior glenoid bone loss

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Materials science

Background:

• Superior glenoid bone wear is a common challenge in rotator cuff arthropathy, complicating shoulder arthroplasty.
• Glenoid bone loss in reverse shoulder arthroplasty (RSA) can compromise baseplate fixation stability.
• Assessing initial fixation stability is crucial for RSA outcomes.

Purpose of the Study:

• To biomechanically evaluate the initial fixation stability of RSA glenosphere baseplates.
• To investigate the impact of varying degrees of superior glenoid bone loss on baseplate stability.

Main Methods:

• Utilized high-density polyurethane foam models simulating glenoid bone with 100%, 90%, 75%, and 50% superior defects.
• Applied cyclic loading (0-750 N at 1 Hz for 5000 cycles) at a 60° glenohumeral angle.
• Measured baseplate micromotion and migration using linear variable differential transformers.

Main Results:

• Micromotion significantly increased in models with 50% superior bone defects compared to smaller defects.
• Significant baseplate migration occurred across all tested defect sizes after cyclic loading.
• Reduced initial fixation stability was observed with increasing superior bone loss.

Conclusions:

• Initial fixation stability of RSA glenosphere baseplates is significantly compromised with 50% superior bone loss.
• Even moderate superior bone loss can negatively impact baseplate stability in RSA.
• Findings highlight the importance of addressing glenoid bone loss in RSA planning.