Maximizing range of motion of reverse total shoulder arthroplasty using design optimization techniques

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Medical device design

Background:

• Range of motion (ROM) is critical for patient satisfaction after reverse shoulder arthroplasty (RSA).
• The optimal RSA design to maximize ROM remains undetermined.
• It is unclear if optimizing for overall ROM versus forward elevation ROM influences RSA design.

Purpose of the Study:

• To determine RSA configurations optimized for overall ROM and forward elevation ROM using computational modeling.
• To compare the design and performance of these optimized RSA configurations.
• To test the hypothesis that optimizing for different ROM envelopes leads to distinct RSA designs.

Main Methods:

• Utilized computer modeling and design optimization techniques.
• Investigated design parameters including glenoid and humeral lateralization, neck-shaft angle, and inferior offset of the center of rotation (COR).
• Compared optimized designs against a representative Grammont-style prosthesis.

Main Results:

• All optimized designs achieved maximum glenoid lateralization and inferior COR offset.
• Designs optimized for forward elevation ROM showed slightly increased neck-shaft angles and humeral lateralization.
• Optimized RSA designs demonstrated a 31% to 39% increase in ROM compared to the Grammont-style prosthesis.

Conclusions:

• RSA designs optimized for overall ROM differ from those optimized for forward elevation ROM.
• Both optimized RSA designs offer significant ROM improvements over a representative commercially available prosthesis.
• The specific ROM envelope targeted influences the optimal RSA design parameters.