Integrated iterative musculoskeletal modeling predicts bone morphology following brachial plexus birth injury (BPBI)

Area of Science:

• Biomechanics
• Pediatric Orthopedics
• Computational Modeling

Background:

• Brachial plexus birth injury (BPBI) is a common pediatric nerve injury.
• BPBI can cause significant glenohumeral joint osseous deformation and altered muscle properties.
• Injury location (preganglionic vs. postganglionic) influences muscle changes and subsequent bone deformity.

Purpose of the Study:

• To investigate if muscle property changes following BPBI mechanically explain bone deformity differences between preganglionic and postganglionic injuries.
• To computationally model the long-term effects of BPBI on glenohumeral joint mechanics and bone growth.

Main Methods:

• Developed a computational framework integrating musculoskeletal and finite element modeling.
• Simulated muscle changes over time and bone growth in response to mechanical and biological stimuli.
• Compared predicted glenohumeral joint loads and bone deformations between preganglionic and postganglionic BPBI models.

Main Results:

• Postganglionic BPBI simulations showed nearly 10.5% greater net glenohumeral joint loads than preganglionic.
• Predicted bone deformations were more severe in the postganglionic case.
• Simulated glenoid deformations included greater decline, increased radius of curvature, and more anteversion in the postganglionic group, consistent with prior studies.

Conclusions:

• Differences in muscle mass and length between preganglionic and postganglionic BPBI are critical mechanical drivers of altered glenohumeral joint shape.
• Computational modeling provides a mechanically-driven explanation for observed bone deformities in BPBI.
• Understanding these mechanical factors can inform clinical management and treatment strategies for BPBI.