Soft tissue structures resisting anterior instability in a computational glenohumeral joint model

Area of Science:

• Biomechanics
• Orthopaedic Engineering
• Computational Modeling

Background:

• The glenohumeral joint is highly susceptible to dislocation due to limited bony stability, relying heavily on soft tissues.
• Understanding the function of muscles and ligaments is crucial for treating shoulder injuries and designing orthopaedic devices.

Purpose of the Study:

• To create a computational model of the glenohumeral joint.
• To simulate joint behavior under various conditions, including muscle loading and external forces.
• To validate the model against cadaveric experimental data.

Main Methods:

• Assembled CT images of the scapula, humerus, and clavicle formed the bone structure.
• Muscles and ligaments were represented by forces and tension-only springs.
• Model predictions were validated by comparing them to cadaveric experiments on anterior joint stability.

Main Results:

• The computational model accurately predicted anterior subluxation force in external rotation, aligning with cadaveric results.
• The subscapularis muscle was identified as critical for stability in both neutral and external rotation.
• The inferior glenohumeral ligament was shown to resist anterior displacement primarily in external rotation.

Conclusions:

• The developed computational model effectively simulates glenohumeral joint mechanics.
• Findings enhance understanding of soft tissue stabilisers' roles in shoulder joint function.
• The model can aid in pre-operative planning and the design of orthopaedic implants.