Comparison of two coracoid process transfer techniques on stress shielding using three-dimensional finite-element...

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Computational modeling

Background:

• Shoulder instability often requires surgical intervention.
• The Latarjet procedure is a common surgical treatment for anterior shoulder instability.
• Variations in the Latarjet technique exist, including traditional (TL) and congruent-arc (CAL) methods.

Purpose of the Study:

• To compare the stress distribution patterns of the CAL and TL Latarjet procedures using patient-specific 3D finite-element models.
• To evaluate the influence of glenoid defects and arm positions on stress distribution in both Latarjet techniques.

Main Methods:

• Developed 3D finite-element models of the glenohumeral joint from CT data of 10 patients.
• Simulated TL and CAL Latarjet procedures with 25% and 35% glenoid bone defects.
• Applied simulated joint loading and analyzed von Mises stress distribution on the coracoid graft.

Main Results:

• The traditional Latarjet (TL) technique exhibited significantly greater mean von Mises stress on the graft compared to the congruent-arc Latarjet (CAL) technique.
• TL models showed higher stress in the distal medial graft, while CAL models had stress concentrated on the distal lateral edge.
• Increasing glenoid defect size significantly increased lateral graft stress in both techniques.

Conclusions:

• Stress distribution patterns and magnitudes differ significantly between CAL and TL Latarjet techniques.
• The CAL technique's lower stress on the proximal-medial graft may impede bone formation, potentially leading to increased graft osteolysis.
• The CAL technique might be associated with a higher incidence of graft osteolysis compared to the TL technique.