Optimal Screw Orientation for Fixation of Type B Intracapsular Condylar Head Fractures: A Comparative Finite Element...

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Maxillofacial reconstruction

Background:

• Optimal screw fixation strategies for condylar head fractures are not well-defined.
• Limited evidence exists to guide intraoperative decision-making for condylar fracture fixation.

Purpose of the Study:

• To compare the biomechanical behavior of four distinct screw orientations for type B condylar fractures.
• To evaluate screw stress, bone stress, and interfragmentary displacement under various biting scenarios.

Main Methods:

• A 3D maxillofacial model with a virtual type B fracture was created using CT and MRI data.
• Twelve simulations tested four screw orientations across three occlusal biting conditions.
• Analysis included stress distribution in screws, bone, and articular structures, along with displacement measurements.

Main Results:

• The first orientation (parallel screws, 90° to fracture line) exhibited the lowest screw stress and superior micromotion control.
• The fourth orientation showed favorable performance under non-fractured side biting.
• The third orientation resulted in the highest screw stress, and the second and third orientations showed higher stress concentrations on the condylar surface.

Conclusions:

• The first screw orientation is biomechanically optimal for condylar fracture fixation, balancing hardware stress and construct stability.
• The fourth orientation serves as a practical alternative when surgical access or anatomy is challenging.
• The third orientation should be avoided due to high stress, risking construct failure or bone resorption.