Prosthesis loading after temporomandibular joint replacement surgery: a musculoskeletal modeling study.

Area of Science:

• Biomechanics
• Biomedical Engineering
• Orthopedic Surgery

Background:

• Condylar component screw loosening is a common complication in temporomandibular joint (TMJ) total joint replacement (TJR).
• Understanding the biomechanical factors influencing prosthetic component stability is crucial for improving TJR outcomes.

Purpose of the Study:

• To develop a musculoskeletal model of the human jaw.
• To assess the influence of prosthetic condylar component orientation and screw placement on condylar component loading during mastication.

Main Methods:

• A 3D musculoskeletal jaw model was created, including bone, cartilage, disks, and muscles.
• Simulations of mastication and maximum bite force were performed for natural and replaced TMJs.
• Variations in condylar component anterior rotation (0-15 degrees) and screw configurations (complete, posterior, minimal-posterior screw) were analyzed.

Main Results:

• Increased anterior rotation of the condylar component elevated contact stresses and screw stresses.
• Utilizing more screws for fixation reduced screw and component stresses.
• Superiorly placed screws experienced higher stress levels compared to other configurations.

Conclusions:

• Condylar component orientation and screw placement are critical factors in TMJ TJR.
• Minimizing anterior rotation and optimizing screw configuration can mitigate stress and enhance prosthetic stability.
• Findings inform surgical placement of prosthetic components to reduce complications.