Cylindrical total ankle joint replacement: surgical and biomechanical rationale

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Materials Science

Background:

• Incongruent total ankle arthroplasty designs exhibit limitations in wear resistance, deformation, and stability.
• Congruent designs have demonstrated potential for improved functional outcomes in ankle replacements.

Purpose of the Study:

• To evaluate the optimal design principles for total ankle arthroplasty based on congruence and motion characteristics.
• To identify desirable geometric features for improved implant performance.

Main Methods:

• Comparative analysis of incongruent versus congruent total ankle arthroplasty designs.
• Evaluation of design parameters such as surface geometry (cylindrical vs. spherical) and their relation to ankle biomechanics.
• Description of the "New Jersey" cylindrical total ankle arthroplasty components and fixation methods.

Main Results:

• Congruent designs generally provide superior function compared to incongruent designs.
• A cylindrical surface design is indicated for ankles with adequate subtalar motion.
• A spherical surface design is recommended for ankles lacking sufficient subtalar motion.

Conclusions:

• Optimal total ankle arthroplasty design depends on the presence or absence of subtalar motion.
• Cylindrical designs are favorable when subtalar motion is present, utilizing specific geometric alignments.
• Spherical designs are advantageous in cases with limited subtalar motion, offering a different biomechanical solution.