Polka dot cementless talar component in enhancing total ankle replacement fixation: A parametric study using the...

Area of Science:

• Biomedical Engineering
• Orthopedic Surgery
• Materials Science

Background:

• Primary stability in total ankle replacement (TAR) is critical for long-term success, preventing aseptic loosening.
• Micromotion at the bone-prosthesis interface under physiological loading is a key indicator of stability.
• Current TAR designs require investigation for optimizing bone-ingrowth and reducing failure risks.

Purpose of the Study:

• To investigate bone-prosthesis interface relative micromotion (BPIRM) in a commercial TAR using 3D finite element analysis.
• To evaluate novel polka dot designs with hemispheric features for enhanced BPIRM.
• To optimize TAR design parameters, including hemispheric feature dimensions and pin length, to minimize micromotion and bone stresses.

Main Methods:

• A 3D finite element analysis (FEA) model of the STAR™ Ankle TAR was developed.
• FEA was used to quantify BPIRM and minimum principal bone stresses (MPBS) under physiological walking loads.
• Parametric studies were performed on polka dot designs, varying hemispheric feature diameter, length, and shape.

Main Results:

• High BPIRM was observed at the talar component, primarily due to debonding between the talus bone and talar component.
• Minimum principal bone stresses (MPBS) were most significant in the superior anterior and superior medial regions of the talus.
• Increasing pin length from 1.5 mm to 3 mm reduced BPIRM below 50 μm, promoting bone ingrowth.

Conclusions:

• The novel polka dot design with 3 mm pin length, arranged in a crisscross pattern, demonstrated reduced BPIRM and MPBS.
• This optimized design offers a favorable solution for improving TAR stability and lowering the risk of long-term aseptic loosening.
• The findings support the clinical practicality and potential efficacy of the enhanced TAR design.