Mohd Moideen Irwan Shah, Lim Chin Tat, Yeow Raye C H, Chong Desmond Y R
Department of Biomedical Engineering, National University of Singapore, Singapore.
Department of Orthopedic Surgery, National University Hospital Singapore, Singapore.
Comput Biol Med. 2022 Feb;141:105142. doi: 10.1016/j.compbiomed.2021.105142. Epub 2021 Dec 14.
The primary stability of a total ankle replacement (TAR) is essential in preventing long-term aseptic loosening failure and could be quantified based on micromotion at the bone-prosthesis interface subjected to physiological loading during the normal walking. A 3D finite element analysis was conducted to investigate the current commercial STAR™ Ankle TAR bone-prosthesis interface relative micromotion (BPIRM) with addition of the talus bone minimum principal bone stresses (MPBS). Comparison was made to the proposed polka dot designs with the hemispheric feature that was demonstrated to enhance BPIRM. Parametric studies were conducted on the hemispheric features with changes in its diameter, length and shape. The FE results indicated high BPIRM at the talar component was primarily contributed by de-bonding (in the normal direction) between the talus bone and talar component. The MPBS were found to be most significant in the superior anterior and superior medial regions of the talus bone. When the pin length was increased from 1.5 to 3 mm, the BPIRM was predicted to fall below 50 μm in favour of bone in-growth. Based on the practicality of the prosthesis implantation during the surgical procedure, the final design that incorporated both the initial polka dot and 3 mm pin length in a crisscross manner was deemed to be a favorable design with reduced BPIRM and MPBS hence lowering the risk of long-term aseptic loosening.
全踝关节置换术（TAR）的初始稳定性对于预防长期无菌性松动失败至关重要，并且可以基于正常行走过程中生理负荷下骨-假体界面的微动来进行量化。进行了三维有限元分析，以研究当前商业化的STAR™全踝关节置换术的骨-假体界面相对微动（BPIRM），并增加距骨的最小主骨应力（MPBS）。将其与具有半球形特征的拟议的波点设计进行比较，该半球形特征已被证明可增强BPIRM。对半球形特征的直径、长度和形状变化进行了参数研究。有限元分析结果表明，距骨组件处的高BPIRM主要是由距骨与距骨组件之间的脱粘（沿法线方向）造成的。发现MPBS在距骨的上前部和上中部区域最为显著。当销钉长度从1.5毫米增加到3毫米时，预计BPIRM将降至50μm以下，有利于骨长入。基于手术过程中假体植入的实用性，最终设计采用初始波点和3毫米销钉长度以交叉方式结合，被认为是一种有利的设计，可降低BPIRM和MPBS，从而降低长期无菌性松动的风险。
