全人工膝關節外置式髖骨植入物之研究分析

EVALUATION OF THE THREE-PEG PATELLAR COMPONENT IN TOTAL KNEE ARTHROPLASTY

在全人工膝關節置換術（TKA）的併發症問題中，植入的誤差及元件設計不佳皆可能是TKA失敗的原因。因此，本研究選擇目前臨床上較常使用之外置式人工膝關節，透過逆向工程的手法建立人工髖股骨之三維有限元素模型，經由電腦輔助分析來找出其造成人工髖骨破壞之主要因素。研究發現，當髖股骨關節隨著屈膝行為之改變時，其所產生之應力分佈情形與狀態雖有很大之差異，但仍於容許範圍內，比較值得注意的是髖骨外傾現象。此外，由研究之結果與臨床比對，本文可以推論出人工髖骨支承栓剪斷行為與原尺寸設計無關，但植體介面之骨水泥反而是支承栓剪斷主要原因。本研究另外也還發現現常用之常用人工膝關節元件，若經稍加改良處理後，應可有效降低手術失敗之比率，故提出一更穩健的髖骨支承栓配置設計。

Even though patellar complications of total knee arthroplasty (TKA) remain unresolved, the technique of patellar re-surfacing is a major surgical feature. However, as has been found from current pathological reports, inaccuracy of implantation and poor component designs may largely comprise the failure causes for operations on patello-femoral joints. The study begins with establishing a 3D finite element model of the joint via reverse engineering (RE). The 3D models are then analyzed by means of computer-aided engineering (CAE). The attention of the computer simulation is on the contact behaviors of the patello-femoral joint as different knee bends occur. Meanwhile, the study is mainly to explore the major factors that result in fractures caused by patellar implants. Attention is also paid to the de-bonding effect that occurs between the interface between the natural patella and the patellar components. It has been found that the contact stresses vary from the three different flexion angles. However, all are within the maximum allowable limit for the corresponding materials. More importantly, the simulation shows that the main reason causing facet wear on patellar component surfaces is geometrical design. In addition, it is worth noting that the reason causing the patellar pegs to break is mainly de-bonding arising from the interface of the patella and the patellar component. Finally, a robust design for the configuration of the three pegs is suggested.