Computational tibial bone remodeling over a population after total knee arthroplasty: A comparative study

Abstract

Periprosthetic bone loss is an important factor in tibial implant failure mechanisms in total knee arthroplasty (TKA). The purpose of this study was to validate computational postoperative bone response using longitudinal clinical DEXA densities. Computational remodeling outcome over a population was obtained by incorporating the strain-adaptive remodeling theory in finite element (FE) simulations of 26 different tibiae. Physiological loading conditions were applied, and bone mineral density (BMD) in three different regions of interest (ROIs) was considered over a postoperative time of 15 years. BMD outcome was compared directly to previously reported clinical BMD data of a comparable TKA cohort. Similar trends between computational and clinical bone remodeling over time were observed in the two proximal ROIs, with most rapid bone loss taking place in the initial months after TKA and BMD starting to level in the following years. The extent of absolute proximal BMD change was underestimated in the FE population compared with the clinical subject group, which might be the result of significantly higher initial clinical baseline BMD values.Large differences in remodeling response were found in the distal ROI, in which resorption was measured clinically, but a large BMD increase was predicted by the FE models. Multiple computational limitations, related to the FE mesh, loading conditions, and strain-adaptive algorithm, likely contributed to the extensive local bone formation. Further research incorporating subject-specific comparisons using followup CT scans and more extensive physiological knee loading is recommended to optimize bone remodeling more distal to the tibial baseplate.

Using Finite Element Modeling in Bone Mechanoadaptation

“…Typically remodeling algorithms use a mechanoadaptive theory [ 57 , 66 , 67 ]: when the mechanical signal of interest is above/below a certain threshold, bone formation/resorption is implemented according to the proposed algorithm [ 53 , 68 ••, 69 ]. Studies have also implemented a lazy zone in which no formation or resorption occurs [ 63 , 70 •, 71 , 72 •]. In addition, response to heavy mechanical loading can be simulated to consider woven bone formation [ 73 •] or damage [ 72 •].…”

“…FE models can also be used to predict bone ingrowth within the implant coating [ 80 ]. FE models of bone adaptation in prosthesis applications are often compared to clinical data [ 71 ].…”