Abstract
Bone adaptation after total hip arthroplasty is associated with the change in internal load environment, and can result in compromised bone stock, which presents a considerable challenge should a revision procedure be required. Under the assumption of a generic mechano-regulatory algorithm for governing bone adaptation, the aim of this study was to understand the contribution of subject specific loading conditions towards explaining the local periprosthetic remodelling variations in patients.CT scans of 3 consecutive THA patients were obtained and used for the construction of subject specific finite element models using verified musculoskeletal loading and physiological boundary conditions. Using either strain energy density or equivalent strain as mechano-transduction signals, predictions of bone adaptation were compared to DEXA derived BMD changes from 7 days to 12 months post-implantation. Individual changes in BMD of up to 33.6% were observed within the 12 month follow-up period, together with considerable inter-patient variability of up to 26%. Estimates of bone adaptation using equivalent strain and balanced loading conditions led to the best agreement with in vivo measured BMD, with RMS errors of only 3.9%, 7.3% and 7.3% for the individual subjects, compared to errors of over 10% when the loading conditions were simplified.This study provides evidence that subject specific loading conditions and physiological boundary constraints are essential for explaining inter-patient variations in bone adaptation patterns. This improved knowledge of the rules governing the adaptation of bone following THA helps towards understanding the interplay between mechanics and biology for better identifying patients at risk of excessive or problematic periprosthetic bone atrophy.
Highlights
Periprosthetic bone loss continues to be a burden after total hip arthroplasty (THA) and exhibits substantial inter-patient variability in clinical radiographic measures [1,2,3,4,5]
FEA predictions of the bone adaptation within each Gruen Zone demonstrated that mechano-regulation based on equivalent strain and that incorporated the complex musculoskeletal loading conditions resulted in the best agreement with the clinical DEXA measurements (Figure 5)
We assumed that generic mechanoregulatory rules govern bone adaptation and evaluated the contribution of subject specific anatomy and loading conditions towards explaining the local periprosthetic remodelling variations in 3 patients
Summary
Periprosthetic bone loss continues to be a burden after total hip arthroplasty (THA) and exhibits substantial inter-patient variability in clinical radiographic measures [1,2,3,4,5]. Abrupt changes to the internal loading environment, such as after the implantation of a joint endoprosthesis, lead to a short term adaptation of the bone, resulting in periprosthetic bone atrophy in regions that become unloaded Such bone loss is believed to influence THA longevity by undermining implant fixation and contributing to the risk of aseptic loosening [9,10]. The mechanisms dictating individual patterns of bone adaptation are thought to be mechanically driven, the rules governing these processes remains unclear To establish these rules of tissue adaptation, a number of computational models have been developed that aim to predict the changes in periprosthetic bone [14,15,16,17,18,19,20,21,22,23,24]. An investigation comparing the adaptation driven by different mechanical remodelling signals did not show strain energy density to be superior against the outcome of animal experiments in vivo [17]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
