Development of a Novel in Silico Model to Investigate the Influence of Radial Clearance on the Acetabular Cup Contact Pressure in Hip Implants

Abstract

A hip joint replacement is considered one of the most successful orthopedic surgical procedures although it involves challenges that must be overcome. The patient group undergoing total hip arthroplasty now includes younger and more active patients who require a broad range of motion and a longer service lifetime of the implant. The current replacement joint results are not fully satisfactory for these patients’ demands. As particle release is one of the main issues, pre-clinical experimental wear testing of total hip replacement components is an invaluable tool for evaluating new implant designs and materials. The aim of the study was to investigate the cup tensional state by varying the clearance between head and cup. For doing this we use a novel hard-on-soft finite element model with kinematic and dynamic conditions calculated from a musculoskeletal multibody model during the gait. Four different usual radial clearances were considered, ranging from 0 to 0.5 mm. The results showed that radial clearance plays a key role in acetabular cup stress-strain during the gait, showing from the 0 value to the highest, 0.5, a difference of 44% and 35% in terms of maximum pressure and deformation, respectively. Moreover, the presented model could be usefully exploited for complete elastohydrodynamic synovial lubrication modelling of the joint, with the aim of moving towards an increasingly realistic total hip arthroplasty in silico wear assessment accounting for differences in radial clearances.

Editorial: Biotribology and Biotribocorrosion Properties of Implantable Biomaterials

“…However, these tests are expensive and require long time, since the simulations run for several million cycles, taking in to account that one million cycles is assumed to correspond to 1 year in-vivo conditions. Considering the above, to date, in-silico wear prediction models of artificial human implants attract the attentions of researchers to obtain complete tribological theoretical and numerical models useful for the in-silico testing (O'Brien et al, 2015;Mattei et al, 2016;Affatato et al, 2018), which could avoid the standard in-vitro time-consuming investigation procedures (simulators) and could contribute as tool for a more and more accurate tribological design of human prostheses. Obviously, the accurate wear prediction of artificial joints requires to develop detailed tribological models accounting for the complexity and the multiscale of wear phenomenon (Vakis et al, 2018) which requires scientific knowledge in many fields, such as contact mechanics (Popov, 2010), topographic contact surfaces characterization (Merola et al, 2016), new materials formulations (Affatato et al, 2015), stress-strain analysis and FEM/BEM simulations (Ruggiero et al, 2018;Ruggiero and D'Amato R, 2019), musculoskeletal multibody modeling (Zhang et al, 2017), unsteady synovial lubrication modeling (boundary/mixed, hydro-dynamic and EHD) (Ruggiero and Sicilia, 2020), tribo-corrosion (Tan et al, 2016), metal transfer phenomena (Affatato et al, 2017), biomaterials characterizations (Ruggiero et al, 2016), etc.…”

A Perspective on Biotribology in Arthroplasty: From In Vitro toward the Accurate In Silico Wear Prediction

“…The experimental tribological devices for the simulation of hip and knee prostheses have been improved over the years in order to make them able to reproduce tribological wear tests in kinematic and dynamic conditions very close to the real ones [30][31][32][33]. The new trend of an in silico approach to the evaluation of the articular prostheses' wear represents, nowadays, a fascinating scientific challenge, which involves many disciplinary fields and which requires a deep collaboration between scientists from different areas [41][42][43][44].…”

“…O'Brien et al proposed an interesting theory based on energy dissipation: the process of wear is inherently dynamically adaptive, and localized high wear can result in faster deformation in The in silico procedure starts by evaluating the human motion kinematics in the framework of inverse dynamic analysis (motion capture) with reference both to normal gait and other desired daily activities [32,45]. The obtained data are used for the calculation of the unsteady joint forces which are used as load conditions in joint Finite Element Analysis (FEM) [42][43][44]. The resulting stress-strain behavior of the artificial coupling have to be joined with the lubrication model for taking into account the complex synovial phenomena acting in the joint [41,46].…”

Design, Optimization, and Evaluation of Additively Manufactured Vintiles Cellular Structure for Acetabular Cup Implant

“…These material properties are consistent with the base powder used to manufacture the experimental implant samples. According to Affatato et al, applied forces and boundary conditions were used to generate an implant model that simulates the loading force on a physical structure [48]. The triangular mesh was generated, and the mesh was refined until stresses converged, with a final average mesh size of approximately 100,000 elements (see Figure 6a,b).…”