Stress Shielding and Bone Resorption of Press-Fit Polyether–Ether–Ketone (PEEK) Hip Prosthesis: A Sawbone Model Study

Abstract

Stress shielding secondary to bone resorption is one of the main causes of aseptic loosening, which limits the lifespan of the hip prostheses and increases the rates of revision surgery. This study proposes a low stiffness polyether–ether–ketone (PEEK) hip prostheses, produced by fused deposition modelling to minimize the stress difference after the hip replacement. The stress shielding effect and the potential bone resorption of the PEEK implant was investigated through both experimental tests and FE simulation. A generic Ti6Al4V implant was incorporated in this study to allow fair comparison as control group. Attributed to the low stiffness, the proposed PEEK implant showed a more natural stress distribution, less stress shielding (by 104%), and loss in bone mass (by 72%) compared with the Ti6Al4V implant. The stiffness of the Ti6Al4V and the PEEK implant were measured through compression tests to be 2.76 kN/mm and 0.276 kN/mm. The factor of safety for the PEEK implant in both static and dynamic loading scenarios were obtained through simulation. Most of the regions in the PEEK implant were tested to be safe (FoS larger than 1) in terms of representing daily activities (2300 N), while the medial neck and distal restriction point of the implant attracts large von Mises stress 82 MPa and 76 MPa, respectively, and, thus, may possibly fail during intensive activities by yield and fatigue. Overall, considering the reduction in stress shielding and bone resorption in cortical bone, PEEK could be a promising material for the patient–specific femoral implants.

Polycrystalline Diamond as a Potential Material for the Hard-on-Hard Bearing of Total Hip Prosthesis: Von Mises Stress Analysis

“…The number of elements used for the von Mises stress investigation of the hard-on-hard bearings of total hip prosthesis was selected based on the convergence studies of six identical models with different elements, including coarse elements (small number of elements) and fine elements (large number of elements) presented in Figure 4 . It aims to select hard-on-hard bearing models with an optimal number of elements, which does not use too many elements in order to not burden the computational load, whilst still being able to provide accurate von Mises stress results [ 40 ]. The convergence study was conducted by analyzing the highest von Mises stress (at the 7th phase of gait loading) on the CoCrMo-on-CoCrMo bearings.…”

Advancement in total hip implant: a comprehensive review of mechanics and performance parameters across diverse novelties

“…In those works, the analysis involved applying axial loads ranging from 600 N to 5 KN on the femoral head. 15,16,33,35,[37][38][39][41][42][43][46][47][48][49][50] In numerous recent studies, dynamic load component values have been utilized to assess the mechanical behaviour of hip implant stems within implanted bones. 12,34,43,45,47,[51][52][53] However, a German study group known as ''Orthoload'' has released dynamic force and moment data of daily activities in various environments.…”

“…As the implant material significantly affects the transmission of stress from the implant to the surrounding bone, it is essential to evaluate the bone remodelling rate and related failure index characteristics for hip implants made from various materials. The predominant bone remodelling estimating model, 48,[90][91][92][93] proposed by Winan et al 94 and Huiskes et al, 95 is based on the strain energy density (SED), which is widely used (J cm À3 ). The bone remodelling rate Dr Dt can be estimated using the following eqn (21).…”

“…The bone remodelling rate Dr Dt can be estimated using the following eqn (21). 42,48,[90][91][92][93] Fig. 6 Indication of Gruen Areas in (a) intact femur and (b) implanted femur.…”

A novel hybrid design and modelling of a customised graded Ti-6Al-4V porous hip implant to reduce stress-shielding: An experimental and numerical analysis

“…Previously, multiple materials were considered to reduce hip implant stiffness, and this has led to the development of ‘isoelastic stems’. Composite materials based on carbon fibre, polyetheretherketone (PEEK), glass fibre and polyethyleneimine (PEI) have been also explored as potential candidates for hip implants ( Brandwood et al, 1992 ; De Santis et al, 2000 ; Srinivasan et al, 2000 ; Bougherara et al, 2011 ; Naghavi et al, 2022a ). Although they have been shown to reduce the stiffness profile of the hip implant, the results have not been promising ( Scholz et al, 2011 ; Saad et al, 2018 ).…”