Isolation of TiNbN wear particles from a coated metal-on-metal bearing: Morphological characterization and in vitro evaluation of cytotoxicity in human osteoblasts.

To improve the wear resistance of articulating metallic joint endoprostheses, the surfaces can be coated with titanium niobium nitride (TiNbN). Under poor tribological conditions or malalignment, wear can occur on these implant surfaces in situ. This study investigated the biological response of human osteoblasts to wear particles generated from TiNbN-coated hip implants.

Influence of analyzed lubricant volumes on the amount and characteristics of generated wear particles from three different types of polyethylene liner materials.

The articulating components of artificial joints consist mainly of metals, ceramics, or polymers. Resulting abrasive wear particles can promote osteolysis and aseptic loosening of the endo-prosthetic implants. Ultra-high-molecular-weight-polyethylene is the material used most for bearing couples in total hip replacement.

High wear resistance of femoral components coated with titanium nitride: a retrieval analysis.

Purpose: The objective of this study was to evaluate the in vivo wear resistance of cobalt-chromium femoral components coated with titanium nitride (TiN). Our null hypothesis was that the surface damage and the thickness of the TiN coating do not correlate with the time in vivo.

Methods: Twenty-five TiN-coated bicondylar femoral retrievals with a mean implantation period of 30.

Intra-prosthetic dislocation of dual-mobility cups after total hip arthroplasty: potential causes from a clinical and biomechanical perspective.

Introduction: Recurrent dislocation of total hip arthroplasty is a frequent indication for revision surgery. Hip joint stability depends on implant design, cup position and crucially on femoral head diameter. Due to an effective ultra-large diameter femoral head, dual-mobility cups are considered an attractive solution to prevent dislocation in unstable conditions.

Wear testing of total hip replacements under severe conditions.

Controlled wear testing of total hip replacements in hip joint simulators is a well-established and powerful method, giving an extensive prediction of the long-term clinical performance. To understand the wear behavior of a bearing and its limits under in vivo conditions, testing scenarios should be designed as physiologically as possible. Currently, the ISO standard protocol 14242 is the most common preclinical testing procedure for total hip replacements, based on a simplified gait cycle for normal walking conditions.

The Divergence of Wear Propagation and Stress at Steep Acetabular Cup Positions Using Ceramic Heads and Sequentially Cross-Linked Polyethylene Liners.

The aim of the present wear simulator study was to assess the effect of steep acetabular cup positions on the wear propagation of highly cross-linked-PE (HX-PE) liners. Furthermore, a finite element analysis (FEA) was performed in order to calculate the stress within the HX-PE material in case of steep cup positions under physiological loadings. The higher stress in the HX-PE at a steep acetabular cup position did not result in increased wear in the present wear simulator study.

Self-centering dual-mobility total hip systems: Prediction of relative movements and realignment of different intermediate components.

The increased jump distance against dislocation and the large range of motion due to the enlarged effective head diameter substantiate the use of dual-mobility systems in cases of total hip joint instability. For this type of total hip endoprostheses, an eccentric design of the outer bearing is assumed in order to provide a force-dependent self-centering mechanism and an improved joint stability against dislocation. The purpose of this study was to determine the relative movements and realignment of different intermediate components during various motion cycles as a result of the eccentric design.

Dynamic behavior of tripolar hip endoprostheses under physiological conditions and their effect on stability.

Tripolar systems have been implanted to reduce the risk of recurrent dislocation. However, there is little known about the dynamic behavior of tripolar hip endoprostheses under daily life conditions and achieved joint stability. Hence, the objective of this biomechanical study was to examine the in vivo dynamics and dislocation behavior of two types of tripolar systems compared to a standard total hip replacement (THR) with the same outer head diameter.

Wear testing and particle characterisation of sequentially crosslinked polyethylene acetabular liners using different femoral head sizes.

Larger femoral heads lead to a decreased risk of total hip dislocation and an improved range of motion. However, the larger diameter is associated with increased wear rates. The low wear rates of crosslinked polyethylene opens up the possibility of using larger heads.

Generation of physiological parameter sets for hip joint motions and loads during daily life activities for application in wear simulators of the artificial hip joint.

At present, wear investigations of total hip replacements are performed in accordance with the ISO standard 14242, which is based on simplified kinematic and force data of the gait cycle. The aim of this analytical study was to generate parameter sets of daily life activities in order to replicate more realistic joint load situations in wear testing. Hence, published in vivo motion and force data of daily life activities were evaluated and adjusted using analytical techniques.