PEEK Biomaterials in Trauma, Orthopedic, and Spinal Implants

Advances in the processing, sterilization, and crosslinking of ultra-high molecular weight polyethylene for total joint arthroplasty.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/jor.1100170203

Development of an extremely wear-resistant ultra high molecular weight polyethylene for total hip replacements.

Recent advances on protein–polysaccharide electrostatic complex and coacervates' formation, structure and properties are presented. The first section emphasises on the thermodynamics of complexes formation, the contribution of enthalpic and entropic effects is specifically discussed. Then, their structure is described at different length scales and recent findings on the phase-ordering dynamics of complex and coacervates formation are covered. Finally, the most relevant functional properties of protein–polysaccharide complexes and coacervates for food applications are described.

Protein–polysaccharide complexes and coacervates

Abstract Recent advances on protein–polysaccharide electrostatic complex and coacervates' formation, structure and properties are presented. The first section emphasises on the thermodynamics of complexes formation, the contribution of enthalpic and entropic effects is specifically discussed. Then, their structure is described at different length scales and recent findings on the phase-ordering dynamics of complex and coacervates formation are covered. Finally, the most relevant functional properties of protein–polysaccharide complexes and coacervates for food applications are described.

Protein-polysaccharide complexes and coacervates.

Lubrication and wear of ultra-high molecular weight polyethylene in total joint replacements

The mechanistic and morphological origins of microscopic wear debris generated from UHMWPE articular surfaces in total joint replacement prostheses are investigated in this study. It was found experimentally that the molecular chain structure at the articulating surface of UHMWPE undergoes a re-organization process due to strain accumulation caused by surface traction. This molecular re-organization process creates a fibre-like surface texture that exhibits an anisotropic behaviour similar to a unidirectionally reinforced polymer composite. This composite responds to stresses favourably if loaded along the fibre axis but unfavourably if loaded off axis. Due to the very complex multi-axial motion/loading nature at the articular surfaces in total joint replacements, the stress tensors applied to each localized asperity contact area continuously change their directions and magnitudes. These changes in the localized stress field create an off-axis loading situation at each localized contact zone with respect ...

http://journals.sagepub.com/doi/pdf/10.1243/PIME_PROC_1996_210_407_02

Mechanistic and morphological origins of ultra-high molecular weight polyethylene wear debris in total joint replacement prostheses.

Orientation softening in the deformation and wear of ultra-high molecular weight polyethylene

Wear mechanisms of UHMWPE in total joint replacements

We studied the effect of femoral head surface roughness on the wear of ultrahigh molecular weight polyethylene (UHMWPE) acetabular cups using a hip joint simulator and a reciprocating wear tester. Compared with the hip simulator, the reciprocating wear tester severely exaggerates the effect of counterface roughness on UHMWPE wear and drastically underestimates the wear rate of the UHMWPE against smooth undamaged counterfaces. According to the hip simulator test results, the wear rate of the UHMWPE cups is approximately proportional to the square root of the femoral head roughness Ra (center-line-average roughness) rather than to Ra raised to a power greater than one as predicted by pin-on-disk studies. Roughening of the femoral heads by an order of magnitude results in a 2- to 3-fold increase in the wear rate. Therefore, the much wider clinical variations of wear cannot be fully explained by variations in surface roughness of the femoral heads.

A. Wang

Papers

Lubrication and wear of ultra-high molecular weight polyethylene in total joint replacements

Mechanistic and morphological origins of ultra-high molecular weight polyethylene wear debris in total joint replacement prostheses.

Orientation softening in the deformation and wear of ultra-high molecular weight polyethylene

Wear mechanisms of UHMWPE in total joint replacements

Effect of femoral head surface roughness on the wear of ultrahigh molecular weight polyethylene acetabular cups