Improving fretting corrosion resistance of CoCrMo alloy with TiSiN and ZrN coatings for orthopedic applications.

Total hip replacement is the most effective treatment for late stage osteoarthritis. However, adverse local tissue reactions (ALTRs) have been observed in patients with modular total hip implants. Although the detailed mechanisms of ALTRs are still unknown, fretting corrosion and the associated metal ion release from the CoCrMo femoral head at the modular junction has been reported to be a major factor.

Differential response of human blood leukocytes to brushite, monetite, and calcium polyphosphate biomaterials.

Calcium phosphate-based biomaterials are extensively used for bone replacement and regeneration in orthopedic, dental, and maxillofacial surgical applications. The injury induced by surgical implantation of bone replacement graft materials initiates a cascade of host responses, starting with blood-biomaterial contact, protein adsorption on the material surface, blood coagulation, and leukocyte responses. During the initial acute inflammatory response, polymorphonuclear neutrophils (PMNs) and monocytes, abundant circulating leukocytes of the myeloid lineage, are recruited to the site of inflammation.

Phase transformations during processing and in vitro degradation of porous calcium polyphosphates.

A 2-Step sinter/anneal treatment has been reported previously for forming porous CPP as biodegradable bone substitutes [9]. During the 2-Step annealing treatment, the heat treatment used strongly affected the rate of CPP degradation in vitro. In the present study, x-ray diffraction and (31)P solid state nuclear magnetic resonance were used to determine the phases that formed using different heat treating processes.

Calcium polyphosphate particulates for bone void filler applications.

This study investigates the characteristics of porous calcium polyphosphate particulates (CPPp) formed using two different processing treatments as bone void fillers in non- or minimally load-bearing sites. The two calcium polyphosphate particulate variants (grades) were formed using different annealing conditions during particulate preparation to yield either more slowly degrading calcium polyphosphate particulates (SD-CPPp) or faster degrading particulates (FD-CPPp) as suggested by a previous degradation study conducted in vitro (Hu et al., Submitted for publication 2016).

Porous calcium polyphosphate bone substitutes: additive manufacturing versus conventional gravity sinter processing-effect on structure and mechanical properties.

Porous calcium polyphosphate (CPP) structures proposed as bone-substitute implants and made by sintering CPP powders to form bending test samples of approximately 35 vol % porosity were machined from preformed blocks made either by additive manufacturing (AM) or conventional gravity sintering (CS) methods and the structure and mechanical characteristics of samples so made were compared. AM-made samples displayed higher bending strengths (≈1.2-1.

Solid freeform fabrication of porous calcium polyphosphate structures for bone substitute applications: in vivo studies.

Porous calcium polyphosphate (CPP) structures with 30 volume percent porosity and made by solid freeform fabrication (SFF) were implanted in rabbit femoral condyle sites for 6-wk periods. Two forms of SFF implants with different stacked layer orientation were made in view of prior studies reporting on anisotropic/orthotropic mechanical properties of structures so formed. In addition, porous CPP implants of equal volume percent porosity made by conventional sintering and machining methods were prepared.

Porous calcium polyphosphate as load-bearing bone substitutes: in vivo study.

Porous calcium polyphosphate (CPP) is being investigated for fabrication of novel biodegradable bone substitutes. In this study, porous CPP implants formed by conventional CPP powder packing and using a two-step sinter/anneal process was used to form 20 and 30 vol % porous samples displaying relatively high strength. These were implanted in rabbit femoral condyle sites to study their ability for secure fixation in prepared sites through bone ingrowth.

Mechanical characteristics of solid-freeform-fabricated porous calcium polyphosphate structures with oriented stacked layers.

This study addresses the mechanical properties of calcium polyphosphate (CPP) structures formed by stacked layers using a powder-based solid freeform fabrication (SFF) technique. The mechanical properties of the 35% porous structures were characterized by uniaxial compression testing for compressive strength determination and diametral compression testing to determine tensile strength. Fracture cleavage surfaces were analyzed using scanning electron microscopy.

Enhanced gap filling and osteoconduction associated with alendronate-calcium phosphate-coated porous tantalum.

Background: Porous tantalum has been shown to be effective in achieving bone ingrowth. However, in some circumstances, bone quality or quantity may be insufficient to allow adequate bone ingrowth. We hypothesized that local delivery of alendronate from porous tantalum would enhance the ability of the tantalum to achieve bone ingrowth when there is a gap between the implant and bone.