PubMed Health⌕ Search

Biomedical subjects

P S Christel

Publications and source records attributed to P S Christel.

6 recordsLinked to original sources
PubMed1993

A composite of natural coral, collagen, bone protein and basic fibroblast growth factor tested in a rat subcutaneous model.

A rat subcutaneous model was used to test the osteoinductive efficacy of a composite consisting of natural coral, collagen, a bone morphogenetic protein-like material [termed bone protein (BP)], and basic fibroblast growth factor (bFGF). Results indicated good ossicle formation only when BP was present, whether with or without bFGF. Initially, cartilage and mineralized cartilage were apparent. With time, osteoblastic bone formation and hematopoietic marrow were evident. bFGF may have enhanced the maturation of the ossicles in the early stages. Coral-collagen appears to be a good carrier vehicle for BP and should be tested in a bony site. This would allow the osteoconductive property of coral to be expressed.

Animals↗
PubMed1992

Biocompatibility of surgical-grade dense polycrystalline alumina.

This article reviews the knowledge about biocompatibility of alumina since its introduction as a material for use in joint replacements. Alumina is a hydrophilic material with high wettability allowing very low friction with negligible wear. Macrophages loaded with alumina particles show no morphologic alteration and do not lose their chemotactic ability. The host response has been studied for bulk and particulate alumina in soft tissues, as well as in human and animal bone under loaded and nonloaded conditions. The soft-tissue response to bulk alumina exhibits minimal fibrosis, and direct bone contact is achieved at compression-loaded interfaces. Examination of human biopsies from failed total hip prostheses reveals a foreign-body reaction containing predominantly macrophages loaded with alumina particles. No lymphocyte or plasma-cell infiltration is observed because of the absence of soluble component release. The amount of necrosis and fibrosis was lower than that associated with metal or polyethylene debris. In summary, alumina exhibits greater bioinertness than all other implant materials currently available for joint replacement.

Aluminum Oxide↗
PubMed1989

Zirconia: the second generation of ceramics for total hip replacement.

Alumina ceramic was successfully introduced into orthopaedic surgery for total hip replacement 20 years ago. Its mechanical properties are currently optimized, and there is a need to develop new ceramics having higher mechanical properties, mainly in tension. Yttrium-oxide partially stabilized zirconia is one of the new ceramics that exhibits much more toughness than alumina. This article reviews the processing as well as the mechanical and biological properties of this new class of materials which are already in clinical use in Europe.

Biocompatible Materials↗
PubMed1988

Role of stem design and material on stress distributions in cemented total hip replacement.

The risk of fatigue fractures of the femoral stem in a cemented total hip arthroplasty can be minimized by either increasing the stem cross-section and/or using a very high strength alloy. The object of this study was to compare important mechanical characteristics of five selected stem designs, differing in configuration and material (stainless steel, cast chrome cobalt alloy, nickel based alloy and titanium alloy). The stain pattern on the stem was analysed in a 3-point-bending jig and also after cementing it into cadaver femurs. Regardless of stem type or test method, the typical tensile stress distribution on the lateral stem was a bell shaped curve. For the cobalt-chrome and stainless steel stems, the larger the stem the lower were the stem stresses and the stress gradient, and the higher was the factor of safety. However, the factor of safety was increased even further by the use of super alloys such as MP35N and Ti6Al4V. In addition, Ti6Al4V alloy allowed the use of larger and stronger stems without the extra penalty of rigidity, which was enforced by either the steel or cobalt based alloy.

Biomechanical Phenomena↗
PubMed1986

Semi-automatic image-analysis applied to the quantification of bone microstructure.

Bone microstructure can be quantified by methods ranging from simple manual techniques to fully automatic image analysis systems. We describe a semi-automatic method, developed in BASIC and running on a laboratory microcomputer. Its core is based on two special algorithms for image conversion and for calculation. These two algorithms produce quantifying characteristics for any irregularly shaped structure, as defined by one or more open or closed contour lines. The quantification of these structural parameters relies only on contour line digitization. The improved efficiency of this semi-automatic method is a consequence of combining automatic calculations and human assistance. The structural parameters chosen were for a specific research project; the correlation between mechanical and microstructural properties of cortical bone, but they may readily be changed as circumstances demand.

Biomechanical Phenomena↗