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Biomedical subjects

J Black

Publications and source records attributed to J Black.

At least 163 records · Page 9Linked to original sources
PubMed1994

Size and shape of biomaterial wear debris.

A literature review of wear debris is presented. Included are debris retrieved at revision of total joint replacement and at autopsy, as well as debris produced in vitro in wear testers and joint simulators or otherwise fabricated for biological experiments. Observations of wear debris in vivo and in vitro are classified in tabular form according to material type, origin, size, shape and color. Polymer particles, most commonly ultra-high molecular weight polyethylene (UHMWPE), exhibit the largest size range and appear as granules, splinters or flakes, while ceramic particles possess the smallest size range and have a granular structure. Metal particles seen in vivo and in vitro, whether from cobalt-chromium alloys or, less frequently, other alloys, form granular or needle-like shapes and generally are smaller than polymer particles but larger than ceramic particles. Particles generated in joint simulators resemble the size and shape of in vivo wear particles from total joint replacement (TJR) retrieved at revision or autopsy. However, particles prepared in vitro, whether in simulators or by other means, do not consistently resemble wear debris particles from TJR.

Biocompatible Materials↗
PubMed1994

Biological performance of tantalum.

A detailed literature search was carried out to define the current knowledge about the biological performance of tantalum. The pure metal appears, to a great degree, to be inert both in vivo and in vitro. Both the pure metal and its principle oxide possess low solubility and toxicity; however, halide compounds are more biologically active. Local host response is benign, characterized by vital encapsulation in soft tissue and frequent osteointegration, reminiscent of titanium, in hard tissue. Tantalum has been in clinical use since before 1940 and has found a wide range of diagnostic and implant applications, with apparently overall excellent results. In some applications, such as for radiographic bone markers and cranial closure, tantalum may well be the current material of choice. In summary, metallic tantalum is a promising biomaterial whose applications have been limited by technical rather than biological performance considerations.

Animals↗
PubMed1994

Deep-plane cervicofacial rotation-advancement flap for reconstruction of large cheek defects.

The blood supply and reliability of cervicofacial rotation-advancement flaps for cheek reconstruction can be improved significantly by dissecting the flap in the deep plane (i.e., below the superficial musculoaponeurotic system and the platysma). This modification, similar in technique to that used in composite or deep-plane face lift, was used successfully in seven patients, including several heavy cigarette smokers who were unlikely to have achieved a successful outcome with a conventional cervicofacial flap. No facial nerve weaknesses were observed. We now believe that the deep plane is the level of choice for dissection of cervicofacial flaps when used for reconstruction of cheek or other facial defects.

Basal Cell Carcinoma↗
PubMed1994

Wear Debris in Total Joint Replacements.

In vivo degradation of prosthetic implant materials is increasingly recognized as a major factor limiting the durability of total joint arthroplasty. In vivo degradation occurs primarily by means of wear processes that can generate large quantities of particulate debris. This debris can stimulate an adverse local host response leading to periprosthetic bone loss, which can compromise implant fixation and bone stock. The authors review the basic mechanisms of implant degradation and the host response to particulate degradation products, particularly in the context of the pathogenesis of osteolysis. Submicron polyethylene particles (mean size, 0.5 um) are the dominant type of wear particle present in periprosthetic tissues associated with uncemented hip replacements. Polyethylene wear can be minimized by improving the quality of the polyethylene, avoiding use of large-diameter (greater than 28 mm) femoral heads in total hip arthroplasty, and improving the design and fabrication of modular connections, which can be important sources of three-body wear particles. Advances in the understanding of the basic mechanisms of osteolysis are critical to the development of preventive measures that will minimize the clinical impact of this phenomenon.

Journal Article↗
PubMed1994

Composition and morphology of wear debris in failed uncemented total hip replacement.

Interfacial membranes collected at revision from 11 failed uncemented Ti-alloy total hip replacements were examined. Particles in the membranes were characterised by electron microscopy, microchemical spectroscopy and particle size analysis. Most were polyethylene and had a mean size of 0.53 micron +/- 0.3. They were similar to the particles seen in the base resin used in the manufacture of the acetabular implants. Relatively few titanium particles were seen. Fragments of bone, stainless steel and silicate were found in small amounts. Most of the polyethylene particles were too small to be seen by light microscopy. Electron microscopy and spectroscopic techniques are required to provide an accurate description of this debris.

Aged↗
PubMed1993

The influence of flange compliance and mechanical loading on the tissue response to percutaneous devices.

The failure of most percutaneous devices (PD) is caused by infection initiated by a lack of a tight seal at the skin-device interface. This interface can be disrupted by both extrinsic and intrinsic forces. Many stress reduction methods have been proposed, the most common being the application of a subcutaneous flange. It is widely believed that the bending compliance of the flange plays a significant role in the success or failure of a PD. A study was conducted to observe the effect of flange compliance on local host response in both a functional and nonfunctional setting. Two PDs having flanges with different bending rigidities were implanted percutaneously in goats (n = 8). After a healing period of 2 weeks, half of these devices were externally stimulated with a random load. All the implants were retrieved after 4 weeks and evaluated histologically. The tissue capsule was significantly thicker and the incidence of severe fibrosis and/or necrosis was higher at the flange rim of the functional implants, irrespective of flange compliance. The more compliant devices were encapsulated with a thick fibrous capsule more frequently than the less compliant ones, irrespective of functional status. The more compliant devices also had a greater incidence of foreign body giant cells in the corner region and elicited severe acute inflammation at the corner and top of the flange more frequently than the less compliant implants.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Development of FRP composite structural biomaterials: fatigue strength of the fiber/matrix interfacial bond in simulated in vivo environments.

Fiber/matrix interfacial bonding in fiber reinforced polymer (FRP) composite materials is potentially sensitive to degradation in aqueous environments. Ultimate bond strength (UBS) in carbon fiber/polysulfone (CF/PSF) and polyaramid/polysulfone (K49/PSF) was previously reported to be significantly decreased in two simulated in vivo environments. While UBS is a useful parameter, for orthopedic implant applications the fatigue behavior of the interface is probably a more relevant indicator of long-term composite material performance. In this article, the effects of simulated in vivo environments (saline, exudate) upon the fatigue behavior of the interface of CF/PSF and K49/PSF are reported. The fatigue behavior of both material combinations was linearly dependent on the logarithm of fatigue life in the dry (control), saline, and exudate environments. Testing either material in saline and exudate resulted in significantly lower fatigue strength than in the dry environment; however, results in the two wet environments were indistinguishable. The CF/PSF interface experienced fatigue failure at approximately 10(5) load cycles at a maximum applied load level of only 15% of its ultimate dry bond strength without indication of an endurance limit being reached. These results raise some important questions regarding the durability of CF/PSF composite in load bearing orthopedic applications.

Animals↗
PubMed1993

Field-dependent fibroblast orientation on charged surfaces is independent of polarity and adsorbed serum proteins.

Electrets were used to induce a dipolar charge on fluorinated ethylene propylene (FEP) and bacteriological grade polystyrene (PS) films. The serum protein surface concentration adsorbed on FEP and PS from cell-free media was dependent on both the magnitude and the polarity of the surface charge density. Chick embryo fibroblasts were cultured on charged and uncharged FEP surfaces, and cellular orientation and biosynthetic activity (protein synthesis) were determined. The orientation of fibroblasts was found to be significantly dependent on the magnitude of the surface charge but independent of its polarity. The biosynthetic activity of fibroblasts was observed to be dependent on both magnitude and polarity of the surface charge density.

Adsorption↗