Search PubMed⌕ Search

Biomedical subjects

J M Dowling

Publications and source records attributed to J M Dowling.

4 recordsLinked to original sources
PubMed1999

Temporomandibular Joint Arthroplasty Using Metal-on-Metal and Acrylic-on-Metal Configurations : Wear In Laboratory Tests and In Retrievals.

In the long-term performance ofthe temporomaridibular joint (TMJ) implant, wear must be considered. Thus retrieved and laboratory test implants were examined both optically and in a scanning electron microscope (SEM). In laboratory testing, the volumetric wear of metal-on-metal was about an order of magnitude less than that of acrylic-on-metal TMJ implants. This metal-on-metal wear was also about half of that reported in the literature for a laboratory test of polyethylene-on-metal TMJ implants, The retrieved TMJ implants showed some abrasive wear occurred during multi-directional articulation with smaller wear zones for the metal-on-metal compared to the acrylic-on-metal configuration. Further efforts to characterize and minimize wear were recommended as prudent in the continuing development of TMJ arthroplasty.

Journal Article↗
PubMed1980

Materials for internal prostheses: the present position and possible future developments.

In this paper we consider solid phase forming as a method of manufacturing acetabular cups. Static and cyclic creep tests have been carried out on Charnley cups and indicate that creep, rather than wear, plays the major role in the penetration of the socket by the femoral ball, at least in the first few years. We have investigated a new type of cross-linked polyethylene and found it to be extremely good from both a wear and creep viewpoint, particularly under high loads and at high sliding velocities.

Alloys↗
PubMed1978

The characteristics of acetabular cups worn in the human body.

In laboratory tests, the ultra-high molecular weight polyethylene used for the acetabular cups of Charnley hip prostheses has a very low wear rate against steel. In the body radiographic measurements indicate that the polyethylene wears more rapidly. In order to investigate this higher wear rate, the sockets of acetabular cups removed at post-mortem have been examined using optical and electron microscopy. It has been shown that a socket wears predominantly on its superior part and that this is a direct consequence of the orientation of the cup in the body and the direction of loading of the hip. In the worn region the femoral head in effect bores out a new socket for itself, a process which is visible with the naked eye after approximately eight years. Electron microscopy shows that the predominant wear mechanism is adhesion, but after about eight years the appearance of surface cracks suggests that surface fatigue is taking place in addition to this. Laboratory wear tests have shown that pure surface fatigue is not sufficient to account for the high clinical wear rate. Other deformation processes are suggested and discussed with regard to the higher clinical wear rate.

Acetabulum↗