, Paul D. Siney1 and Patricia A. Fleming1
(1)
The John Charnley Research Institute Wrightington Hospital, Wigan, Lancashire, UK
The failure, if it does eventually supervene, is to be expected from one, or both, of two possible causes:
“Tissue reaction to particles abraded from the bearing surface;” and
Mechanical loosening of the cement bond in the bone. 1961.
The study of socket wear/creep and the resultant loosening is urgent, and at this stage may appear to be the one factor limiting the life of the arthroplasty. (1984).
Wear
Removal or transfer of material from contacting surfaces due to their relative movement under load. Wear can be measured by mass change, volume measurement or by the depth of the wear tracks. The two inevitable consequences are shedding of wear products and change of the geometry of the articulation.
Study of wear in THA is a complex task. It involves a number of closely related topics: materials, design, surgical technique as well as the consequences of wear be they mechanical or biological. It is therefore important that the whole topic is studied in the context of the principle of the design, clinical practice and the long term results.
Some repetition in the text is not only inevitable, but also essential to maintain the continuity.
The Information Gathered from the Teflon Era
It was during that period that the design of the components, “the mechanical details of the technique became stabilised in the period 1959 to 1962 …” (1979)
Sockets did not wear by enlargement … in all directions in a random fashion … plastic socket in the hip joint retains permanently a close fit against the spherical metal head.
… it would follow that the smallest volume of harmful particulate matter would be generated by using the smallest head which anatomical and mechanical considerations would permit.
… from consideration of the geometry and wear characteristics … the sphere should have a diameter not greater than half that of the external diameter of the socket.Related posts:
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