By Professor Sir John Charnley C.B.E., F.R.S., F.R.C.S., F.A.C.S (auth.)
The subject of this paintings is the applying of the engmeermg idea of frictional torque to overall hip alternative. the writer adhered tenaciously to this concept, concerning using a small-diameter femoral head, in the course of the epoch while the large-diame ter, metal-to-metal layout ruled the sector. in the course of that significant interval basic pride with the early effects rendered criticisms of the large-diameter head unwelcome. there has been an impressive array of counter feedback: the small head might pierce a movie of synovial fluid; the small head might put on the socket too speedily; the small head could continually have a excessive hazard of dislocation; detachment of the trochanter, to accomplish specified orientation for the small head, was once unacceptable. yet most of these objections have now been mostly triumph over. Lubrication of excessive molecular weight polyethylene (HMWP) on steel is now approved as being generally by means of the boundary regime with thick fluid motion pictures enjoying no half. We now be aware of that HMWP can certainly tolerate the very excessive stresses imposed through the small head and in tribological concept there will even be a few virtue in excessive pressure. Dislocation is referred to now to not be an automated sequel to the small head.