Hip-prothesis with the Thomson, moore endoprothesis in Viet Duc Hospital Hanoi’s. Proximal prothesis of the hip used about 50 years, for old patients over 60 years with fractures of the neck of the femur. 62 proximal prothesis since 1983 were done in Viet Duc Hospital. Fractures of the neck of the femur: 27. Necrosis of the femoral head: 35. Out - dated fractures: 22. After osteosynthesis: 9. Tumor: 4. Best: 40. Good: 21. Bad: 1.
Hip Prosthesis ; Arthroplasty, Replacement, Hip

Arthroplasty, Replacement, Hip ; Hip Prosthesis

The reported clinical results following revision of failed cemented hip arthroplasties have varied. The most improtaint aspect of revision surgery, especially in case of removal of well injected femoral cement need not be daunting if certain essential principles are understanding. The prohlem is hasically that of a tuhe (cement) fixed within another tube (femur). Otherwise, any attempt to work between the two will cause the instruments to skid off the cement and penetrate the femoral cortex. Therefore, on the first step to deal with the problem and theoretical ground, we have investigated the mode of fracture in bone cement. Prior to this study, a comparision of various cement strength been published by A.J.C. Lee, University of Exetcr, UK is rviewed for our reference. As far as cement crack is concerned, the re are three modes of fracture, namely, mode I, mode II and mode III. As seen in the Fig. 5, mode I fracture is defined to be the fracture under symmetic loading, which is perpendicular to the crack surface. Mode II fracture is the fracture under anti-symmetric loading, which is parallel to the crack surface. In mode III, the loading is perpendicular to both crack surface and the plan of the paper. On the left is the situation shown when using osteotome to crush the cement Fig. 6. The prohlem here is of dynamical nature, however, this kind of prohlem has not been solved yet. Prediction of the direction of propagation is possible by assuming the static nature when the osteotome just gets inside the cement. Small element with distance and angle from the osteotome tip under stress is also,shown on the left, Here, th mode of fracture is mode I. ∂θθ is obstained from fracture mechanics as this, and the direction of crack propagation is given by solving ∂θθ = o,i.e, the direction of maximum ∂θθwhich turns out to be 0=0. When chisel is used, the mode of fracture is th combined mode, i. e. Mode I + Mode II (Fig. 7). In an angiogous approach to the previous one, aθθis obtained, thus, the direction of propagation is given by solving ∂θθ/∂θ = 0. which results in θ=(−)α, the half of the included angle of the chisel, Note, however, that the direction of propagation given here is the initial direction of crack propagation. In practiee, the crack often gets curves, however, this phenomena is governed by other factors neglected in this presentation, such as inhomogenity, state of stress of bone, cement and stem, etc, Thus, quantitative study is required in addition to so've these phenomenon.
Arthroplasty ; Hip Prosthesis ; Hip ; Mechanics

No abstract available in English.
Arthroplasty, Replacement, Hip ; Ceramics ; Hip Prosthesis ; Hip

In 1971, for purpose of reduction of peak stress occuring in cement and trabecular bone of the acetabulum, Harris reported a series of metal-backed acetabular components with removable polyethylene liners that could be replaced if excessive wear occured. Modular designs of hip prostheses have become popular recently, but they introduce the risk of disassembly of the components postoperatively. And introduce of loosening and infection of femoral or acetabular components by debris of polyethylene liner. We report a case of mechanical disassembly of polyethylene liner in cementless metal backed cup, and review previously reported articles.
Acetabulum ; Hip Prosthesis ; Polyethylene

BACKGROUNDArtificial joints present certain problems such as osteal absorption and lysis induced by wear debris which leads to loosening of the prosthesis over a period of time. Here we propose a design of an artificial magnetic suspension joint that was prepared by integrating the medical theories of modern material science, magnetism, and medical physics.

METHODSAccording to clinical characteristic of biological and mechanical for hip joint, we designed the appearance and dimensions of magnetic suspension joint and placed neodymium-iron-boron permanent magnets in the prosthesis. As the same time, we performed mechanical and biological experiments using artificial magnetic suspension hip joints models.

RESULTSBy simulated the human hip structure and the external load, we discovered the artificial magnetic suspension hip joints models had much lesser amount and size of wear debris than the ceramic/ceramic artificial hip joint prosthesis in friction wear tests. The force between the artificial joints with magnetic materials that we have calculated is feasible for application of artificial joint. The design of artificial magnetic suspension hip joints models was plausible technically and safe biologically.

CONCLUSIONArtificial magnetic suspension hip joints may effectively reduce the incidence of the loosening of prosthesis over a period of time.

Arthroplasty, Replacement, Hip ; Hip Prosthesis ; Humans ; Reoperation

Arthroplasty, Replacement, Hip ; trends ; China ; Hip Prosthesis ; Humans ; Prosthesis Failure

Based on the introduction of multi-agent and individual artificial hip joints, this paper reports a multi-agent design system for individual artificial hip joints. Three agents are defined, the first is to optimize the diameter of hip joint, the second for FEM, the third for simulation between the prosthesis and acetabulum cup. The paper lays emphasis on the second agent.
Acetabulum ; Hip Joint ; Hip Prosthesis ; Humans ; Prosthesis Design

Because of increases in degenerative diseases and trauma of the hip joint, diverse treatment modalities have been developed. Because of this increase in demand in the field of hip joint medicine, the need for scientific studies in orthopaedics have been considered to be more important. In fact, currently, total hip arthroplasty is the most commonly performed reconstructive hip procedure. Total hip arthroplasty evolved as a result of many improvements in the design of a femoral head prosthesis, the availability of suitable component materials and manufacturing techniques, a better understanding of hip mechanics, and the need for resurfacing the acetabulum. An awareness of the history of hip arthroplasty is necessary to appreciate not only its current status, but also its future. This article discusses the history of and current trends in hip arthroplasty including implant design, materials, and the renewed interest in resurfacing procedures, minimally invasive techniques and robotic surgery.
Acetabulum ; Arthroplasty ; Hip ; Hip Joint ; Hip Prosthesis ; Mechanics