This section will give a overview of medical publications from
Hip International, with permission of the Publisher.
|
|
Hip International 2004; 14: 1 - 10
Metallurgical considerations in the wear of metal-on-metal hip bearings
J. Nevelos 1, J.C. Shelton 2, J. Fisher3
1Corin Group, Cirencester - UK
2IRC in Biomedical Materials and Department of Engineering, Queen Mary, University of London - UK
3Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds - UK
ABSTRACT
Metal-on-metal bearings offer one possible solution to problems of osteo-lysis associated with ultra high molecular weight
polyethylene (UHMWPE) wear debris generated during articulation in total joint replacements. Designs using larger bearing diameters are also possible with associated improvements in both range of motion and stability. There has been considerable debate as to the optimum metallurgical structure of the cobalt chrome alloys used in these metal-on-metal bearings. This review addresses the main metallurgical design issues in metal-on-metal bearing design and reviews some recent studies
from two independent academic centres. Cobalt chrome alloys with a low carbon content, when paired against themselves, have been shown to have poor wear properties under both simple configuration and simulator testing. Other cobalt chrome alloy couples with higher carbon content, whether wrought, cast or cast and heat-treated, appear to have similar performance in clinically relevant wear simulation studies. (Hip International 2004; 14: 1-10). Hip International 2003; 13: 25 - 28
Is the Birmingham Hip Resurfacing worthwhile?
T.C.B. Pollard1, C. Basu1, R. Ainsworth1, W. Lai1, G.C. Bannister 2
1Avon Orthopaedic Centre and BUPA Glen Hospital, Bristol - England
2European Hip Society
ABSTRACT
The highest failure rates of cemented hip replacement are in males under 50 years of age, usually from acetabular loosening and polyethylene wear. The metal-on-metal Birmingham Resurfacing offers potential advantages to this group because of its
wear properties. It also has a low dislocation rate and consequently less restricted activity. The aim of this study was to compare early outcome in young patients, treated for osteo-arthritis, either by the Birmingham Resurfacing or hybrid cemented stem with an uncemented cup and press-fit polyethylene liner. 54 patients in each arm were matched for age, sex, body mass index, and pre-operative activity. Outcome was measured by the Oxford Hip Score, with supplementary questions
about sporting activity and manual work. 37% of hybrid hip replacements undertook sport or heavy manual work despite specific instruction to the contrary. The Birmingham Resurfacings scored significantly better than the hybrid hip replacements (Mean 3.4 points, 1.3-5.5, 95% Confidence Interval, p<0.05.). Age and duration of symptoms pre-operatively were associated with outcome in the resurfacing group. In the early stages there appears to be justification for using the Birmingham
Resurfacing in active young patients. Only long-term follow-up will indicate whether metallosis and neck fracture are lesser complications than polyethylene wear and whether activity can be maintained. (Hip International 2003; 13: 25-8). Hip International 2003; 13: 41 - 53
Development of Metal/Metal Hip Resurfacing
D.J.W. McMinn1
1Royal Orthopaedic Hospital, Birmingham - UK
ABSTRACT
This author's development of metal/metal hip resurfacing began in 1989, with the first patient implantation in February 1991. In the first three years a pilot study identified optimum fixation as hydroxyapatite coated uncemented cups and cemented femoral components. From March 1994 hybrid fixed components have been used. These implants have generally been satisfactory with respect to fixation but high wear of the bearing, metallosis and osteolysis have been seen with some
components inserted during 1996, a period during which the metal microstructure was altered by the heat processes, hot isostatic pressing and solution heat treatment. The Birmingham Hip Resurfacing was developed taking account of experience with earlier resurfacing designs. This implant employs hybrid fixation with a porous ingrowth acetabular component and has an as-cast metal microstructure having had no post casting heat treatments. During the past 4 years the author has performed
over 1,000 Birmingham Hip Resurfacingís with a total failure rate of less than 1.0%. (Hip International 2003; 13 (suppl 2): S41-53). Hip International 2002; 12: 158 - 162
Early results of primary Birmingham hip resurfacing using a hybrid metal-on-metal couple
K.A. De Smet1, C. Pattyn1, R. Verdonck2
1Ghent University Hospital, Ghent – Belgium
2Ghent University Hospital, Ghent – Belgium
ABSTRACT
Click here for de published text.
This section will give some abstracts of other medical publications,
related to Hip Resurfacing.
|
|
http://www.sicot.org/abstracts/Paris/abstract156.html
Paris: August 29 - September 1, 2001
THR : Bearings : Metal-Metal
Surface replacement of the hip - are the problems of the historic hip resurfacings solved with the metal-on-metal bearing and the cementless cup ?
WITZLEB W-C., BAUER R., UWE H., KURT-JOACHIM C., KURT-JOACHIM S.
Orthopaedic Hospital and Pathologic Institute of the University of Dresden, Germany
ABSTRACT
High volumetric wear of polyethylene was the main factor in periprosthetic bone resorption and the failure of historic metal on polyethylene total hip resurfacing prosthesis. Metal on metal devices reduce the wear substantially and may solve this problem
. High volumetric of early results and histological findings of 80 patients implanted in 1998-2000 with the McMinn Birmingham Hip Resurfacing (BHR) prosthesis is presented and compared with long time results of Wagner Metal on Polyethylene hip resurfacings (SEP) in 305 cases of the years 1977-1987. The SEP showed a revision rate of 73,4% after 12 years. Mainly the cups failed and failure was often accompanied by substantial loss of acetabular bone stock. In to much
varus/valgus position or in male inclination implanted components showed a significantly higher revision rate. In opposition to that the BHR showed even in dysplastic hip with acetabular bone grafting a stabile osteointegration and an exact component position in all cases and mainly good and very good clinical results. One prosthesis had be revised in cause of a septic cup loosening 14 months after the implantation. In one case we had to revise periarticular ossifications. In histological
examinations of the capsule tissue of these joints no debris and no foreign body inflammation was found. Otherwise à 28 mm metal on metal prosthesis (MetaSUL) which was revised under equal circumstances showed a marked foreign body inflammation and even under the light microscope detachable metallic debris.
Last Updated: 09.09.2004 | 
