Advanced

The fixation of joint prostheses. Aspects on mechanics and biology

Hansson, Ulrik LU (2008) In Lund University Faculty of Medicine Doctoral Dissertation Series 2008:14.
Abstract
Abstract:

In the interface, between implant and bone or between the cement and bone, there will develop some amount of fibrous tissue. The synovial fluid, the synovium, the cartilage and the subchondral bone from the non-replaced knee compartment that had been exposed to wear particles were studied by histological analyses.

These analyses showed polyethylene wear particles in all tissues except the cartilage. The analysed tissues showed frequently foreign body reactions. These reactions are a possible cause of bone resorption that may eventually lead to loosening of the implant. The lack of finding particles or foreign-body reactions in the cartilage is possibly an effect of the cartilage being without blood supply and... (More)
Abstract:

In the interface, between implant and bone or between the cement and bone, there will develop some amount of fibrous tissue. The synovial fluid, the synovium, the cartilage and the subchondral bone from the non-replaced knee compartment that had been exposed to wear particles were studied by histological analyses.

These analyses showed polyethylene wear particles in all tissues except the cartilage. The analysed tissues showed frequently foreign body reactions. These reactions are a possible cause of bone resorption that may eventually lead to loosening of the implant. The lack of finding particles or foreign-body reactions in the cartilage is possibly an effect of the cartilage being without blood supply and thus less exposed to the immune system. In our second study we tried to enhance the possibilities for bone ingrowth in the porous coated surface of a knee implant. We tried by either using cement only in central, or in peripheral parts of the tibial bone bed. The results after 8 years did not differ between the groups.

Minimising the shear forces at the implant-bone interface is a possibility to enhance the fixation, resulting in less migration, of the tibial implant. This was studied in a randomised clinical study where the patients were randomised to a group with fixed insert or a group with mobile insert.The study showed that the mobile inserts did move according to the design, however, no signs of improved migration characteristics during the first two years were found.

Improving the fixation strength with hydroxyapatite coating of the implants surfaces facing the bone have been proven successful. A solution deposition technique of hydroxyapatite coating of the porous surface of the implant while preserving the porosities and also allowing more precise monitoring of the thickness was tested. Uncemented fixation of a knee prosthesis with or without this HA coating was studied. Initially the RSA results showed a more stable migratory pattern in the HA coated group but after two years there were no difference.

In order to enhance fixation by minimising the bone resorption that occurres after the bone-cutting and implantation of the prosthesis, bisphosphonate may be used. We studied the effects of treatment started after surgery using uncemented fixation. The patients did either get the active substance, alendronate, or placebo. The follow-up using RSA did not show any differences regarding migration during the first two years. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Docent Ivarsson, Ingemar, Linköping University
organization
publishing date
type
Thesis
publication status
published
subject
keywords
radiostereometry, histology, interface, micromotion, knee, joint replacement
in
Lund University Faculty of Medicine Doctoral Dissertation Series
volume
2008:14
pages
91 pages
publisher
Department of Orthopaedics, Lund University
defense location
Föreläsningssal F2,Centralblocket,Universitetssjukhuset i Lund
defense date
2008-02-29 13:15
ISSN
1652-8220
ISBN
978-91-85897-67-4
language
English
LU publication?
yes
id
4d462aa8-9b0c-4813-bf2f-0e5a3f776e0e (old id 1025946)
date added to LUP
2008-02-06 14:06:02
date last changed
2016-09-19 08:44:47
@phdthesis{4d462aa8-9b0c-4813-bf2f-0e5a3f776e0e,
  abstract     = {Abstract:<br/><br>
In the interface, between implant and bone or between the cement and bone, there will develop some amount of fibrous tissue. The synovial fluid, the synovium, the cartilage and the subchondral bone from the non-replaced knee compartment that had been exposed to wear particles were studied by histological analyses. <br/><br>
These analyses showed polyethylene wear particles in all tissues except the cartilage. The analysed tissues showed frequently foreign body reactions. These reactions are a possible cause of bone resorption that may eventually lead to loosening of the implant. The lack of finding particles or foreign-body reactions in the cartilage is possibly an effect of the cartilage being without blood supply and thus less exposed to the immune system. In our second study we tried to enhance the possibilities for bone ingrowth in the porous coated surface of a knee implant. We tried by either using cement only in central, or in peripheral parts of the tibial bone bed. The results after 8 years did not differ between the groups.<br/><br>
Minimising the shear forces at the implant-bone interface is a possibility to enhance the fixation, resulting in less migration, of the tibial implant. This was studied in a randomised clinical study where the patients were randomised to a group with fixed insert or a group with mobile insert.The study showed that the mobile inserts did move according to the design, however, no signs of improved migration characteristics during the first two years were found.<br/><br>
Improving the fixation strength with hydroxyapatite coating of the implants surfaces facing the bone have been proven successful. A solution deposition technique of hydroxyapatite coating of the porous surface of the implant while preserving the porosities and also allowing more precise monitoring of the thickness was tested. Uncemented fixation of a knee prosthesis with or without this HA coating was studied. Initially the RSA results showed a more stable migratory pattern in the HA coated group but after two years there were no difference.<br/><br>
In order to enhance fixation by minimising the bone resorption that occurres after the bone-cutting and implantation of the prosthesis, bisphosphonate may be used. We studied the effects of treatment started after surgery using uncemented fixation. The patients did either get the active substance, alendronate, or placebo. The follow-up using RSA did not show any differences regarding migration during the first two years.},
  author       = {Hansson, Ulrik},
  isbn         = {978-91-85897-67-4},
  issn         = {1652-8220},
  keyword      = {radiostereometry,histology,interface,micromotion,knee,joint replacement},
  language     = {eng},
  pages        = {91},
  publisher    = {Department of Orthopaedics, Lund University},
  school       = {Lund University},
  series       = {Lund University Faculty of Medicine Doctoral Dissertation Series},
  title        = {The fixation of joint prostheses. Aspects on mechanics and biology},
  volume       = {2008:14},
  year         = {2008},
}