DOS BULLETIN - Dansk Ortopædisk Selskab
DOS BULLETIN - Dansk Ortopædisk Selskab DOS BULLETIN - Dansk Ortopædisk Selskab
2010-378_DOS nr. 3 2010 29/09/10 10:08 Side 132 The effect of Mild Hyperthermia on Extravasation of USPIO Particles in a murine tumor model Claus Tvedesøe, Søren, Bach, Michael Horsman, Esben Larsen, Steffen Hokland, Cody Bünger Orthopaedic research laboratory, Aarhus University Hospital, Department of Clinical Experimental Oncology, Interdisciplinary Nanoscience Center, MR-research center, Aarhus University Hospital Background: Ultrasmall Iron Oxide (USPIO) particles have superparamagnetic characteristics. It is possible to attach various compounds to USPIO particles such as chemotherapy and silencing RNA sequences. Mild hyperthermia can disrupt tumor vessel endothelial barrier allowing USPIO particles to diffuse into the interstitial space of tumor. Purpose: In this study we have investigated the effect of various lengths of localized mild hyperthermia on the extravasation of i.v injected USPIO particles in a murine tumor. Methods: Tumor model Mammary carcinoma tumors were grown in the rear right foot of CDF1 mice. Hyperthermia Heat treatment was performed locally by submerging the tumor bearing foot in a circulating water bath at 41.5 °C. Animals were randomized into four groups 1, USPIO particles only; 2, USPIO particles and 5 min of HT; 3, USPIO particles and 30 min of HT and 4, USPIO particles and 60 min of HT. N=9 in each group. Animals were MR scanned prior to injections and after 90-, 390- and 1140 min. Findings: Change in T2* in response to heating length shows a significant difference between animals heated for 30- and 60 minutes compared to animals heated for only 5 minutes and controls (p
2010-378_DOS nr. 3 2010 29/09/10 10:08 Side 133 Demineralised bone matrix and human cancellous bone enhance fixation of titanium implants Hassan Babiker, Ming Ding, Søren Overgaard Orthopedic Research Unit, Department of Orthopedics and Traumatology, OUH Background: Allogenic bone graft has been considered as gold standard for replacement of bone stock in the revision joint arthroplasty. However, the reduced heeling response and the limited supply are clinical challenges. The use of osteoinductive materials such as demineralised bone matrix (DBM) alone or in combination with allograft or commercially available human cancellous bone (CB) may substitute allograft. To date no clinical investigations of the influence of DBM and CB on implant fixation has been done. Only few preclinical studies are available Purpose: The purpose of this study was to investigate the effect of DBM alone or with CB and allograft on the fixation of porous-coated titanium implants Methods: DBM100 and CB produced from human tissue were included (IsoTis OrthoBiologics, Inc. USA). Both materials are commercially available. DBM granules are placed in pure DBM and don’t content any other carrier. Titanium alloy implants (Biomet Inc.) of 10 mm in length and 10 mm in diameter were inserted bilaterally into the femoral condyles of 8 skeletally mature and elderly sheep. Thus four implants with a concentric gap of 2 mm were implanted in each sheep. The gap was filled with: DBM; DBM/CB with ratio of 1/3; DBM/allograft with ratio of 1/3; or allograft (Gold standard), respectively. Standardised surgical procedure was used. At sacrifice, 6 weeks after surgery, both distal femurs were harvested. The implant fixation was evaluated by mechanical push-out testing to test shear mechanical properties between implant and the host bone, and by histomorphometric analysis Findings: The strength among the DBM/CB, the DBM/allograft and allograft groups was not statistically different. The strength of the DBM alone was 0.026 MPa, which was statistically significant lower than the other three groups. The bone ingrowth in the DBM group was statistically significant lower than the other three groups, while the volume fraction of new bone showed no significant different among all of the groups. Conclusion: Our data have revealed that by adding DBM to allograft or to CB resulted in comparable mechanical properties relative to the gold standard, allograft. We found no early effect of DBM alone on the fixation of porous coated titanium implant in this animal model, while the long term effects have to be investigated. The combination of DBM with CB, which can be used off the shelf, may represent an alternative to allograft 133
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2010-378_<strong>DOS</strong> nr. 3 2010 29/09/10 10:08 Side 133<br />
Demineralised bone matrix and human cancellous<br />
bone enhance fixation of titanium implants<br />
Hassan Babiker, Ming Ding, Søren Overgaard<br />
Orthopedic Research Unit,<br />
Department of Orthopedics and Traumatology, OUH<br />
Background: Allogenic bone graft has been considered as gold standard for<br />
replacement of bone stock in the revision joint arthroplasty. However, the<br />
reduced heeling response and the limited supply are clinical challenges. The use<br />
of osteoinductive materials such as demineralised bone matrix (DBM) alone or<br />
in combination with allograft or commercially available human cancellous bone<br />
(CB) may substitute allograft. To date no clinical investigations of the influence<br />
of DBM and CB on implant fixation has been done. Only few preclinical studies<br />
are available<br />
Purpose: The purpose of this study was to investigate the effect of DBM alone<br />
or with CB and allograft on the fixation of porous-coated titanium implants<br />
Methods: DBM100 and CB produced from human tissue were included (IsoTis<br />
OrthoBiologics, Inc. USA). Both materials are commercially available. DBM<br />
granules are placed in pure DBM and don’t content any other carrier. Titanium<br />
alloy implants (Biomet Inc.) of 10 mm in length and 10 mm in diameter were<br />
inserted bilaterally into the femoral condyles of 8 skeletally mature and elderly<br />
sheep. Thus four implants with a concentric gap of 2 mm were implanted in<br />
each sheep. The gap was filled with: DBM; DBM/CB with ratio of 1/3;<br />
DBM/allograft with ratio of 1/3; or allograft (Gold standard), respectively. Standardised<br />
surgical procedure was used. At sacrifice, 6 weeks after surgery, both<br />
distal femurs were harvested. The implant fixation was evaluated by mechanical<br />
push-out testing to test shear mechanical properties between implant and the<br />
host bone, and by histomorphometric analysis<br />
Findings: The strength among the DBM/CB, the DBM/allograft and allograft<br />
groups was not statistically different. The strength of the DBM alone was 0.026<br />
MPa, which was statistically significant lower than the other three groups. The<br />
bone ingrowth in the DBM group was statistically significant lower than the<br />
other three groups, while the volume fraction of new bone showed no significant<br />
different among all of the groups.<br />
Conclusion: Our data have revealed that by adding DBM to allograft or to CB<br />
resulted in comparable mechanical properties relative to the gold standard, allograft.<br />
We found no early effect of DBM alone on the fixation of porous coated<br />
titanium implant in this animal model, while the long term effects have to be<br />
investigated. The combination of DBM with CB, which can be used off the<br />
shelf, may represent an alternative to allograft<br />
133