DOS BULLETIN - Dansk Ortopædisk Selskab

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
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