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Evaluation of hydroxyapatite ceramic vertebral spacers with different porosities and their binding capability to the vertebral body : an experimental study in sheep

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Title: Evaluation of hydroxyapatite ceramic vertebral spacers with different porosities and their binding capability to the vertebral body : an experimental study in sheep
Other Titles: Effects of Porosity Changes in Hydroxyapatite Ceramics Vertebral Spacer on Its Binding Capability to the Vertebral Body : An Experimental Sheep Study
Authors: Ito, Manabu Browse this author
Kotani, Yoshihisa Browse this author →KAKEN DB
Hojo, Yoshihiro Browse this author
Abumi, Kuniyoshi Browse this author
Kadosawa, Tsuyoshi Browse this author
Minami, Akio Browse this author →KAKEN DB
Keywords: spinal fusion
anterior vertebral spacer
bone graft substitute
Issue Date: May-2007
Publisher: American Association of Neurological Surgeons
Journal Title: Journal of Neurosurgery-Spine
Volume: 6
Issue: 5
Start Page: 431
End Page: 437
PMID: 17542509
Abstract: OBJECT. The aim of this study was to evaluate the degree of bone ingrowth and bonding stiffness at the surface of hydroxyapatite ceramic (HAC) spacers with different porosities in an animal model and to discuss the ideal porous characteristics of these spacers for anterior spinal reconstruction. METHODS. Twenty-one adult sheep (age 1–2 years, mean weight 70 kg) were used in this experiment. Surgery consisted of anterior lumbar interbody fusion at L2–3 and L4–5, insertion of an HAC spacer (10 * 13 * 24 mm) with three different porosities (0, 3, and 15%), and single-rod anterior instrumentation. At 4 and 6 months postoperatively, the lumbar spines were harvested. Bonding conditions at the bone–HAC spacer interface were evaluated using neuroimages and biomechanically. A histological evaluation was also conducted to examine the state of bone ingrowth at the surface of the HAC spacer. Biomechanical testing showed that the bonding strength of HAC at 6 months postoperatively was 0.047 MPa in 0% porosity spacers, 0.39 MPa in 3%, and 0.49 MPa in 15% porosity spacers. The histological study showed that there was a soft-tissue layer at the surface of the HAC spacer with 0% porosity. Direct bonding was observed between bone and spacers with 3 or 15% porosity. Micro–computed tomography scans showed direct bonding between the bone and HAC with 3 or 15% porosity. No direct bonding was observed in HAC with 0% porosity. CONCLUSIONS. Dense (0%) HAC anterior vertebral spacers did not achieve direct bonding to the bone in the sheep model. The HAC vertebral spacers with 3 or 15% porosity showed proof of direct bonding to the bone at 6 months postoperatively. The higher porosity HAC spacer showed better bonding stiffness to the bone.
Rights: The final version of the paper was published in JOURNAL OF NEUROSURGERY-SPINE, 6(5). For reuse of any of the materials, including editorial copy, figures, or tables please contact the Journal of Neurosurgery at
Type: article (author version)
Appears in Collections:北海道大学病院 (Hokkaido University Hospital) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 伊東 学

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