A porous bioactive titanium implant for spinal interbody fusion: an experimental study using a canine model.
OBJECTIVE
Porous biomaterials with adequate pore structure and appropriate mechanical properties are expected to provide a new generation of devices for spinal interbody fusion because of their potential to eliminate bone grafting. The purpose of this study was to evaluate the fusion characteristics of porous bioactive titanium implants using a canine anterior interbody fusion model.


METHODS
Porous titanium implants sintered with volatile spacer particles (porosity 50%, average pore size 303 microm, compressive strength 116.3 MPa) were subjected to chemical and thermal treatments that give a bioactive microporous titania layer on the titanium surface (BT implant). Ten adult female beagle dogs underwent anterior lumbar interbody fusion at L6-7 using either BT implants or nontreated (NT) implants, followed by posterior spinous process wiring and facet screw fixation. Radiographic evaluations were performed at 1, 2, and 3 months postoperatively using X-ray fluoroscopy. Animals were killed 3 months postoperatively, and fusion status was evaluated by manual palpation and histological examination.


RESULTS
Interbody fusion was confirmed in all five dogs in the BT group and three of five dogs in the NT group. Histological examination demonstrated a large amount of new bone formation with marrowlike tissue in the BT implants and primarily fibrous tissue formation in the NT implants.


CONCLUSIONS
Bioactive treatment effectively enhanced the fusion ability of the porous titanium implants. These findings, coupled with the appropriate mechanical properties in load-bearing conditions, indicate that these porous bioactive titanium implants represent a new generation of biomaterial for spinal interbody fusion.
Takemoto
Mitsuru
M
Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan. m.take@kuhp.kyoto-u.ac.jp
Fujibayashi
Shunsuke
S
Neo
Masashi
M
So
Kazutaka
K
Akiyama
Norihiro
N
Matsushita
Tomiharu
T
Kokubo
Tadashi
T
Nakamura
Takashi
T
D000818:Animals; D020099:Coated Materials, Biocompatible; D004285:Dogs; D004867:Equipment Design; D005260:Female; D016268:Internal Fixators; D008159:Lumbar Vertebrae; D008422:Materials Testing; D016348:Osseointegration; D016062:Porosity; D013123:Spinal Fusion / Q000295:instrumentation*; D014025:Titanium
D020099:Coated Materials, Biocompatible; D014025:Titanium