Titanium alloy osseointegration in cancellous and cortical bone of ovariectomized animals: histomorphometric and bone hardness measurements.
OBJECTIVE
Histomorphometry and microhardness measurements were performed after Ti6AI4V implantation in cancellous and cortical bone of healthy and ovariectomized animals to determine characterization of the bone-biomaterial interface in osteopenic bone.


METHODS
Nine ovariectomized and 9 sham-aged rats were used. Four months later, nails were implanted in the distal femurs, and the animals were sacrificed after 8 weeks. Moreover, 3 ovariectomized and 3 sham-aged sheep were used. Twenty-four months later, screws were implanted in the tibial diaphyses and the animals were sacrificed after 12 weeks.


RESULTS
Histomorphometry showed the development of osteopenia in both trabecular and cortical bone, and revealed a significant decrease in the osseointegration rate in osteopenic versus sham-aged animals for both trabecular (Affinity Index: -18.6%, P < .001) and cortical bone (Affinity Index: -23.5%, P < .005; Bone Ingrowth: -9%, P <.05). At the interfaces of the sham-aged animals in both trabecular and cortical bone, a decrease of bone microhardness was observed in comparison with preexisting bone (trabecular: -9.8%, P < .0005; cortical: -19.3%, P < .0005). In case of osteopenia, this decrease was even more extensive (trabecular: -15.5%, P < .0005; cortical: -24.7%, P < .0005).


CONCLUSIONS
The present data suggest that bone formation around Ti6AI4V was not associated with complete bone maturation, even in healthy animals. In case of osteopenia, both bone formation and maturation were delayed.


CONCLUSIONS
These results apparently demonstrate the utility of investigating biomaterials in osteopenic bone and the importance of careful evaluation of the healing rate and bone maturation degree around implanted biomaterials.
Fini
Milena
M
Experimental Surgery Department, Research Institute Codivilla-Putti, Rizzoli Orthopaedic Institute, Bologna, Italy. milena.fini@ior.it
Giavaresi
Gianluca
G
Rimondini
Lia
L
Giardino
Roberto
R
D000497:Alloys; D000818:Animals; D015519:Bone Density; D001842:Bone and Bones / Q000473:pathology; D003722:Dental Alloys; D005260:Female; D006244:Hardness; D020007:Implants, Experimental / Q000009:adverse effects*; D016348:Osseointegration; D010024:Osteoporosis / Q000209:etiology / Q000503:physiopathology*; D010052:Ovariectomy / Q000009:adverse effects; D010053:Ovary / Q000502:physiology*; D051381:Rats; D012756:Sheep; D013977:Tibia; D014025:Titanium
D000497:Alloys; D003722:Dental Alloys; C031462:titanium alloy (TiAl6V4); D014025:Titanium