Peri-implant and systemic effects of high-/low-affinity bisphosphonate-hydroxyapatite composite coatings in a rabbit model with peri-implant high bone turnover.
BACKGROUND
Hydroxyapatite (HA) coatings composed with bisphosphonates (BPs) which have high mineral-binding affinities have been confirmed to successfully enhance implant stability. However, few previous studies focused on HA coatings composed with low-affinity BPs or on systemic effects of locally released BPs.


METHODS
In this long-term study, we developed two kinds of BP-HA composite coatings using either high-affinity BP (alendronate, ALN) or low-affinity BP (risedronate, RIS). Thirty-six rabbits were divided into three groups according to different coating applications (group I: HA, group II: ALN-HA, and group III: RIS-HA). Implants were inserted into the proximal region of the medullary cavity of the left tibiay. At insertion, 2 × 10(8) wear particles were injected around implants to induce a peri-implant high bone turnover environment. Both local (left tibias) and systemic (right tibias and lumbar vertebrae) inhibitory effect on bone resorption were compared, including bone-implant integration, bone architecture, bone mineral density (BMD), implant stability, and serum levels of bone turnover markers.


RESULTS
The results indicated that ALN-HA composite coating, which could induce higher bone-implant contact (BIC) ratio, bone mass augmentation, BMD, and implant stability in the peri-implant region, was more potent on peri-implant bone, while RIS-HA composite coating, which had significant systemic effect, was more potent on non-peri-implant bone, especially lumbar vertebrae.


CONCLUSIONS
It is instructive and meaningful to further clinical studies that we could choose different BP-HA composite coatings according to the patient's condition.
Department of Orthopaedics, Xi Jing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi, China.
Shun
S
Niu
Xiaorui
X
Cao
Yan
Y
Zhang
Qingsheng
Q
Zhu
Jinyu
J
Zhu
Ping
P
Zhen
D019386:Alendronate / Q000494:pharmacology*; D000818:Animals; D050071:Bone Density Conservation Agents / Q000494:pharmacology*; D020099:Coated Materials, Biocompatible / Q000009:adverse effects / Q000494:pharmacology*; D004195:Disease Models, Animal; D017886:Durapatite / Q000494:pharmacology*; D008297:Male; D008422:Materials Testing; D016348:Osseointegration / Q000187:drug effects*; D010012:Osteogenesis / Q000187:drug effects*; D019736:Prostheses and Implants; D011474:Prosthesis Design; D019919:Prosthesis Implantation; D011817:Rabbits; D013977:Tibia / Q000601:surgery
D050071:Bone Density Conservation Agents; D020099:Coated Materials, Biocompatible; D017886:Durapatite; D019386:Alendronate