Poly(2-hydroxyethyl methacrylate) biomimetic coating to improve osseointegration of a PMMA/HA/glass composite implant: in vivo mechanical and histomorphometric assessments.
Bone implants must simultaneously satisfy many requirements, even though the surface properties remain a crucial aspect in osseointegration success. Since a single material with a uniform structure cannot satisfy all of these requirements, composite materials specifically designed for orthopedic or dental implant application should be envisaged. Two poly(methylmethacrylate)/hydroxyapatite composites reinforced by E-glass fibres, uncoated (PMMA/HA/Glass) and poly(2-hydroxyethyl methacrylate) (PMMA/HA/Glass+pHEMA) coated by the biomimetic method, were mechanically (push-out test) and histomorphometrically (Affinity Index, AI) investigated in an in vivo rabbit model. Cylindrical implants (diameter 2 mm x 5 mm length) were inserted into rabbit femoral cortical (mid-diaphysis) and cancellous (distal epiphysis) bone, under general anesthesia. The highest values of push-out force and ultimate shear strength were observed for the PMMA/HA/Glass at 12 weeks, which significantly (p < 0.001) differed from those of PMMA/HA/Glass+pHEMA at the same experimental time and from those of PMMA/HA/Glass at 4 weeks. At both experimental times, significantly (p < 0.0005) lower values of AI were observed in the PMMA/HA/Glass+pHEMA versus PMMA/HA/Glass (distal femoral epiphysis: 4 weeks = 33%; 12 weeks = 19%; femoral diaphysis: 4 weeks = 15%; 12 weeks = 11%). The good mechanical and histomorphometric results obtained with PMMA/HA/Glass should be followed by further evaluation of bone remodeling processes and mechanical strength around loaded PMMA/HA/Glass implants at longer experimental times. Finally, the biomimetic method applied to pHEMA needs to be further investigated in order to improve the positive effect of SBF on pHEMA and to enhance the coating adhesion.
Department of Experimental Surgery, Research Institute Codivilla-Putti, Rizzoli Orthopedic Institute, Bologna, Italy.
G
G
Giavaresi
F
F
Branda
F
F
Causa
G
G
Luciani
M
M
Fini
N
N
Nicoli Aldini
L
L
Rimondini
L
L
Ambrosio
R
R
Giardino
D000818:Animals; D018786:Bone Substitutes / Q000737:chemistry*; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D018483:Diaphyses / Q000601:surgery; D005269:Femur / Q000601:surgery; D005898:Glass; D008297:Male; D008422:Materials Testing; D023421:Models, Animal; D016348:Osseointegration; D011102:Polyhydroxyethyl Methacrylate / Q000737:chemistry*; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D019736:Prostheses and Implants; D011817:Rabbits; D033081:Shear Strength; D013499:Surface Properties
D018786:Bone Substitutes; D020099:Coated Materials, Biocompatible; D011102:Polyhydroxyethyl Methacrylate; D019904:Polymethyl Methacrylate