title: Evaluation of a fiber reinforced drillable bone cement for screw augmentation in a sheep model--mechanical testing.
abstract: We evaluated the mechanical properties of a novel fiber reinforced calcium phosphate at time zero and after 12 weeks in vivo using a sheep long bone osteotomy model. Time zero data were obtained and compared by pullout testing of 4.5 mm bone screws from bone proper and overdrilled defects of 4.5 and 8 mm diameter. Defects were augmented with: polymethylmethacrylate (PMMA), calcium phosphate, and fiber reinforced calcium phosphate using cadaveric sheep tibiae. Twelve-week data were obtained from explanted tibiae of sheep that underwent unilateral tibial osteotomy surgery repaired with a locking compression plate. The most distal hole was overdrilled to 4.5 or 8 mm diameter, filled with fiber reinforced cement, drilled, tapped and a 4.5 mm screw was placed. Screw holding strength at t= 0 was significantly higher for reinforced when compared to nonreinforced cement, but not different from bone or PMMA in 4.5 mm defects. There was no difference in pullout strength for the 8 mm defect data. After 12 weeks fiber reinforced pullout strength increased by 45% and 8.9% for 4.5 and 8 mm defects, respectively, when compared to t= 0 testing. Fiber reinforced calcium phosphate bone cement can be drilled and tapped to support orthopedic hardware for trauma applications.
authors.affiliation: Comparative Orthopedic Research Laboratory, Department of Clinical Studies, School of Veterinary Medicine, New Bolton Center, University of Pennsylvania, Kennett Square, PA, USA.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Ahern
authors.forename: Robert D
authors.initials: RD
authors.lastname: Harten
authors.forename: Elliott A
authors.initials: EA
authors.lastname: Gruskin
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Schaer
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001843:Bone Cements / Q000494:pharmacology*; D001863:Bone Screws; D002102:Cadaver; D005260:Female; D008422:Materials Testing / Q000379:methods*; D023421:Models, Animal; D019637:Orthopedic Procedures / Q000379:methods*; D012756:Sheep; D013977:Tibia / Q000502:physiology; D013997:Time Factors
chemical_list: D001843:Bone Cements