title: Holding power and reinforcement of cancellous screws in human bone.
abstract: The authors report an in vitro biomechanical evaluation of a biodegradable material that might be used for the reinforcement of surgical screws in fractures involving severely osteoporotic bone. The material is a particulate composite with a matrix phase consisting of a hydrolyzable prepolymer, polypropylene fumarate (PPF), crosslinked with methacrylate monomer, and a particulate phase consisting of tricalcium phosphate and calcium carbonate. Pullout force and stripping load of cancellous screws were determined along with screw pullout force before and after reinforcement with either polymethylmethacrylate (PMMA) or PPF composite. Pullout force was moderately correlated (R2 = 0.59) with apparent density by a power law relationship of the form 0.065p1.37-1.77. Stripping load was strongly correlated (R2 = 0.91) with apparent density by a power law of the form 0.13p1.35-93.8. Mean pullout force before and after reinforcement with PMMA was 382 +/- 100 N (mean +/- standard deviation) and 879 +/- 315 N, respectively. Mean pullout force before and after reinforcement with PPF composite was 571 +/- 294 N and 829 +/- 354 N, respectively. Although the increase in pullout force with cement reinforcement was highly significant in both cases, the magnitude of the increase did not depend on the type of cement. Thus PPF seems to provide reinforcement that is equivalent to that provided by PMMA.
authors.affiliation: Department of Orthopaedic Surgery, Long Island Jewish Medical Center, New Hyde Park, New York.
authors.forename: B C
authors.initials: BC
authors.lastname: Kleeman
authors.forename: T
authors.initials: T
authors.lastname: Takeuchi
authors.forename: T N
authors.initials: TN
authors.lastname: Gerhart
authors.forename: W C
authors.initials: WC
authors.lastname: Hayes
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001672:Biocompatible Materials; D001696:Biomechanical Phenomena; D015519:Bone Density; D001863:Bone Screws; D001842:Bone and Bones / Q000601:surgery*; D002119:Calcium Carbonate; D002130:Calcium Phosphates; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008689:Methacrylates; D008768:Methylmethacrylates; D008875:Middle Aged; D010024:Osteoporosis / Q000601:surgery; D011126:Polypropylenes
chemical_list: D001672:Biocompatible Materials; D002130:Calcium Phosphates; D008689:Methacrylates; D008768:Methylmethacrylates; D011126:Polypropylenes; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; C485838:calcium phosphate, monobasic, anhydrous; C020243:calcium phosphate; D002119:Calcium Carbonate; C485829:calcium phosphate, dibasic, anhydrous