title: Subject-specific planning of femoroplasty: an experimental verification study.
abstract: The risk of osteoporotic hip fractures may be reduced by augmenting susceptible femora with acrylic polymethylmethacrylate (PMMA) bone cement. Grossly filling the proximal femur with PMMA has shown promise, but the augmented bones can suffer from thermal necrosis or cement leakage, among other side effects. We hypothesized that, using subject-specific planning and computer-assisted augmentation, we can minimize cement volume while increasing bone strength and reducing the risk of fracture. We mechanically tested eight pairs of osteoporotic femora, after augmenting one from each pair following patient-specific planning reported earlier, which optimized cement distribution and strength increase. An average of 9.5(±1.7) ml of cement was injected in the augmented set. Augmentation significantly (P<0.05) increased the yield load by 33%, maximum load by 30%, yield energy by 118%, and maximum energy by 94% relative to the non-augmented controls. Also predicted yield loads correlated well (R(2)=0.74) with the experiments and, for augmented specimens, cement profiles were predicted with an average surface error of <2 mm, further validating our simulation techniques. Results of the current study suggest that subject-specific planning of femoroplasty reduces the risk of hip fracture while minimizing the amount of cement required.
authors.affiliation: Laboratory for Computational Sensing & Robotics, Johns Hopkins University, Baltimore, MD, USA. Electronic address: basafa@jhu.edu.
authors.forename: Ehsan
authors.initials: E
authors.lastname: Basafa
authors.affiliation: Laboratory for Computational Sensing & Robotics, Johns Hopkins University, Baltimore, MD, USA; Research and Exploratory Development Department, Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA.
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: Murphy
authors.affiliation: Graduate School of Information Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan.
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Otake
authors.affiliation: US Naval Academy, Annapolis, MD, USA.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Kutzer
authors.affiliation: International Center for Orthopaedic Advancement, Bayview Medical Center, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Belkoff
authors.affiliation: Total Joint Replacement Center, Baylor Regional Medical Center, Plano, TX, USA.
authors.forename: Simon C
authors.initials: SC
authors.lastname: Mears
authors.affiliation: Laboratory for Computational Sensing & Robotics, Johns Hopkins University, Baltimore, MD, USA; Research and Exploratory Development Department, Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA.
authors.forename: Mehran
authors.initials: M
authors.lastname: Armand
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena / Q000502:physiology; D001843:Bone Cements; D002102:Cadaver; D005260:Female; D005269:Femur / Q000502:physiology* / Q000601:surgery*; D020342:Finite Element Analysis; D006620:Hip Fractures / Q000453:epidemiology / Q000517:prevention & control; D006801:Humans; D008297:Male; D008954:Models, Biological; D058866:Osteoporotic Fractures / Q000453:epidemiology / Q000517:prevention & control; D019904:Polymethyl Methacrylate; D012307:Risk Factors; D013314:Stress, Mechanical
chemical_list: D001843:Bone Cements; D019904:Polymethyl Methacrylate
keywords: Cement augmentation; Femoroplasty; Mechanical test; Planning