title: Biomechanics of low-modulus and standard acrylic bone cements in simulated vertebroplasty: A human ex vivo study.
abstract: The high stiffness of bone cements used in vertebroplasty has been hypothesised to contribute to the propensity of adjacent vertebral fractures after treatment. Therefore, new low-modulus cements have been developed; however, there are currently no studies assessing the biomechanical aspects of vertebroplasty with these cements in an ex vivo non-prophylactic model. In this study, we induced wedge fractures through eccentric uniaxial compression to single whole-vertebrae, before and after augmentation with either standard or low-modulus cement. Compressive strength and stiffness of individual vertebrae were measured, on 19 samples from metastatic spines and 20 samples from elderly, osteopenic spines. While both cement types increased the strength of both the metastatic (+34% and +63% for standard and low-modulus cement, respectively) and the elderly vertebrae (+303% and +113%, respectively), none of them restored the initial stiffness of metastatic specimens (-51% and -46%, respectively). Furthermore, low-modulus cement gave a lower total stiffness (-13%) of elderly specimens whereas standard cement increased it above initial levels (+17%). Results show that vertebroplasty with low-modulus cement could provide restoration of the initial stiffness while increasing the strength of fractured elderly vertebrae and hence represent a treatment modality which is closer to pre-augmented behaviour. Also, this study indicates that stiffness-modified cement needs to be optimised for patient/pathology specific treatment.
authors.affiliation: School of Mechanical Engineering, University of Leeds, Leeds, UK.
authors.forename: Ondrej
authors.initials: O
authors.lastname: Holub
authors.affiliation: Division of Applied Materials Science, Department of Engineering Sciences, The Ångström Laboratory, Uppsala University, Uppsala, Sweden.
authors.forename: Alejandro
authors.initials: A
authors.lastname: López
authors.affiliation: School of Mechanical Engineering, University of Leeds, Leeds, UK.
authors.forename: Vishal
authors.initials: V
authors.lastname: Borse
authors.affiliation: Division of Applied Materials Science, Department of Engineering Sciences, The Ångström Laboratory, Uppsala University, Uppsala, Sweden.
authors.forename: Håkan
authors.initials: H
authors.lastname: Engqvist
authors.affiliation: School of Mechanical Engineering, University of Leeds, Leeds, UK.
authors.forename: Nik
authors.initials: N
authors.lastname: Kapur
authors.affiliation: School of Mechanical Engineering, University of Leeds, Leeds, UK.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Hall
authors.affiliation: Division of Applied Materials Science, Department of Engineering Sciences, The Ångström Laboratory, Uppsala University, Uppsala, Sweden. Electronic address: cecilia.persson@angstrom.uu.se.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Persson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D001843:Bone Cements / Q000737:chemistry*; D019245:Compressive Strength; D005260:Female; D006801:Humans; D008297:Male; D008954:Models, Biological; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D011859:Radiography; D013125:Spinal Neoplasms / Q000473:pathology / Q000556:secondary; D013131:Spine / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D054854:Vertebroplasty / Q000379:methods*
chemical_list: D001843:Bone Cements; D019904:Polymethyl Methacrylate
keywords: Adjacent vertebral fracture; Compression fracture; Low-modulus cement; Metastasis; Osteoporosis; Vertebroplasty