title: Bone growth resumption following in vivo static and dynamic compression removals on rats.
abstract: Mechanical loadings influence bone growth and are used in pediatric treatments of musculoskeletal deformities. This in vivo study aimed at evaluating the effects of static and dynamic compression application and subsequent removal on bone growth, mineralization and neuropathic pain markers in growing rats. Forty-eight immature rats (28 days old) were assigned in two groups (2- and 4 weeks experiment duration) and four subgroups: control, sham, static, and dynamic. Controls had no surgery. A micro-loading device was implanted on the 6th and 8th caudal vertebrae of shams without loading, static loading at 0.2 MPa or dynamic loading at 0.2 MPa ± 30% and 0.1 Hz. In 2-week subgroups, compression was maintained for 15 days prior to euthanasia, while in 4- week subgroups, compression was removed for 10 additional days. Growth rates, histomorphometric parameters and mineralization intensity were quantified and compared. At 2 weeks, growth rates and growth plate heights of loaded groups (static/dynamic)were significantly lower than shams (p b 0.01).However, at 4 weeks, both growth rates and growth plate heights of loaded groups were similar to shams. At 4 weeks, alizarin red intensity was significantly higher in dynamics compared to shams (p b 0.05) and controls (p b 0.01). Both static and dynamic compressions enable growth resumption after loading removal, while preserving growth plate histomorphometric integrity. However, mineralization was enhanced after dynamic loading removal only. Dynamic loading showed promising results for fusionless treatment approaches for musculoskeletal deformities.
authors.affiliation: Dept. of Mechanical Engineering, École Polytechnique of Montreal, P.O. Box 6079, Station "Centre-Ville", Montréal, Québec H3C 3A7, Canada; Sainte-Justine University Hospital Research Center, 3175 Côte-Ste-Catherine Rd., Montréal, Québec H3T 1C5, Canada. Electronic address: anne-laure.menard@polymtl.ca.
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Ménard
authors.affiliation: Sainte-Justine University Hospital Research Center, 3175 Côte-Ste-Catherine Rd., Montréal, Québec H3T 1C5, Canada; Sainte-Justine University Hospital Center, 3175 Côte-Ste-Catherine Rd., Montréal, Québec, H3T 1C5, Canada. Electronic address: guy.grimard@umontreal.ca.
authors.forename: Guy
authors.initials: G
authors.lastname: Grimard
authors.affiliation: Sainte-Justine University Hospital Research Center, 3175 Côte-Ste-Catherine Rd., Montréal, Québec H3T 1C5, Canada. Electronic address: irene.londono@recherche-ste-justine.qc.ca.
authors.forename: Irène
authors.initials: I
authors.lastname: Londono
authors.affiliation: Research Group in Animal Pharmacology of Québec, Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, Québec J2S 2M2, Canada; Department of Veterinary Biomedicine, Faculty of Veterinary Medicine, University of Montreal, 320e0 rue Sicotte, Saint-Hyacinthe, Québec J2S 2M2, Canada. Electronic address: francis.beaudry@umontreal.ca.
authors.forename: Francis
authors.initials: F
authors.lastname: Beaudry
authors.affiliation: Department of Veterinary Biomedicine, Faculty of Veterinary Medicine, University of Montreal, 320e0 rue Sicotte, Saint-Hyacinthe, Québec J2S 2M2, Canada. Electronic address: pascal.vachon@umontreal.ca.
authors.forename: Pascal
authors.initials: P
authors.lastname: Vachon
authors.affiliation: Sainte-Justine University Hospital Research Center, 3175 Côte-Ste-Catherine Rd., Montréal, Québec H3T 1C5, Canada; Faculty of Dentistry, University of Montreal, P.O. Box 6128, Station "centre-ville", Montréal, Québec H3C 3J7, Canada. Electronic address: florina.moldovan@umontreal.ca.
authors.forename: Florina
authors.initials: F
authors.lastname: Moldovan
authors.affiliation: Dept. of Mechanical Engineering, École Polytechnique of Montreal, P.O. Box 6079, Station "Centre-Ville", Montréal, Québec H3C 3A7, Canada; Sainte-Justine University Hospital Research Center, 3175 Côte-Ste-Catherine Rd., Montréal, Québec H3T 1C5, Canada. Electronic address: isabelle.villemure@polymtl.ca.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Villemure
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D015519:Bone Density / Q000502:physiology; D001846:Bone Development / Q000502:physiology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013314:Stress, Mechanical; D016474:Weight-Bearing / Q000502:physiology*
keywords: Growth plate histomorphometry; Growth rate; Mechanical modulation; Mineralization; Pain peptides