title: Static and dynamic compression application and removal on the intervertebral discs of growing rats.
abstract: Fusionless implants are used to correct pediatric progressive spinal deformities, most of them spanning the intervertebral disc. This study aimed at investigating the effects of in vivo static versus dynamic compression application and removal on discs of growing rats. A microloading device applied compression. 48 immature rats (28 d.o.) were divided into two groups (43d, 53d). Each group included four subgroups: control (no surgery), sham (device installed without loading), static (0.2 MPa) and dynamic compressions (0.2 MPa ± 30% with 0.1 Hz). In 43d subgroups, compression was applied for 15 days. In 53d subgroups, compression was followed by 10 days without loading. Disc heights, nucleus/annulus volumetric proportions and nucleus proteoglycan contents were analyzed using one-way ANOVA and post-hoc Tukey comparisons (p < 0.05). Disc heights of 43d and 53d static and dynamic loading rats were lower than shams (p < 0.05). Volumetric proportions remained similar. At 43d, nucleus proteoglycan contents increased in both static and dynamic loading rats. However, at 53d, static loading rats had lower proteoglycan content than dynamic loading rats (p < 0.05). Disc structure is altered following static compression removal, but nucleus proteoglycan content remaining elevated in dynamic group. Dynamic fusionless implants would better preserve disc integrity.
authors.affiliation: Department 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.
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.
authors.forename: Guy
authors.initials: G
authors.lastname: Grimard
authors.affiliation: Department 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.|École Nationale Supérieure des Mines de Saint-Etienne, 158 cours Fauriel, 42023 Saint-Étienne cédex 2, France.
authors.forename: Elise
authors.initials: E
authors.lastname: Massol
authors.affiliation: Sainte-Justine University Hospital Research Center, 3175 Côte-Ste-Catherine Rd., Montréal, Québec, H3T 1C5, Canada.
authors.forename: Irène
authors.initials: I
authors.lastname: Londono
authors.affiliation: Sainte-Justine University Hospital Research Center, 3175 Côte-Ste-Catherine Rd., Montréal, Québec, H3T 1C5, Canada.|Faculty of Dentistry, Université de Montreal, P.O. Box 6128, Station "centre-ville", Montréal, Québec, H3C 3J7, Canada.
authors.forename: Florina
authors.initials: F
authors.lastname: Moldovan
authors.affiliation: Department 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.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Villemure
mesh_terms: D000818:Animals; D007403:Intervertebral Disc / Q000502:physiology*; D008297:Male; D019736:Prostheses and Implants; D011509:Proteoglycans / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D013122:Spinal Diseases / Q000601:surgery*; D013314:Stress, Mechanical; D016474:Weight-Bearing
chemical_list: D011509:Proteoglycans
keywords: histomorphometry; in vivo static/dynamic compression; intervertebral disc; microCT; proteoglycan