title: Micro-computed tomography evaluation of vertebral end-plate trabecular bone changes in a porcine asymmetric vertebral tether.
abstract: We conducted a micro-CT analysis of subchondral bone of the vertebral end-plates after application of compressive stress. Thoracic and lumbar vertebral units were instrumented by carrying out left asymmetric tether in eleven 4-week-old pigs. After 3 months of growth, instrumented units and control units were harvested. Micro-CT study of subchondral bone was performed on one central and two lateral specimens (fixated side and non-fixated side). In control units, bone volume fraction (BV/TV), number of trabeculae (Tb.N), trabecular thickness (Tb.Th), and degree of anisotropy (DA) were significantly higher, whereas intertrabecular space (Tb.Sp) was significantly lower in center than in periphery. No significant difference between the fixated and non-fixated sides was found. In instrumented units, BV/TV, Tb.N, Tb.Th, and DA were significantly higher in center than in periphery. BV/TV, Tb.N, and Conn.D were significantly higher in fixated than in non-fixated side, while Tb.Sp was significantly lower. We noted BV/TV, Tb.N, and Tb.Th significantly lower, and Tb.Sp significantly higher, in the instrumented levels. This study showed, in instrumented units, two opposing processes generating a reorganization of the trabecular network. First, an osteolytic process (decrease in BV/TV, Tb.N, Tb.Th) by stress-shielding, greater in center and on non-fixated side. Second, an osteogenic process (higher BV/TV, Tb.N, Conn.D, and lower Tb.Sp) due to the compressive loading induced by growth on the fixated side. This study demonstrates the densification of the trabecular bone tissue of the vertebral end-plates after compressive loading, and illustrates the potential risks of excessively rigid spinal instrumentation which may induce premature osteopenia.
authors: Service de Chirurgie Orthopédique et Traumatologique-Institut Locomoteur, Centre Hospitalier Universitaire de Toulouse-Rangueil, 31059 Toulouse Cedex 9, France. jean-michel.laffosse@wanadoo.fr
authors: Jean-Michel
authors: JM
authors: Laffosse
authors: Thierry
authors: T
authors: Odent
authors: Franck
authors: F
authors: Accadbled
authors: Thibault
authors: T
authors: Cachon
authors: Charles
authors: C
authors: Kinkpe
authors: Eric
authors: E
authors: Viguier
authors: Jérôme
authors: J
authors: Sales de Gauzy
authors: Pascal
authors: P
authors: Swider
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D016880:Anisotropy; D019245:Compressive Strength; D008159:Lumbar Vertebrae / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000502:physiology; D023421:Models, Animal; D013314:Stress, Mechanical; D034421:Sus scrofa; D013904:Thoracic Vertebrae / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000502:physiology; D055114:X-Ray Microtomography / Q000379:methods