Abstract
Vertebral growth remains a mystery, especially with regards to the contribution of different growth plates and the mechanisms of growth after closure of these plates. As an example of vertebral growth in general, the growth of the vertebral canal was assessed in a rat model using fluorochromes. Although 80–90% of vertebral canal growth was due to growth plates, the remaining canal growth occurred via periosteal absorption and deposition. This is contrary to the traditional idea that periosteal mechanisms do not change the shape or dimensions of bone and suggests that the vertebrae exhibit a different model of growth than typical bones.
Vertebral growth remains largely a mystery. The contributions of different growth plates and the mechanisms of growth after closure of these plates requires further exploration. As an example of vertebral growth, vertebral canal growth was assessed in a living rat model using fluorochromes.
Vertebral canal growth and presumably vertebral growth in general occurred by different mechanisms at different phases of development. Growth plates accounted for the majority of growth although periosteal mechanisms also resulted in changes in the size and shape of the vertebrae. This is contrary to the traditional concept of periosteal growth and suggests that vertebrae may exhibit a different model of growth than typical bones.
The growth of the vertebrae in a particular dimension and during a particular phase of development is dependent on different mechanisms of growth, which may play a role in interpreting vertebral growth anomalies.
The interspinous junction closed by the end of the first week, whereas the neurocentral junction closed between weeks three and four. By four weeks, the vertebral canal had achieved 80–90% of its growth in area and diameter. After growth plate closure, the canal continued to grow by periosteal mechanisms and was displaced posteriorly.
Thirty-six Sprague-Dawley rats (age one week-seven weeks) were injected with tetracycline and alizarin using a dosing interval of four days. Thoracic vertebrae were sectioned using a cryostat and examined under a fluorescence microscope. In addition to noting fluoro-chrome deposition, the dimensions of the growth plates and canal were noted.
Funding: Edmonton Orthopaedic Research Association and University of Alberta Department of Radiology and Diagnostic Imaging
Correspondence should be addressed to Cynthia Vezina, Communications Manager, COA, 4150-360 Ste. Catherine St. West, Westmount, QC H3Z 2Y5, Canada
