European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society
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Comparative Study
Does the thickness of the vertebral subchondral bone reflect the composition of the intervertebral disc?
Degeneration of the intervertebral disc, seen radiologically as loss of disc height, is often associated with apparent remodelling in the adjacent vertebral body. In contrast, maintenance or apparent increase in disc height is a common finding in osteoporosis, suggesting the properties of the intervertebral disc may be dependent on those of the vertebral body or vice versa. We have investigated this relationship by measuring the radiological thickness of the subchondral bone and comparing it to the chemical composition of the adjacent disc. ⋯ A weaker correlation was seen here between water content and thickness, whilst there was no significant correlation at the annulus or between the bone thickness and collagen content. The positive relationship between the radiographic thickness of vertebral subchondral bone and the proteoglycan content of the adjacent disc seen in human cadaveric material could be due to the bone responding to a greater hydrostatic pressure being exerted by discs with higher proteoglycan content than by those with less proteoglycan present. It is suggested that while this is true in "normal" specimens, the relationship becomes altered in disease states, possibly because of changes to the nutritional pathway of the disc, with resultant endplate-bone remodelling affecting the flow of solutes to and from the intervertebral disc.
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Comparative Study
Restoration of the spinal canal by the internal fixator and remodeling.
It has been observed that after reduction of an unstable vertebral fracture, treated either conservatively or operatively, the encroachment of the spinal canal remaining after reduction can decrease considerably with time. A series of 31 cases, each with a set of CT scans taken preoperatively, immediately after surgery and after implant removal respectively, was assessed using computer-aided planimetry. The mean initial narrowing of the spinal canal was 44.6%. ⋯ Comparing the values of the spinal canal for T12-L5 directly after surgery and after implant removal, an almost identical degree of restoration for each level can be seen. This additional and gradual restoration of the spinal canal is termed remodeling. This study demonstrates that a residual postoperative narrowing of the spinal canal of up to 25% can be ignored, provided there is no initial neurologic damage.
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Angiogenesis is essential in tissue growth and regeneration. There are several factors that are able to stimulate vascular endothelial cell growth, including platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF). Disc herniation tissue (DHT) contains vascular ingrowth, which promotes granulation tissue formation. ⋯ In all age groups it was higher than 80%. Thus capillaries in disc herniation tissue are evidently newly formed and our results demonstrate that PDGF and VEGF participate in the neovascularization process. The presence of PDGF in fibroblasts and in disc cells suggests that this growth factor regulates the function of these cells, possibly the proliferation of the cells and the production of extracellular matrix components.
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Case Reports
Brucellosis of the spine with a synchronous Staphylococcus aureus pyogenic elbow infection.
Staphylococcus aureus osteomyelitis and pyogenic arthritis has a different pattern in the elderly than in the young. The axial skeleton is the most frequent site of infection and treatment is usually by intravenous antibiotics. We report a case of Staph. aureus septic arthritis of the elbow with concomitant osteomyelitis of the spine that was thought to be due to Staph. aureus, but culture of debrided material from the lesion grew Brucella in culture. We suggest that in the elderly it is advisable to obtain a tissue culture diagnosis and not to instigate therapy based on positive blood cultures or a concomitant infection.
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Multiple hereditary osteochondromatosis is a genetically transmitted disorder consisting of multiple projections of bone capped by cartilage, which are called exostoses. Spinal cord compression due to expansion of a laminar osteochondroma is rare but well recognized. Surgical decompression usually improves the patient's neurological status but, in cervical exostosis, post-laminectomy kyphosis and instability problems, especially in the high-risk adolescent group, form the most significant potential difficulties in the postoperative period. We report a case of cervical laminar exostosis that was treated by anterior stabilization and fusion and discuss the benefits of this technique.