the mid-sagittal plane of 10 male and 10 female discs aged 13–79 years; 7 parasagittal slices through a single disc; discs showing various types of tears.
Most chondrocytes were unicellular but bicellular and multicellular chondrons were common in the margins of large tears and the nucleus in degenerate discs. Cellularity was highest in the right posterior quadrant, lowest in the left anterior quadrant, about equal in the left posterior and right anterior quadrants, and substantially higher in the right half of the nucleus. The correlation of increasing age with declining cell density was much stronger for the nucleus than for the annulus. Nucleus cellularity continued to decline throughout life whereas the annulus ceased its decline after the age of 50. Cell density was low in the vicinity of tears but elsewhere the disc was unaffected. Extensive inferior and superior end-plate separations reduced cellularity throughout the disc. Increased thickness of the cartilage end-plate was associated with higher cellularity in the nucleus.
much better, better, un changed or worse after treatment; was obtained at 3 months. Patients were also asked the duration of any relief obtained. Statistical methods utilized included the two tailed t-test, the Wilcoxon Rank Sum test, Odds ratio (OR) and the Chi Squared Test.
For an antibiotic to be effective against the infecting organism it must diffuse through the disc matrix. Blood vessels that surround the disc facilitate the diffusion process, but with age this vascularity decreases and may impede diffusion. The aims of the pilot study were to assess the effectiveness of antibiotic in treating infection in both normal and degenerate sheep discs and to measure the concentration of antibiotic in non-operated discs at varying ages.
INTRODUCTION: Numerous in-vitro studies demonstrating increased stress at levels adjacent to a lumbar fusion have raised concerns of accelerated degeneration. However, the significance of this increased stress in the in-vivo setting remains unclear, especially with long-term follow-up. The objective of this study is to assess the level of degeneration on MRI in this same cohort of patients at a minimum of twenty years follow-up. METHODS: Twenty-five patients undergoing one or two level anterior lumbar interbody fusion at the L5-S1 or L4-5 levels with a minimum of twenty-years follow-up were identified. Only patients with normal pre-operative discograms at the level adjacent to the fusion were considered in this study. MRI scans were performed and evaluated for any evidence of degeneration by an independent radiologist. Advanced degeneration was defined as either: (1) absence of T2 signal intensity in the disk, (2) disk herniation, or (3) spinal canal stenosis. RESULTS: Advanced degeneration was identified in five (20%) patients, with three (12%) being isolated to the adjacent level. Fourteen (56%) other patients had evidence of early degeneration in their lumbar spine. Overall, eight (32%) patients had some evidence of degeneration isolated to the level adjacent to the disk whereas seven (28%) patients had multilevel degeneration and four patients (16%) had degeneration in their lumbar spine but preservation of the adjacent level. DISCUSSION AND CONCLUSION: Without a control group, it is difficult to make firm conclusions on whether the changes seen on MRI represent the natural history of spinal deterioration or represent accelerated degeneration. However, after twenty years, only a handful of patients developed advanced adjacent level degeneration. Furthermore, the majority of degenerative changes seen occurred over multiple levels or at levels not adjacent to the fusion, suggesting that changes seen may be more likely related to constitutional factors inherent within the individual as opposed to the increased biomechanical stresses at the adjacent levels.