The pathophysiology of intervertebral disc degeneration has been extensively studied. Various factors have been suggested as influencing its aetiology, including mechanical factors, such as compressive loading, shear stress and vibration, as well as ageing, genetic, systemic and toxic factors, which can lead to degeneration of the disc through biochemical reactions. How are these factors linked? What is their individual importance? There is no clear evidence indicating whether ageing in the presence of repetitive injury or repetitive injury in the absence of ageing plays a greater role in the degenerative process. Mechanical factors can trigger biochemical reactions which, in turn, may promote the normal biological changes of ageing, which can also be accelerated by genetic factors. Degradation of the molecular structure of the disc during ageing renders it more susceptible to superimposed mechanical injuries. This review supports the theory that degeneration of the disc has a complex multifactorial aetiology. Which factors initiate the events in the degenerative cascade is a question that remains unanswered, but most evidence points to an age-related process influenced primarily by mechanical and genetic factors.

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It has been proposed that intervertebral disc degeneration might be caused by low-grade infection. The purpose of the present study was to assess the incidence of herpes viruses in intervertebral disc specimens from patients with lumbar disc herniation. A polymerase chain reaction based assay was applied to screen for the DNA of eight different herpes viruses in 16 patients and two controls. DNA of at least one herpes virus was detected in 13 specimens (81.25%). Herpes Simplex Virus type-1 (HSV-1) was the most frequently detected virus (56.25%), followed by Cytomegalovirus (CMV) (37.5%). In two patients, co-infection by both HSV-1 and CMV was detected. All samples, including the control specimens, were negative for Herpes Simplex Virus type-2, Varicella Zoster Virus, Epstein Barr Virus, Human Herpes Viruses 6, 7 and 8. The absence of an acute infection was confirmed both at the serological and mRNA level. To our knowledge this is the first unequivocal evidence of the presence of herpes virus DNA in intervertebral disc specimens of patients with lumbar disc herniation suggesting the potential role of herpes viruses as a contributing factor to the pathogenesis of degenerative disc disease.

The lumbar spines of 25 long-distance runners were examined using an upright magnetic resonance imaging scanner. All volunteer runners were scanned before and after running for 1 h. Scanning was performed with the runners seated upright (neutral), leaning forwards (flexion) and leaning backwards (extension). All measured discs showed a reduction in disc height after 1 h of running. A significant reduction in disc height was observed in all three body positions (neutral, flexion and extension) after 1 h of running. The results showed that, in flexion, extension and neutral positions, intervertebral discs undergo significant strain after 1 h of running. The lowest disc-height reduction was found at the L5 -S1 space in the neutral position; the same space had the highest percentage of disc degeneration.

The aim of this study was to investigate the effect of nasal calcitonin on chronic back pain and disability attributed to osteoporosis. The study design involved three groups of osteoporotic postmenopausal women suffering from chronic back pain. Group I consisted of 40 women with vertebral fractures, group II of 30 women with degenerative disorders and group III of 40 patients with non specific chronic back pain and without abnormality on plain X-rays. Pain intensity was measured using a numerical rating scale (NRS) and disability due to back pain was measured using the Oswestry disability questionnaire. The patients were randomly assigned to receive, for three months, either 200 IU intranasal salmon calcitonin and 1,000 mg of oral calcium daily (groups IA, IIA, IIIA) or 1,000 mg of oral calcium daily (groups IB, IIB, IIIB). Repeated measures ANOVA showed that there were no significant time, group or interaction effects for pain intensity and disability in any of the groups studied. Mean Oswestry and NRS scores were reduced during the follow-up period in the groups IA, IIIA, but the differences between the two time points were not statistically significant. Intranasal calcitonin has no effect on chronic back pain intensity and functional capacity of osteoporotic women regardless of the presence of fractures, degenerative disorders or chronic back pain of non-specific etiology.