Healing of a painful intervertebral disc should not be confused with reversing disc degeneration: implications for physical therapies for discogenic back pain

Complexity in the physiotherapy management of low back disorders: clinical and research implications

Over the past decade a wide variety of approaches for the management of low back disorders (LBD) have been developed and evaluated in clinical trials. As a consequence physiotherapists and researchers interested in LBD are faced with a range of issues to do with complexity. These issues will be explored and suggestions made to improve the delivery of high quality research evidence and better patient outcomes.

New treatments and imaging strategies in degenerative disease of the intervertebral disks

Magnetic resonance (MR) imaging in patients with persistent low back pain and sciatica effectively demonstrates spine anatomy and the relationship of nerve roots and intervertebral disks. Except in cases with nerve root compression, disk extrusion, or central stenosis, conventional anatomic MR images do not help distinguish effectively between painful and nonpainful degenerating disks. Hypoxia, inflammation, innervation, accelerated catabolism, and reduced water and glycosaminoglycan content characterize degenerated disks, the extent of which may distinguish nonpainful from painful ones. Applied to the spine, "functional" imaging techniques such as MR spectroscopy, T1ρ calculation, T2 relaxation time measurement, diffusion quantitative imaging, and radio nucleotide imaging provide measurements of some of these degenerative features. Novel minimally invasive therapies, with injected growth factors or genetic materials, target these processes in the disk and effectively reverse degeneration in controlled laboratory conditions. Functional imaging has applications in clinical trials to evaluate the efficacy of these therapies and eventually to select patients for treatment. This report summarizes the biochemical processes in disk degeneration, the application of advanced disk imaging techniques, and the novel biologic therapies that presently have the most clinical promise.

Intervertebral disc degeneration: evidence for two distinct phenotypes

We review the evidence that there are two types of disc degeneration. 'Endplate-driven' disc degeneration involves endplate defects and inwards collapse of the annulus, has a high heritability, mostly affects discs in the upper lumbar and thoracic spine, often starts to develop before age 30 years, usually leads to moderate back pain, and is associated with compressive injuries such as a fall on the buttocks. 'Annulus-driven' disc degeneration involves a radial fissure and/or a disc prolapse, has a low heritability, mostly affects discs in the lower lumbar spine, develops progressively after age 30 years, usually leads to severe back pain and sciatica, and is associated with repetitive bending and lifting. The structural defects which initiate the two processes both act to decompress the disc nucleus, making it less likely that the other defect could occur subsequently, and in this sense the two disc degeneration phenotypes can be viewed as distinct.

Pathoanatomy and classification of low back disorders

Over the past decade research into the effectiveness of low back disorders (LBDs) has focused on the classification of subgroups more likely to respond to specific treatment. Much of this research has explicitly excluded a focus on pathoanatomical factors based on a questionable interpretation of the biopsychosocial model. Common justifications and potential issues with this approach are explored with recommendations made for future clinical and research practice.

Lumbar intervertebral disc degeneration associated with axial and radiating low back pain in ageing SPARC-null mice

Chronic low back pain (LBP) is a complex, multifactorial disorder with unclear underlying mechanisms. In humans and rodents, decreased expression of secreted protein acidic rich in cysteine (SPARC) is associated with intervertebral disc (IVD) degeneration and signs of LBP. The current study investigates the hypothesis that IVD degeneration is a risk factor for chronic LBP. SPARC-null and age-matched control mice ranging from 6 to 78 weeks of age were evaluated in this study. X-ray and histologic analysis revealed reduced IVD height, increased wedging, and signs of degeneration (bulging and herniation). Cutaneous sensitivity to cold, heat, and mechanical stimuli were used as measures of referred (low back and tail) and radiating pain (hind paw). Region specificity was assessed by measuring icilin- and capsaicin-evoked behaviour after subcutaneous injection into the hind paw or upper lip. Axial discomfort was measured by the tail suspension and grip force assays. Motor impairment was determined by the accelerating rotarod. Physical function was evaluated by voluntary activity after axial strain or during ambulation with forced lateral flexion. SPARC-null mice developed (1) region-specific, age-dependent hypersensitivity to cold, icilin, and capsaicin (hind paw only), (2) axial discomfort, (3) motor impairment, and (4) reduced physical function. Morphine (6 mg/kg, i.p.) reduced cutaneous sensitivity and alleviated axial discomfort in SPARC-null mice. Ageing SPARC-null mice mirror many aspects of the complex and challenging nature of LBP in humans and incorporate both anatomic and functional components of the disease. The current study supports the hypothesis that IVD degeneration is a risk factor for chronic LBP.

Rhein: a potential biological therapeutic drug for intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is regarded as an important cause of low back pain, which continues to be a common disability. IDD is thought to involve sequential changes of intervertebral disc that lead to the reduction of disc cells and the extracellular matrix. In addition, inflammation is crucially involved in IDD. Currently, there is urgent need to develop biological therapies for IDD that can both relieve symptoms and directly reverse the process of degeneration. Rhein (RH) is an anthraquinone molecule with the abilities of enhancing the synthesis of matrix components and inhibiting inflammatory response. Recently, the metabolic precursor of RH called diacerein has been demonstrated to have significant effects on pain relief and function improvement in the treatment of osteoarthritis. Given the occurrence of matrix degeneration and involvement of inflammation in IDD, we propose that RH might be a promising biological therapeutic drug for IDD due to its bioactivities. In addition, we hypothesize that the underlying mechanisms might be that RH has the ability to diminish interleukin-1 (IL-1) induced apoptosis and inhibit IL-1 induced secretion of MMPs and aggrecanases.