Healing of painful intervertebral discs: implications for physiotherapy: Part 1 — the basic science of intervertebral discs healing

Background: Population studies show close associations between intervertebral disc degeneration and back pain, with structural changes such as annulus tears being most closely related to pain. However, little effort has been made to link back pain to disc injury in individual patients, or to treat the disc injury in a similar way to a ligament or tendon sprain. Objectives: To re-interpret the scientific literature in order to provide a rationale for physical therapy treatments that aim to promote ‘disc healing’. Major Findings: Intervertebral discs deteriorate over many years, from the nucleus outwards, to an extent that is influenced by genetic inheritance, metabolite transport, and mechanical loading. Additionally, surgically-removed ‘painful’ human discs usually show an active inflammatory process proceeding from the outside-in. There is growing evidence that the ligamentous outer annulus can be re-innervated, and sensitized to pain by inflammatory-like responses to injury, and from displaced nucleus pulposus. Animal studies confirm that effective disc healing occurs only in the outer annulus and endplate, where cell density and metabolite transport are greatest. Identifying discogenic pain is not easy, but techniques are available. Healing of the disc periphery has the potential to relieve pain, by reducing inflammation and restoring function. Conclusion: Physical therapies should aim to promote healing in the disc periphery, by stimulating cells, boosting metabolite transport, discouraging adhesion formation, and preventing re-injury. Such an approach, which can be applied through information sessions and classes, has the potential to bring about pain relief to large numbers of back pain sufferers through self-treatment.