Notes on Anatomy and Physiology: Degenerative Disc Disease

Let’s continue with the examination of intervertebral discs begun in the last post. This will also give us a chance to examine some of the normal changes associated with aging of the spine and to have a look at degenerative disc disease, a difficulty frequently encountered in the lumbar region.

Many mysteries remain about how the spine actually works. But because low back pain is common, the intervertebral discs of the lumbar spine have been extensively studied. One of the things well established is the varying pressure generated within a normal lumbar disc as the spine moves with the activities of daily life. This information helps us think about preventing disc disease and how to avoid aggravating an already established disc injury.

Fig 1 Two studies of the pressures generated within a lumbar disc during the usual activities and postures of life. The disc pressure experienced when the person is simply standing is taken to be 100. Neumann, 2010, page 331

The above chart points out several things of interest to us as practitioners of the Taoist Tai Chi™ internal arts of health:

  • pressure within the nucleus pulposus is lowest when we lie supine. This is one of the benefits of sleeping meditation.
  • pressures are maximal when we carry something in front of the body while bending forward
  • whilst sitting or standing, forward bending (flexion) puts greater pressure on the discs than does an upright posture. As we see in figure 2 below, it also invites the disc to bulge posteriorly towards nervous tissue that is very sensitive to pressure. When doing the tor yu or the set, we are asked to first send out the hands and then the whole body (not just head and chest), to keep looking out at eye level, and to settle the weight without tipping forward at the waist. All these instructions discourage forward bending of the lumbar spine, minimize the pressures to which the discs are subjected and allow those with degenerative disc disease to practice safely.

Figure 2 Forward bending with the low back, seen in the image to the right, encourages the disc to migrate towards the tender nervous tissue lying within the spinal canal while opening the facet (apophyseal) joint and intervertebral foramen. Bending backwards (extension), shown in the image to the left, tends to shift the nucleus away from the nervous tissue lying in the canal but closes the facet joint and intervertebral foramen. Neumann, 2010, page 355

Now, what we consider to be normal structure in the spine is certainly altered by disease, trauma, misuse, inactivity and poor posture. But it is also very much influenced by age:

  • From infancy to age 10, the always meagre blood flow to the disc diminishes further and the disc begins to adapt to a lifetime of working in conditions of low oxygen (anaerobic metabolism). By early adulthood, biochemical changes occur that cause everyone’s discs to start drying out. With a decline in water-retaining capacity, the discs lose volume and intrinsic pressure, and begin to bulge out when compressed. Think of the shape of a tire that is insufficiently inflated with air. The discs are now less able to cushion the endplates and vertebral bodies from compressive loads.
  • The disc’s connective tissue alters with an increase in collagen fibers and a decrease in elastin. The distinction between annulus and nucleus becomes less apparent. A greater share of the vertical load falls to the annulus and tears begin to appear in its rings.
  • The endplates become less permeable to nutrients passing from vertebral body to disc.
  • The trabecular bone of the vertebrae weakens, leading to a greater reliance on cortical bone for load bearing, and the vertebral bodies become more susceptible to injury.
  • Wear and tear appears in the cartilage covering the articular surfaces of the facet joints.

All these degenerative changes form part of aging but are seldom severe enough to cause trouble.

With sufficient damage to a disc, however, herniation may develop and we move from a normal aging process to pathology. This is especially likely to occur in the lumbar spine. The annulus can no longer contain the nucleus and a portion of the latter migrates posteriorly or posterior-laterally. If it drifts far enough, the nuclear material impinges on and injures the delicate nerve tissue normally protected by the spinal column. Commonly, it is one of the nerve roots making up the sciatic nerve (the L3,4 and S1,2 roots) that is affected, producing sciatica –  a variable pattern of pain, altered sensation, loss of reflexes and weakness in one leg. The exact symptoms of sciatica are determined by which spinal nerve root is compressed and how severely.

Fig 3 A damaged annulus allows part of the nucleus pulposus to move posteriorly and pinch either the cauda equina (seen from the side in the upper image) or a nerve root on its way to exiting the vertebral column (seen from above in the lower drawing). Neumann, 2010, page 351

As suggested by the disc pressure studies outlined earlier, people suffering from lumbar disc disease do not like to bend forward. Nor are they comfortable with sitting. Both activities aggravate their disc protrusion and symptoms.

Clearly, the seated set is not meant for people with pain from a bulging lumbar disc. And the forward bend in Push Needle To Sea Bottom and The Opening and Closing of Tai Chi may well need to be abbreviated – as gauged by how those movements feel to the student. Otherwise, as long as bending at the waist is avoided, the 108 moves of the standing set are remarkably safe and allow someone with lumbar disc disease to remain active and build strength, flexibility, endurance and balance despite the trouble with their back.

In the next post, we will consider another back problem encountered in the practice hall, spinal stenosis, a condition with quite different implications for movement.

1. Kinesiology of the Musculoskeletal System, Foundations for Rehabilitation, Second Edition, Donald A. Neumann, 2010, Mosby Elsevier, ISBN 978-0-323-03989-5

Bruce McFarlane MD

© 2010 Taoist Tai Chi Society of Canada

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4 Comments

Filed under Anatomy and Physiology, Health Watch

4 responses to “Notes on Anatomy and Physiology: Degenerative Disc Disease

  1. Cliff Yerex

    Pain associated with the lumbar disc conditions described above has presented me with the opportunity to learn more about aligning the spine and the form the Society teaches in taijiquan.

    With the patient and freely given assistance from Society instructors, the 108 move set has become a therapeutic and pain reducing experience. The instructors keet me in the form and make my taiji simpler, i.e. it works, as long as I stick to the instruction. It is always how well I stick to the form and avoid deep pain that determines how much benefit is received.

    I strongly support Dr. McFarlane’s comments about protecting the sensitive nerve tissue given the pain and damage I’ve sustained from years of ruptures and herniations.

    What a fool; in 1995 a disc ruptured from an old herniation, and without instruction I tried to return to my standing jong exercises and 108 move set after 9 months of absence from practice. That foolishness caused me so much pain. Luck was with me when someone from the Society, hearing that “I could not return to taiji due to health concerns” suggested a return to beginners and “do nothing to cause any pain”.

    That was the best piece of advice I’ve ever received. I experienced the best ever and longest lasting relief from pain I’d ever had, including the years extensive standard western medical treatment, in my then 28 years of chronic back pain. The Society has provided me with a tool that has most certainly kept me off of canes or perhaps even a walker.

    Many thanks to Master Moy’s for sharing his knowledge and experience.

    I strongly recommend the Health Recovery Program for everyone.
    Sincerely,
    Cliff Yerex, Wpg

  2. Arthur Kluger

    are there specific Tai Chi exercises for liver, kidney and spleen?

    • David Kemp

      Chinese medicine would suggest that the functions of the Liver, Kidney and Spleen could benefit from ensuring that the channels or meridians associated with these organs are free from obstruction. The main pathway of these particular channels ascends the inner aspect of the legs, therefore the “snake” exercise stimulates this area. Of course, Chinese medicine attributes different functions to these organs than does Biomedicine, so to stimulate these systems would help to stimulate the storage, regulation and transformation of Qi movement in the Chinese model, rather than say, blood filtration or cleansing from the Western approach. Using the same Chinese model, stretching the spine stimulates ALL the internal organs, as the paraspinal muscles are thought to be associated with areas where Qi of the organs collects. These “Shu” or Gathering points lay around 2″ lateral to the midline, and are stimulated by the stretching and turning motions of the tai chi. I remember a time when I saw Mr Moy massage these points on a student whilst he was stretching forward in the Toryu, although I can’t be sure of the intention behind his action.

      On another level the turning motions that create the internal massage help to resolve “stagnation” in the internal organs. Ideas of fluid physiology in Chinese medicine make little separation between the circulation of say, blood and lymph, and the movement of Qi, as these are interdependent functions; actions intended to improve movement of blood by default moves Qi. However, restrictions can arise that limit the movement of Qi and fluids, possibly from inactivity or poor lifestyle choices. In addition, emotional constraints also affect Qi movement. To approach tai chi on a purely physical level whilst continuing to feel say, worry, frustration or anger would limit the deeper effects. Letting go of any negative attitudes can only help with the further transforming of body and mind.

      A further relationship between the tissues of the body and the internal organs exists in the Chinese model of physiology. The Liver has a relationship with the Tendons, therefore stretching the tendons and ligaments helps to improve Liver function; the same goes for Kidneys and the bones- load up the bones to improve Kidney function. The Spleen relates to the muscles- work the muscles to improve Spleen function. Furthermore, as each of these organs is affected by a specific emotion, working the related tissues helps offset the effects of the emotion. For instance, Liver is affected by frustration and anger; Chinese logic would dictate that stretching the Tendons (associated with the Liver) dissipates frustration that affects Liver function. A kind of fuzzy logic, admittedly, but have you noticed how you feel after a good session of stretching? More relaxed, maybe?

      Tai chi is generally thought of as a whole body exercise. The usual recommendation is to use the whole system of foundation exercises and the set itself to create transformation, rather than focusing totally on just one aspect exclusively. Too much attention to just one aspect runs the risk of “overwork”, which is seen in chinese medicine as a source of pathology (think of repetitive strain injuries). A balanced approach is usually the best.

  3. Good information. I have degenerative disc disease and have a lot of pain in my lower back, hip, and leg. Tai Chi has helped a lot and there’s not much I can’t do in the form. Sometimes I’m limited in movement, sometimes not, but it has helped keep me limber and moving easier. My chiro wonders how I’m so limber at 55. Thanks for the info.

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