Friday, May 29, 2009

Low Back Segmental Stiffness

By Jonathan Blood Smyth

As children we have the great gift of a mobile, strong, well designed and painless spine and it is unusual for stiffness to be an issue as the lumbar spine has evolved to do the job of weight bearing and providing movement. Intervertebral discs separate the spinal vertebrae, allowing more movement in areas where they are thicker and also coping with variable loads. The posterior spinal facet joints limit and control segmental movement, preventing the spine from displacing inappropriately under the shear forces. Strong, balanced and coordinated muscle actions complete the picture.

Inhibition of the stabilising musculature occurs with an episode of acute spinal pain and this can persist beyond the resolution of the pain to generate a long-lasting instability which puts the segment at increased risk of re-injury over time. Longer term effects include the occurrence of degenerative alterations in the spinal structures such as joints and discs, causing segmental levels to develop stiffness and eventually chronic back pain. The discs have fluid forced out of them by gravitational compression forces and must counteract them by generating a fluid absorption force.

Discs will narrow and lose part of their hydration under the forces of compression which occur in normal life, the disc becoming stiffer and narrower. X-rays can show up this narrowing when it reaches a certain level, but many discs will be troublesome long before this stage. The intervertebral disc and the two vertebrae each side of it are referred to as a vertebral segment and an abnormal stiff segment will move in such a way as to impose inappropriate levels of load upon structures not adapted to take them. The stiffness of individual spinal segments can be felt by a physiotherapist palpating the spine.

Muscle spasms are a typical reaction to an acute injury and has a protective function, stopping the damaged segment from moving while it is so inflamed and thereby giving it some freedom to heal. As the pain settles and the injury heals the back spasms should gradually settle and allow normal movement to be restored. Unfortunately this does not always happen, with some muscles remaining over protective and eventually forming a contracture, an abnormally shortened tissue structure which maintains an abnormal joint position.

Sitting for extended periods can increase the likelihood of suffering from increased compression of the lumbar discs with consequent fluid loss. Repeated flexion maintains the regular cycle of fluid uptake and avoidance of this movement interferes with this important process for disc health. The maintenance of abnormal posture and lack of strength in the abdominal muscles are also important factors.

A typical history is to have an episode of severe low back pain which gradually develops into a segmental stiffness problem. The stiff areas may be present asymptomatically for many years in many individual areas of the spine before one of them develops into a painful segment which causes restriction. Sitting for a long time or spending time bent into flexion will tend to aggravate this condition once established as joints are moved beyond their comfortable limits. The lumbar facet joints become fixed into extension and the whole segment suffers from adaptive shortening, forfeiting its ability to move normally. I have back problems very like this and it can be quite difficult, forcing me to limit heavy or repetitive work or any significant time in flexion.

However, I have been significantly improved by following Sarah Key's method of back care, popularised in her book Sarah Key's Back Sufferers Bible. While it is hard to agree with all the assertions she states in her book (as she herself admits), there is no doubt she has some very good ideas on how to practically manage low back pain. She describes the chronically stiff segmental back along with several other back pain syndromes and prescribes an exercise and management regime for treating them. The regime is not difficult but has very good results, particularly in my case where I felt I was stuck with my lower back pain and now realise this may not be the case.

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