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- Discussion:
    - when the innervated ligamentous layer of the outer annulus fibrosis is stretched because of segmental instability, pain results;
    - acute sprain probably represents partial tearing of annular tissue;
    - if annular tissue becomes weakened to the point of allowing nucleus to protrude beyond the normal confines of the annulus, it may actually
            be a prelude to subsequent episodes of frank disc herniation;
    - if rent develops in annulus becomes complete tear to point of allowing nuclear liquid to escape, it may lead to a frank annular tear;
    - instability or chronic ligament stretch produces discomfort ranging from mild and intermittent to persistent and disabling;
    - mild discomfort compels us all to reduce lumbar lordosis inorder to ease the discomfort;
    - more persistent variety can be recognized by strengthening spine flexors and correcting lordotic postures;
    - pain from ligament stretch is midline & worse w/ lordotic postures;
    - like most other mechanical back pain it is worse w/ bending & lifting;
    - on PE, these pts also lack features identifying other pain syndromes;
    - any diagnositic features to be found are in positive instability sign or a positive wt relief flexion test;

- Instability:
    - instability test is performed with the patient prone w/ arms at sides;
    - examiners thumbs finds interspace and exerts sharp downward pressure seeking a reproduction of pain;
    - several interspaces are tested to find levels that are not painful for comparison;
    - if no interspace is found or if all are painful, the test cannot be performed;
    - if one or two levels are painful, the patient is asked to lift his head, shoulders, and arms and the downward pressure is repeated;
    - if pain is greater when pt is prone & relaxed than when extended with paravertebral muscles tight, the test is positive;
    - test stresses painful annulus in relaxed position, but contracted muscles stabilize segment, reducing stress & pain from pressure;
    - if pain is greater w/ muscles contracted or pain is equal with both maneuvers, the test is negative;
    - wt relief flexion is performed w/ pt supine, hips & knees flexed;
    - examiner places one arm under pts knees and lifts pt's buttocks up from the examination table;
    - if the pain is decreased with this maneuver, the test is positive;
    - x-rays may show a narrowed disc space or a spondylolysis or spondylo-lithesis corresponding with the painful interspace - or interspace may be normal;

- Treatment Considerations:
    - initial treatment is conservtive (as in most forms of low back pain);
    - in the study by K. Suseki et al (JBJS Vol 80-B 1998), the authors used a rat model to demonstrate that sensory information from the
            lumbar disc is conducted through rami communicantes;
            - the authors point out that if the same non segmental pattern is found in man, then simple decompression of the nerve root would not
                    be expected to relieve discogenic pain;

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