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Dysplastic Spondylolisthesis


- Discussion:
    - involves a congenital insufficiency of facet joints (of S1 or L5) & disk complex, resulting
          in displacement w/o a defect or elongation of pars interarticularis;
          - there is gradual attenuation of the pars interarticularis, but  no gap or defect in pars interarticularis;
          - fifth lumbar facets appear to subluxate ventrally on the sacral facets;
          - pedicles may appear elongated as well, & they may further contribute to the forward subluxation;
          - when slip is severe, however, a defect may appear in the center;
    - these pts are more prone to recurrent symptoms and clinical deformity if forward slipping is allowed to progress;

- Clinical Findings:
    - neurologic injury:
          - there is a high occurance of nerve root pressure due to intact lamina of
                 L5 being pulled against dural sac;
          - significant neurologic impairment may occur in  presence of only minor degrees of slip;
          - pts are at risk for cauda equina dysfunction because neural arch is intact;
    - gait: pt's abnormal gait is secondary to hamstring tightness;

- Radiographs:
    - lateral x-rays may show that the entire posterior neural arch of L5 appears to slide ventrally;
    - if lamina and posterior elements remain intact, spondylolisthesis is limited to 25 per cent of the width
            of the first sacral vertebra;
    - myelography is indicated in pts w/ bladder or  bowel dysfunction or w/ neurologic deficit



Surgical treatment of dysplastic spondylolisthesis. Results after in situ fusion.