The Hip: Preservation, Replacement and Revision

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.



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Wednesday, December 21, 2011 1:22 pm