Spondylolisthésis par lyse isthmique

Abstract

Spondylolisthesis refers to a permanent forward slippage of the vertebral body, in most cases L5, more rarely L4 or higher lumbar vertebrae. Spondylolisthesis by isthmic spondylolysis or fractures of the pars interarticularis - acquired most of the time by repeated microtrauma during childhood – differ from congenital spondylolisthesis in which developmental abnormalities of the posterior arch are often associated to a pars stress fracture. Other causes of lower lumbar spondylolisthesis (gross trauma, degenerative or neoplastic disease, or surgical, iatrogenic injury) are not included in the present chapter. In terms of etiopathological mechanisms, isthmic spondylolysis involves genetic factors, since it has been observed that whites are more frequently affected than blacks, and less affected than some ethnic groups such as the Eskimos. Obviously, there is a contribution of a mechanical factor to the development of pars lesion since only bipeds with lumbar lordosis are affected, after acquisition of ambulation and, because repeated sports-related microtrauma in positions of hyperextension considerably increases the frequency of spondylolysis. Clinically, asymptomatic forms are frequent. Acute low-back pain may involve initial episode of fracture. At a later stage, chronic lower lumbar pain develops; in some patients sciatica occurs, in most cases by compression of the L5 nerve root. In severe dysplastic spondylolisthesis, this may even lead to lumbosacral kyphosis with pelvic retroversion. Radiologically, the diagnosis of isthmic spondylolysis is based upon oblique lumbar images, CT scans perpendicular to the isthmus and radionuclide bone scans performed early after initial pains. Spondylolisthesis is assessed using lateral films that allow, for prognosis determination, both the quantification of the degree of slippage and the determination of the lumbosacral kyphosis angle. Magnetic resonance imaging may reveal recent spondylolysis. MRI also permits evaluation of the state of discs adjacent to the spondylolisthesis and it can show radicular compromise. The natural history of spondylolisthesis by isthmic spondylolysis depends on the possible collapse of the intervertebral disc. The course of dysplastic spondylolisthesis is more severe, because it affects young subjects before maturity, and the deformity depends on osteocartilaginous growth. In terms of therapy, orthopedic treatment that consists of an orthosis immobilizing one of the thighs to prevent movement of the lumbosacral junction can be proposed at early stages. Isthmic reconstruction should be considered in young athletes reluctant to limit their physical activity. In case of spondylolisthesis, conservative treatment by immobilization using an orthosis, facet joint infiltrations and physical therapy can be proposed. In case of failure, or in case of compressive radicular pain, decompressive surgery followed by arthrodesis should be considered, by posterior approach. Combined anterior and posterior access should be considered in severe isthmic dysplastic spondylolisthesis, in adolescents who have a high potential for exacerbation with loss of normal lordosis.