Abstract and Introduction
Abstract
Isthmic spondylolisthesis, which is demonstrated in 4 to 8% of the general population, is one of the most common types of spondylolisthesis. The three subtypes of this condition all manifest some variation of a pars interarticularis defect as a result of recurrent injury to that structure. A multifactorial origin is postulated for this disease; mechanical, hereditary, and hormonal factors are believed to play a role. Presenting signs and symptoms may include those referable to neurological compromise or those related to the spinal deformity. The majority of patients with spondylolysis and spondylolisthesis respond to conservative, nonoperative treatment. Pain, neurological compromise, and cosmetic defects unresponsive to traditional therapies may require surgical intervention. Surgical options include any combination of the following: neural decompression, bone fusion, instrument-assisted fusion, and reduction. In this paper, the natural history and treatment options are presented, and the supporting literature is reviewed.
Introduction
The first written description of spondylolisthesis is attributed to Herbiniaux, a Belgian obstetrician; in 1782, he described an osseous prominence anterior to the sacrum that caused narrowing of the birth canal. This obstruction was due to anterior subluxation of L-5 onto S-1. The term spondylolisthesis was coined approximately one century later, in 1854, by Kilian. He proposed that various forces caused subluxation of the lumbosacral facets; this in turn was believed to cause gradual VB subluxation. Soon thereafter, anatomical studies conducted by Robert and Lambl revealed that, typically, a neural arch defect preceded the subluxation. This defect, at the pars interarticularis, was termed spondylolysis. In 1888, Neugebauer demonstrated that both lysis and elongation of the pars interarticularis could lead to spondylolisthesis. A new dimension was added when Junghanns detailed a series of patients with spondylolisthesis in whom pars defect or elongation was absent.
As knowledge of the origin of spondylolisthesis was gained, attempts were made to classify its various types; the classification proposed by Wiltse, Newman, and Mac-Nab is universally accepted today as providing the means for discussing spondylolisthesis. In this system, spondylolisthesis is subdivided into five subtypes: isthmic, degenerative, dysplastic, traumatic, and pathological types. The different types refer to the various underlying abnormalities that give rise to subluxation of one vertebra over another. In this paper, we will specifically consider isthmic spondylolisthesis.