Spine/SRS Spondylolisthesis Summary Statement

Abstract

While a number of classification systems exist to describe the various types of spondylolisthesis, that proposed by Marchetti and Bartolozzi is based on etiology and most clearly distinguishes between developmental and acquired forms of this deformity. We recommend the use of this system, as it highlights the pathogenesis of the different types of spondylolisthesis, and therefore potentially has the most relevance to natural history, risk of progression, and implications for treatment. Other radiographic parameters that are of importance include translational displacement, best described by the Meyerding classification, and lumbosacral kyphosis, best described by the slip angle of Boxall. A number of other radiographic measurements that are important are detailed within the chapters of this issue. The development of spondylolisthesis is influenced by sacral and spinopelvic morphology, which can be measured by the sacral table angle and the pelvic incidence, respectively. Standing radiographs of the entire spine and pelvis are required to assess segmental, regional, and global sagittal balance. Alterations in these parameters are commonly seen is spondylolisthesis. During slip progression, nonuniform forces are applied to the growth plate, resulting in upper sacral endplate deformities. Early recognition of these anterior changes in the immature spine, followed by appropriate surgical intervention, may prevent progressive deformity, including spondyloptosis. Global sagittal plane alignment is important in both adult and pediatric patients with spondylolisthesis. In patients with high-grade developmental spondylolisthesis, this has provided a compelling rationale to reduce and realign the spondylolisthesis deformity, thus restoring global spinal balance and improving the biomechanical environment for fusion. Decisions on whether to perform a reduction should be individualized and should take into consideration the extent and location of neural compression, sagittal balance, and posterior element dysplasia. In particular, reduction should be given strong consideration in pediatric patients with high-grade developmental spondylolisthesis and significant lumbosacral kyphosis. Circumferential fusion with instrumentation is recommended when a reduction is performed. In patients with spondyloloptosis, vertebral body resection appears to be a safer and more feasible approach than reduction. In adult patients with low-grade acquired lytic spondylolisthesis who undergo surgery, the achievement of fusion is associated with better clinical outcome. Long-term follow-up in patients with degenerative spondylolisthesis reveals a positive correlation between fusion and improved clinical outcome. The clear association between spinal instrumentation and improved fusion rates therefore supports the use of spinal fixation in these settings. A number of anterior and posterior techniques are available for achieving fusion in patients with spondylolisthesis, but the optimal approach has not yet been established. Spondylolisthesis surgery is associated with a set of complications unique to this pathology. Neural deficits secondary to surgical intervention have many possible etiologies. Electrophysiologic monitoring may be helpful during spondylolisthesis surgery, particularly in the setting of intraoperative reduction. Numerous techniques are available and deserve consideration, but the limitations of these monitoring techniques need to be recognized. In particular, it should be recognized that even the most sophisticated monitoring technology does not eliminate the risk of neurologic impairment after these often technically challenging procedures. As new spinal technologies that concentrate on motion preservation move into the mainstream of surgical interventions, the presence of any posterior element deficiency that may increase segmental mobility must be recognized. Spondylolysis and spondylolisthesis serve as relative contraindications to these motion preservation surgeries, especially lumbar disc replacement procedures. It is incumbent on the surgeon to seek and rule out these common pathologies before recommending a disc replacement procedure. The Scoliosis Research Society collects and analyzes surgical and postoperative data on patients with spondylolisthesis. This information is used to improve the quality of care by identifying the nature and incidence of problems and complications. Continuing educational initiatives will hopefully reduce the risk to future patients undergoing treatment for this condition. Other important topics for future study include the identification of individuals at risk for developing spondylolysis and spondylolisthesis and identification of markers of progression in those who are at risk. This may be derived from a combination of genetic, clinical, and radiographic parameters. The inadequacies of current classification systems highlight the need for a comprehensive classification schema for spondylolisthesis. This classification should take into account the etiology, radiographic parameters, and clinical manifestations of this disorder. It should aid the surgeon in identifying those at risk for developing clinical symptoms or progression of deformity, and guide treatment decisions. This summary statement has been developed by consensus with contributions from the authors during a Spine journal focus group workshop on spondylolisthesis on October 29–30, 2004.