Classification of High-Grade Spondylolistheses Based on Pelvic Version and Spine Balance: Possible Rationale for Reduction

Study Design. Retrospective review of a radiographic database of high-grade spondylolisthesis patients in comparison with asymptomatic controls. Objective. To analyze the sagittal spinopelvic alignment in high-grade spondylolisthesis patients and identify subgroups that may require reduction to restore sagittal balance. Summary of Background Data. High-grade spondylolisthesis is associated with an abnormally high pelvic incidence (PI); however, the spatial orientation of the pelvis, determined by sacral slope (SS) and pelvic tilt (PT), is not known. We hypothesized that sagittal spinal alignment would vary with the pelvic orientation. Methods. Digitized sagittal radiographs of 133 high-grade spondylolisthesis patients (mean age, 17 years) were measured to determined sagittal alignment. K-means cluster analysis identified 2 groups based on the PT and SS, which were compared by paired t test. Comparisons were made to asymptomatic controls matched for PI. Results. High-grade spondylolisthesis patients had a mean PI of 78.9° ± 12.1°. Cluster analysis identified a retroverted, unbalanced pelvis group with high PT (36.5° ± 8.0°)/low SS (40.3° ± 9.0°) and a balanced pelvic group with low PT (mean 21.3° ± 8.2°)/high SS (59.9° ± 11.2°). The retroverted pelvis group had significantly greater L5 incidence and lumbosacral angle with less thoracic kyphosis than the balanced pelvic group. A total of 83% of controls had a “balanced pelvis” based on the categorization by SS and PT. Conclusion. Analysis of sagittal alignment of high-grade spondylolisthesis patients revealed distinct groups termed “balanced” and “unbalanced” pelvis. The PT and SS were similar in controls and balanced pelvis patients. Unbalanced pelvis patients had a sagittal spinal alignment that differed from the balanced pelvis and control groups. Treatment strategies for high-grade spondylolisthesis should reflect the different mechanical strain on the spinopelvic junction in each group; reduction techniques might be considered in patients with an unbalanced pelvis high-grade spondylolisthesis.

[1]  J. Hecquet,et al.  Pelvic incidence: a fundamental pelvic parameter for three-dimensional regulation of spinal sagittal curves , 1998, European Spine Journal.

[2]  H. Labelle,et al.  The Importance of Spino-Pelvic Balance in L5–S1 Developmental Spondylolisthesis: A Review of Pertinent Radiologic Measurements , 2005, Spine.

[3]  R. Betz,et al.  Sagittal spinopelvic balance in normal children and adolescents , 2007, European Spine Journal.

[4]  H. Labelle,et al.  Analysis of the Sagittal Balance of the Spine and Pelvis Using Shape and Orientation Parameters , 2005, Journal of spinal disorders & techniques.

[5]  J. Pélissier,et al.  Sagittal alignment of spine and pelvis regulated by pelvic incidence: standard values and prediction of lordosis , 2006, European Spine Journal.

[6]  Hubert Labelle,et al.  Computerized Assessment of Sagittal Curvatures of the Spine: Comparison Between Cobb and Tangent Circles Techniques , 2006, Journal of spinal disorders & techniques.

[7]  H Labelle,et al.  A Variability Study of Computerized Sagittal Spinopelvic Radiologic Measurements of Trunk Balance , 2005, Journal of spinal disorders & techniques.

[8]  Hubert Labelle,et al.  Sagittal Alignment of the Spine and Pelvis During Growth , 2004, Spine.

[9]  P. Roussouly,et al.  Sagittal Balance of the Spine in Ankylosing Spondylitis , 2006 .

[10]  Hubert Labelle,et al.  Spondylolisthesis, Pelvic Incidence, and Spinopelvic Balance: A Correlation Study , 2004, Spine.

[11]  R. Dewald,et al.  Sagittal plane configuration of the sacrum in spondylolisthesis. , 2000, Spine.

[12]  E. Berthonnaud,et al.  Sagittal morphology and equilibrium of pelvis and spine , 2002, European Spine Journal.

[13]  Gunnar B. J. Andersson,et al.  Effects of Slip Severity and Loading Directions on the Stability of Isthmic Spondylolisthesis: A Finite Element Model Study , 2003, Spine.