Spino-pelvic sagittal balance of spondylolisthesis: a review and classification

Abstract

Introduction In L5-S1 spondylolisthesis, it has been clearly demonstrated over the past decade that sacro-pelvic morphology is abnormal and that it can be associated to an abnormal sacro-pelvic orientation as well as to a disturbed global sagittal balance of the spine. The purpose of this article is to review the work done within the Spinal Deformity Study Group (SDSG) over the past decade, which has led to a classification incorporating this recent knowledge. Material and methods The evidence presented has been derived from the analysis of the SDSG database, a multicenter radiological database of patients with L5-S1 spondylolisthesis, collected from 43 spine surgeons in North America and Europe. Results The classification defines 6 types of spondylolisthesis based on features that can be assessed on sagittal radiographs of the spine and pelvis: (1) grade of slip, (2) pelvic incidence, and (3) spino-pelvic alignment. A reliability study has demonstrated substantial intra-and inter-observer reliability similar to other currently used classifications for spinal deformity. Furthermore, healthrelated quality of life measures were found to be significantly different between the 6 types, thus supporting the value of a classification based on spino-pelvic alignment. ConclusionsThe clinical relevance is that clinicians need to keep in mind when planning treatment that subjects with L5-S1 spondylolisthesis are a heterogeneous group with various adaptations of their posture. In the current controversy on whether high-grade deformities should or should not be reduced, it is suggested that reduction techniques should preferably be used in subjects with evidence of abnormal posture, in order to restore global spino-pelvic balance and improve the biomechanical environment for fusion.

The lumbar spine has an intrinsic shape specific to each individual that remains a characteristic throughout flexion and extension

“…This might explain our findings such that the desired flexion posture was achievable largely through flexion in the upper lumbar levels with the lower lumbar spine remaining lordotic. The amount of curvature in the lumbar spine can affect the stresses and strains in the spine [8,14,36] and the distribution of curvature has been linked to some spinal pathologies [37]. Twin studies have reported a genetic influence on LBP occurrence [38,39] and with suggestions of postural familial associations it begs the question of whether intrinsic spinal shape might be genetically influenced and whether certain shapes might be more prone to LBP than others.…”

“In situ” fusion or reduction in high-grade high dysplastic developmental spondylolisthesis (HDSS)

“…In the current controversy on whether high-grade deformities should or should not be reduced, Hresko et al [7] divided HDDS in two different groups: the balanced deformities, which do not need reduction, and the unbalanced deformities, in which correction is mandatory, and Labelle et al [13] provided a compelling rationale to reduce and realign the deformity, in order to restore global spino-pelvic balance and improve the biomechanical environment for fusion.…”

“…This paper reports the results of a retrospective study of 16 consecutive patients with lumbar high-grade HDDS managed according with the proposal by Labelle et al [13] with the aim to assess the clinical usefulness of their classification.…”

Middle-Column Gap Balancing and Middle-Column Mismatch in Spinal Reconstructive Surgery

“…The errors are additive and they can grossly distort global spinal relationships. Labelle et al, 1 Lafage et al, 2 and Schwab et al 3 should be credited with highlighting the global parameters in sagittal imbalance that often resulted from reconstructing the disc with rectangular, nonlordotic spacers, These investigators should also be credited with formulating a sagittal plane þ pelvis coordinate system, which allows a surgeon to perform local sagittal angular corrective osteotomies to maintain the correct global balance.level for reconstructing complex deformities to restore and optimize spinal height on a global level. The importance of coronal balance was realized in the 1980s when Cotrel-Dubousset segmental instrumentation could cause coronal decompensation (xaxis imbalance).…”