Sagittal balance and spine-pelvis relation: A French speciality?

Hip-Spine Relationship between Sagittal Balance of the Lumbo-Pelvi-Femoral Complex and Hip Extension Capacity: An EOS Evaluation in a Healthy Caucasian Population

STUDY DESIGN

A prospective study of healthy volunteers.

OBJECTIVES

The influence of the sagittal alignment of the spine and its influence on the extension reserve have been reported in the literature. However, specific analysis of the intrinsic coxofemoral and extrinsic pelvic component in subjects without any spinal or hip pathologies remains poorly reported. The aim of this study was to categorize the hip extension capacity, or extension reserve (ER), in relation to spinal sagittal alignment whilst standing, in a young healthy population. We hypothesized that the global extension reserve (GER) of the hip joint was influenced by the sagittal spinopelvic alignment.

METHODS

We evaluated the ER of 120 healthy Caucasian volunteers (56 females (46.7%), 74 males (53.3%); mean age 25.6 years), using low dose radiographs from an EOS® X-ray imaging system in 2 functional positions; neutral standing position and in a forward lunge position. The GER is defined as the sum of the intrinsic (hip) extension reserve (IER) and the extrinsic (pelvic) extension reserve (EER). Cases were grouped into 4 sagittal alignment subtypes according to the Roussouly classification, and analyzed.

RESULTS

Global extension reserve values were not significantly different between the 4 Roussouly subtypes (P = .094), nor between patients with a sacral slope (SS) <35° (types 1/2) and ≥ 35° (type 3/4) (P = .837). Statistically significant differences were seen between IER in each subtype (P = .015), and EER (P = .006). No difference in ER was seen between subtypes regarding pelvic incidence (PI).

CONCLUSION

An inverse relationship was found between IER and EER among Roussouly subtypes. The range of motion of the pelvis and the hip joint was higher in patients with a greater sacral slope.

Global malalignment in adolescent idiopathic scoliosis: the axial deformity is the main driver

PURPOSE

To evaluate the global alignment of non-operated subjects with adolescent idiopathic scoliosis.

METHOD

A total of 254 subjects with AIS and 64 controls underwent low dose biplanar X-rays and had their spine, pelvis, and rib cage reconstructed in 3D. Global alignment was measured in the sagittal and frontal planes by calculating the OD-HA angle (between C2 dens to hip axis with the vertical). Subjects with AIS were classified as malaligned if the OD-HA was > 95th percentile relative to controls.

RESULTS

The sagittal OD-HA in AIS remained within the normal ranges. In the frontal plane, 182 AIS were normally aligned (Group 1, OD-HA = 0.9°) but 72 were malaligned (Group 2, OD-HA = 2.9°). Group 2 had a more severe spinal deformity in the frontal and horizontal planes compared to Group 1 (Cobb: 42 ± 16° vs. 30 ± 18°; apical vertebral rotation AVR: 19 ± 10° vs. 12 ± 7°, all p < 0.05). Group 2 subjects were mainly classified as Lenke 5 or 6. 19/72 malaligned subjects had a mild deformity (Cobb < 30°) but a progressive scoliosis (severity index ≥ 0.6). The frontal OD-HA angle was found to be mainly determined (adjusted-R² = 0.22) by the apical vertebral rotation and secondarily by the Lenke type.

CONCLUSIONS

This study showed that frontal malalignment is more common in distal major structural scoliosis and its main driver is the apical vertebral rotation. This highlights the importance of monitoring the axial plane deformity in order to avoid worsening of the frontal global alignment.

Effects of posterior hemivertebra resection and short segment fusion on the evolution of sagittal balance in children with congenital scoliosis

There is a paucity of data describing sagittal alignment changes in children with congenital scoliosis (CS) treated by hemivertebra (HV) resection. This study aimed to evaluate the effects of posterior HV resection on spine sagittal alignment in children with CS. This is a retrospective analysis of 31 children with CS (mean age at surgery: 49.61 ± 10.21 months; range, 39-72; mean follow-up time: 5.16 ± 1.21 years; range: 3-7) treated at our Institution. Only patients with single thoracic or single lumbar, fully segmented HV managed by posterior HV resection and two segments fusion with four screws and two robs were included. According to the anatomical location of the HV, patients were divided into two groups: thoracic (group A) and lumbar (group B). Thoracic kyphosis (T1-T12; TK) and lumbar lordosis (L1-S1; LL) were measured pre- and postoperatively at 6 months interval. Postoperative TK and LL were 30.3 ± 11.47 and 28.8 ± 9.47, and were 31.98 ± 9.66 and 46.7 ± 11.37 at the last follow-up visit, respectively. The incidence of thoracic hypokyphosis in group B was 53.3%, and it was significantly higher compared to group A (12.5%, P = 0.04). During follow-up, TK changes were comparable between the two groups of patients while LL improved in all patients 6 months after surgery, and continued to improve thereafter. Posterior HV resection and short segment fusion have limited impact on the evolution of TK; in particular, children with lumbar HV were more likely to be hypokyphotic preoperatively, but less likely postoperatively with an increase in LL and a stabilization of TK.

The role of femoral obliquity angle and T1 pelvic angle in predicting quality of life after spinal surgery in adult spinal deformities

BACKGROUND

Adult spinal deformities (ASD) represent a growing clinical condition related to chronic pain, disability and reduction in quality of life (QoL). A strong correlation among spinal alignment, spinopelvic parameters and QoL after spinal fusion surgery in ASD patients was thoroughly investigated over the last decade, However, only few studies focused on the relationship between lumbo-pelvic-femoral parameters - such as Femoral Obliquity Angle (FOA), T1 Pelvic Angle (TPA) and QoL.

METHODS

Radiological and clinical data from 43 patients surgically treated with thoracolumbar posterior spinal fusion for ASD between 2015 and 2018 were retrospectively analyzed. The primary outcomes were the correlation between preoperative spino-pelvic-femoral parameters and postoperative clinical, functional outcomes and QoL. Secondary outcomes were: changes in sagittal radiographic parameters spino-pelvic-femoral, clinical and functional outcomes and the rate of complications after surgery.

RESULTS

Using Spearman's rank correlation coefficients, spinopelvic femoral parameters (FOA, TPA, pre and post-operative) are directly statistically correlated to the quality of life (ODI, SRS-22, pre and post-operative; > 0,6 strong correlation, p <  0.05). Stratifying the patients according pre preoperative FOA value (High FOA ≥ 10 and Normal/Low FOA <  10), those belonging to the first group showed worse clinical (VAS: 5.2 +/- 1.4 vs 2.9 +/- 0.8) and functional outcomes (ODI: 35.6+/- 6.8 vs 23.2 +/- 6.5) after 2 years of follow-up and a greater number of mechanical complications (57.9% vs 8.3% p <  0.0021).

CONCLUSION

Based on our results, preoperative FOA and TPA could be important prognostic parameters for predicting disability and quality of life after spinal surgery in ASD patients and early indicators of possible spinal sagittal malalignment. FOA and TPA, like other and better known spinopelvic parameters, should always be considered when planning corrective surgery in ASD patients.

Description of spine motion during gait in normal adolescents and young adults

INTRODUCTION

Standing radiographs allow analysis of spinal segments and their relative positioning. However, it requires a specific positioning influencing spinal alignment. Knowledge of trunk movements when walking is therefore an essential step to evaluate dynamic sagittal balance. Our objective was to define spinal junction kinematics and their correlations during gait in a healthy population.

METHOD

This is a prospective, single-center study. Between 2015 and 2017, 25 healthy volunteers were included. The measurements were taken in a motion analysis laboratory. Several kinematic parameters were studied, including spinal junction movements in the three planes and dynamic sagittal vertical axis (Dyn-SVA). Pearson correlation coefficients were calculated to determine the interactions between the spinal junctions.

RESULTS

In the sagittal plane, the average amplitude of variation of the dyn-SVA was 25.5 cm (SD = 8.9). The average range of motion of the lumbosacral and thoracolumbar junction was approximately 3°, they operated in anti-phase during the gait cycle and were strongly correlated (r = -0.5069, p = 0.01). In the transverse plane, the anti-rotation of the upper body relative to the pelvis was mainly ensured by the opposite movements of the lumbosacral and thoracolumbar junction (r = 0.5689, p = 0.003). In the frontal plane, the lateral inclination in the lumbar region was made in the opposite direction from the pelvis toward the carrying member.

CONCLUSION

Although there is substantial inter-subject variability, our study characterized the angular movements in the three planes of the different spinal junctions, of the pelvis and the lower limbs during a gait cycle in a healthy population.