THE GLOBAL TILT: EVALUATION OF A PARAMETER CONSIDERING THE GLOBAL SPINOPELVIC ALIGNMENT

Alterations of gait kinematics depend on the deformity type in the setting of adult spinal deformity

PURPOSE

To evaluate 3D kinematic alterations during gait in Adult Spinal Deformity (ASD) subjects with different deformity presentations.

METHODS

One hundred nineteen primary ASD (51 ± 19y, 90F), age and sex-matched to 60 controls, underwent 3D gait analysis with subsequent calculation of 3D lower limb, trunk and segmental spine kinematics as well as the gait deviation index (GDI). ASD were classified into three groups: 51 with sagittal malalignment (ASD-Sag: SVA > 50 mm, PT > 25°, and/or PI-LL > 10°), 28 with only frontal deformity (ASD-Front: Cobb > 20°) and 40 with only hyperkyphosis (ASD-HyperTK: TK > 60°). Kinematics were compared between groups.

RESULTS

ASD-Sag had a decreased pelvic mobility compared to controls with a decreased ROM of hips (38 vs. 45°) and knees (51 vs. 61°). Furthermore, ASD-Sag exhibited a decreased walking speed (0.8 vs. 1.2 m/s) and GDI (80 vs. 95, all p < 0.05) making them more prone to falls. ASD-HyperTK showed similar patterns but in a less pronounced way. ASD-Front had normal walking patterns. GDI, knee flex/extension and walking speed were significantly associated with SVA and PT (r = 0.30-0.65).

CONCLUSION

Sagittal spinal malalignment seems to be the driver of gait alterations in ASD. Patients with higher GT, SVA, PT or PI-LL tended to walk slower, with shorter steps in order to maintain stability with a limited flexibility in the pelvis, hips and knees. These changes were found to a lesser extent in ASD with only hyperkyphosis but not in those with only frontal deformity. 3D gait analysis is an objective tool to evaluate functionality in ASD patients depending on their type of spinal deformity.

LEVEL OF EVIDENCE I

Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

Multiple-rod constructs in adult spinal deformity surgery for pelvic-fixated long instrumentations: an integral matched cohort analysis

PURPOSE

Multiple-rod constructs (Multi-Rod: extra rods for additional pillar support) are occasionally used in adult spinal deformity (ASD) surgery. We aimed to compare and analyze the general outcome of multi-rod constructs with a matched two-rod cohort, to better understand the differences and the similitudes.

METHODS

This is a retrospective matched cohort study including patients with ASD that underwent surgical correction with long posterior instrumentation (more than five levels), pelvic fixation and a minimum 1-year follow-up. Matching was considered with demographical data, preoperative radiographical parameters, preoperative clinical status [health-related quality-of-life (HRQoL) scores] and surgical characteristics (anterior fusion, decompression, rod material, osteotomies). Postoperative radiographical and clinical parameters, as well as complications, were obtained. Univariate and multivariate analysis was performed regarding postoperative improvement, group variables comparison and parameters correlation.

RESULTS

Thirty-three patients with multi-rod construct and 33 matched with a two-rod construct were selected from a database with 346 ASD-operated patients. Both groups had a significant improvement with surgical management in the radiographical and HRQoL parameters (p < 0.001). Differences between groups for the postoperative radiographical, clinical and perioperative parameters were not significant. Rod breakage was more frequent in the two-rod group (8 vs 4, p = 0.089), as well as the respective revision surgery for those cases (6 vs 1 p = 0.046). Risk factors related to revision surgery were greater kyphosis correction (p = 0.001), longer instrumentation (p = 0.037) and greater sagittal vertical axis correction (p = 0.049).

CONCLUSION

No major disadvantage on the use of multi-rod construct was identified. This supports the benefit of using multi-rod constructs to avoid implant failure. These slides can be retrieved under Electronic Supplementary Material.

Surgical Outcomes of Long Fusion Using Dual Iliac Screws Bilaterally for Adult Spinal Deformities: The Effect on the Loosening Rate and Sacroiliac Joint Correction

Introduction

We recently demonstrated that pelvic incidence (PI) decreases after long fusion using iliac screws (ISs) and plays a role in good sagittal balance postoperatively. By contrast, the IS loosening rate may cause reversion, increasing the PI and causing loss of sagittal balance. The aim of this study was to determine the effect of the number of ISs inserted into the iliac bone for long fusion to correct adult spinal deformities (ASDs) on the frequency of IS loosening, postoperative PI, and surgical outcomes.

Methods

We included data from 70 consecutive patients. Cases in which two ISs were inserted bilaterally comprised the dual IS group (Group D), whereas cases in which one IS was inserted bilaterally comprised the single IS group (Group S).

Results

IS loosening was observed in four patients in Group D (9%) and 14 patients in Group S (61%). Both early and one-year postoperative PI were significantly smaller in Group D (P < 0.001). The sagittal vertical axis (SVA) one-year postoperatively was significantly smaller in Group D (P = 0.003).

Conclusions

The loosening rate of dual ISs was as low as about one-seventh that of single ISs. Using dual ISs, postoperative PI can be kept small, possibly resulting in a smaller SVA.

[The disputes in the radiographic measurements of sagittal balance and how to deal with them]

Objective

To review the process of radiographic measurements of sagittal balance and offer reference for the clinical practice.

Methods

The related literature of spino-pelvic sagittal parameters and their clinical application was reviewed and analyzed from the aspects such as the clinical application, the advantages and disadvantages, and how to use them effectively.

Results

All parameters have their advantages and disadvantages, and they are influenced by age and race. Sagittal vertical axis can only reflect the global balance, and T 1 pelvic angle which accounts for both spinal inclination and pelvic tilt can't be controlled in the surgery. The correction goal for western people may be not suitable for Chinese.

Conclusion

The parameters should be used wisely when evaluating the sagittal balance, the global balance and local balance should be considered together and the different groups of people need different correction goals.