Sagittal balance in scoliosis associated with Marfan syndrome: a stereoradiographic three-dimensional analysis

Evaluating the sagittal spinal and pelvic parameters in Marfan syndrome patients affected by scoliosis

INTRODUCTION

Spinal deformities present a common finding in patients affected with Marfan syndrome (MFS). More specifically, sagittal spine imbalances reflect the typical finding of such deformities. Observing spino-pelvic radiographs, we focused on eliciting any correlation between the pelvic incidence (PI), sacral slope (SS) and thoracolumbar kyphosis measurements, and categorising them according to a sagittal spinal classification system.

MATERIALS AND METHODS

One hundred seventy patient records were found over a 6 year period, and further refined to incorporate a total of 44 patients. 25 males and 19 females with an average age of 20 years at imaging. Electronic and hard copies of radiographs were used and measurements were made with virtual Cobb meters, rulers and protractors.

RESULTS

The mean PI was significantly different between type-I (46°) and type-II spines (35°) (p = 0.04), and the values for each class were as follows: type IA-53°, type IB-44°, type IC-36°, type IIA-42°, and type IIB-34°. Type II spines had a lower PI compared to type IA spines (p = 0.037) and to that of an unaffected population. Statistically significant differences were noted in SS between groups (t test; p < 0.001), and ANOVA demonstrated that the largest differences between spinal classes were found in SS.

CONCLUSION

In our study, PI values were much higher in type I compared to type II spines. Type II spines had PI values as expected, however, had higher than expected SS values. SS followed a down trending pattern across all spinal classes. Type IIA spines had a much greater preponderance for male patients. Overall, we wish to highlight in particular that type II spines were associated with a much lower PI and SS, and report these differences in pelvic morphology and sagittal spine patterns seen in MFS patients. The pelvic tilt and sacral slope parameters observed in our Type II spines may further reflect and characterize the deformity.

A three-dimensional analysis of scoliosis progression in non-idiopathic scoliosis: is it similar to adolescent idiopathic scoliosis?

PURPOSE

To evaluate the three-dimensional (3D) characteristics of spine deformity in patients with non-idiopathic scoliosis compared with those observed in patients with adolescent idiopathic scoliosis (AIS).

METHODS

A retrospective chart review was conducted to identify patients with non-idiopathic scoliosis. Twenty-eight patients with neural axis (NA) abnormalities (Chiari 1, syrinx) and 20 patients with connective tissue disorder (CTD) (Marfan's, Beal's, Ehlers-Danlos syndrome, mixed) were identified. The 3D parameters of the coronal, sagittal, and axial plane were compared with 284 AIS patients with a similar range of coronal deformity.

RESULTS

The average coronal curve was similar between all three groups (AIS 48 ± 15°, CTD 43 ± 22°, and NA 49 ± 18°; p = 0.4). The NA patients had significantly greater 3D thoracic kyphosis (20 ± 18° vs 10 ± 15°, p = 0.001) and less thoracic apical vertebral rotation (- 5 ± 18° vs - 12 ± 10°, p = 0.003) when compared with AIS. The CTD group's 3D thoracic kyphosis (p = 0.7) and apical vertebral rotation (p = 0.09) did not significantly differ from AIS. Significant negative correlations were found in all three groups between thoracic kyphosis and coronal curve magnitude (AIS r = - 0.49, CTD r = - 0.772, NA r = -0.677, all p < 0.001).

CONCLUSIONS

Scoliotic patients with NA abnormalities have a more kyphotic, less-rotated 3D profile than patients with AIS, while scoliosis patients with CTD have 3D features similar to AIS. Irrespective of the underlying diagnosis, however, greater scoliotic curves were associated with a greater loss of intersegmental kyphosis, suggesting a similar biomechanical pathophysiology for curve progression.