Is vertebral rotation correction maintained after thoracoscopic anterior scoliosis surgery? A low-dose computed tomography study

Assessing progressive changes in axial plane vertebral deformity in adolescent idiopathic scoliosis using sequential magnetic resonance imaging

PURPOSE

To understand how the axial plane deformity contributes to progression of the three-dimensional spinal deformity of Adolescent Idiopathic Scoliosis (AIS), with a main thoracic curve type, using a series of sequential magnetic resonance images (MRI).

METHODS

Twenty-seven AIS patients (at scan 1: mean 12.4 years (± 1.5), mean Cobb angle 29.1°(± 8.8°)) had 3 MRI scans (T4-L1) performed at intervals of mean 0.7 years (± 0.4). The outer profile of the superior and inferior endplates were traced on a reformatted axial image using ImageJ (NIH). Endplate AVR, and intravertebral rotation (IVR), defined as the difference between superior and inferior endplate AVR, was calculated for each vertebral level.

RESULTS

For all patients and scans, the mean AVR was greatest at the curve apex, with AVR diminishing in a caudal and cephalic direction from the apex. At scan 3 the mean apical AVR was 15.1°(± 4.6°) with a mean change in apical AVR between MRI 1 and 3 of 2.7°(± 2.9°). The increase in standing height between MRI 1 and 3 was mean 7.4 cm (± 4.6). Linear regression showed a positive correlation between apical AVR and Cobb angle (R2 = 0.57, P < 0.001), and a positive correlation between apical AVR and rib hump (R2 = 0.54, p < 0.001). The mean change in IVR was greater 3 vertebral levels cephalic and caudal to the apex (1.4°(± 4.1°) and 1.2°(± 2.0°), respectively), compared to the apex (0.4°(± 3.1°)).

CONCLUSIONS

AVR increased, during curve progression, most markedly at the curve apex. The greatest IVR was observed at the periapical levels, with the apex by contrast having only a modest degree of rotation, suggesting the periapical vertebral levels of the scoliosis deformity may be a significant driver in the progression of AIS.

Long-term experience with simultaneous prone video-assisted thoracoscopic anterior spinal release and posterior spinal fusion in severe rigid pediatric spinal deformities

PURPOSE

While posterior-alone techniques have been successful for most pediatric spinal deformities, anterior spinal release may be useful for severe rigid deformities. Traditional lateral-positioned video-assisted thoracoscopic surgical release (VATSR) followed by prone posterior spinal fusion (PSF) has been criticized for adding extensive operative morbidity. We aimed to reduce its disadvantages by performing prone VATSR and PSF simultaneously and evaluate its long-term outcomes.

METHODS

All consecutive patients from 1991 to 2012 undergoing VATSR and PSF at one institution were retrospectively reviewed. The inclusion criteria comprised severe rigid thoracic scoliosis (> 70°, bending correction > 45°) or kyphosis (> 75°, bolster correction > 45°), and a minimum 2 year follow-up. Demographics, operative data, hospital stay, and radiographic correction data were compared between patients who had undergone sequential VATSR followed by PSF and those who had undergone these procedures simultaneously.

RESULTS

Of 153 patients who had undergone VATSR and PSF, 53 met the inclusion criteria (31 sequential, 22 simultaneous; average follow-up, 50 [range, 24-86] months). Age, preoperative measurements and flexibility, and perioperative complications did not differ significantly. The simultaneous group showed significantly lower operative time (449 vs. 618 min), blood loss (1039 vs. 1906 cc), and hospital stay (6.3 vs. 8.5 days) (all, p < 0.05). Postoperative radiographic correction and maintenance at the final follow-up showed a non-significant trend favoring the simultaneous group.

CONCLUSION

Our simultaneous prone VATSR and PSF technique showed significantly lower operative time, blood loss, and hospital stay compared with the traditional sequential VATSR and PSF method, suggesting its value in treating rigid deformities.