Pulmonary function recovery demonstrated by ventilation-perfusion scan after posterior vertebral column resection for severe adolescent idiopathic scoliosis: a case report

Impact of Physical Flexibility Changes on Respiratory Function after Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis Surgery

Introduction

Corrective scoliosis surgery in patients with adolescent idiopathic scoliosis (AIS) increases thoracic volume but does not improve respiratory function (RF). This study evaluates the effect of physical flexibility (PF) improvement after scoliosis surgery on RF.

Methods

This study reviewed the records of 61 consecutive patients with AIS (56 female and 5 male; mean±standard deviation age: 14.8±2.2 years, range: 11-20 years) who had undergone posterior spinal fusion (PSF) of the thoracic curve. PF evaluated as finger-floor distance (FFD) was measured preoperatively and one year after surgery. After dividing the cohort into the PF improvement group and the PF nonimprovement group, RF changes at two years postoperative were statistically compared. Using logistic regression analysis, we evaluated the impact of a PF improvement on % forced vital capacity (%FVC) two years after surgery.

Results

The rate of patients with increased FVC, %FVC, and forced expiratory volume 1.0 second two years after surgery was 79%, 51%, and 80%, respectively. The PF improvement group exhibited a significantly higher gain in %FVC versus the PF nonimprovement group (P=0.043). Moreover, PF improvement significantly prevented a %FVC decrease (odds ratio 8.43, 95% confidence interval 1.92-59.70; P<0.001), with an adjusted odds ratio of 11.86 (P<0.001).

Conclusions

Patients with diminished PF after PSF for AIS may be less likely to achieve postoperative %FVC improvement. As increased postsurgical %FVC had a positive effect on physical function, treatment strategies that focus on maintaining and increasing PF are desirable from an RF viewpoint.

Is There a Correlation Between Cobb Angle and Pulmonary Function Tests at 2-year Follow-up in Patients With Severe Spinal Deformity Treated by Posterior Vertebral Column Resection?

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim was to evaluate the relationships of Cobb angle and pulmonary function tests (PFTs) changes in severe spinal deformity and underwent posterior vertebral column resection (PVCR).

SUMMARY OF BACKGROUND DATA

No previous study focused on the correlation of deformity correction and PFTs changes in patients with cobb angle >90 degrees.

METHODS

PFTs values [forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and percent-predicted values FVC%, FEV1%] were evaluated preoperative and at 2 years after PVCR. FVC% <80% were defined as restrictive ventilation dysfunction (RVD), the severity of RVD were divided into mild (FEV1% ≥70%), moderate (70% > FEV1% ≥50%) and severe (FEV1% <50%). The relationships among PFTs values improvements and all possible impact factors (mainly correction cobb angle) collected in this study were analyzed. PFTs data were compared among the 3 RVD subgroups (mild vs. moderate vs. severe) and between residual >30 versus <30 degrees.

RESULTS

A total of 53 cases (28 male/25 female, mean ages 18.9 Y) underwent PVCR in one center from 2004 to 2016 were enrolled cobb angle. When 2 years after PVCR, average PFTs values showed significant improvements. PFTs values changes showed no correlation with correction rate and correction angle. The only significant impact factor in this study for FVC, FVC%, FEV1 improvements was preoperative FVC% and the only impact factor for FEV1% improvement was preoperative FEV1%, the relationships were negative. In accordance with the regression analysis, PFTs values improvements among the 3 RVD subgroups from high to low was severe>moderate>mild. However, patients with residual cobb angle <30 degrees had less PFTs values improvements than patients with residual cobb angle >30 degrees.

CONCLUSIONS

Two years after PVCR, PFTs values were significantly improved. There is no linear correlation between cobb angle change and PFTs values improvements. Lower preoperative FVC% and FEV1% indicate more PFTs values improvements at 2 years post-PVCR.

LEVEL OF EVIDENCE

Level III.

Thoracic Morphology and Bronchial Narrowing Are Related to Pulmonary Function in Adolescent Idiopathic Scoliosis

BACKGROUND

In adolescent idiopathic scoliosis (AIS), lung function impairment is not necessarily related to the coronal spinal deformity. Recently, right-sided bronchial narrowing has been reported in thoracic AIS. The aim of this study was to describe the relation of chest and spinal deformity parameters, bronchial narrowing, and lung volumes with pulmonary function in preoperative AIS.

METHODS

Spinal radiographs, low-dose computed tomographic (CT) scans of the spine including the chest, and pulmonary function tests were retrospectively collected for 85 preoperative patients with thoracic AIS in 2 centers and were compared with 14 matched controls. Three-dimensional lung and airway reconstructions were acquired. Correlation analysis was performed in which radiographic spinal parameters, CT-based thoracic deformity parameters (rib-hump index [RHi], spinal penetration index, endothoracic hump ratio, hemithoracic-width ratio), lung volume asymmetry, and bronchial cross-sectional area were compared with percent-of-predicted spirometry results.

RESULTS

Forty-one patients (48%) had a percent-of-predicted forced expiratory volume in 1 second (FEV1%) or percent-of-predicted forced vital capacity (FVC%) of <65%, and 17 patients (20%) had obstructive lung disease. All thoracic deformity parameters correlated significantly with FEV1% and FVC%; RHi was found to be the best correlate (rs = -0.52 for FEV1% and -0.54 for FVC%). Patients with AIS with impaired pulmonary function had hypokyphosis, a larger rib hump, increased spinal and thoracic rotation, a narrower right hemithorax, and increased intrusion of the spine into the chest. Spinal intrusion correlated with right-sided bronchial narrowing, relative right lung volume loss, and decreased FEV1% and FVC%. Multivariate regression including spinal and thoracic deformity parameters, lung volume asymmetry, and airway parameters could explain 57% of the variance in FEV1% and 54% of the variance in FVC%.

CONCLUSIONS

Chest intrusion by the endothoracic hump is related to right-sided bronchial narrowing and lung function loss in preoperative AIS. The findings support the theory that ventilatory dysfunction in thoracic AIS is not only restrictive but frequently has an obstructive component, especially in patients with hypokyphosis. RHi is the most predictive chest parameter for lung function loss.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Analysis of the pulmonary function in patients undergoing vertebral body tethering for adolescent idiopathic scoliosis

PURPOSE

The literature concerning the effects of scoliosis correction on pulmonary function (PF) is scarce and solely related to spinal fusion. Vertebral body tethering (VBT) represents a new option for scoliosis correction; however, its effects on PF have not yet been investigated. As VBT is a fusion-less technique that does not limit the dynamics of the chest wall, it is expected not to have a negative impact on PF despite the anterior surgical approach.

METHODS

We analyzed the PF preoperatively and compared it with the PF at 6-weeks, 6-months and 12-monthts postoperatively. Considered parameters were total lung capacity (TLC), forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) expressed as percentages. A change of more than 10% was considered clinically significant.

RESULTS

Before VBT, overall TLC, FEV1 and FVC measured 98 ± 15%, 85 ± 16% and 91 ± 17%, respectively. Six weeks after surgery, all parameters were comparable to the preoperative values (TLC 96 ± 17%, FEV1 84 ± 14%, FVC 90 ± 16%) and remained so at the last follow-up (TLC 99 ± 15%, FEV1 89 ± 9%, FVC 86 ± 9). While a reduction in FEV1 and FVC was observed at 6-weeks and 6-months in patients with thoracic or double curves compared to thoracolumbar curves, no significant differences were observed at the 12-months follow-up.

CONCLUSIONS

VBT does not cause a reduction in PF values at a short-term follow-up.

The effect of direct vertebral rotation on the spine parameters (coronal and sagittal) in adolescent idiopathic scoliosis

BACKGROUND

Idiopathic scoliosis is accompanied by postural alterations, instability of gait, and functional disabilities. The objective was to verify radiographic parameters (coronal and sagittal) of adolescents with idiopathic scoliosis (AIS) pre- and post-surgery with direct vertebral rotation (DVR), associated with type 1 osteotomies in all segments (except the most proximal) and type 2 in the periapical vertebrae of the curves.

METHODS

A prospective study design was employed in which 41 AIS were evaluated and compared pre- and post-surgery. Scoliosis was confirmed by a spine X-ray exam (Cobb angle). Eight radiographic parameters were measured: Cobb angles (thoracic proximal and distal), segmental kyphosis, total kyphosis, lumbar lordosis, pelvic incidence, sacral slope, and pelvic tilt.

RESULTS

The Cobb angle averaged 51.3∘± 14.9∘. Post-surgery, there were significant reductions for the following spine measurement parameters: Cobb angle thoracic proximal (p= 0.003); Cobb angle thoracic distal (p= 0.001); Cobb angle lumbar (p= 0.001); kyphosis (T5-T12, p= 0.012); and kyphosis (T1-T12, p= 0.002). These reductions showed the effectiveness of surgical correction to reduce Cobb angles and improve thoracic kyphosis. The values obtained for lumbar lordosis, pelvic incidence, sacral slope, and pelvic tilt were not significantly different pre- and post-surgery.

CONCLUSION

The surgical technique of DVR in AIS proved to be effective in the coronal and sagittal parameters directed at Cobb angles and thoracic kyphosis in order to favor the rehabilitation process.

Essential lordosis revisited

AIMS

Significant correction of an adolescent idiopathic scoliosis in the coronal plane through a posterior approach is associated with hypokyphosis. Factors such as the magnitude of the preoperative coronal curve, the use of hooks, number of levels fused, preoperative kyphosis, screw density, and rod type have all been implicated. Maintaining the normal thoracic kyphosis is important as hypokyphosis is associated with proximal junctional failure (PJF) and early onset degeneration of the spine. The aim of this study was to determine if coronal correction per se was the most relevant factor in generating hypokyphosis.

METHODS

A total of 95 patients (87% female) with a median age of 14 years were included in our study. Pre- and postoperative radiographs were measured and the operative data including upper instrumented vertebra (UIV), lower instrumented vertebra (LIV), metal density, and thoracic flexibility noted. Further analysis of the post-surgical coronal outcome (group 1 < 60% correction and group 2 ≥ 60%) were studied for their association with the postoperative kyphosis in the sagittal plane using univariate and multivariate logistic regression.

RESULTS

Of the 95 patients, 71.6% (68) had a thoracic correction of > 60%. Most (97.8%) had metal density < 80%, while thoracic flexibility > 50% was found in 30.5% (29). Preoperative hypokyphosis (< 20°) was present in 25.3%. A postoperative thoracic hypokyphosis was four times more likely to occur in patients with thoracic correction ≥ 60% (odds ratio (OR) 4.08; p = 0.005), after adjusting for confounding variables. This association was not affected by metal density, thoracic flexibility, LIV, UIV, age, or sex.

CONCLUSION

Our study supports the 'essential lordosis' hypothesis of Roaf and Dickson, i.e. with a greater ability to translate the apical vertebra towards the midline, there is a commensurate lengthening of the anterior column due to the vertebral wedging. Cite this article: Bone Joint J 2020;102-B(4):513-518.

Does Posterior Scoliosis Correction Improve Respiratory Function in Adolescent Idiopathic Scoliosis? A Systematic Review and Meta-analysis

STUDY DESIGN

A systematic review and meta-analysis.

OBJECTIVES

Pulmonary dysfunction is often advocated among the indications for surgical correction of adolescent idiopathic scoliosis (AIS). Previous studies have discussed the effect of scoliosis correction on respiratory function without reaching a definitive conclusion: Some showed that the respiratory function can improve after scoliosis surgery without defining the precise role of anterior, posterior, and combined approaches on this improvement; furthermore, the majority of these studies did not take normal growth into account. As a result, the role of surgery remains to be clarified. The object of the present study was to synthesize the current knowledge regarding changes in respiratory function after posterior corrective surgery for AIS.

METHODS

A comprehensive systematic search was performed to identify all relevant studies in the following electronic databases: MEDLINE, EMBASE, CINAHL (EBSCO). We focused on the studies (1) that discussed posterior fusion surgery for AIS without thoracoplasty, (2) that discussed comparisons of pre- and postoperative percent-predicted values of forced vital capacity (%FVC) or forced expiratory volume (%FEV), and (3) with minimum 2-year follow-up. Forest plots were depicted and Z value was calculated as a test for overall effect.

RESULTS

Ten studies (6 prospective and 4 retrospective studies) met our inclusion criteria. The overall effect showed that there was no significant difference in %FVC or %FEV between pre- and postoperative measurements (very low evidence).

CONCLUSIONS

Posterior correction surgery for mild to moderate AIS patients showed no significant improvement of postoperative respiratory function measured by relative, percent-predicted values at minimum 2-year follow-up.

Current concepts in the surgical management of adolescent idiopathic scoliosis

Adolescent idiopathic scoliosis (AIS) is a complex 3D deformity of the spine. Its prevalence is between 2% and 3% in the general population, with almost 10% of patients requiring some form of treatment and up to 0.1% undergoing surgery. The cosmetic aspect of the deformity is the biggest concern to the patient and is often accompanied by psychosocial distress. In addition, severe curves can cause cardiopulmonary distress. With proven benefits from surgery, the aims of treatment are to improve the cosmetic and functional outcomes. Obtaining correction in the coronal plane is not the only important endpoint anymore. With better understanding of spinal biomechanics and the long-term effects of multiplanar imbalance, we now know that sagittal balance is equally, if not more, important. Better correction of deformities has also been facilitated by an improvement in the design of implants and a better understanding of metallurgy. Understanding the unique character of each deformity is important. In addition, using the most appropriate implant and applying all the principles of correction in a bespoke manner is important to achieve optimum correction.

In this article, we review the current concepts in AIS surgery.

Cite this article: Bone Joint J 2018;100-B:415–24.

Change in Lung Volume Following Thoracoscopic Anterior Spinal Fusion Surgery: A 3-Dimensional Computed Tomography Investigation

STUDY DESIGN

Lung volumes and thoracic anatomy were measured from low-dose computed tomography (CT) scans preoperatively and 2 years following thoracoscopic anterior spinal fusion (TASF) for adolescent idiopathic scoliosis (AIS).

OBJECTIVE

The aim of this study was to assess changes in lung volume after TASF surgical correction.

SUMMARY OF BACKGROUND DATA

AIS patients are known to have decreased pulmonary function as a consequence of their spinal and ribcage deformity. Several studies have evaluated changes in pulmonary function clinically after scoliosis correction surgery showing varied results. To date, there have been no published studies using CT to evaluate lung volume changes following TASF.

METHODS

Twenty-three female AIS patients with both pre- and 2 years postoperative low-dose CT scans were selected from an ethically approved, historical databank. Three-dimensional lung volumes were reconstructed to determine anatomical lung volumes. Right and left lung volumes, total lung volume, and right-to-left lung volume ratio were obtained as well as hemithoracic symmetry, to indicate the extent of thorax deformity. Cobb angle, rib hump, levels fused in surgery, and patient height were used for correlation analysis with the lung volume results.

RESULTS

Left lung volume, total lung volume, and hemithoracic ratio all increased significantly 2 years after surgery. There was no significant change in right-to-left lung volume ratio (P = 0.36). Statistical regression found significant positive correlation between lung volume changes, reduction in Cobb angle, increase in height, and improvement in hemithoracic symmetry ratio.

CONCLUSION

TASF resulted in a statistically significant increase in lung volume following surgery, as well as improvement in the symmetry of the thoracic architecture; however, the postoperative lung volumes remained in the lower 50th percentile relative to females without thoracic deformity. Furthermore, change in lung volume was significantly correlated with changes in Cobb angle, hemithoracic asymmetry, and increased patient height, which are important consequences of thoracic deformity correction surgery.

LEVEL OF EVIDENCE

3.