Reproducibility of thoracic kyphosis measurements in patients with adolescent idiopathic scoliosis

Why Are Some Intervertebral Discs More Prone to Degeneration?: Insights Into Isolated Thoracic "Dysgeneration"

STUDY DESIGN

Prospective observational study.

OBJECTIVE

To determine the prevalence of isolated thoracic degeneration on magnetic resonance imaging (MRI), demographic factors and imaging features, as well as the patient-reported quality of life outcomes associated with this condition.

SUMMARY OF BACKGROUND DATA

Thoracic intervertebral discs are least susceptible to disc degeneration (DD) and may represent a manifestation of "dysgeneration." These discs may never be hydrated from the beginning and seem hypointense on MRI.

PATIENTS AND METHODS

A population-based MRI study of 2007 volunteers was conducted. Each disc from C2/3 to L5/S1 was measured by Pfirrmann and Schneiderman grading. Disc herniation, Schmorl node (SN), high-intensity zones (HIZ), and Modic changes were studied. DD was defined by Pfirrmann 4 or 5. patient-reported quality of life scores, including a 36-item short-form questionnaire and visual analog scale for low back pain, were recorded. Subjects were divided into "isolated thoracic degeneration" (only thoracic segment) and "tandem thoracic degeneration" (thoracic with other segments). The association between imaging findings and isolated thoracic degeneration was determined using multivariate logistic regression.

RESULTS

The mean age of the subjects was 50.0 ± 0.5 and 61.4% were females (n = 1232). Isolated thoracic degeneration was identified in 2.3% of the cohort. Factors associated with isolated thoracic degeneration included lower age, C6/7 HIZ, T8/9 HIZ, and T8/9 SN. Factors associated with tandem thoracic degeneration included L4/5 posterior bulging. The thoracic and lumbar tandem degeneration group demonstrated higher bodily pain, despite a lower visual analog scale, and a higher physical component score of the 36-item short form.

CONCLUSIONS

Isolated thoracic degeneration demonstrated an earlier age of onset, mostly involving the mid-thoracic region (T5/6-T8/9), and in association with findings such as SN. Subjects with tandem thoracolumbar degeneration had less severe lumbar DD and low back pain as compared with those with isolated lumbar degeneration. This paints the picture of "dysgeneration" occurring in the thoracic and lumbar spine.

LEVEL OF EVIDENCE

1.

Intra- and inter-rater reliabilities and differences of kyphotic angle measurements on ultrasound images versus radiographs for children with adolescent idiopathic scoliosis: a preliminary study

PURPOSE

To develop a new method based on 3D ultrasound information to measure the kyphotic angle (KA) on ultrasound (US) images in adolescents with idiopathic scoliosis (AIS) and to evaluate the intra-rater and inter-rater reliabilities and accuracy of the US measurements.

METHODS

Twenty subjects with AIS (17F, 3 M, aged 13.7 ± 2.2 years old) were recruited. One 20 + years experienced rater (R3) measured the KA on radiographs twice using the Cobb method. Two raters (R1, R2), both have at least 1-year experience measured US images twice using the new spinous processes method. The intraclass correlation coefficients (ICC[2,1]) of the intra-rater and inter-rater reliabilities of US KA measurements were calculated. An equation based on US KA measurements to calculate the radiographic KA was generated.

RESULTS

The intra-rater reliability ICC[2,1] (R3) of the X-ray measurement was 0.92 and US KA measurements for R1 and R2 were 0.94 and 0.95, respectively. The inter-rater reliability ICC[2,1] for R1 versus R2 were 0.85 and 0.86, respectively. The mean absolute differences (MAD) of US versus radiography measurements were 4.2 ± 3.0° (R1 vs R3) and 5.0 ± 4.1° (R2 vs R3), respectively. The radiographic equivalent KA = 0.82 × US KA - 5.6°. When using this equation, the overall MAD between US and radiographic KA was 2.9 ± 1.6°.

CONCLUSIONS

The ultrasound spinous process method was reliable to measure the KA. Although there was a systematic bias on the US measurements, after the correction, the MAD of the US and radiographic KA was 2.9 ± 1.6°. Using US allows clinicians to monitor KA without exposing children to ionizing radiation.

Factors contributing to neck pain in patients with degenerative cervical myelopathy: A prospective multicenter study

PURPOSE

Although the understanding of the mechanisms of low back pain due to spinopelvic sagittal imbalance has strengthened, the understanding of the mechanisms of neck pain remains insufficient. Thus, this study aimed to identify the factors associated with preoperative and postoperative neck pain in patients with degenerative cervical myelopathy who underwent laminoplasty.

METHODS

In this prospective multicenter study, we prospectively enrolled patients who were scheduled for laminoplasty for degenerative cervical myelopathy. The associations between different variables and the Numerical Pain Rating Scale (NRS) scores for neck pain were investigated using univariate and multiple linear regression models.

RESULTS

In total, 92 patients were included in the current study. The univariate analysis showed that age, sex, cervical lordosis in neutral and extension, and thoracic kyphosis were significantly associated with the preoperative NRS score for neck pain; moreover, preoperative cervical lordosis in extension and range of motion and postoperative cervical lordosis in neutral, flexion, and extension were significantly associated with the postoperative NRS Scale score for neck pain. Stepwise multiple regression analysis showed that the independent factors contributing to preoperative neck pain were preoperative cervical lordosis in extension, sex, and age. The independent preoperative predictor and contributor to postoperative neck pain were preoperative cervical lordosis in extension and postoperative cervical lordosis in extension, respectively.

CONCLUSIONS

Cervical lordosis in extension showed significant association with neck pain in patients with degenerative cervical myelopathy. Therefore, when performing laminoplasty for patients with a low cervical lordosis in extension, attention should be paid to residual postoperative neck pain.

Factors Negatively Influencing Postoperative Improvement After Laminoplasty in Degenerative Cervical Myelopathy

STUDY DESIGN

This was a retrospective study of prospectively collected data.

OBJECTIVE

In this study, we aimed to characterize a population of patients with degenerative cervical myelopathy (DCM) and a history of poor postoperative neurological recovery and to identify risk factors associated with poor neurological recovery after laminoplasty.

SUMMARY OF BACKGROUND DATA

Kyphotic cervical alignment has been considered a relative contraindication to laminoplasty in recent years; hence, laminoplasty has been decreasingly performed for the treatment of DCM in patients with cervical kyphosis. However, the effect of global spinal alignment on postoperative outcomes has not been extensively investigated.

MATERIALS AND METHODS

We prospectively enrolled patients who were scheduled for laminoplasty for DCM. Outcome (at enrollment and 1 y after surgery) and risk factor analyses were performed by comparing the good recovery and poor recovery groups. The Spearman correlation coefficient was used to evaluate the relationships between the recovery rate and the preoperative radiographic factors.

RESULTS

In total, 101 patients completed the 1-year follow-up. Regarding clinical outcomes, the Japanese Orthopedic Association score for the assessment of cervical myelopathy, European Quality of Life-5 Dimensions, and Neck Disability Index scores improved postoperatively. The recovery rate was significantly correlated with the preoperative sagittal vertical axis (SVA). The patients in the poor recovery group were older than those in the good recovery group. Univariate analyses showed that the SVA and T1 pelvic angle were significantly higher in the poor recovery group. Lastly, stepwise logistic regression analysis showed that a higher SVA was an independent predictor of poor recovery after laminoplasty.

CONCLUSIONS

The SVA and T1 pelvic angle were significantly higher in the poor recovery group. A high preoperative SVA is an independent predictor for poor recovery after laminoplasty. Therefore, indications for laminoplasty in elderly DCM patients with a high preoperative SVA should be carefully considered.

LEVEL OF EVIDENCE

Level III.

Determining the validity and reliability of spinopelvic parameters through comparing standing whole spinal radiographs and upright computed tomography images

Background

Standing whole spinal radiographs are used to evaluate spinal alignment in adult spinal deformity (ASD), yet some studies have reported that pelvic incidence, pelvic tilt, and thoracic kyphosis (TK) intra- and inter-observer reliability is low. This study aimed to evaluate the accuracy of spinopelvic parameters through comparing standing whole spinal radiographs and upright CT images.

Methods

We enrolled 26 patients with ASD. All standing whole spinal posterior/anterior and lateral radiographs and upright whole spinal CT had been obtained in a natural standing position. Two examiners independently measured 13 radiographic parameters. Interclass correlation coefficients (ICCs) were used to analyze measurement intra- and inter-observer reliability. Paired t- and Pearson’s correlation tests were used to analyze validity of the standing whole spinal radiographs.

Results

ICCs of upright CT were excellent in both intra- and inter-observer reliability. However, intra-observer ICCs for TK2–12, TK1–5, TK2–5, and TK5–12 on standing lateral radiographs were relatively low, as were inter-observer ICCs for TK2–12, TK1–5, TK2–5, and TK5–12. Concerning TK values, the difference between the radiographs and CT in TK1–12 and TK2–12 were 4.4 ± 3.1 and 6.6 ± 4.6, respectively, and TK values from T2 showed greater measurement error (p < 0.05).

Conclusions

Upright CT showed excellent intra- and inter-observer reliability in the measurement of spinopelvic parameters. Measurement of TK with T2 on standing whole spinal radiographs resulted in a greater measurement error of up to 6.6°. Surgeons need to consider this when planning surgery and measuring postoperative TK changes in patients with ASD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04786-5.

Predictors of Falls in Patients with Degenerative Cervical Myelopathy: A Prospective Multi-institutional Study

STUDY DESIGN

Prospective multicenter study.

OBJECTIVES

The purpose of this study was to characterize a population of patients with degenerative cervical myelopathy (DCM) combined with a history of falling, and to identify the predictors associated with those falls.

SUMMARY OF BACKGROUND DATA

Falls among patients with DCM are common and can lead to the worsening of neurological symptoms. However, there are no prospective studies that have investigated the risk factors for falls in these patients.

METHODS

We prospectively enrolled patients scheduled for surgery for DCM and evaluated the significance of various preoperative measures for predicting falls. We then examined the correlation between the number of falls and the preoperative factors. Lastly, we performed stepwise logistic regression analysis to assess the concurrent effects of various factors on the occurrence of falls.

RESULTS

Among the 135 patients analyzed, 64 experienced one or more falls from the time of enrollment to 1 year postoperatively. Univariate analysis showed that the preoperative potassium and albumin levels, handgrip strength, and the Japanese Orthopaedic Association score for the assessment of cervical myelopathy (C-JOA score) were lower and Nurick grade was higher in the fallers group. Serum potassium level, handgrip strength, C-JOA score, Nurick grade, European Quality of Life-5 Dimensions (EQ-5D) score, t1 pelvic angle, and sagittal vertical axis had weak correlations with the number of falls. The fallers group had a lower C-JOA and EQ-5D scores and a lower recovery rate at one year postoperatively. Stepwise multiple logistic regression analysis identified preoperative potassium level and handgrip strength as the independent preoperative predictors for falling.

CONCLUSION

We identified preoperative lower serum potassium level and weaker handgrip strength as significant predictors of falls in patients with DCM. Therefore, DCM patients with these risk factors should be cautious about falls and might be candidates for immediate surgical intervention.Level of Evidence: 3.

Assessment of sagittal spinopelvic parameters in a Taiwanese population with spondylolysis by the EOS imaging system: a retrospective radiological analysis

Background

The impact of sagittal spinopelvic alignment on spondylolysis is well established in Caucasian populations. However, prior studies suggest that people from different ethnological backgrounds showed divergence, and a few studies that focused on Asian populations reported conflicting results. The aim of this study is to use the EOS imaging system to evaluate the spinopelvic parameters of spondylolysis patients, and their relationship with spondylolisthesis, disc degeneration, and age in a Taiwanese population.

Methods

Radiographic sagittal spinopelvic parameters for 45 spondylolysis patients and 32 healthy people were evaluated, including pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), thoracic kyphosis (TK), and lumbar lordosis (LL). The spinopelvic parameters were compared between spondylolytic and control groups. These parameters were further compared between spondylolytic subjects with and without spondylolisthesis, with and without high-grade disc degeneration, and young (< 30 years old) and middle-aged.

Results

The PI and LL of the spondylolytic group (52.6°±12.0° and 41.3°±15.2°) were significantly higher than those of the healthy control group (47.16°±7.95° and 28.22°±10.65°). Further analysis of the spondylolytic patients revealed that those with high-grade disc degeneration were more prone to spondylolisthesis (92.3 %) compared to those without (50 %; p = 0.001). The middle-aged group had significantly higher rates of spondylolisthesis (80 %) and high-grade disc degeneration (52.4 %) compared with those for the young group (45 and 16.7 %, respectively; p = 0.017 and 0.047, respectively). No statistically significant difference in the sagittal spinopelvic parameters was found when spondylolytic patients were divided according to the occurrence of spondylolisthesis or high-grade disc degeneration.

Conclusions

In a Taiwanese population, PI and LL were significantly larger in spondylolytic patients. Disc degeneration and age were associated with the occurrence of spondylolisthesis. Ethnological differences should thus be taken into account when making clinical decisions regarding spondylolysis in a Taiwanese population.

Predictors for quality of life improvement after surgery for degenerative cervical myelopathy: a prospective multi-center study

BACKGROUND

Degenerative cervical myelopathy (DCM) can significantly impair a patient's quality of life (QOL). In this study, we aimed to identify predictors associated with QOL improvement after surgery for DCM.

METHODS

This study included 148 patients who underwent surgery for DCM. The European QOL-5 Dimension (EQ-5D) score, the Japanese Orthopedic Association for the assessment of cervical myelopathy (C-JOA) score, and the Nurick grade were used as outcome measures. Radiographic examinations were performed at enrollment. The associations of baseline variables with changes in EQ-5D scores from preoperative to 1-year postoperative assessment were investigated using a multivariable linear regression model.

RESULTS

The EQ-5D and C-JOA scores and the Nurick grade improved after surgery (P < 0.001, P < 0.001, and P < 0.001, respectively). Univariable analysis revealed that preoperative EQ-5D and C-JOA scores were significantly associated with increased EQ-5D scores from preoperative assessment to 1 year after surgery (P < 0.0001 and P = 0.045). Multivariable regression analysis showed that the independent preoperative predictors of change in QOL were lumbar lordosis (LL), sacral slope (SS), and T1 pelvic angle (TPA). According to the prediction model, the increased EQ-5D score from preoperatively to 1 year after surgery = 0.308 - 0.493 × EQ-5D + 0.006 × LL - 0.008 × SS + 0.004 × TPA.

CONCLUSIONS

Preoperative LL, SS, and TPA significantly impacted the QOL of patients who underwent surgery for DCM. Less improvement in QOL after surgery was achieved in patients with smaller LL and TPA and larger SS values. Patients with these risk factors may therefore require additional support to experience adequate improvement in QOL.

Predictors associated with neurological recovery after anterior decompression with fusion for degenerative cervical myelopathy

BACKGROUND

Anterior decompression with fusion (ADF) has often been performed for degenerative cervical myelopathy (DCM) in patients with poor cervical spine alignment and/or anterior cord compression. We aimed to identify clinical and radiological predictors associated with neurological recovery after ADF.

METHODS

This post-hoc analysis from a prospective multicenter study included patients who were scheduled for ADF for DCM. The patients who received other surgeries (laminoplasty, posterior decompression and fusion) were excluded. The associations between baseline clinical and radiographic variables (age, sex, body mass index, etiology, cervical lordosis, range of motion, C7 slope, C2-7 sagittal vertical axis [SVA], thoracic kyphosis [TK], lumbar lordosis, sacral slope, SVA, pelvic tilt, T1 pelvic angle [TPA], the Japanese Orthopedic Association score for the assessment of cervical myelopathy [C-JOA], European Quality of Life Five Dimensions Scale [EQ-5D], Neck Disability Index [NDI], Physical Component Summary of the SF-36 [PCS], and Mental Component Summary of the SF-36) and the recovery rates as the outcome variables were investigated in the univariate regression analysis. Then, the independent predictors for increased recovery rates were evaluated using a stepwise multiple regression analysis.

RESULTS

In total, 37 patients completed the 1 year follow-up. The recovery rate was significantly correlated with SVA (p = 0.001) and TPA (p = 0.03). Univariate regression analyses showed that age (Regression coefficient = - 0.92, p = 0.049), SVA (Regression coefficient  = - 0.57, p = 0.004) and PCS (Regression coefficient = 0.80, p = 0.03) score were significantly associated with recovery rate. Then, a stepwise multiple regression analysis identified the independent predictors of recovery rate after ADF as TK (p = 0.01), PCS (p = 0.03), and SVA (p = 0.03). According to this prediction model, the following equation was obtained: recovery rate = - 8.26 + 1.17 × (TK) - 0.45 × (SVA) + 0.85 × (PCS) (p = 0.002, R² = 0.44).

CONCLUSION

Patients with lower TK, lower PCS score, and higher SVA were more likely to have poor neurological recovery after ADF. Therefore, patients with DCM and these predictors who undergo ADF should be warned about poor recovery and be required to provide adequate informed consent.

The role of radiography in the study of spinal disorders

Despite the growing use of computed tomography (CT) and magnetic resonance imaging (MRI) in the study of spinal disorders, radiography still plays an important role in many conditions affecting the spine. However, the study and interpretation of spine radiograph is receiving less attention and radiologists are increasingly unfamiliar with the typical findings in normal and pathologic conditions of the spine. The aim of this article is to review the radiologic indications of radiograph in different pathologic conditions that affect the spine, including congenital, traumatic, degenerative, inflammatory, infectious and tumour disorders, as well as their main radiographic manifestations.

Determinants of Postoperative Spinal Height Change among Adult Spinal Deformity Patients with Long Construct Circumferential Fusion

Study Design

Retrospective clinical study.

Purpose

To describe postoperative height changes and identify the predictive factors of spinal height (SH) changes among patients with adult spinal deformity (ASD) who underwent circumferential lumbar fusion with instrumentation.

Overview of Literature

Postoperative height changes remain an important issue after spinal fusion surgery that affects the overall satisfaction with surgery. Previous studies of postoperative height change have focused exclusively on young patients with adolescent idiopathic scoliosis (AIS).

Methods

We retrospectively reviewed the clinical and imaging data of ASD patients who underwent lumbar corrective circumferential fusion of ≥3 levels (n=106). SH was defined as the vertical distance between C2 and S1 on a standing lateral image. As potential predictors of postoperative height change, the number of lateral lumbar interbody fusion (LLIF) levels, change in spino-pelvic parameters, total number of levels fused, and pedicle subtraction osteotomies (PSO) were documented. Univariate and multivariate linear regression analyses were performed to identify the predictors of postoperative height change.

Results

The mean SH change was -2.39±50.8 mm (range, -160 to 172 mm). The univariate analyses showed that the number of LLIF levels (coefficient=10.9, p=0.03), the absolute coronal vertical axis change (coefficient=0.6, p=0.01), and the absolute Cobb angle change (coefficient=-0.9, p=0.03) were significant predictors for height change. Patients with PSOs (n=14) tended to have a shorter height postoperatively (coefficient=-26.1); however, this difference was not significant (p=0.07). Multivariate analyses conducted with variables of p<0.20 showed that pelvic tilt (PT) change is an independent contributor to SH change (coefficient=-0.99, p=0.04, R2=0.11).

Conclusions

Utilizing a modified definition of SH used in previous AIS studies, we demonstrated that patients with ASD lose SH postoperatively and that PT change was an independent contributor of SH change.

Automatic analysis of global spinal alignment from simple annotation of vertebral bodies

Purpose: Measurement of global spinal alignment (GSA) is an important aspect of diagnosis and treatment evaluation for spinal deformity but is subject to a high level of inter-reader variability. Approach: Two methods for automatic GSA measurement are proposed to mitigate such variability and reduce the burden of manual measurements. Both approaches use vertebral labels in spine computed tomography (CT) as input: the first (EndSeg) segments vertebral endplates using input labels as seed points; and the second (SpNorm) computes a two-dimensional curvilinear fit to the input labels. Studies were performed to characterize the performance of EndSeg and SpNorm in comparison to manual GSA measurement by five clinicians, including measurements of proximal thoracic kyphosis, main thoracic kyphosis, and lumbar lordosis. Results: For the automatic methods, 93.8% of endplate angle estimates were within the inter-reader 95% confidence interval ( CI 95 ). All GSA measurements for the automatic methods were within the inter-reader CI 95 , and there was no statistically significant difference between automatic and manual methods. The SpNorm method appears particularly robust as it operates without segmentation. Conclusions: Such methods could improve the reproducibility and reliability of GSA measurements and are potentially suitable to applications in large datasets-e.g., for outcome assessment in surgical data science.

Predictability of Coronal Curve Flexibility in Postoperative Curve Correction in Adolescent Idiopathic Scoliosis: The Effect of the Sagittal Profile

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

To assess how the thoracic kyphosis affects the ability of the fulcrum bending radiograph (FBR) to predict the coronal thoracic curve correction.

METHODS

A retrospective study of prospectively collected data was conducted of 107 consecutive patients with thoracic adolescent idiopathic scoliosis (AIS) treated with a standard screw-fixation protocol. Radiographic variables were assessed preoperatively and at 2-year follow-up. Curve flexibility was determined based on the FBR and the Fulcrum Bending Flexibility Index (FBCI). Radiographic variables included preoperative Cobb angle, T5-T12 kyphosis, T12-S1 lordosis, sagittal vertical axis, list, T1-T12 length, truncal shift, and radiographic shoulder height. Patients were also categorized as hypo-, normo-, or hyperkyphotic.

RESULTS

Based on multivariate modeling, an increase in FBR Cobb angle and thoracic kyphosis were significantly associated with an increase in FBCI (increased mismatch between the FBR and postoperative Cobb angles) at 2-year follow-up (P < 0.001). In patients with hyperkyphosis, a longer instrumented length existed despite similar curve size and shorter curve length than the hypo- and normokyphotic groups. Based on these findings, we developed a new predictive postoperative curve correction index, known as the Multiprofile Flexibility Index (MFI).

CONCLUSIONS

Our results show that an increase in preoperative thoracic kyphosis is associated with an increased difference between the preoperative coronal curve flexibility and the postoperative coronal curve correction. Our findings broaden the understanding of curve flexibility and indicate that selection of fusion levels may need to take into consideration the sagittal profile to improve clinical decision making and optimize outcome.

Reproducibility of the classification of early onset scoliosis (C-EOS)

STUDY DESIGN

Reproducibility study.

OBJECTIVES

Assess the agreement and reliability of the classification of early onset scoliosis (C-EOS). C-EOS is a promising tool for patients with early onset scoliosis (EOS). However, the reliability has only been examined without measuring radiographs and not including the annual progression rate (APR) modifier.

METHODS

We included a single-center consecutive cohort of patients diagnosed with EOS seen in our outpatient clinic. Patients had no previous spine surgery. Four raters rated 60 cases. Two anterior-posterior full-spine radiographs, taken minimum 6 months apart, and one sagittal radiograph were measured twice by all raters in a blinded test-retest setup. Results were assessed using crude frequency of overall agreement (OA), intra- and inter-rater Fleiss kappa (κ) statistics, and intraclass correlation coefficient (ICC). We calculated the 95% limits of agreement (LOA) for major curve angle (MCA), kyphosis, and APR using a linear mixed-effects model. Inter- and intra-rater LOA were analyzed for each etiology separately.

RESULTS

Mean age was 8.7 ± 3.4 years and the etiology were congenital/structural (n = 20), idiopathic (n = 19), neuromuscular (n = 13), or syndromic (n = 8). For etiology, OA was 75.8% and κ = 0.80. For major curve angle, OA was 84.2%, κ = 0.86, ICC = 0.97, and LOA = 12.8°. For kyphosis, OA was 55.8%, κ = 0.52, ICC = 0.87, and LOA = 20.6°. For APR, OA was 76.7%, κ = 0.61, ICC = 0.77, and LOA = 17.4°/year. Inter- and intra-rater LOA were generally largest for neuromuscular and smallest for idiopathic patients.

CONCLUSIONS

We found substantial agreement for etiology, however, with disagreement in certain cases. The reliability of MCA was excellent; however, somewhat lower for kyphosis and APR with less accuracy. The measurement errors of MCA, kyphosis, and APR depended largely on the etiology. Regarding APR, LOA exceeded the 10°/year increments proposed in the C-EOS, suggesting a revision of this optional modifier.

LEVEL OF EVIDENCE

Diagnostic study level 1.

The Sagittal Thoracic Modifier Component of the Lenke Classification System in Moderate and Severe Adolescent Idiopathic Scoliosis: Reliability and Reproducibility of Measurements Among 5 Observers

STUDY DESIGN

A prospective radiographic study.

SUMMARY OF BACKGROUND DATA

As the importance of the spinal sagittal profile becomes increasingly evident, there is a need to ensure that the measuring methods used to evaluate thoracic kyphosis (TK) are both accurate and reproducible.

OBJECTIVE

The purpose of the following study was to determine the intraobserver and interobserver variability of measurements of the sagittal profile in moderate and severe thoracic scoliosis.

METHODS

Five experienced Faculty Spine surgeons independently reviewed thirty standing long 30-inch cassette lateral radiographs of preoperative moderate and severe curves ≥50 degrees of adolescent idiopathic scoliosis (AIS) patients on 2 different occasions. The parameters measured were the vertebral endplate clarity and measurability of the sagittal angle from D5 to D12 and categories of thoracic sagittal modifier. κ statistics and Intraclass Correlation Coefficient (ICC) were used for analysis.

RESULTS

The interobserver percentage of agreement for the Sagittal modifier was 58% in both trials. The mean κ coefficient value was only moderate 0.43 (range, 0.14-0.66) for both trials. The number of the vertebral endplates that were difficult to identify was 201 of 300 measurements (67%). There was a predominance of difficulty to identify vertebral endplate clarity in all curve types.

CONCLUSIONS

The results of this study yielded poor to moderate interobserver reliability of the thoracic sagittal profile component of the Lenke classification system in moderate and severe AIS. This was attributed to the difficulty in identification of the vertebral endplates. The current standard lateral radiographs routinely used in AIS patients have inherent difficulties and limitations to visualize, identify, and analyze the thoracic endplates in moderate and severe curves.

The Management of Kyphosis in Metatropic Dysplasia

DESIGN

Retrospective review.

OBJECTIVE

To describe the presentation and progression, and compare treatments of severe thoracic kyphosis in a cohort of patients with metatropic dysplasia.

SUMMARY OF BACKGROUND DATA

Metatropic dysplasia is a rare skeletal dysplasia characterized by several abnormalities, including severe platyspondyly and vertebral wedging. These lead to marked kyphoscoliosis that begins in the first year of life and progresses to a stiff, short thorax and restrictive lung disease. There is no study that specifically addresses treatment of kyphosis in this cohort.

METHODS

A 12-year retrospective chart review at a single institution was performed to identify metatropic dysplasia patients. Comparison between four main treatment groups-observation, bracing, anterior release and growing construct, and anterior release and final fusion-were made radiographically with regard to thoracolumbar, T2-T12, and major Cobb kyphosis; sagittal vertical alignment; and C7-kyphosis apex distance, taken at presentation, pre- and posttreatment, and final follow-up.

RESULTS

Twenty patients with metatropic dysplasia presented at an average age of 3.1 years with a kyphosis of 75°, and were followed an average of 8.5 years. Those treated surgically presented with an average of 86.7° kyphosis, 88 mm C7-kyphosis apex distance, and 50 mm positive sagittal vertical alignment (SVA). Postsurgical reduction of kyphosis averaged 43° with less than 4° loss of correction in all groups except the constructs involving rib fixation. Recent use of staged thoracoscopic anterior soft tissue release, halo traction, and growing rod construct has produced the most dramatic results with average kyphosis correction of 71° and evidence of anterior bony remodeling. In those treated with observation, kyphosis progressed less than a quarter degree per year.

CONCLUSIONS

Thoracic kyphosis in metatropic dysplasia does not uniformly progress in all patients and therefore can be initially observed. In those who progress, several surgical options exist including growth-friendly constructs that have demonstrated success without a higher rate of complications.

LEVEL OF EVIDENCE

Level IV.

Reliability of Rod Lengthening, Thoracic, and Spino-Pelvic Measurements on Biplanar Stereoradiography in Patients Treated With Magnetically Controlled Growing Rods

STUDY DESIGN

Cross-sectional study.

OBJECTIVE

To assess the inter- and intraobserver reliability of thoracic, spino-pelvic, and rod lengthening measurements made on biplanar spinal stereoradiography (EOS imaging) in children treated with magnetically controlled growing rod (MCGR).

SUMMARY OF BACKGROUND DATA

MCGR treatment aims to gain spine length while gradually correcting the spinal deformity. Monitoring thoracic and spino-pelvic parameters is crucial for successful management. EOS imaging is widely used for diagnosis and monitoring of children with Early Onset Scoliosis. However, there is a paucity of literature on the reliability of thoracic and spino-pelvic parameters on EOS imaging in children treated with MCGR.

METHODS

Three independent reviewers independently read a random assortment of 20 whole spine posteroanterior and lateral radiographs from patients treated with MCGR. The measurements were repeated 4 weeks after the initial read. The following radiological parameters were measured: Cobb angle of the main and compensatory curves, coronal balance, coronal T1-S1 and T1-T12 length, chest width and depth at T6, pelvic inlet width, MCGR distracted lengths, global kyphosis, proximal and distal junctional angle, lordosis, sagittal balance, pelvic incidence, pelvic tilt and sacral slope. Statistical analysis was performed with paired t test and Cronbach alpha for inter- and intraobserver reliability.

RESULTS

All measurements had good or excellent intra- and interobserver reliability (α>0.8; P < 0.05), except measurements of the proximal junctional angle which showed only poor intra- and interobserver reliability for patients with an upper instrumented vertebra cranial to T4.

CONCLUSION

EOS imaging is reliable for diagnosis and monitoring of children with Early Onset Scoliosis treated with MCGR. EOS imaging is particularly excellent for assessment of MCGR lengthening. Diagnosis and interpretation of early proximal junctional kyphosis within the cervicothoracic junction should be made with caution.

LEVEL OF EVIDENCE

3.

Predictability of Supine Radiographs for Determining In-Brace Correction for Adolescent Idiopathic Scoliosis

STUDY DESIGN

Retrospective radiographic study.

OBJECTIVE

To assess whether flexibility as revealed by the supine radiograph, predicts in-brace curve correction.

SUMMARY OF BACKGROUND DATA

Currently there is no consensus regarding a standard method to assess curve flexibility and immediate brace effectiveness in treating adolescent idiopathic scoliosis (AIS). Brace fabrication methods may be variable but ideally it should achieve maximal curve correction. Curve flexibility governs the degree of curve correction in-brace and hence dynamic radiographs are commonly performed prior to brace fitting.

METHODS

This was a radiographic analysis of AIS patients treated with underarm bracing. Correlation of pre-brace, supine, and immediate in-brace Cobb angles was performed. Relationship with possible contributing factors including age, sex, body height, weight, age at menarche and Risser staging was studied. Major and minor curves were compared independently for correlation but the regression model was constructed based on the major curve only.

RESULTS

From 105 patients with mean age of 12.2 ± 1.2 years at brace fitting, supine Cobb angle measurement has significant correlation with immediate in-brace Cobb angle (r = 0.740). Univariate analyses showed no significant relationship with age, weight, height, date of menarche, Risser stage or pre-brace Cobb angle. Our regression model (in-brace Cobb angle = 0.809 × supine Cobb angle) had good fit of the data.

CONCLUSION

Supine radiograph predictably determines the flexibility of the scoliotic curve to brace treatment. It can be used as a guideline to determine the amount of correction achievable with brace-wear. The effectiveness of the brace is dependent on the inherent flexibility of the curve rather than its size or type.

LEVEL OF EVIDENCE

3.

Fulcrum flexibility of the main curve predicts postoperative shoulder imbalance in selective thoracic fusion of adolescent idiopathic scoliosis

PURPOSE

To identify preoperative predictors for postoperative shoulder imbalance (PSI) after corrective surgery of adolescent idiopathic scoliosis (AIS) and using the fulcrum-bending radiograph to assess flexibility.

METHODS

A consecutive surgical cohort of AIS patients undergoing selective thoracic fusion with alternate-level pedicle screw fixation was prospectively studied. Preoperative anteroposterior, lateral and fulcrum-bending radiographs were analysed. Postoperatively, a minimum of 2 years clinical and imaging follow-up was performed of all patients. PSI was defined as a radiographic shoulder height difference of more than 20 mm.

RESULTS

A total of 80 patients were included, and 14 patients (18%) were confirmed with PSI at final follow-up. The flexibility of MT curve was an independent risk factor for PSI (odds ratio (OR) = 3.3 per 10% decrease, 95% confidence interval (CI) 1.6-8.2). Twenty-seven patients had a preoperative MT flexibility of < 55% (OR = 11.5, 95% CI 2.8-46.2). Postoperative T1 tilt was significantly higher in the PSI group (p < 0.001), and a T1 tilt of more than 9° resulted in 7.2 times higher odds of developing PSI (95% CI 2.0-26.0). Fulcrum-bending correction index (FBCI) was significantly higher in the PSI group at final follow-up, and 25 patients had a final postoperative MT FBCI above 120% (OR = 8.5 (95% CI 2.3-31.0).

CONCLUSIONS

A low preoperative curve flexibility is a significant predictor for PSI. The surgical strategy should consider proximal fusion in presence of low-flexibility MT curves and consider less aggressive MT curve correction. Achieving a level T1 should be a main priority during intraoperative correction and may require fusion of the PT curve.

LEVEL OF EVIDENCE

III. These slides can be retrieved under Electronic Supplementary Material.