Poor visualization limits diagnosis of proximal junctional kyphosis in adolescent idiopathic scoliosis

Postoperative proximal junctional kyphosis correlated with thoracic inlet angle in Lenke 5c adolescent idiopathic scoliosis patients following posterior surgery

Background

Proximal junctional kyphosis is a common complication after posterior fusion in patients with adolescent idiopathic scoliosis and is correlated with postoperative changes of thoracic kyphosis. In lenke 5c patients, higher postoperative LL and spontaneous change of TK may produce an effect on final PJK. However, no studies has been performed to evaluate the correlation of PJK with thoracocervical parameters in patients with AIS.

Methods

Data from 98 patients who underwent posterior fusion for Lenke 5C AIS with 2 years of follow-up were retrospectively reviewed. Patients in the extended fusion group underwent fusion at levels higher than upper-end vertebra + 2 (n = 38), and those in the thoracolumbar/lumbar (TL/L) fusion group underwent fusion at UEV + 2 or lower (n = 60).

Results

During an average follow-up of 38.1 months, 23 of 98 patients developed PJK. The extended fusion group had a higher incidence of PJK than the TL/L fusion group (14/38 vs. 9/60, respectively; P = 0.01) and a significantly greater decrease in thoracic kyphosis than the TL/L group (P < 0.01). Patients with PJK had a significantly larger preoperative thoracic inlet angle (TIA) than those without PJK (P < 0.01). Multivariate analysis showed that a greater preoperative TIA and extended fusion were associated with PJK. The Scoliosis Research Society 22-item questionnaire score did not significantly differ between the PJK and non-PJK groups.

Conclusions

The preoperative TIA could be a predictor of PJK. Among patients with Lenke 5C AIS, those with a TIA of > 71° are more likely to develop PJK. Additionally, extended fusion in patients with Lenke 5C may increase the risk of PJK.

No added value of 2-year radiographic follow-up of fusion surgery for adolescent idiopathic scoliosis

PURPOSE

For fusion surgery in adolescent idiopathic scoliosis (AIS) consensus exists that a 2-year radiographic follow-up assessment is needed. This standard lacks empirical evidence. The purpose of this study was to investigate the radiographic follow-up after corrective surgery in AIS, from pre-until 2 years postoperative.

METHODS

In this historical cohort study, 63 patients surgically treated for AIS, age ≤ 25 years, with 2-year radiographic follow-up, were enrolled. The primary outcome measure was the major Cobb angle. Secondary outcomes were coronal and sagittal spino-pelvic parameters, including proximal junction kyphosis (PJK) and distal adding-on. Change over time was analyzed using a repeated measures ANOVA.

RESULTS

The major curve Cobb angle showed a statistically significant change for pre- to 1 year postoperative, but not for 1- to 2-year follow-up. Seven out of 63 patients did show a change exceeding the error of measurement (5°) from 1- to 2-year follow-up (range -8° to +7°), of whom 2 patients showed curve progression and 5 showed improvement. PJK or distal adding-on was not observed.

CONCLUSIONS

No statistically significant changes in major curve Cobb angle were found during postsurgical follow-up, or in adjacent non-fused segments. The findings of this study are not supportive for routine radiographs 2 years after fusion surgery in AIS patients.

Thoracic pedicle subtraction osteotomy for correction of proximal junctional kyphosis after surgery for adolescent idiopathic scoliosis: A case report

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Proximal junctional kyphosis in adolescent idiopathic scoliosis is frequent.

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Poor visualization of the sagittal plane leads to incorrect identification of curve type.

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Residual or progressive symptomatic kyphosis may require surgical treatment.

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Pedicle subtraction osteotomy may be an effective corrective technique.

Introduction

Complications in the upper thoracic spine are not uncommon after corrective surgery for deformities in adults and adolescents. Proximal junctional failure has been linked to structural osseous or ligamentous failure and proximal junctional kyphosis has been described as an increase in preoperative proximal kyphosis.

Case description

A 20-year-old male patient intervened after atypical development of idiopathic scoliosis, with rapid progression nearing skeletal maturity. While an increase in the magnitude of the main thoracic curve in the coronal plane was observed, the progression of structural sagittal plane deformity of the proximal thoracic curve was not identified due to poor visualization. This resulted in improper identification of curve type and choice of fusion levels, with progressive residual kyphosis across follow-up. At the age of 27, the patient was re-intervened by means of pedicle subtraction osteotomy in the apical area of the proximal thoracic deformity. Although an adequate correction was achieved, the remaining deformity of 50° and the proximal failure required extending the instrumentation and fusion to the cervical spine. This has shown itself to be an effective technique for correction of proximal residual or progressive symptomatic fixed kyphosis, thereby avoiding the morbidity of the anterior or combined approaches.

Conclusions

In adolescent deformity, an adequate preoperative planning including clinical and radiological study must be carried out, paying special attention to the sagittal plane to identify major and minor structural curves.

The pedicle subtraction osteotomy, despite being a demanding technique and not entirely risk-free, has shown itself to be an effective corrective technique.

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.

Grayscale Inversion View Can Improve the Reliability for Measuring Proximal Junctional Kyphosis in Adolescent Idiopathic Scoliosis

BACKGROUND

Proximal junctional kyphosis (PJK) is a common phenomenon after long segmental fusion surgery of adolescent idiopathic scoliosis. However, the inability to reliably identify vertebral endplates on lateral upright radiographs has made an accurate measurement of proximal junctional angle (PJA) technically impossible in many patients. The aim of this study was to determine whether a grayscale inversion view is more reliable to measure PJA and to assess PJK accurately.

METHODS

A total of 162 patients with adolescent idiopathic scoliosis who underwent posterior spinal fusion surgeries were included in this study. PJA was measured on preoperative lateral standing films using 3 methods (upper-instrumented vertebrae [UIV] + 1, UIV + 2, and UIV to T2) on both standard view and grayscale inversion view. Two physicians independently measured the PJA twice at a 1-month interval. Intra- and interobserver reliabilities were compared between the 2 radiographic views. Forty patients with preoperative magnetic resonance imaging (MRI) scans were randomly selected. PJA was measured for these patients on both views of lateral standing films and MRI images. The correlation coefficients between PJA obtained on MRI and PJA obtained on radiographs with different views were calculated respectively.

RESULTS

The intraclass correlation coefficients were greater in a grayscale inversion view than in a standard view in all 3 methods for both observers, and the intraclass correlation coefficients of interobserver reliabilities also were greater in a grayscale inversion view. The correlation coefficient between PJA obtained on grayscale inversion view and preoperative MRI was greater in all methods compared with standard view.

CONCLUSIONS

Grayscale inversion view can be a more reliable tool for the evaluation of PJK as compared with the conventional measurement. We recommend the application of a grayscale inversion view to measure PJA and assess PJK in clinical practice, particularly for patients instrumented to the upper thoracic spine.

Reproducibility of thoracic kyphosis measurements in patients with adolescent idiopathic scoliosis

Background

Current surgical treatment for adolescent idiopathic scoliosis (AIS) involves correction in both the coronal and sagittal plane, and thorough assessment of these parameters is essential for evaluation of surgical results. However, various definitions of thoracic kyphosis (TK) have been proposed, and the intra- and inter-rater reproducibility of these measures has not been determined. As such, the purpose of the current study was to determine the intra- and inter-rater reproducibility of several TK measurements used in the assessment of AIS.

Methods

Twenty patients (90% females) surgically treated for AIS with alternate-level pedicle screw fixation were included in the study. Three raters independently evaluated pre- and postoperative standing lateral plain radiographs. For each radiograph, several definitions of TK were measured as well as L1–S1 and nonfixed lumbar lordosis. All variables were measured twice 14 days apart, and a mixed effects model was used to determine the repeatability coefficient (RC), which is a measure of the agreement between repeated measurements. Also, the intra- and inter-rater intra-class correlation coefficient (ICC) was determined as a measure of reliability.

Results

Preoperative median Cobb angle was 58° (range 41°–86°), and median surgical curve correction was 68% (range 49–87%). Overall intra-rater RC was highest for T2–T12 and nonfixed TK (11°) and lowest for T4–T12 and T5–T12 (8°). Inter-rater RC was highest for T1–T12, T1-nonfixed, and nonfixed TK (13°) and lowest for T5–T12 (9°). Agreement varied substantially between pre- and postoperative radiographs. Inter-rater ICC was highest for T4–T12 (0.92; 95% CI 0.88–0.95) and T5–T12 (0.92; 95% CI 0.88–0.95) and lowest for T1-nonfixed (0.80; 95% CI 0.72–0.88).

Conclusions

Considerable variation for all TK measurements was noted. Intra- and inter-rater reproducibility was best for T4–T12 and T5–T12. Future studies should consider adopting a relevant minimum difference as a limit for true change in TK.

Electronic supplementary material

The online version of this article (doi:10.1186/s13013-017-0112-4) contains supplementary material, which is available to authorized users.

Sagittal alignment changes and proximal junctional kyphosis in adolescent idiopathic scoliosis

Commentary On Basques BA, Long WD, 3rd, Golinvaux NS, Bohl DD, Samuel AM, Lukasiewicz AM, et al. Poor visualization limits diagnosis of proximal junctional kyphosis in adolescent idiopathic scoliosis. Spine J 2015. doi:10.1016/j.spinee.2015.10.040.