Prognostic Role of Rib Hump in Overlying Thoracic Curve Correction Above Selective Fusion for Lenke 5 Idiopathic Adolescent 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.

Patient-specific rods for thoracic kyphosis correction in adolescent idiopathic scoliosis surgery: Preliminary results

INTRODUCTION

Restoring a degree of kyphosis consistent with good sagittal alignment of the spine is a key concern when performing surgery to correct adolescent idiopathic scoliosis (AIS). The objective of this study was to assess the preliminary outcomes of posterior fusion for AIS using patient-specific rods that were pre-contoured based on pelvic incidence. The primary evaluation criterion was thoracic kyphosis at last follow-up.

HYPOTHESIS

The use of pre-bent patient-specific rods has a favourable effect on thoracic kyphosis at last follow-up.

MATERIAL AND METHODS

A total of 37 patients with AIS, including 17 with hypokyphosis, managed with patient-specific rods were included in a prospective study. The rod contouring angles were based on predefined pelvic incidence criteria (25° to 40° for the rod on the convex side and the same value plus 10° for the rod on the concave side). Thoracic kyphosis was assessed before surgery and at last follow-up, after 12-36 months (mean, 19 months). Student's t test was applied to compare means. Multivariate linear regression analysis was performed.

RESULTS

At last follow-up, the mean increase in kyphosis was 14° and was comparable to the planned increase (mean difference=0, p=0.85). Factors associated with kyphosis at last follow-up were the concave rod contouring angle and the pre-operative kyphotic angle of the thoracic segment to be instrumented (p<0.05). Mean differences between kyphosis of the instrumented thoracic segment at last follow-up and target kyphosis were -5° in the subgroup with hypokyphosis (<20°) before surgery and +4° in the subgroup with normal kyphosis before surgery.

CONCLUSION

With patient-specific rods, kyphosis at last follow-up was close to the target value. Predictors of kyphosis at last follow-up were the concave rod contouring angle and pre-operative kyphotic angle of the thoracic segment to be instrumented. Over-contouring of the concave rod seems necessary in patients with preoperative hypokyphosis but not in patients with normal kyphosis.

LEVEL OF EVIDENCE

III, prospective non-comparative study.

Surgical Treatment of Lenke Type 5 Adolescent Idiopathic Scoliosis: A Systematic Review

STUDY DESIGN

A systematic review.

OBJECTIVE

To systemically review the previous literature regarding surgical treatment of Lenke type 5 adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

The Lenke classification was published in 2001 as the classification of AIS. Since then, numerous articles have been published reporting the outcomes of surgical treatment of Lenke type 5 AIS.

METHODS

The electronic databases PubMed, EMBASE, and Web of Science were queried up to Aug 2018 for articles regarding surgical treatment of Lenke type 5 AIS. Surgical variables, radiographic assessments, and clinical outcomes of surgical treatment of Lenke type 5 AIS were summarized.

RESULTS

Fifty studies met the inclusion criteria. The average fused levels, % correction of thoracolumbar/lumbar curve at final follow-up, and % correction of thoracic curve at final follow-up for anterior and posterior procedures were reported to be 3.6-5.3 and 4.3-7.8 levels, 53-86 and 55-94% and 17-52 and 19-67%, respectively. Average coronal balance was imbalanced (≥20 mm) at preoperation in 22/43 reporting study groups and balanced (<20 mm) at final follow-up in all 37 reporting study groups. Scoliosis Research Society Version 22 scores showed no difference between anterior and posterior procedures in most of the reporting studies (5/6).

CONCLUSION

Overall, the outcomes of surgical treatment of Lenke type 5 AIS are excellent. The thoracic curve was spontaneously corrected after surgery and coronal balance after surgery was better than before surgery. Both anterior and posterior procedures demonstrated satisfactory outcomes.

LEVEL OF EVIDENCE

4.

Why a P-Value is Not Enough

BACKGROUND

All doctors know that P-value<0.05 is "the Graal," but publications require further parameters [odds ratios, confidence interval (CI), etc.] to better analyze scientific data.

AIM

The aim of this study was to present P-values, CI, and common effect-sizes (Cohen d, odds ratio, and various coefficients) in a simple way.

DESCRIPTION

The P-value is the probability, when the null hypothesis is true (eg, no difference or no association), of obtaining a result equal to or more extreme than what we actually observed. Simplistically, P-value quantifies the probability that the result is due to chance. It does not measure how big the association or the difference is. The CI on a value describes the probability that the true value is within a given range. A 95% CI means that the CI covers the true value in 95 of 100 performed studies. The test is significant if the CI does not include the null hypothesized difference or association (eg, 0 for difference). The effect-sizes are quantitative measures of the strength of a difference or association. If the P-value is <0.05 but the effect size is very low, the test is statistically significant but probably, clinically not so.

CONCLUSIONS

Scientific publications require more parameters than a P-value. Statistical results should also include effect sizes and CIs to allow for a more complete, honest, and useful interpretation of scientific findings.

Influence of Derotation Connectors on 3D Surgical Correction of Adolescent Idiopathic Scoliosis

STUDY DESIGN

Monocentric study comparing results of simultaneous translation on 2 rods (ST2R) with derotation connectors (prospective series) or without derotation connectors (retrospective series) in Adolescent Idiopathic Scoliosis (AIS) surgery.

OBJECTIVE

The objective of this study was to assess if derotation connectors influence axial, coronal, and sagittal results in AIS surgery.

SUMMARY OF BACKGROUND DATA

Conventional reduction techniques remain limited in their ability to reduce axial torsion. Direct vertebral derotation technique accomplishes partial axial derotation but decreases thoracic kyphosis.

METHODS

Monocentric study including AIS surgeries performed using ST2R technique with derotation connectors (group D+, n=44) or without derotation connectors (group D-, n=24). The axial intervertebral rotation was measured between apical and neutral vertebra on pre and postoperative computed tomography scan. T test was used to compare mean values. ANCOVA analyzed the influence of connectors and covariates on the primary outcome, which was the difference between preoperative and postoperative intervertebral rotation.

RESULTS

The mean axial torsion gain in the D+ group was 23% (+3.84 degrees, 95% confidence interval, +1.95/+5.73). In the D- group, mean axial torsion increase of 4% (-0.42 degrees, 95% confidence interval, -1.19/+2.03). The result was significantly different between the 2 groups (P=0.005). The coronal correction of the main curve angle was 80% in the D+ group and 64% in the D- group (P=0.004). Kyphosis correction was similar between the 2 groups (P=0.3) with significant increase of thoracic kyphosis in the whole series (P=0.02) and no patients with postoperative hypokyphosis <10 degrees. Multivariate analysis confirmed the influence of derotation connectors on both axial and coronal correction (P<0.05).

CONCLUSIONS

The use of derotation connectors in the surgical treatment of AIS significantly improved axial and coronal correction compared to nonuse of connectors without compromising the sagittal plane.