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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 12  |  Issue : 1  |  Page : 42-48

Correlation of curve flexibility analysis with patient health outcomes after scoliosis surgery using Scoliosis Research Society-22 Questionnaire


Department of Orthopaedics and Traumatology, Chinese University of Hong Kong, New Territories, Hong Kong, China

Date of Submission27-Nov-2019
Date of Acceptance02-Mar-2020
Date of Web Publication26-Jun-2020

Correspondence Address:
Dr. Bobby Kin-Wah Ng
Department of Orthopaedics and Traumatology, Chinese University of Hong Kong, New Territories, Hong Kong
China
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jotr.jotr_54_19

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  Abstract 


Introduction: Outcome of corrective scoliosis surgery is dependent on radiographic improvements as well as patients' perspective and satisfaction, where the inter-relationship has not yet been reported elsewhere. The lack of discussion on this inter-relationship between the change in spinal curvatures before and after surgery and health-related quality of life explained by Scoliosis Research Society (SRS) domains remains an important topic to discuss. Patients' quality of life was also influenced by how best surgical planning on spinal bending correction. Materials and Methods: Seventy-six adolescent idiopathic scoliosis patients who underwent posterior spinal fusion from 2014 to 2017 in our specialized center were recruited. Demographic variables and radiological measurements were collected. Patients filled out the SRS-22 questionnaire from a mobile device, of which the SRS-22 was digitally adopted using mobile technology and cloud computation. Results: The mean age at surgery is 17.52 years. “Function” and “pain” scores showed a similar pattern of score changing over the four time points. The patterns of SRS-22 score changes over the three time periods were similar in the six domain scores except a slight difference in “satisfaction,” which showed an increase 12–24 months after surgery, and the scores at “>24 months” returned to the scores at “<12 months” after surgery. Conclusions: Results from SRS-22 outcome measurements showed that “function” and “pain” were increased and better than “preoperative” years after surgery. “Mental” and “self-image” were improved after surgery. “Self-image” will be better with a more flexible spinal curve. Surgery was recommended when higher curve flexibility was detected to conserve a higher self-image.

Keywords: Adolescent idiopathic scoliosis, curve flexibility, health outcomes, quality of life


How to cite this article:
Chau WW, Illescas V, Ng BK. Correlation of curve flexibility analysis with patient health outcomes after scoliosis surgery using Scoliosis Research Society-22 Questionnaire. J Orthop Traumatol Rehabil 2020;12:42-8

How to cite this URL:
Chau WW, Illescas V, Ng BK. Correlation of curve flexibility analysis with patient health outcomes after scoliosis surgery using Scoliosis Research Society-22 Questionnaire. J Orthop Traumatol Rehabil [serial online] 2020 [cited 2020 Jul 6];12:42-8. Available from: http://www.jotr.in/text.asp?2020/12/1/42/287719




  Introduction Top


Adolescent idiopathic scoliosis (AIS) is a three-dimensional (3D) deformity presenting with back deformity, rib hump, and/or shoulder asymmetry.[1]

The etiology of AIS is complex, although genetic influence was reported to be one of the major factors.[2],[3],[4],[5],[6],[7] The prognosis of AIS depends on several factors including curve morphology, trunk imbalance, curve magnitude, age of onset, stage of bone growth, and rate of progression.[2],[3],[4],[8] Progression results in body deformities such as uneven shoulders and asymmetric waistline that leads to chronic pain, decreased or poor function self-image and mental health, and in severe cases, disturbed pulmonary function.[9],[10],[11],[12] The current indications of surgery are curves >45°–50° at skeletal maturity or patients with 1–2 years of growth remaining.[4],[8] The quality of life of patients before and after and many years after surgery is always an important life-affecting topic, but attention has not yet to be paid. Young patients who have received this kind of deformity corrective surgery may experience irreversible unpromising body conditions which could have been observed at an earlier stage.

Outcome of corrective scoliosis surgery is dependent on radiographic improvements as well as patients' perspective and satisfaction.[13] Objective success in correction is not correlated with subjective satisfaction of the patient and the family because their perception of appearance differs from that of surgeons and other factors.[14] Improvements in the general self-image, function, level of activity domains, and pain are reported after surgical correction and had no significant correlation between magnitude of curve correction and outcome scores.[2],[15] Scoliosis Research Society-22 (SRS-22) is proven to be a valid and reliable instrument for assessing patients with AIS that is sensitive to changes following surgery.[16] The questionnaire is reliable with internal consistency and reproducibility. It is shorter and more focused on the health issues related to idiopathic scoliosis than Short Form-26.[17]

Literatures on the quality of life of AIS patients undergoing surgery were few. The underestimation of different health-related quality of life scores on major complications in lumbar degenerative scoliosis surgery in 138 patients was an important finding, although the data generalizability was limited to adult patients (mean age: 59.8) and those who underwent lumbar deformities.[18] Another single-institute study on the effect of age on the quality of life for adult patients with spinal deformity after surgery demonstrated that age was an important factor on patients' perceptions on their functions and mental health.[19] Another Japanese group worked on long-term health outcomes in severe AIS patients and noticed significant decreases in function and self-image with controls many years after surgery.[20],[21] The statistical comparisons were straightforward without considering any preoperative conditions. A literature review on the influences of surgery on the quality of life of AIS patients using SRS outcomes concluded general improvements in pain and self-image domains from baseline to 2 years postoperatively, and the natural history of AIS was important in surgical decision-making.[22] The lack of discussion on the relationship between the change in spinal curvatures before and after surgery and health-related quality of life explained by SRS domains remains an important topic to discuss. Patients' quality of life was directly related to how best the surgical planning on spinal bending correction.

The purpose of this study is to evaluate the influence of preoperative body mass index (BMI), length of fused levels, and curve correction based on 3D correction strategy and to correlate these factors to postoperative radiographic and outcome measure (SRS-22).


  Materials and Methods Top


We reviewed 76 AIS patients who underwent posterior spinal fusion from 2014 to 2017. Informed consent was signed and obtained from every study participant and their legal guardians as required. Ethical approval was obtained from the Ethics Review Board of the Joint NTEC/CUHK Ethics Committee (Research Ethics Committee approval number: 2019.213).

Demographic variables, for example, sex, age at surgery, number of operated levels (L), number of pedicle screws (PSs), and percentage of PS density (PS/L). Patients were grouped preoperatively as underweight (BMI: <18.5), normal weight (BMI: 18.5–23), overweight (BMI: 23–25), and obese (BMI: >25).[23] Preoperative standing Cobb angle, side-bending Cobb angle, and postoperative Cobb angle were measured. Side-bending percent correction (SBC) was used to check for curve rigidity/flexibility using the formula: ([preoperative Cobb angle – side-bending Cobb angle]/preoperative Cobb angle) ×100%. Evaluation of groups of patients with rigid (<30% side bending correction) and flexible curve (>30% side-bending correction) was analyzed by operative percentage correction (preoperative Cobb angle – postoperative Cobb angle/preoperative Cobb angle). All patients underwent posterior surgery instrumented fusion with PS and using the 3D correction method done by a single surgeon.

Side-bending and fulcrum-bending measurements

Side-bending correction is calculated using the following formula: 100× ([preoperative Cobb angle −side-bending Cobb angle]/preoperative Cobb angle). Fulcrum-bending correction is calculated as follows: 100× ([preoperative Cobb angle -fulcrum-bending Cobb angle]/preoperative Cobb angle).

Scoliosis Research Society-22 questionnaire

Patients filled out the SRS-22 questionnaire through a web browser on either a mobile device or tablet. The SRS-22 questionnaire has been transformed into an electronic format (https://aisq.ort.cuhk.edu.hk).

Statistical analysis

Variables were calculated using the Student's t-test or Chi-square test where appropriate. Surgical information regarding the three curvatures was tabulated. SRS-22 domain scores (function/activity, pain, self-image, mental, satisfaction with treatment, and mean) and years between the date of preoperative, maximally three postoperative follow-up sessions (postoperative 1, 2, and 3), and data of surgery were compared using ANOVA. Linear regression modeling was carried out to evaluate the possible potential factors affecting SRS-22 domain scores being the psychosocial outcome indicators. Both crude and multivariate comparisons with confounding factors controlled (sex and BMI). Data analysis was carried out using IBM SPSS 25.0 (Armonk, New York, USA). A two-sided P ≤ 0.05 was considered statistically significant.


  Results Top


A total of 304 fully completed questionnaires were retrieved from the patients (304 SRS-22 questionnaires in 4 follow-up points by 76 patients). Population consisted of 14 males (18.4%) and 62 females (81.6%). The mean age at surgery was 17.52 years [Table 1]a and [Table 1]b. The average number of PS placed was 17.75, with an average PS density at 73.49%.
Table 1:

Click here to view


Surgical information

Surgical information, particularly on the major curvature (usually the second curve), was tabulated in [Table 2]. Surgical data and different indexes were reported per the three spinal curvatures; however, the major curve (Curve 2) provided the most comprehensive information. The average percentages of side-bending correction and fulcrum-bending correction were 35.78% and 53.58%, respectively, and the percentage of Cobb correction was 70.56%. Lower instrumented vertebra (LIV) level at T12 was found in 40.8% of patients, followed by 22.4% at T11.
Table 2: Comparing surgical information among curvatures

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Scoliosis Research Society-22 domain scores across the treatment periods

SRS-22 mean scores were calculated through two different approaches on how the follow-up period classified (i.e., x-axis) [Table 3]a and [Table 3]b. The follow-up period was classified by (1) follow-up time points (preoperative, postoperative 1, postoperative 2, and postoperative 3), and (2) ≤12 months, 12–24 months, and >24 months since surgery. The reason using these two classifications serves two purposes: (1) the first series showed the SRS-22 domain scores by clinic visit without considering the period between follow-ups and (2) the second series defined the x-axis as definitive follow-up period which made the comparisons more clinically meaningful.
Table 3:

Click here to view


The corresponding findings were also graphically presented in [Figure 1] and [Figure 2]. “Function” and “pain” scores showed a similar pattern of score changing over the 4 time points. Mean scores were dropped at “postoperative 1” and gradually returned back to “preoperative 1.” The mean scores at “postoperative 3” were higher than “postoperative 2;” however, the mean score differences between “postoperative 3” and “postoperative 2” were much smaller compared with the differences between “postoperative 1” and “preoperative.” The mean scores of “mental,” “self-image,” and “satisfaction” were gradually increasing over the four time points, for example, from 3.24, 3.74, 4.06, to 4.08 in “self-image.” “Mean” scores were momentously similar at the four time points. Except “mental,” statistical significances were observed in the other 5 mean scores.
Figure 1: The six Scoliosis Research Society-22 domain score across the four time points (preoperative, postoperative 1, postoperative 2, and postoperative 3)

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Figure 2: The six Scoliosis Research Society-22 domain score across the three periods 1<(2 months, 12–24 months, and >24 months)

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The patterns of SRS-22 score changes over the three time periods were similar in the six domain scores except a slight difference in “satisfaction,” which showed an increase 12–24 months after surgery, and the scores at “>24 months” returned to the scores at “<12 months” after surgery.

Regression analysis on different surgical information on Scoliosis Research Society-22 scores over time

Linear regression modeling was carried out on all six SRS-22 domain scores against number of levels done in surgery, percentage of PS density, fulcrum-bending flexibility (FBF), fulcrum-bending correction index (FBCI), and LIV at Curve 2 [Table 4]a, [Table 4]b, [Table 4]c, [Table 4]d. Crude analyses were followed by the same models controlled by sex and/or BMI. All models which did not reach statistical significance were not shown in the tables. The r2 values were comparatively better explained on “self-image” at “postoperative 3” by FBF after controlled by both sex and BMI (B = −0.026, r2 = 0.423, P = 0.047). FBCI was a positive predictor on “self-image” at “postoperative 3” as well after controlling for sex only (B = 0.008, r2 = 0.389, P = 0.034). “Mental” and “satisfaction” did not show any statistical significance in any comparisons (i.e., no table showed for these two scores).
Table 4:

Click here to view



  Discussion Top


The present study discusses the implant density and surgical information on health-related quality of life using SRS-22. “Function” and “pain” were even better than “preoperative” after a decrease soon after surgery. “Mental” and “self-image” were always improved after surgery. Better “self-image” was associated with better FBF and better FBCI corrections (i.e., the more flexible the spinal curve, the better the self-image).

Asher et al. showed a significant correlation with increasing Cobb angle and decrease in SRS-22.[24] In a study by Chaib et al., SRS-22 scores of patients 2 years after corrective surgery showed a significant improvement with patients' self-image and function but no statistical improvement with other domains.[25] This is in comparison to the study of Ersbergand Gerdhem, where they showed improvement in all domains of SRS-22 in AIS.[26] Our study shows a statistical improvement in up to 2-year follow-up with all domains. We apply SRS-22 being a long-term outcome assessment tool for surgical cases because we observe changes in patients' quality of life years after surgery.

This is the first report discussing the relationship between flexibility analysis and quality of life evaluated by SRS-22 questionnaire in AIS. Recently, discussions on curve flexibility in AIS have been gradually increasing. A retrospective study on 40 Lenke 1 AIS patients compared their FBF, correction rate, and correction index before and after surgery.[27] Lenke 1 patients showed that distal segments were more flexible than the proximal ones, as seen through the differences in FBF.[27] More flexibility analyses aiming at Lenke 1 patients on predicting height using preoperative radiological parameters,[28] using advanced imaging technique to analyze flexibility analysis,[29] and looking for predictors of curve flexibility[30] were targeted to surgical approach without adding any quality of life component. On the other side, studies looking at quality of life of surgical cases did not correlate the observations with flexibility parameters. A study in Brazil recruiting 49 Lenke 1 patients who completed the SRS-30 questionnaire before surgery and 2 years after surgery, and results showed that the higher age at surgery the poorer the back pain happened at dorsal and/or lumbar.[31] Our observations showed that “self-image” was better, and this was significantly associated with better FBF and better FBCI corrections. A systematic review on Spanish AIS bracing and surgical patients found bracing patients had a better self-image than surgical patients.[32] Our findings provided explanations on the observation that better self-image after operation could be associated with better curve flexibility. Since larger Cobb angle and apical vertebral rotation showed less curve flexibility,[30] surgery was recommended for severe AIS patients with curve flexibility determined to be good in order for the patients to have a better self-image. This is a very important observation for surgeons to consider the patients' perception on appearance and mental care apart from pure surgery point of view.

Limitations

The statistical results might have been limited by the number of patients recruited in this study. Recall bias being the retrospective nature of this study was inevitable. Confounding factors existed, although statistical controlling of confounding factors was applied trying to minimize the error effect.


  Conclusions Top


In the 76 AIS patients undergoing surgery, the mean number of PSs used was 17.75, and the percentage of PS density was 73.49%. Results from SRS-22 outcome measurements showed that “function” and “pain” were increased and better than “preoperative” years after surgery. “Mental” and “self-image” were improved after surgery. “Self-image” will be better with a more flexible spinal curve.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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