The impact of spinal fusion of adolescent idiopathic scoliosis in Salah (Islamic Prayer) movement: a retrospective case-control study

Background: Corrective spine surgery is widely accepted for treating severe adolescent idiopathic scoliosis (AIS). Postoperative spinal range of motion (ROM) could be affected after such surgery. In certain populations, such as Muslims, this ROM change can impact daily life, as it may affect the five-times-a-day prayer (Salah). This study aims to assess the influence of spinal fusion (SF) in Adolescent Idiopathic Scoliosis (AIS) during the daily Islamic prayer (Salah). Methods: SF-AIS patients were videoed while performing Salah prayer. The kinematic documentation was assessed and compared to Salah movements of a control group of age-matched Muslim AIS patients, who had not had surgery. The prayer quality changes were subjectively classified into improved, no change/remained, and worsened, according to the Global Perceived Effect (GPE). Functional outcome and pain were assessed by the Scoliosis Research Society Questionnaire Version 30 (SRS-30). Results: Thirty-nine women and five men (mean age±SD: 14.8±2.3 years) met the inclusion criteria, and unoperated AIS patients were used as control (twenty-two women, mean age±SD: 15.32±1.43 years). The prostrations ROM of the SF-AIS group differed significantly from the control group (p<0.05). The GPE of the prayer movement showed improvement in 36.4%, no change in 59.1%, and worsening in 4.5% of the SF-AIS patients. The worsened group had a significantly lower bowing ROM and higher prostrations ROM compared to all groups of prayer quality changes (p<0.05). SRS-30 scores showed good outcomes (function 4.0±0.2, pain 4.2±0.5), along with the overall bowing ROM and prostrations ROM (84.2±12.0° and 53.4±9.6°, respectively). Moreover, a significant moderate positive correlation between the bowing ROM and pain (r=0.417, p=0.007) was also found. Conclusion: Spinal fusion positively affects AIS Islamic patients in maintaining their daily Salah movement, ROM and prayer quality. Prayer quality assessment should be given extra attention as an adjuvant of the SRS-30 questionnaire to evaluate Muslim patients.

Methods: SF-AIS patients were videoed while performing Salah prayer.The kinematic documentation was assessed and compared to Salah movements of a control group of age-matched Muslim AIS patients, who had not had surgery.The prayer quality changes were subjectively classified into improved, no change/remained, and worsened, according to the Global Perceived Effect (GPE).Functional Vibhu Krishnan Viswanathan, Rela Institute 2.

Introduction
Corrective spine surgery is widely accepted to improve the overall quality of life (QOL) for adolescent idiopathic scoliosis (AIS).Maximal deformity correction in achieving the coronal and sagittal balance while retaining the spine flexibility will attain the desired cosmetic look and potentially bring back patient's lost self-esteem. 1,2A study by Weiss and Goodall, discovered that patients' ability to perform flexion was reduced by 20-60% following scoliosis correction surgery. 3Meanwhile, physical impairment in any disease corresponds to physiological abnormalities.In AIS, self-esteem is one of the most important aspects that build the patient's courage to endure a serious high-risk spinal surgery.Likewise, physical function is an important outcome that could portray a meaningful individual's QOL. 4 For decades, the AIS surgical treatment has encompassed pedicle screw fixation to fuse vertebral segments while maintaining growth preservation in the immature AIS.However, the older Harrington instrumentation technique has a higher risk of loose correction. 1 Studer et al., studied 157 AIS patients who underwent spinal fusion surgery.Although they reported minimal complications with no revision surgery, they did not relate to the outcome of QOL.Therefore, an additional evaluation of clinical and patients' health-related QOL as a reliable outcome is needed rather than solely radiologic or curve measurement. 5AIS in untreated patients seems to limit axial and coronal plane ROM based on the degree of curve severity, with more severe curves having less ROM.In those undergoing spinal fusions, the lowest instrumented vertebra and surgical approach appear to minimize further reductions in ROM. 6oliosis correction surgery in AIS could reduce back pain and improve QOL compared to untreated AIS patients.The QOL outcome was similar to healthy patients. 1Therefore, utilizing an objective assessment to measure functional outcomes is essential, in addition to subjective questionnaires.Scoliosis Research Society Questionnaire Version 30 (SRS-30) has been used in many studies to objectively measure the functional outcome of scoliosis patients. 7,8he questionnaire contains 30 questions covering five domains, including 1) function/activity, 2) pain, 3) self-image/ appearance, 4) mental health, and 5) satisfaction with management.Nevertheless, existing tools used to assess postsurgery impacts on the activities of daily living (ADL) could not portray an important activity for Muslim patients, for instance, practicing five-times-a-day prayer.In Indonesia, the largest Muslim-populated country, it is essential to have AIS patients fully informed about the possible impact of the post-surgery spinal fusion on their Salah (Islamic prayer).
Islamic prayers consist of a certain number of Rak'ah, which involves several repetitive movements and postures.Every day, Muslims are obligated to perform 119 postures from 7 to 10 years old. 9,101][12] The Salah movements are composed of standing upright, bowing, prostration, and sitting with knees bent; these movements need maximum extension and flexion of the spine. 11,12AIS patients expect their ADL (including the compulsory prayers for Muslims) to be unaffected following the spinal fusion corrective surgery.In this study, we compared prayer movement pre-and post-surgery conditions.To the best of our knowledge, the evaluation of Islamic prayer (Salah) movements in scoliotic patients and the possible impact of corrective spinal fusion on practicing Salah movements has not yet been studied.Therefore, this study aims to primarily assess the influence of spinal fusion (SF) in AIS during the daily Islamic prayer (Salah) by assessing the Salah prayer quality changes following spinal fusion surgery.By comparing the postoperative Salah movement ROM to age-matched Muslim unoperated AIS patients, this study aims to identify whether spinal fusion surgery affects the Muslims' quality of life (including their prayer quality).We hypothesize that spinal fusion positively affects AIS Islamic patients in maintaining their daily Salah movement ROM and prayer quality.

Ethics
Ethical clearance was approved by the Ethical Review Committee of Faculty of Medicine, Airlangga University (institutional review board approval no.285/EC/KEPK/FKUA/2020).The research team obtained written informed consent from participants before study commencement.All participants consented to be video recorded and photographed during one Salah movement.The participants also consented to having their videos/images and data (excluding name/contact details) published.

REVISED Amendments from Version 2
The newer version of our manuscript addressed several concerns raised by the reviewers.The title was amended.We shorten the introduction while focusing on ROM and add a hypothesis at the end of the introduction.Moreover, we present all relevant p-values in the Results section, amend the grammar and typographical errors in the Discussion section, and discuss similar literature investigating ROM after AIS surgeries.Lastly, we provide an in-depth discussion of how the limitations of our study may affect our results.
Any further responses from the reviewers can be found at the end of the article Setting, patient selection, eligibility criteria, and surgical technique This restrospective case-control study was conducted in three orthopedic centers in Surabaya and Yogyakarta, Indonesia, by retrieving data from physical and electronic medical records from 2010 to 2020.The three orthopedic centers were chosen due to their roles as the main referral centers and prime affiliated teaching hospitals in the region.Four research team members (KAI, NRF, CGS, and YMS) screened patients' data for their eligibility with a predefined form (containing the patient's personal information such as name and phone number, age during surgery, sex, religion, medical history, pre-operative Cobb angle, post-operative Cobb angle, fusion level, Lenke classification, and follow-up duration).No additional authorization (in addition to the ethical clearance) was required to access patients' records because the researchers involved in data collection were the relevant orthopedic surgeons in the respective centers.Patients who met the inclusion criteria were telephoned by the authorized research team members (KAI, NRF, CGS, and YMS) to be invited to the research program.
The inclusion criteria for this study were: 1) patients suffering from AIS alone (without any neuromuscular deficit), who underwent spinal fusion corrective surgery; 2) completed at least two years of follow-up post-surgery; 3) are Muslim; 4) consented to be video recorded during one Salah movement.As for the surgical indication, we follow the indication outlined by the Scoliosis Research Society (SRS), namely when the curves exceed 45°-50°.Patients with less than 45°c urvature are generally treated with conservative treatment, unless in skeletally immature patients who are at high risk of developing progressive deformity.In the "gray zone" cases (i.e., 45°-50°), the clinical complaints (pain, diminished capacity for activities) along with psychological state play a major role in determining the treatment choice.However, other contributing factors, such as the patient's socioeconomic condition, willingness to undergo a surgical procedure, and family support, may also affect the final decision of treatment choice.
The surgery was offered by all three orthopedic centers using freehand technique and fluoroscopy assistance for final confirmation.Posterior spinal fusion surgery was conducted by bilateral segmental pedicle screw instrumentation following a combination of vertebral column derotation and selective translation, compression, and distraction maneuver.

Outcome data collection and assessment
Eligible patients were invited to the outpatient clinic in all three orthopedic centers and asked to perform one Salah movement, during which they were video recorded and photographed by orthopedic residents.The range of movement (ROM) during the Salah were evaluated and analyzed via video recordings and photos using the Kinovea software application (version 0.8.15). 13This tool can track computed points, distances (up to 5 m distance from an object), and measure angles.The Salah's movement consisted of four postures (Figure 1). 9,10The first and second postures, namely standing upright (Qayyam) and bowing (Ruku), comprise a series of movements involving: the standing position (Figure 1A) and bowing (approximately 90 degrees), while the fingers are stretched with two knees clasped firmly, elbows are extended and facing inwards, back is flattened, and the head is not tilted nor bent (i.e., parallel to the back) (Figure 1B).Next, sitting with knees bent (Taashahhud) is performed by kneeling and sitting on the top of the left foot while the right foot rests on the toes.The toes should face forward towards the Qibla (the direction in which the Muslims are praying) (Figure 1C).Finally, prostration (Sajdah) places both palms, knees, feet, forehead, and nose on the floor (Figure 1D).The ROM of standing-to-bow (i.e., bowing ROM) movement was measured by obtaining the angle difference between Figure 1A and Figure 1B.The ROM of the sitting position between two prostrations to prostration (i.e., prostrations ROM) was measured by obtaining the angle difference between Figure 1C and Figure 1D. Figure 2 shows the incorrect Salah movement.
The patients were then asked to fill out the SRS-30 questionnaire as an assessment for their QOL.Among five assessment categories in the questionnaire (pain, function or activity, self-image, mental health, and satisfaction with management), we only utilized two of them (pain and function or activity) as these are the most relevant assessment categories to our study.The score ranges from 1 to 5, with a higher SRS score showing a better outcome.The patients were also categorized based on their subjective perception of their prayer quality changes, which were classified into 1) Improved, 2) No change/remained, and 3) Worsened.This subjective perception is based on global perceived effect (GPE) scale, a commonly used tool to assess patients' own viewpoint on how much their condition has improved or deteriorated since a particular time point in interest. 14In the present study, the GPE was used to assess the overall situation concerning their prayer movement compared to pre-surgery conditions.To acquire an objective comparison, 22 age-matched Muslim unoperated AIS patients were recruited as a control group.

Data analysis
We analyzed several outcomes, such as postoperative SRS-30 (pain and functional outcome) and postoperative Salah prayer ROM (bowing and prostrations) of the SF-AIS patients, which were compared to the control group.The patients in the intervention (operated) group were grouped based on their prayer quality changes perception/GPE (improved, no  change/remained, worsened) and compared.We also conducted a correlation analysis to identify whether the outcomes (including some variables such as Cobb angle correction and total fused level) affect one another.
All statistical analyses were performed using SPSS software version 23.0 (IBM, Chicago, USA).The normality test was performed using the Shapiro-Wilk test. 15Discrete data were presented in frequency and percentage (%), while continuous data were presented in mean and standard deviation (meanAESD).When the data were normally distributed, the outcome comparison among the groups was analyzed using the ANOVA parametric test.In contrast, the non-normally distributed data were analyzed using the non-parametric Kruskal-Wallis test. 15Differences between group means were compared using appropriate Post Hoc tests (Post hoc Games-Howell test following ANOVA, post hoc Mann-Whitney test following Kruskal Wallis). 16The correlation analysis among the outcomes was calculated using the Spearman rank test. 15A p-value of <0.05 was considered to be statistically significant.

Patient characteristics
Forty-four SF-AIS Muslim patients met the inclusion criteria, consisting of 39 women (88.6%) and five men (11.4%).Moreover, unoperated AIS patients were included in the control group (22 women).The summary of demographics, characteristics, and outcomes of the AIS patients is presented in Table 1.In contrast, a detailed description of the included patients is provided in Extended data. 42Overall, the average SF-AIS patients' age at surgery was 14.8AE2.3years (range 10-18 years), with an average follow-up time of 4.4AE1.9(range 2-9) years.
Similarly, the average age of the control group was 15.32AE1.43(range 13-18) years.Although the preoperative Cobb angles between the two groups differed significantly (67.1AE16.2°and52.3AE14.0°,respectively, p=0.000), it does not necessarily reflect a non-homogeneity between them.The nature of this study is to compare the operated and unoperated patients.Those who underwent surgery would generally have a higher degree of Cobb angle, though the clinical significance of 14.9°mean difference is debatable.Moreover, the mean Cobb angle correction of the intervention

Outcome description
Despite the overall relatively good postoperative SRS-30 score (4.0AE0.2 for function and 4.2AE0.5 for pain), the quality of prayer movement, which was subjectively expressed by the patients as a global perceived effect (GPE), improved only in fifteen women and one man (36.4%) (Table 1).Figure 3 shows the example of Salah movements from a patient who expressed an improved prayer quality following surgery.Whereas the majority of the patients (22 women and four men) reported the same prayer quality compared to preoperative condition (no changes/remained) (59.1%).Two women (4.5%) felt that their prayer movement worsened due to the difficulties in bowing and bending properly.Interestingly, the SRS-30 scores of both worsened patients were reasonably good, i.e., 3.7 and 4.1 for functional outcome and 3.2 and 4 for pain (maximum score of 5) (see Extended data).
The mean postoperative bowing ROM in SF-AIS patients was lower than the control group but not significantly different (84.2AE12.0°,range 26-101°vs.87.8AE9.3°,range 71.5-106.4°,respectively, p=0.366) (Table 2 and Extended data).One SF-AIS patient (in the "worsened" group) had lower bowing ROM than the control group.Moreover, the mean prostrations ROM in SF-AIS patients was also lower (53.4AE9.6°,range 39.6-100°) compared to the control group (58.5AE4.7°,range 49.2-66.4°)and significantly different (p=0.000).Twelve SF-AIS patients (five in the "improved"  group, seven in the "no change" group) had lower prostrations ROM compared to controls.Interestingly, there was one SF-AIS patient who complained of an overall "worsened" prayer quality (Patient 43), but their bowing and prostrations ROM were within the normal range (Figure 4).Moreover, the other patient who also reported "worsened" prayer quality (Patient 44) had a strictly limited bowing ROM but excessive prostrations ROM instead (26°and 100°, respectively) (see Extended data).None of the operated patients had revision surgery or complication.

Outcome analysis
We compared bowing and prostration ROM between SF-AIS patients and the control group (Table 2) and the outcomes across the three GPE prayer quality (improved, no change/remained, worsened) groups (Table 3).The prostrations ROM of the SF-AIS group differed significantly from the control group (p=0.000).However, the bowing ROM differences between the SF-AIS and control groups were insignificant (p=0.366)(Table 2).Although the Cobb angle correction was lower and the total fused levels were higher in the "worsened" group than the "improved" and "remained" group, their differences were insignificant (p=0.678 and 0.115, respectively).Similarly, the "worsened" group showed worse SRS-30 function and pain than the other two groups, but the differences were insignificant (p=0.253 and 0.700, respectively) (Table 3).
In general, the "remained" group had the highest bowing ROM while the "worsened" group had the lowest (45.5AE27.6°)(Table 3).Surprisingly, the "worsened" group showed the highest prostrations ROM compared to the other groups of prayer quality changes (as high as 86.7AE18.9°),with a significant mean difference (p=0.040).The pairwise comparison post hoc tests (Tables 4 and 5) showed that the "worsened" group had a significantly lower bowing ROM and higher prostrations ROM compared to all groups of prayer quality changes.
The correlation analyses (Table 6) showed that the Cobb angle correction and total fused levels did not correlate with either the quality of life (SRS-30 function and pain) or Salah ROM (bowing and prostrations ROM).Likewise, we found that SRS-30 function and pain did not correlate significantly with Salah ROM, except for bowing ROM.Our study showed a significant moderate positive correlation between bowing ROM and pain score (r=0.401,p=0.007) (Table 6).

Discussion
Posterior spinal fusion is a primary surgical treatment for adolescent idiopathic scoliosis, which led to QOL improvement. 1,3,5,13,14A Bayesian meta-analysis study on the effectiveness and safety of surgical interventions for treating AIS revealed that posterior spinal fusion is a primary surgical treatment due to the lower complication rate. 17Our present study showed surgical outcomes following single-stage reconstruction to objectively measure values for the quality of Islamic prayer (Salah) range of motion (ROM) following spinal fusion in adolescent idiopathic scoliosis (AIS).The world's Muslim population as of 2021 is estimated as high as over 1.9 billion people, making 24.7% of the world's total population today. 18This number is projected to increase at a rate of 1.5% annually.By 2030, a study approximated that Muslims will make up 26.4% (2.2 billion people) of the world's total population. 19Muslims inhabit almost all countries (over 70 countries) globally, with Asia-Pacific and Africa being the largest populated regions (60% and 35%, respectively).As the country with the single largest Muslim population, Indonesia is home to over 242 million Muslims (making over 87% of the total population of the country and 12.5% of the world's Muslim population) in 2021. 19,20In Indonesia, the scoliosis prevalence in secondary school screening was 2.9%. 21Indeed, most Indonesian AIS patients are presumably Muslims.Thus, they will need all the information about the postoperative outcomes for their lifelong quality of life.However, the quality of Islamic prayer practiced regularly (five times a day) concerning spinal ROM as a crucial part of practicing the whole serial movement is not covered by all generic surgical outcome evaluations for healthrelated QOL.

The impact of spinal fusion surgery on Salah prayer quality and ROM
In general, we found that spinal fusion surgery did not negatively affect the Salah prayer quality, as 95.5% of the operated patients reported improved or similar prayer quality as the preoperative condition.The quality of life, including daily prayers five times a day, could improve after the surgery.Although the ROM improvement may only be modest, spinal fusion surgery still enhances patients' quality of life. 22Only two patients (4.5%) reported a worsened prayer quality following surgery, one of whom showed a somewhat extreme value of bowing and prostrations ROM (26°and 100°, respectively).There are several possible factors contributing to this phenomenon.
Firstly, despite longer fused levels (15.0AE1.4), the Cobb angle correction in the "worsened" group is less than in the other groups (28.0AE4.2°),which might partly explain the restricted bowing ROM.A study by Cho et al., reported that longer fused levels were associated with significantly better Cobb angle correction than shorter fused levels (72% and 39%, respectively, p=0.001). 23Secondly, the excessive prostration ROM is probably due to the hyperextended lumbar condition.Longer fused levels could restore lumbar lordosis better; however, hypercorrection might lead to lumbar hyperextension. 24Thirdly, the patient could only make a sitting position between the two prostrations and could not proceed to the prostration movement.Thus, the prostration ROM might have seemed greater.
During the bowing movement, one should maintain the lower back flexed, followed by resting the forehead gently on the floor (i.e., prostration movement), activating postural neck muscles to control the neutral head position when lowering down and lifting it from the floor. 12The stretch felt along the spine as the individual curls the torso over the legs also creates a space between the dorsal surfaces of the vertebra, aiding spinal distraction, allowing neural glides and nerves lengthening. 12Our findings showed insignificant differences (p≥0.05) in bowing ROM between treated AIS patients in comparison to the controls but not prostrations ROM (Table 2), implying that bowing ROM following surgery is comparable to the unoperated AIS patients.This distinct finding might be caused by the difference in muscles used during the two movements.Ruku' (bowing) uses neck extensors (NE), deltoid (DT), triceps brachii (TB), and rectus abdominal (RA) muscles; in contrast, Sajdah (prostration) uses sternocleidomastoideus (SCM), trapezius (TRP), biceps brachii (BB), and erector spinae (ES) muscles. 22Since the ES and other paraspinal muscles are retracted for long hours during surgery, ischemia may occur and cause fibrosis. 25Nonetheless, further studies might be needed to thoroughly understand the differences in each specific muscle used in Ruku' and Sajdah to understand the effect on muscle after spinal fusion surgery.
Similar studies investigating spinal ROM after AIS surgeries showed that ROM generally decreases.2AE9.5°afterspinal fusion surgeries in AIS patients.They further found that the overall spinal ROM and forward flexion significantly decreased as the lowest instrumented vertebra (LIV) moved further down the spine, and suggested that fewer fusion levels can maintain better lumbar flexibility by preserving more motion segments. 2In relation to our present study, although we did not directly compare pre-and post-operative ROM, we observed no negative effect of spinal fusion on ROM needed in performing Salah prayer.
Interestingly, we obtained a positive correlation between the bowing ROM and pain (Table 6).During Ruku's (bowing) movement, the surgical wound along the spinal axis will be stretched, causing pain and restricted motion.This finding needs to be informed to the AIS Muslim patients because their prayers and QOL might be affected due to pain.Moreover, Bastrom et al., who investigated the prevalence of postoperative pain in AIS and its association with preoperative pain, reported a 7% prevalence of unexplained postoperative pain within two years of follow-up.The unexplained pain was significantly correlated with preoperative pain. 279][30] Altogether, proper patient education is required since patients expect less pain and return-to-normal activities after corrective surgery.

Prayer quality assessment as an adjuvant of QOL measurement using SRS-30 in Muslim patients
The results of this study showed that the scoliosis surgical outcome indicators (SRS-30; function and pain domain) in the three orthopedic centers were within good scores for all patients.The functional outcome and pain after posterior spinal fusion in our study were comparable to the SRS score reported by existing literature. 8The SRS-30 questionnaire score for the normal population ranged from 4.1-4.6,while our patients' score was 4.0AE0.2for function and 4.2AE0.5 for pain.However, the GPE, which values the patients' perception of the quality of their prayer movement, seemed to be not affected by SRS-30.Although the patients who reported a worsened prayer quality showed an overall lower SRS-30 score, the differences were insignificant (Table 3).This finding could imply that the SRS-30 score (especially function and pain domain) might have different aspects for particular daily activities in a certain population.The quality of prayer has not been reflected in the SRS questionnaire, which warrants further consideration for orthopedic surgeons when explaining to Muslim scoliotic patients.
Patient number 44, who complained of pain in prostration posture while praying, scored 4 for pain, and the ROM was very limited compared to normal control.Patient 43 scored 3.2 for pain; nonetheless, the ROM for praying was within the normal range (Figure 4).This was possibly due to her determination to pray as perfectly as possible to gain "normal" ROM, reflecting her coping mechanism.Several studies have reported that spinal fused-AIS patients (SF-AIS) have adapted to the fused condition to maintain the demanded posture in performing particular physical activities. 31,32A casecontrol study by Kakar et al., which investigated the kinematics of the spine and lower extremity during high-effort running, found that SF-AIS patients expressed a significantly excessive lower trunk (by 6.1°) and pelvis (by 6.3°) segmental axial rotation while running compared to healthy controls but reduced ankle plantarflexion (by 9.2°) in the support phase; implying their compensatory mechanisms are possibly due to increased lumbar muscle stiffness and reduced proprioception. 31Another study by Holewijn et al., who performed gait analysis on SF-AIS at increasing walking speeds (0.45 to 2.22 m/s), revealed that transverse plane thoracic-pelvic ROM was significantly diminished following spinal fusion surgery, with higher walking speeds showing more obvious differences.However, the lower body ROM, step length, and cadence remain unaffected, and SF-AIS patients could still walk with somewhat unaltered spatiotemporal parameters. 324][35] However, these phenomena could not be covered by SRS-30 and its variants.The evaluation of scoliosis treatment comprises the surgical aspects, radiology aspects, and most importantly, the quality of life (function, pain, and deformity). 8,36The outcome instruments must be proven reliable, standardized, and validated to be applicable worldwide. 37The generic instruments used to assess health-related quality of life (HRQL) are the SF-36 questionnaire, SRS 30, SRS 22, and the EuroQol5D instrument. 8In spite of that, previous studies have reported that it is preferable to assess the condition of specific populations with certain needs. 32,37,38As the SRS questionnaire and its variants could not fully portray important aspects of physical functioning, such as mobility in praying for individuals with AIS, we suggest orthopedic surgeons incorporate prayer quality assessment as an adjuvant of QOL measurement in Muslim patients.
Cobb angle correction and total fused levels effects on prayer quality changes, SRS-30, and Salah ROM Our study found no significant nor strong correlation between Cobb angle correction and total fused level with prayer quality changes (Table 3), quality of life (SRS-30 function and pain), and Salah ROM (bowing and prostrations) (Table 6).To our knowledge, we are the first to identify whether curve correction and total fused levels are associated with Muslim prayer quality and Salah ROM.It seems that in the sagittal plane, the spine-pelvic-hip alignment following spinal fusion is well achieved regardless of the degree of curve correction and total fused level; hence, they are not associated with the ROM of Salah movements.Moreover, our findings are in agreement with previous studies that have reported the irrelevance of Cobb angle correction degree with postoperative SRS-30 function and pain. 7,39A study by Ghandehari et al., revealed that the percentage of radiographic correction was positively correlated only with the total SRS-30 score (r=0.52,p<0.001) and the satisfaction domain (r=0.386,p=0.026) but not with the function and pain domains. 7Likewise, Chaudhary et al., reported similar findings (p-values of SRS-30 function and pain correlation analyses with curve correction: 0.688 and 0.453, respectively). 39Moreover, our results showed that total fused levels were not associated with function or pain.Likewise, existing literature has reported that despite resulting in better ROM, fewer fusion levels did not correlate with SRS-22 function and pain in 2-10 years of follow-up. 2,40,41rength, limitation, and future direction Our study has several limitations, such as small sample size, reliance on patient's perception (GPE), use of a newly proposed standardized prayer movement ROM evaluation, potential for incorrect landmark identification when measuring the ROM, and the retrospective case-control design, which could impact our findings in several ways.The small sample size may limit the generalizability of our results, making it difficult to draw definitive conclusions applicable to a broader population.The use of patient perception introduces a subjective element that might affect the objectivity and consistency of the data.The newly proposed Salah prayer ROM evaluation method, while innovative, lacks extensive validation, which could affect the reliability of our measurements.The possibility of incorrect landmark identification could lead to measurement errors and compromise the accuracy of our findings.Additionally, the retrospective casecontrol design, without blinding, introduces potential biases, such as recall bias and observer bias, which may influence the study outcomes.Readers should interpret our results with caution and consider these limitations when applying our findings to clinical practice.We recommend that future studies address these issues by using a larger sample size in a multicenter prospective clinical trial, blinding assessors to minimize bias, and using more standardized objective measurement tools and well-validated evaluation methods to enhance the reliability and applicability of the results.
Moreover, due to the nature of this study, the control group had a lesser Cobb angle value.This difference is unavoidable because the larger curves group would most unequivocally be offered surgery rather than conservative treatment; hence, this condition has become a natural limitation of this study.Another drawback is that we only assessed two items of the SRS-30 questionnaire (pain and function), as we deem the most critical evaluation tools for performing the Islamic Salah prayer activity.Future studies should attempt to assess all five items of SRS-30 for a more comprehensive evaluation.Lastly, we acknowledge that an a priori sample size calculation was not performed for this retrospective case-control study.Instead, we utilized all available patient data from our records, which were determined by the specific inclusion and exclusion criteria we applied.While we recognize that this approach may limit the statistical power of our findings, we believe that the insights gained from analyzing the existing data are still meaningful and contribute to understanding the topic.In future research, we plan to conduct prospective studies with a priori sample size calculations to ensure adequate power and generalizability of the results.
However, we believe that we are the first to assess the Islamic prayer ROM following spinal fusion surgery and attempt to identify whether spinal fusion surgery affects the Muslims' quality of life (including their quality of prayer).Thus, spine surgeons in largely Muslim countries should start evaluating the impact of spinal fusion on the Salah movement as part of the daily activity functional outcome.

Conclusion
Our study found that spinal fusion positively affects AIS Islamic patients in maintaining their daily Salah movement ROM and prayer quality.Orthopedic surgeons should consider incorporating prayer quality assessment as an adjuvant of the SRS-30 questionnaire to evaluate Muslim patients' specific functional outcomes and quality of life.
• Appendix 2. docx (A detailed description of demographics and characteristics of the control group (i.e., agematched unoperated AIS patients).
Data are available under the terms of the Creative Commons Attribution 4.0 International license (CC-BY 4.0).
statistical analysis more effectively.
2. The study could be strengthened by detailing specific measures undertaken to mitigate potential sources of bias, such as selection bias and measurement bias.This includes strategies like blinding, matching cases and controls, or adjusting for confounders, which are crucial for enhancing the validity and reliability of the findings.
3. A more comprehensive discussion on how the study's limitations might affect the findings would lend greater credibility to the research.Understanding these limitations' potential direction and magnitude would allow for a more balanced interpretation of the results.
4. Including a justification for determining study size regarding considerations for statistical power and expected effect size is vital.This would provide critical insights into the study's capacity to detect meaningful differences, thereby affirming the robustness of its conclusions.

Is the work clearly and accurately presented and does it cite the current literature? Yes
Is the study design appropriate and is the work technically sound?Yes

If applicable, is the statistical analysis and its interpretation appropriate? Yes
Are all the source data underlying the results available to ensure full reproducibility?Yes

Are the conclusions drawn adequately supported by the results? Yes
Competing Interests: No competing interests were disclosed.

Reviewer Expertise: Scoliosis, Biomechanics
I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.Control group degree of scoliosis is less than study material.It would be better if the control group has nearly the same degree of scoliosis as patient group. 2.
In Fig. 3, it was mentioned that the patient had got 50° scoliosis and in Fig. 4, 45° scoliosis which from my point of view can be treated conservative.what were the measures for patient selection i.e. degree of scoliosis 3.
I would prefer to write muscle fibrosis instead of muscle degeneration (4th paragraph in discussion) 4.

Is the work clearly and accurately presented and does it cite the current literature? Yes
Is the study design appropriate and is the work technically sound?Yes

Are sufficient details of methods and analysis provided to allow replication by others? Yes
If applicable, is the statistical analysis and its interpretation appropriate?Yes Are all the source data underlying the results available to ensure full reproducibility?Yes

Are the conclusions drawn adequately supported by the results? Yes
Competing Interests: No competing interests were disclosed.
Reviewer Expertise: spine surgery I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.
"Moreover, due to the nature of this study, the control group had a lesser Cobb angle value.This difference is unavoidable because the larger curves group would most unequivocally be offered surgery rather than conservative treatment; hence, this condition has become a natural limitation of this study." 3. "In Fig. 3, it was mentioned that the patient had got 50° scoliosis, and in Fig. 4, 45° scoliosis which from my point of view can be treated conservatively.what were the measures for patient selection i.e. degree of scoliosis" Answer: We thank the reviewer for their meticulous review.There are several considerations for the treatment choice (explained below), which is specific for each patient.
We have added our surgery indication in the Method section: "As for the surgical indication, we follow the indication outlined by the Scoliosis Research Society (SRS), namely when the curves exceed 45°-50°.Patients with less than 45° curvature are generally treated with conservative treatment, unless in skeletally immature patients who are at high risk of developing progressive deformity.In the "gray zone" cases (i.e., 45°-50°), the clinical complaints (pain, diminished capacity for activities) along with psychological state play a major role in determining the treatment choice.However, other contributing factors, such as the patient's socioeconomic condition, willingness to undergo a surgical procedure, and family support, may also affect the final decision of treatment choice."

4."I would prefer to write muscle fibrosis instead of muscle degeneration (4th paragraph in discussion)"
Answer: We agree with your opinion.We have replaced the degeneration with "fibrosis".
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Figure 2 .
Figure 2. Incorrect bowing (ruku') movements during Muslim prayer.(A) The back is overly bent; (B) the back is too upright.Image source: authors.

Figure 1 .
Figure 1.Standard movements' series of Muslim prayers.The position of the Salah movement involves: (A) standing position, (B) bowing, (C) sitting between prostrations, and (D) prostration.The ROM of standing-tobowing movement was measured by obtaining the angle difference between A and B. The ROM of the sitting position between two prostrations to prostration was measured by obtaining the angle difference between C and D. Image source: authors.

Figure 3 .
Figure 3. Patient number 6 (20-year-old woman, surgery was at 14 years old) experienced an improvement in the quality of prayer.ROM measurement of the prayer movement: (A) standing position (179.6 o ); (B) bowing position (86.4 o ); (C) sitting between prostrations (90.4 o ); to (D) prostration (40.4 o ).The patient's radiographs showed the preoperative (E) and postoperative (F) conditions of the spine.In these radiographs, the preoperative Cobb angle was 50 o , and the postoperative Cobb angle was 18 o (Cobb angle difference: 32 o ).Image source: authors.

Figure 4 .
Figure 4. Patient number 43 (16-year-old woman, surgery at 13 years old) complained of worsening prayer quality following surgery.(A) The patient's bowing movement ROM was within the normal range: (178 o to 73 o ), but she experienced a worsened prayer quality because of pain.(B) She can perform sitting motion between two prostrations and prostration as good as normal (108 o to 45 o ) but accompanied by pain.(C) Preoperative radiograph showing Cobb angle 45 o .(D) Postoperative radiograph showing Cobb angle 20 o (Cobb angle difference: 25 o ).Image source: authors.

©
2023 Allam Y.This is an open access peer review report distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Yasser Allam 1 Department of Orthopaedic Surgery and Traumatology Faculty of Medicine, Alexandria University, Alexandria, Egypt 2 Waldklinikum Gera, Gera, Germany It would be interesting to include the whole 5 items of SRS 30 in this study and not only pain and function.1.

Table 1 .
Demographics, characteristics, and outcomes of the AIS patients included in the study*.operated) group was 34.8AE12.8°,with an average total fused level of 11.4AE2.8.The highest spinal fusion level was T1, and the lowest was L5, with L3 being the most frequent lowest fused level (31.8%).

Table 2 .
Bowing and Prostration ROM in intervention vs. control group.
Note: Analyzed using Mann-Whitney non-parametric test.P-values of the tests are shown.*Statistically significant (p<0.05).

Table 4 .
Post hoc analysis of bowing ROM means across three groups of prayer quality changes (intervention group).
Note: Mann-Whitney test was used for post hoc analysis.P-values of the tests are shown.*Statistically significant (p<0.05).

Table 3 .
Comparison of the outcomes across three groups of prayer quality changes (intervention group).

Table 5 .
Post hoc analysis of prostration ROM means across three groups of prayer quality changes (intervention group).
Note: Mann-Whitney test was used for post hoc analysis.P-values of the tests are shown.*Statistically significant (p<0.05).

Table 6 .
Correlation analysis among the outcomes (intervention group).