Diagonal Paraspinal Sarcopenia and Osteoporosis contribute to the Rotatory Subluxation in patients with Degenerative Lumbar Scoliosis

Diagonal Paraspinal Sarcopenia and Osteoporosis contribute to the Rotatory Subluxation in patients with Degenerative Lumbar Scoliosis | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Diagonal Paraspinal Sarcopenia and Osteoporosis contribute to the Rotatory Subluxation in patients with Degenerative Lumbar Scoliosis ming wang, Abdukahar Kiram, Jie Li, Peiyu Li, Zhen Tian, Qiang Liu, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6202643/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 27 Aug, 2025 Read the published version in European Spine Journal → Version 1 posted 9 You are reading this latest preprint version Abstract Purpose This study aims to investigate the potential association between paraspinal sarcopenia, osteoporosis, and vertebral rotational subluxation (VRS) in patients with degenerative lumbar scoliosis (DLS). Methods This retrospective study analyzed standing anteroposterior radiographs to assess coronal (Cobb angle, CA; coronal balance distance, CBD; lateral translation, LT) and sagittal parameters (thoracic kyphosis, TK; lumbar lordosis, LL; sagittal vertical axis, SVA). Patients were categorized into Rotatory Subluxation (RS, LT ≥ 5mm) and Non-RS groups, with the RS group further subdivided into single and double level subgroups based on the frequency of RS occurrence. Bilateral paraspinal muscle (PSM) cross-sectional area (CSA) and fat infiltration rate (FI%) at L1-S1 were evaluated via lumbar MRI. Vertebral rotation angles and Hounsfield units (HU) were quantified using reconstructed axial CT images, with osteoporosis defined as L1 HU ≤ 110. Ratios of convex-to-concave measurements (Ro FI%, Ro CSA, Ro HU) were calculated. Spearman correlation and logistic regression analyses explored associations among paraspinal sarcopenia, osteoporosis, and VRS. Intraoperative multifidus muscle (MF) samples from RS-1 (upper RS level) and RS + 1 (below RS level) in DLS patients underwent histological analysis to assess regional fat infiltration and muscle atrophy. Results 166 patients were included in this study, 90 (54.2%) with VRS and 76 without. The apex vertebrae were predominantly at the RS-1 level (67%). Both single level and double level RS groups showed significantly higher FI% of PSM (erector spine, ES and MF) compared to the Non-RS group at various levels (P < 0.05). Patients with VRS generally exhibited osteoporosis. The HU value for both single level and double level RS patients were significantly lower than those in the Non-RS group at multiple levels (P < 0.05). Notably, the FI% of bilateral MF and HU value in RS group showed more severe asymmetry at multiple levels compared to the Non-RS group (P < 0.05). Both Ro HU and Ro FI% of MF muscle were generally 1 below the RS level, suggesting that asymmetric paraspinal sarcopenia and osteoporosis above and below the RS level was reversed. Logistic regression analysis showed that VRS was significantly associated with the Ro FI% above RS (odds ratio, 0.021; 95% confidence interval, 0.001–0.147; P < 0.001) and Ro FI% below RS (odds ratio, 1.956; 95% confidence interval, 0.930–4.114; P = 0.007). Cobb angle and osteoporosis were additional independent factors associated with VRS. Conclusion VRS in DLS is characterized by diagonal paraspinal sarcopenia patterns and vertebral osteoporosis. The reversed sarcopenia-osteoporosis gradient across subluxation levels suggests a biomechanical coupling mechanism driving curve progression. Preoperative quantification of these parameters may stratify progression risk and guide targeted rehabilitation. paraspinal sarcopenia osteoporosis vertebral rotational subluxation degenerative lumbar scoliosis Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Vertebral rotatory subluxation (VRS) is a triaxial deformity consisting of axial rotation and lateral translation toward curve convexity, with a prevalence of 19.5% in adult scoliosis [ 1 ]. Degenerative lumbar scoliosis (DLS), the predominant adult-onset spinal deformity in China, exhibits a 13.3% prevalence among individuals over 40 years, with characteristic Cobb angle progression [ 2 ]. Unlike adolescent idiopathic scoliosis where VRS rarely occurs [ 3 ], VRS serves both as a risk factor for DLS progression and a pathognomonic feature distinguishing degenerative from idiopathic etiologies. Clinically, VRS correlates with debilitating low back pain and radicular symptoms that severely compromise quality of life [ 4 – 6 ], primarily attributed to foraminal height reduction from lateral translation (LT) exceeding 6 mm—a critical threshold for symptom progression [ 7 ]. However, the etiopathology of VRS remains unknown. The degeneration of the lumbar structures was widely accepted as a pathological mechanism for VRS [ 1 , 8 ]. Identified risk factors include advanced age, curve magnitude, facet joint degeneration, and the location of apical vertebra [ 1 , 7 – 10 ]. Bao et al., reported facet tropism as one of the anatomic structural risk factors for VRS in DLS patients [ 10 ]. Weishi Li et al., found the asymmetrical vertebral degeneration that manifested as high Hounsfield unit (HU) value within concavity and a low HU value within convexity both in the major and compensatory curve in DLS patients [ 11 ]. Existing evidence predominantly focuses on osseous degeneration, leaving muscular contributions underexplored. The paraspinal musculature—comprising multifidus (MF), erector spinae (ES), and quadratus lumborum—plays a pivotal role in maintaining spinal stability through dynamic load distribution [ 12 – 15 ]. Emerging data associate paraspinal muscle (PSM) degeneration with spinal pathologies ranging from disc herniation to adult spinal deformity progression [ 16 – 19 ]. Our prior work revealed that DLS patients with coronal imbalance exhibit greater PSM fatty infiltration compared to balanced counterparts [ 20 ]. Besides, PSM has been found an asymmetrical fat composition in DLS and determined that the PSM in patients with DLS showed different degrees of degeneration in different levels of the lumbar spine [ 19 , 21 ]. Biomechanically, asymmetrical degeneration of the PSM in different vertebral levels can lead to unequal muscle strength on concave and convex sides, generating lateral shear force during rotational subluxation segments. Besides, low bone density and uneven gravity load transmitted lead to vertebral wedge deformities [ 11 , 22 ], which increases lateral instability of the lumbar spine, thus becoming a risk factor for VRS. However, to our knowledge, limited studies have described the contribution of paraspinal muscle and bone quality on VRS in Patients with DLS. Thus, this study aimed to investigate the correlation between the paraspinal sarcopenia-osteoporosis and VRS in patients with DLS. MATERIALS AND METHODS Patient Cohort This retrospective study enrolled DLS patients undergoing corrective surgery at a single center between August 2013 and March 2023. Inclusion criteria comprised: 1) age ≥ 50 years; 2) BMI 20–28 kg/m²; 3) coronal Cobb angle 10°-60°. Exclusion criteria included: neuromuscular/idiopathic scoliosis etiology, prior spinal surgery, spinal infection, malignancy, neurodegenerative disorders, or thoracolumbar kyphosis > 20°. LT ≥ 5 mm was used as the cutoff value to define rotatory subluxation (RS) [ 7 ]. Patents were stratified into RS (≥ 5 mm translation) and Non-RS (< 3 mm translation) groups. The RS group was further divided into single level RS group and double level RS group based on the number of VRS level occurring. The study protocol received institutional review board approval (No. 2021-389-01) and adhered to the Declaration of Helsinki (2013 revision). Written informed consent was obtained for histological analyses. Radiographic Evaluation Comprehensive radiographic assessment included lumbar CT scans, standing whole-spine posteroanterior & lateral radiographs, and lumbar MRI. Standard radiographic parameters were quantified per Spine Deformity Study Group guidelines: Coronal parameters: Including the intervertebral LT (Fig. 1), major curve Cobb angle, apical vertebra location, and coronal balance distance (CBD). CBD measured as horizontal deviation between C7 plumb line (C7PL: vertical through C7 midpoint) and central sacral vertical line (CSVL). Sagittal parameters: The measurements include: sagittal vertical axis (SVA, the horizontal distance between the vertical-line from the midpoint of C7 vertebrae to the posterior upper endplate of the sacrum), thoracic kyphosis (TK, T5-T12 Cobb angle) and lumbar lordosis (LL, L1-S1 Cobb angle). HU measurement and rotation evaluation: Lumbar CT scans (Light Speed 32, GE Healthcare) were acquired at 2.0 mm slice thickness (120 kV, 220 mA) parallel to inferior disc margins. The vertebral rotation was measured using preoperative axial CT as described previously [ 23 ]. Concretely the angle between the vertical line of the which vertebra CT scanning table and the axis of the spine were measured at RS level. The Picture Archiving and Communication System (PACS) was utilized for the computation of CT HU values [ 24 ]. An oval region of interest (ROI) was positioned at L1-L5 mid-vertebral levels, maximizing trabecular inclusion while excluding cortical bone and vascular structures. Osteoporosis was defined as L1 HU ≤ 110 [ 25 ]. Convex-concave HU ratios (Ro HU) were calculated per spinal level. Measurement of PSM Parameters 1.5T MRI (Magetom Skyra, Siemens) T2-weighted sequences (axial/sagittal planes, 4 mm slices) were analyzed. Sagittal images identified lumbar endplates, with axial slices at L1-S1 disc levels selected for analysis. Using ImageJ (v1.3, NIH), bilateral PSM (MF&ES) cross-sectional areas (CSA) were quantified within thoracolumbar fascial boundaries. Fat infiltration (FI%) was calculated via validated pseudo-coloring techniques [ 26 , 27 ], with convex-concave FI% ratios (Ro FI%) determined per level. Histological assessment The MF muscle from the concave and convex side at the upper level of RS (RS-1), and below level of RS (RS + 1) level was collected during corrective surgery. The muscle tissues were snap-frozen in nitrogen-cooled isopentane embedded O.C.T. 10 µm cryosections (Leica CM3050S) underwent H&E and Oil Red O staining for morphological and adipocytic infiltration assessment. Statistical Analysis Data normality was verified using Shapiro-Wilk tests. Continuous variables are expressed as mean ± SD or median (IQR) based on distribution normality. All analyses were conducted in SPSS 23.0 (IBM Corp.), employing parametric/non-parametric tests according to data characteristics. Multicollinearity was assessed through variance inflation factors. Binary logistic regression models identified VRS-associated risk factors, with predictive capacity evaluated via receiver operating characteristic (ROC) curve analysis. Statistical significance was set at P < 0.05. RESULTS The study enrolled 166 patients (153 female; mean age 61.4 ± 6.5 years). 90 patients (54.2%) were categorized into RS group and 76 were Non-RS group, with comparable demographics and radiographic parameters (Table 1). Single-level VRS was found in 74 patients, double-level VRS was found in 16 patients. Among all the 106 levels defined as VRS, 66 were located at L3/L4 level, 26 were L4/L5 level, 13 were L2/L3 level, and 1 was L1/L2 level. The apex vertebrae were mainly located at RS-1 level (67%). Table 1. Demographics and radiographic parameters of RS and Non-RS group. All RS Non-RS P value Demographics parameters N(Female/Male) 166(153/13) 90(84/6) 76(69/7) 0.614 Age (years) 61.4±6.5 60.9±6.3 62.0±6.8 0.288 BMI (kg/m 2 ) 26.1±1.3 26.4±1.2 25.8±1.4 0.689 Radiographic parameters Cobb angle (°) 33.5±7.6 34.1±8.7 31.8±6.4 0.174 CBD (mm) 20.9±8.2 21.0±8.8 20.7±7.6 0.935 TK (°) 17.1±2.3 17.3±2.4 16.8±2.0 0.887 LL (°) 25.4±3.1 22.7±2.8 26.0±3.3 0.460 SVA (mm) 56.2±8.3 57.4±7.9 55.5±10.2 0.887 Data are expressed as mean ± standard deviation. RS, rotatory subluxation. BMI, body mass index; CBD, coronal balance distance; SVA, sagittal vertical axis; TK, thoracic kyphosis; LL, lumbar lordosis. Comparison of PSM measurements Non-RS group vs RS group : Patients with double level VRS (RS L3/4, L4/5 ) showed smaller CSA of ES than those without RS (L4/L5 disc level: 21.9[18.6, 24.3] cm 2 vs 16.0[14.2, 25.7] cm 2 , P = 0.027). single level RS group with RS L4/5 and double level RS group demonstrated significant smaller CSA of MF compared to the Non-RS group on multiple levels (P < 0.05). Both Single level RS group and double level RS group showed significant higher FI% of PSM (ES and MF) compared to the Non-RS group at different levels (P < 0.05), shown as Table 2. Single level RS group vs Double level RS group : Patients with RS L2/3 level demonstrated significantly larger CSA of MF on L1-L4 disc level and lower FI% of ES on L3-L5 disc level compared to the RS L2/3, L3/4 level (P < 0.05). RS L3/4 level demonstrated significantly larger CSA of MF on L1-L3 disc level and lower FI% of ES on L3-L5 disc level compared to the RS L2/3, L3/4 level (P < 0.05). RS L3/4 level showed significant larger CSA of MF on L1-L3 disc level, lower FI% of ES (L2/L3, L5/S1) and MF (L3/L4) compared to the RS L3/4, L4/5 level (P < 0.05), shown as Table 2. Convex side vs Concave side: The single level RS group showed higher FI% of MF on the concave side above RS level and higher FI% of MF on the convex side below RS level, the HU measurement demonstrated significant difference between convex and concave side on multiple levels (P < 0.05, Table 3). On the double level RS group, the FI% of MF and HU value showed significant difference between convex and concave side on multiple levels (P < 0.05, Table 4). comparison of the PSM and HU asymmetry degree among single and double level RS groups on each disc level were shown as Fig. 2. The FI% of MF and HU value of single level RS group and double level RS group showed more severe asymmetry in multiple levels than those of Non-RS group (P < 0.05). The asymmetrical degeneration was reversed above and below the RS level. Comparison of HU measurement Based on the cutoff ≤ 110 HU at L1 vertebrae, patients with VRS generally showed osteoporosis (RS L2/3 level: 89.8 [82.3, 94.6]; RS L3/4 level: 104.3 [98.3, 109.2]; RS L4/5 level: 96.5 [90.5, 101.7]; RS L2/3, L3/4 level: 103.3 [93.6, 108.3]; RS L3/4, L4/5 level: 101.7 [94.3, 108.0]). The HU value of the both single level RS and double level RS group was significantly lower than that in the Non-RS group on multiple levels (P < 0.05, Table 2). The correlation analysis The spearman correlation was performed between Ro FI% of MF, lateral translation (LT) and intervertebral rotation at the VRS level. LT was positively correlated with Ro FI% of MF on RS + 1 level (R = 0.498, P = 0.003) and negatively correlated with Ro FI% of MF on RS-1 level (R = 0.537, P < 0.001). Binary Logistic Regression Analysis Comprehensive modeling incorporating demographic (age), radiographic (Cobb angle), and compositional parameters (HU values, vertebral rotation) identified three independent VRS predictors (Table 5): 1. MF Ro FI% above RS (OR = 0.02, 95%CI 0.001–0.15, p < 0.001). 2. MF Ro FI% below RS (OR = 1.96, 95%CI 0.93–4.11, p = 0.007). 3. Cobb angle magnitude (p < 0.05). 4. Osteoporosis status (p < 0.05). Histological analysis Of the 4 participants with measurable muscle in the sample, a greater proportion of fat on the concave side of the RS-1 level (convex side vs concave side, 27.8 ± 10.2% vs 39.4 ± 12.6%, P = 0.012) and the convex side of the RS + 1 level (convex side vs concave side, 43.1 ± 11.8% vs 36.8 ± 10.7%, P = 0.05) was observed. (Fig. 3). DISCUSSION In this study, we found DLS patients with VRS demonstrated significantly greater FI% compared to the Non-RS. These phenomena were aggravated with the increase of VRS numbers in RS group. Notably, diagonally asymmetric patterns of multifidus (MF) FI% were observed between adjacent spinal segments proximal and distal to VRS sites, demonstrating significant correlations with subluxation severity. Multivariate logistic regression analysis identified diagonal paraspinal sarcopenia and osteoporosis as independent contributing factors for VRS development. These findings collectively suggest that diagonal paraspinal sarcopenia and osteoporosis may be involved in VRS development in DLS patients and should be considered in surgical decision-making. VRS, osteoporosis, and PSM degeneration have been implicated as predictive biomarkers for DLS [ 28 – 31 ]. As a pathognomonic feature of DLS, VRS manifests as rotational instability predominantly observed in degenerative scoliosis onset phases, contrasting with its rare occurrence in idiopathic scoliosis. VRS has demonstrated prognostic value for surgical outcomes, making it frequently targeted for surgical intervention in DLS [ 4 – 6 , 32 ]. Despite established associations with age-related degeneration, the multifactorial etiology of VRS remains controversial [ 1 , 7 – 10 ]. Emerging evidence highlights the significance of PSM integrity, particularly the MF as a dynamic stabilizer modulating vertebral rotation [ 12 – 15 ]. While Kiram et al. revealed correlations between PSM degeneration and coronal imbalance [ 20 ]. Loss of MF muscle function may cause abnormal. However, the relationship between PSM degeneration and VRS has yet to be determined. This study presents novel investigation focused on the phenomenon of diagonal paraspinal sarcopenia in VRS. While previous reports have documented enhanced PSM degeneration in VRS cohorts, particularly affecting spinal extensors and flexors [ 27 , 33 ], our findings align with Ferrero et al.'s volumetric analysis demonstrating comparable CSA between RS and non-RS groups [ 34 ]. Notably, our FI% quantification complements previous observations of elevated muscular degeneration in VRS. Both concave and convex measurements confirmed significantly higher FI% in VRS, corroborating Ferrero's 3D volumetric evidence of preferential fat deposition over absolute muscle loss as a hallmark of rotational instability. We noted the inverse Ro FI% (concave/convex) across VRS levels: 1 at RS-1, indicating inverse severity of fat infiltration around the VRS level. This spatial inversion of degeneration patterns echoes the Parallelogram Effect described in apical vertebral degeneration [ 35 ], though occurring at distinct anatomical locations - a divergence potentially attributable to our specific focus on VRS. Histological validation confirmed enhanced FI% in convex RS + 1 level and concave RS-1 level musculature, establishing concordance between imaging analysis and tissue-level degeneration. Fat infiltration results in decreased contractile composition of muscle, which in turn leads to the decline of musculature power production[ 36 ]. Thus, the asymmetric fat inflation in bilateral paraspinal muscle generates uncompensated muscle power sheer. Specifically, diagonal fat infiltration across VRS may cause inversed muscle force, which may accelerate spinal instability and the VRS, and we collectively concluded this phenomenon as diagonal degeneration. The relationship between PSM degeneration and vertebral rotation were assessed. Xie et al found that apical vertebral rotation and lateral vertebral translation can aggravate the asymmetric degree of PSM [ 27 ]. Our study found the asymmetrical changes in PSM were associated with the degree of vertebral rotation and lateral displacement. Recently, Schonnagel L et al. demonstrated a significant and independent association between lumbar spinal stenosis and the composition of the posterior paraspinal musculature, patients with lumbar spinal stenosis might be especially susceptible to axial muscle wasting, which could worsen lumbar spinal stenosis due to increased spinal instability, leading to a positive feedback loop [ 37 ]. Likewise, VRS may result in intervertebral foraminal stenosis and neural impingement and leading to the positive feedback mentioned above. Our study indicated that PSM diagonal degeneration at different disc levels would allow increased lateral instability and proposed that this was responsible for VRS in DLS. Low HU value may exacerbate spinal instability. Multiple studies have found that osteoporosis may contribute to DLS [ 38 , 39 ]. Our findings showed that the RS group demonstrated lower HU values than those of Non-RS group on multiple lumbar levels, especially on L1. Vibhu et al. demonstrated that upper lumbar HU measurements show stronger correlations with bone mineral density [ 24 ]. The observed HU variations could be attributed to degenerative alterations in lower lumbar vertebrae, including osteophyte formation, subchondral bone involvement, and trabecular microdamage. Weishi Li et al. emphasize that osteoporosis evaluated by HU value could increase the asymmetrical vertebral degeneration [ 11 ]. The transition zone between the main curve and fractional curve undergoes concave-convex side transformation. The vertebral body in this area bears the largest gravitational load, and patients with low HU values are more prone to wedge collapse of the vertebral body in this area. The gravitational load is decomposed into vertical and lateral stress, exacerbating lumbar instability. In conclusion, diagonal paraspinal sarcopenia and osteoporosis contribute to the occurrence and development process of VRS. As VRS was important in evaluating curve progression and quality of life, a careful analysis of lumbar MRI and CT images in patients with initial degenerative scoliosis would be required to determine PSM-bone quality and thus potential VRS, as well as predicting the possible natural history of scoliosis. There are several limitations in this study. Firstly, this is a retrospective study with a relatively small sample size. Second, 2D axial measurements of CSA and FI% lack volumetric accuracy; future studies employing 3D musculoskeletal modeling could mitigate measurement biases arising from positional variability. 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Supplementary Files supplementarytable.docx supplementaryFig.jpg Table2to5.docx Cite Share Download PDF Status: Published Journal Publication published 27 Aug, 2025 Read the published version in European Spine Journal → Version 1 posted Editorial decision: Revision requested 20 Apr, 2025 Reviews received at journal 13 Apr, 2025 Reviews received at journal 08 Apr, 2025 Reviewers agreed at journal 01 Apr, 2025 Reviewers agreed at journal 30 Mar, 2025 Reviewers invited by journal 28 Mar, 2025 Editor assigned by journal 17 Mar, 2025 Submission checks completed at journal 17 Mar, 2025 First submitted to journal 11 Mar, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6202643","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":442381596,"identity":"db73430a-2e73-4f23-8146-b9b1e3fb20e8","order_by":0,"name":"ming wang","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital, Nanjing University","correspondingAuthor":false,"prefix":"","firstName":"ming","middleName":"","lastName":"wang","suffix":""},{"id":442381597,"identity":"7a42f4b2-1d24-4374-a0c3-77db80ed758a","order_by":1,"name":"Abdukahar Kiram","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital, Nanjing University","correspondingAuthor":false,"prefix":"","firstName":"Abdukahar","middleName":"","lastName":"Kiram","suffix":""},{"id":442381598,"identity":"50dfc4ae-f7ae-456b-96c1-0e592ab4d311","order_by":2,"name":"Jie Li","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital, Nanjing University","correspondingAuthor":false,"prefix":"","firstName":"Jie","middleName":"","lastName":"Li","suffix":""},{"id":442381599,"identity":"7ee54f20-773a-4f19-b0e9-3a3880d29487","order_by":3,"name":"Peiyu Li","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital, Nanjing University","correspondingAuthor":false,"prefix":"","firstName":"Peiyu","middleName":"","lastName":"Li","suffix":""},{"id":442381600,"identity":"9f61a894-90f1-4774-89c6-bcf9563e97ba","order_by":4,"name":"Zhen Tian","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital, Clinical College of Nanjing University of Chinese Medicine","correspondingAuthor":false,"prefix":"","firstName":"Zhen","middleName":"","lastName":"Tian","suffix":""},{"id":442381601,"identity":"f8e3b786-343d-40f2-ada3-99832c45608c","order_by":5,"name":"Qiang Liu","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital, Clinical College of Nanjing University of Chinese Medicine","correspondingAuthor":false,"prefix":"","firstName":"Qiang","middleName":"","lastName":"Liu","suffix":""},{"id":442381602,"identity":"1e523a30-c346-4206-8f3f-0b4a1b58a743","order_by":6,"name":"Zezhang Zhu","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital, Nanjing University","correspondingAuthor":false,"prefix":"","firstName":"Zezhang","middleName":"","lastName":"Zhu","suffix":""},{"id":442381603,"identity":"ab0b8cb6-3ebe-4fc7-8998-cc083ac35eb9","order_by":7,"name":"Yong Qiu","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital, Nanjing University","correspondingAuthor":false,"prefix":"","firstName":"Yong","middleName":"","lastName":"Qiu","suffix":""},{"id":442381604,"identity":"6c9e8827-b7c1-4386-ad70-de2c06e57a87","order_by":8,"name":"Zhen Liu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAwUlEQVRIiWNgGAWjYDCCA8wNB4AkAwN7Y+PDD8RpYYRq4TncbCxBrBYGsBaJ9DYBHmJ08N0+2HiY588dOXPJh20MEgx2croNBLRInktsOMzD88zYcnZi24MChmRjswMEtBicYQRqkTicuOF2YruBBMOBxG3EaTE4XL/h5sE2CR7itSQcTjC4wUikFkmgloNzDhw23HAmERjIBkT4he8M8+EPb/4cljc4fvzhww8VdnIEtaC7kzTlo2AUjIJRMApwAADXbUwX7Va3FgAAAABJRU5ErkJggg==","orcid":"","institution":"Nanjing Drum Tower Hospital, Nanjing University","correspondingAuthor":true,"prefix":"","firstName":"Zhen","middleName":"","lastName":"Liu","suffix":""}],"badges":[],"createdAt":"2025-03-11 11:53:17","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6202643/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6202643/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00586-025-09292-z","type":"published","date":"2025-08-27T15:58:06+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":80813495,"identity":"fb893082-43f8-46c2-89e1-611eb8f06a60","added_by":"auto","created_at":"2025-04-17 10:41:05","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":49066,"visible":true,"origin":"","legend":"\u003cp\u003eThe centroid method: starts by drawing 2 diagonal lines within the cephalad and caudal vertebral bodies, from each superior corner to the contralateral inferior corner (including osteophytes). The point where these lines intersect represents the centroid. Draw 2 vertical lines through each centroid. RS by the centroid method is the horizontal distance between these 2 lines (yellow line).\u003c/p\u003e","description":"","filename":"Figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6202643/v1/a12616a3825dd60ea374d3cb.jpg"},{"id":80813501,"identity":"0da5afe3-4789-4220-8629-6be52cfe379d","added_by":"auto","created_at":"2025-04-17 10:41:05","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":435028,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of Ro FI% of MF and Ro HU on each disc level among RS\u003csup\u003e \u003c/sup\u003egroup. Ro FI%, the ratio of convex side FI% to concave side FI%. Ro HU, the ratio of convex side HU to concave side HU.\u003c/p\u003e","description":"","filename":"Figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6202643/v1/2a5b0118bca4ca527a09a0c7.jpg"},{"id":80813503,"identity":"56e26102-fd11-44b8-9b04-5e17565c3145","added_by":"auto","created_at":"2025-04-17 10:41:05","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":221263,"visible":true,"origin":"","legend":"\u003cp\u003eThe representative hematoxylin and eosin (H\u0026amp;E) image of muscle biopsies from a 60-year-old DLS patient with VRS. (A): The convex side at RS-1 level; (B): The concave side at RS-1 level; (C) The convex side at RS+1 level; (D) The concave side at RS+1 level. Morphological features including fat (*), and muscle fibers with centralized nuclei (black arrows) are highlighted. Black line is 100 μm.\u003c/p\u003e","description":"","filename":"Figure3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6202643/v1/a2d6e1ac5a325d8349cdf7a4.jpg"},{"id":80814348,"identity":"7e5c9256-c274-41ab-96c2-1a3bdbf7f6bc","added_by":"auto","created_at":"2025-04-17 10:49:05","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":342609,"visible":true,"origin":"","legend":"\u003cp\u003eA 60-year-old female with lumbar degenerative scoliosis (Cobb angle: 39 °); vertebral rotatory subluxation could be seen on L3/L4 level. Diagonal paraspinal sarcopenia could be observed at axial T2-weighted MRI in both coronal and cross section.\u003c/p\u003e","description":"","filename":"Figure4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6202643/v1/adf487e7daee69be0cebc7e5.jpg"},{"id":80813508,"identity":"324c3fe7-d757-4395-97af-a4880038a10d","added_by":"auto","created_at":"2025-04-17 10:41:05","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":65117,"visible":true,"origin":"","legend":"\u003cp\u003eThe model of diagonal paraspinal sarcopenia and osteoporosis in VRS.\u003c/p\u003e","description":"","filename":"Figure5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6202643/v1/d09f77d1e5127c565139c449.jpg"},{"id":90344922,"identity":"f585374b-f6a3-42fc-afce-3e5c14dbd10b","added_by":"auto","created_at":"2025-09-01 16:07:49","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1810265,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6202643/v1/b68c6060-6d74-4168-9564-e82c6ef2db16.pdf"},{"id":80813496,"identity":"4fa3ef5d-4d4a-4ea4-811d-e1675d0bd777","added_by":"auto","created_at":"2025-04-17 10:41:05","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":31179,"visible":true,"origin":"","legend":"","description":"","filename":"supplementarytable.docx","url":"https://assets-eu.researchsquare.com/files/rs-6202643/v1/1b0172eaba3459d21f1ce2e9.docx"},{"id":80813502,"identity":"78a11c21-84d4-40fd-8677-42ef4e55f51c","added_by":"auto","created_at":"2025-04-17 10:41:05","extension":"jpg","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":209684,"visible":true,"origin":"","legend":"","description":"","filename":"supplementaryFig.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6202643/v1/9c5bfd994cbcefbc257e0cc4.jpg"},{"id":80814345,"identity":"9dc52f30-7ae3-4886-8449-4f89b3a67f41","added_by":"auto","created_at":"2025-04-17 10:49:05","extension":"docx","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":50570,"visible":true,"origin":"","legend":"","description":"","filename":"Table2to5.docx","url":"https://assets-eu.researchsquare.com/files/rs-6202643/v1/8da1e394eec936e0b1c92d9c.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Diagonal Paraspinal Sarcopenia and Osteoporosis contribute to the Rotatory Subluxation in patients with Degenerative Lumbar Scoliosis","fulltext":[{"header":"Introduction","content":"\u003cp\u003eVertebral rotatory subluxation (VRS) is a triaxial deformity consisting of axial rotation and lateral translation toward curve convexity, with a prevalence of 19.5% in adult scoliosis [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Degenerative lumbar scoliosis (DLS), the predominant adult-onset spinal deformity in China, exhibits a 13.3% prevalence among individuals over 40 years, with characteristic Cobb angle progression [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Unlike adolescent idiopathic scoliosis where VRS rarely occurs [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], VRS serves both as a risk factor for DLS progression and a pathognomonic feature distinguishing degenerative from idiopathic etiologies. Clinically, VRS correlates with debilitating low back pain and radicular symptoms that severely compromise quality of life [\u003cspan additionalcitationids=\"CR5\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], primarily attributed to foraminal height reduction from lateral translation (LT) exceeding 6 mm\u0026mdash;a critical threshold for symptom progression [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. However, the etiopathology of VRS remains unknown.\u003c/p\u003e \u003cp\u003eThe degeneration of the lumbar structures was widely accepted as a pathological mechanism for VRS [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Identified risk factors include advanced age, curve magnitude, facet joint degeneration, and the location of apical vertebra [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan additionalcitationids=\"CR8 CR9\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Bao et al., reported facet tropism as one of the anatomic structural risk factors for VRS in DLS patients [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Weishi Li et al., found the asymmetrical vertebral degeneration that manifested as high Hounsfield unit (HU) value within concavity and a low HU value within convexity both in the major and compensatory curve in DLS patients [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Existing evidence predominantly focuses on osseous degeneration, leaving muscular contributions underexplored.\u003c/p\u003e \u003cp\u003eThe paraspinal musculature\u0026mdash;comprising multifidus (MF), erector spinae (ES), and quadratus lumborum\u0026mdash;plays a pivotal role in maintaining spinal stability through dynamic load distribution [\u003cspan additionalcitationids=\"CR13 CR14\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Emerging data associate paraspinal muscle (PSM) degeneration with spinal pathologies ranging from disc herniation to adult spinal deformity progression [\u003cspan additionalcitationids=\"CR17 CR18\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Our prior work revealed that DLS patients with coronal imbalance exhibit greater PSM fatty infiltration compared to balanced counterparts [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Besides, PSM has been found an asymmetrical fat composition in DLS and determined that the PSM in patients with DLS showed different degrees of degeneration in different levels of the lumbar spine [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eBiomechanically, asymmetrical degeneration of the PSM in different vertebral levels can lead to unequal muscle strength on concave and convex sides, generating lateral shear force during rotational subluxation segments. Besides, low bone density and uneven gravity load transmitted lead to vertebral wedge deformities [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e], which increases lateral instability of the lumbar spine, thus becoming a risk factor for VRS. However, to our knowledge, limited studies have described the contribution of paraspinal muscle and bone quality on VRS in Patients with DLS. Thus, this study aimed to investigate the correlation between the paraspinal sarcopenia-osteoporosis and VRS in patients with DLS.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003ePatient Cohort\u003c/h2\u003e \u003cp\u003eThis retrospective study enrolled DLS patients undergoing corrective surgery at a single center between August 2013 and March 2023. Inclusion criteria comprised: 1) age\u0026thinsp;\u0026ge;\u0026thinsp;50 years; 2) BMI 20\u0026ndash;28 kg/m\u0026sup2;; 3) coronal Cobb angle 10\u0026deg;-60\u0026deg;. Exclusion criteria included: neuromuscular/idiopathic scoliosis etiology, prior spinal surgery, spinal infection, malignancy, neurodegenerative disorders, or thoracolumbar kyphosis\u0026thinsp;\u0026gt;\u0026thinsp;20\u0026deg;.\u003c/p\u003e \u003cp\u003eLT\u0026thinsp;\u0026ge;\u0026thinsp;5 mm was used as the cutoff value to define rotatory subluxation (RS) [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Patents were stratified into RS (\u0026ge;\u0026thinsp;5 mm translation) and Non-RS (\u0026lt;\u0026thinsp;3 mm translation) groups. The RS group was further divided into single level RS group and double level RS group based on the number of VRS level occurring.\u003c/p\u003e \u003cp\u003eThe study protocol received institutional review board approval (No. 2021-389-01) and adhered to the Declaration of Helsinki (2013 revision). Written informed consent was obtained for histological analyses.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eRadiographic Evaluation\u003c/h3\u003e\n\u003cp\u003eComprehensive radiographic assessment included lumbar CT scans, standing whole-spine posteroanterior \u0026amp; lateral radiographs, and lumbar MRI. Standard radiographic parameters were quantified per Spine Deformity Study Group guidelines:\u003c/p\u003e\n\u003ch3\u003eCoronal parameters:\u003c/h3\u003e\n\u003cp\u003eIncluding the intervertebral LT (Fig.\u0026nbsp;1), major curve Cobb angle, apical vertebra location, and coronal balance distance (CBD). CBD measured as horizontal deviation between C7 plumb line (C7PL: vertical through C7 midpoint) and central sacral vertical line (CSVL).\u003c/p\u003e\n\u003ch3\u003eSagittal parameters:\u003c/h3\u003e\n\u003cp\u003eThe measurements include: sagittal vertical axis (SVA, the horizontal distance between the vertical-line from the midpoint of C7 vertebrae to the posterior upper endplate of the sacrum), thoracic kyphosis (TK, T5-T12 Cobb angle) and lumbar lordosis (LL, L1-S1 Cobb angle).\u003c/p\u003e\n\u003ch3\u003eHU measurement and rotation evaluation:\u003c/h3\u003e\n\u003cp\u003eLumbar CT scans (Light Speed 32, GE Healthcare) were acquired at 2.0 mm slice thickness (120 kV, 220 mA) parallel to inferior disc margins. The vertebral rotation was measured using preoperative axial CT as described previously [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Concretely the angle between the vertical line of the which vertebra CT scanning table and the axis of the spine were measured at RS level.\u003c/p\u003e \u003cp\u003eThe Picture Archiving and Communication System (PACS) was utilized for the computation of CT HU values [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. An oval region of interest (ROI) was positioned at L1-L5 mid-vertebral levels, maximizing trabecular inclusion while excluding cortical bone and vascular structures. Osteoporosis was defined as L1 HU\u0026thinsp;\u0026le;\u0026thinsp;110 [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Convex-concave HU ratios (Ro HU) were calculated per spinal level.\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eMeasurement of PSM Parameters\u003c/h2\u003e \u003cp\u003e1.5T MRI (Magetom Skyra, Siemens) T2-weighted sequences (axial/sagittal planes, 4 mm slices) were analyzed. Sagittal images identified lumbar endplates, with axial slices at L1-S1 disc levels selected for analysis. Using ImageJ (v1.3, NIH), bilateral PSM (MF\u0026amp;ES) cross-sectional areas (CSA) were quantified within thoracolumbar fascial boundaries. Fat infiltration (FI%) was calculated via validated pseudo-coloring techniques [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e], with convex-concave FI% ratios (Ro FI%) determined per level.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eHistological assessment\u003c/h3\u003e\n\u003cp\u003eThe MF muscle from the concave and convex side at the upper level of RS (RS-1), and below level of RS (RS\u0026thinsp;+\u0026thinsp;1) level was collected during corrective surgery. The muscle tissues were snap-frozen in nitrogen-cooled isopentane embedded O.C.T. 10 \u0026micro;m cryosections (Leica CM3050S) underwent H\u0026amp;E and Oil Red O staining for morphological and adipocytic infiltration assessment.\u003c/p\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eData normality was verified using Shapiro-Wilk tests. Continuous variables are expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD or median (IQR) based on distribution normality. All analyses were conducted in SPSS 23.0 (IBM Corp.), employing parametric/non-parametric tests according to data characteristics. Multicollinearity was assessed through variance inflation factors. Binary logistic regression models identified VRS-associated risk factors, with predictive capacity evaluated via receiver operating characteristic (ROC) curve analysis. Statistical significance was set at P\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/div\u003e"},{"header":"RESULTS","content":"\u003cp\u003eThe study enrolled 166 patients (153 female; mean age 61.4\u0026thinsp;\u0026plusmn;\u0026thinsp;6.5 years). 90 patients (54.2%) were categorized into RS group and 76 were Non-RS group, with comparable demographics and radiographic parameters (Table\u0026nbsp;1). Single-level VRS was found in 74 patients, double-level VRS was found in 16 patients. Among all the 106 levels defined as VRS, 66 were located at L3/L4 level, 26 were L4/L5 level, 13 were L2/L3 level, and 1 was L1/L2 level. The apex vertebrae were mainly located at RS-1 level (67%).\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eTable 1.\u003c/strong\u003e Demographics and radiographic parameters of RS and Non-RS group.\u003c/p\u003e\n\u003cdiv\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"658\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 20.0608%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 19.4529%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAll\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.3647%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eRS\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.3647%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNon-RS\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 19.7568%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eP\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"5\" valign=\"top\" style=\"width: 100%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eDemographics parameters\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 20.0608%;\"\u003e\n \u003cp\u003eN(Female/Male)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 19.4529%;\"\u003e\n \u003cp\u003e166(153/13)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.3647%;\"\u003e\n \u003cp\u003e90(84/6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.3647%;\"\u003e\n \u003cp\u003e76(69/7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 19.7568%;\"\u003e\n \u003cp\u003e0.614\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 20.0608%;\"\u003e\n \u003cp\u003eAge (years)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 19.4529%;\"\u003e\n \u003cp\u003e61.4\u0026plusmn;6.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.3647%;\"\u003e\n \u003cp\u003e60.9\u0026plusmn;6.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.3647%;\"\u003e\n \u003cp\u003e62.0\u0026plusmn;6.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 19.7568%;\"\u003e\n \u003cp\u003e0.288\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 20.0608%;\"\u003e\n \u003cp\u003eBMI (kg/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 19.4529%;\"\u003e\n \u003cp\u003e26.1\u0026plusmn;1.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.3647%;\"\u003e\n \u003cp\u003e26.4\u0026plusmn;1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.3647%;\"\u003e\n \u003cp\u003e25.8\u0026plusmn;1.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 19.7568%;\"\u003e\n \u003cp\u003e0.689\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"5\" valign=\"top\" style=\"width: 100%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eRadiographic parameters\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 20.0608%;\"\u003e\n \u003cp\u003eCobb angle (\u0026deg;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 19.4529%;\"\u003e\n \u003cp\u003e33.5\u0026plusmn;7.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.3647%;\"\u003e\n \u003cp\u003e34.1\u0026plusmn;8.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.3647%;\"\u003e\n \u003cp\u003e31.8\u0026plusmn;6.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 19.7568%;\"\u003e\n \u003cp\u003e0.174\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 20.0608%;\"\u003e\n \u003cp\u003eCBD (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 19.4529%;\"\u003e\n \u003cp\u003e20.9\u0026plusmn;8.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.3647%;\"\u003e\n \u003cp\u003e21.0\u0026plusmn;8.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.3647%;\"\u003e\n \u003cp\u003e20.7\u0026plusmn;7.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 19.7568%;\"\u003e\n \u003cp\u003e0.935\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 20.0608%;\"\u003e\n \u003cp\u003eTK (\u0026deg;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 19.4529%;\"\u003e\n \u003cp\u003e17.1\u0026plusmn;2.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.3647%;\"\u003e\n \u003cp\u003e17.3\u0026plusmn;2.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.3647%;\"\u003e\n \u003cp\u003e16.8\u0026plusmn;2.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 19.7568%;\"\u003e\n \u003cp\u003e0.887\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 20.0608%;\"\u003e\n \u003cp\u003eLL (\u0026deg;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 19.4529%;\"\u003e\n \u003cp\u003e25.4\u0026plusmn;3.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.3647%;\"\u003e\n \u003cp\u003e22.7\u0026plusmn;2.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.3647%;\"\u003e\n \u003cp\u003e26.0\u0026plusmn;3.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 19.7568%;\"\u003e\n \u003cp\u003e0.460\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 20.0608%;\"\u003e\n \u003cp\u003eSVA (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 19.4529%;\"\u003e\n \u003cp\u003e56.2\u0026plusmn;8.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.3647%;\"\u003e\n \u003cp\u003e57.4\u0026plusmn;7.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.3647%;\"\u003e\n \u003cp\u003e55.5\u0026plusmn;10.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 19.7568%;\"\u003e\n \u003cp\u003e0.887\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eData are expressed as mean \u0026plusmn; standard deviation. RS, rotatory subluxation. BMI, body mass index; CBD, coronal balance distance; SVA, sagittal vertical axis; TK, thoracic kyphosis; LL, lumbar lordosis.\u003c/p\u003e\n\u003cdiv id=\"Sec12\"\u003e\n \u003ch2\u003e\u003cstrong\u003eComparison of PSM measurements\u003c/strong\u003e\u003c/h2\u003e\n \u003cp\u003e\u003cstrong\u003eNon-RS group vs RS group\u003c/strong\u003e: Patients with double level VRS (RS\u003csup\u003eL3/4, L4/5\u003c/sup\u003e) showed smaller CSA of ES than those without RS (L4/L5 disc level: 21.9[18.6, 24.3] cm\u003csup\u003e2\u003c/sup\u003e vs 16.0[14.2, 25.7] cm\u003csup\u003e2\u003c/sup\u003e, P\u0026thinsp;=\u0026thinsp;0.027). single level RS group with RS\u003csup\u003eL4/5\u003c/sup\u003e and double level RS group demonstrated significant smaller CSA of MF compared to the Non-RS group on multiple levels (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Both Single level RS group and double level RS group showed significant higher FI% of PSM (ES and MF) compared to the Non-RS group at different levels (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05), shown as Table 2.\u003c/p\u003e\n \u003cdiv\u003e\u003cstrong\u003eSingle level RS group\u003c/strong\u003e vs \u003cstrong\u003eDouble level RS group\u003c/strong\u003e: Patients with RS\u003csup\u003eL2/3\u003c/sup\u003e level demonstrated significantly larger CSA of MF on L1-L4 disc level and lower FI% of ES on L3-L5 disc level compared to the RS\u003csup\u003eL2/3, L3/4\u003c/sup\u003e level (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). RS\u003csup\u003eL3/4\u003c/sup\u003e level demonstrated significantly larger CSA of MF on L1-L3 disc level and lower FI% of ES on L3-L5 disc level compared to the RS\u003csup\u003eL2/3, L3/4\u003c/sup\u003e level (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). RS\u003csup\u003eL3/4\u003c/sup\u003e level showed significant larger CSA of MF on L1-L3 disc level, lower FI% of ES (L2/L3, L5/S1) and MF (L3/L4) compared to the RS\u003csup\u003eL3/4, L4/5\u003c/sup\u003e level (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05), shown as Table 2.\u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec13\"\u003e\n \u003ch2\u003eConvex side vs Concave side:\u003c/h2\u003e\n \u003cp\u003eThe single level RS group showed higher FI% of MF on the concave side above RS level and higher FI% of MF on the convex side below RS level, the HU measurement demonstrated significant difference between convex and concave side on multiple levels (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05, Table 3). On the double level RS group, the FI% of MF and HU value showed significant difference between convex and concave side on multiple levels (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05, Table 4). comparison of the PSM and HU asymmetry degree among single and double level RS groups on each disc level were shown as Fig. 2. The FI% of MF and HU value of single level RS group and double level RS group showed more severe asymmetry in multiple levels than those of Non-RS group (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The asymmetrical degeneration was reversed above and below the RS level.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec14\"\u003e\n \u003ch2\u003eComparison of HU measurement\u003c/h2\u003e\n \u003cp\u003eBased on the cutoff\u0026thinsp;\u0026le;\u0026thinsp;110 HU at L1 vertebrae, patients with VRS generally showed osteoporosis (RS\u003csup\u003eL2/3\u003c/sup\u003e level: 89.8 [82.3, 94.6]; RS\u003csup\u003eL3/4\u003c/sup\u003e level: 104.3 [98.3, 109.2]; RS\u003csup\u003eL4/5\u003c/sup\u003e level: 96.5 [90.5, 101.7]; RS\u003csup\u003eL2/3, L3/4\u003c/sup\u003e level: 103.3 [93.6, 108.3]; RS\u003csup\u003eL3/4, L4/5\u003c/sup\u003e level: 101.7 [94.3, 108.0]). The HU value of the both single level RS and double level RS group was significantly lower than that in the Non-RS group on multiple levels (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05, Table\u0026nbsp;2).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec15\"\u003e\n \u003ch2\u003e\u003cstrong\u003eThe correlation analysis\u003c/strong\u003e\u003c/h2\u003e\n \u003cp\u003eThe spearman correlation was performed between Ro FI% of MF, lateral translation (LT) and intervertebral rotation at the VRS level. LT was positively correlated with Ro FI% of MF on RS\u0026thinsp;+\u0026thinsp;1 level (R\u0026thinsp;=\u0026thinsp;0.498, P\u0026thinsp;=\u0026thinsp;0.003) and negatively correlated with Ro FI% of MF on RS-1 level (R\u0026thinsp;=\u0026thinsp;0.537, P\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec16\"\u003e\n \u003ch2\u003e\u003cstrong\u003eBinary Logistic Regression Analysis\u003c/strong\u003e\u003c/h2\u003e\n \u003cp\u003eComprehensive modeling incorporating demographic (age), radiographic (Cobb angle), and compositional parameters (HU values, vertebral rotation) identified three independent VRS predictors (Table\u0026nbsp;5): 1. MF Ro FI% above RS (OR\u0026thinsp;=\u0026thinsp;0.02, 95%CI 0.001\u0026ndash;0.15, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). 2. MF Ro FI% below RS (OR\u0026thinsp;=\u0026thinsp;1.96, 95%CI 0.93\u0026ndash;4.11, p\u0026thinsp;=\u0026thinsp;0.007). 3. Cobb angle magnitude (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). 4. Osteoporosis status (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e\n \u003cdiv id=\"Sec17\"\u003e\n \u003ch2\u003eHistological analysis\u003c/h2\u003e\n \u003cp\u003eOf the 4 participants with measurable muscle in the sample, a greater proportion of fat on the concave side of the RS-1 level (convex side vs concave side, 27.8\u0026thinsp;\u0026plusmn;\u0026thinsp;10.2% vs 39.4\u0026thinsp;\u0026plusmn;\u0026thinsp;12.6%, P\u0026thinsp;=\u0026thinsp;0.012) and the convex side of the RS\u0026thinsp;+\u0026thinsp;1 level (convex side vs concave side, 43.1\u0026thinsp;\u0026plusmn;\u0026thinsp;11.8% vs 36.8\u0026thinsp;\u0026plusmn;\u0026thinsp;10.7%, P\u0026thinsp;=\u0026thinsp;0.05) was observed. (Fig.\u0026nbsp;3).\u003c/p\u003e\n\u003c/div\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eIn this study, we found DLS patients with VRS demonstrated significantly greater FI% compared to the Non-RS. These phenomena were aggravated with the increase of VRS numbers in RS group. Notably, diagonally asymmetric patterns of multifidus (MF) FI% were observed between adjacent spinal segments proximal and distal to VRS sites, demonstrating significant correlations with subluxation severity. Multivariate logistic regression analysis identified diagonal paraspinal sarcopenia and osteoporosis as independent contributing factors for VRS development. These findings collectively suggest that diagonal paraspinal sarcopenia and osteoporosis may be involved in VRS development in DLS patients and should be considered in surgical decision-making.\u003c/p\u003e \u003cp\u003eVRS, osteoporosis, and PSM degeneration have been implicated as predictive biomarkers for DLS [\u003cspan additionalcitationids=\"CR29 CR30\" citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. As a pathognomonic feature of DLS, VRS manifests as rotational instability predominantly observed in degenerative scoliosis onset phases, contrasting with its rare occurrence in idiopathic scoliosis. VRS has demonstrated prognostic value for surgical outcomes, making it frequently targeted for surgical intervention in DLS [\u003cspan additionalcitationids=\"CR5\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Despite established associations with age-related degeneration, the multifactorial etiology of VRS remains controversial [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan additionalcitationids=\"CR8 CR9\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Emerging evidence highlights the significance of PSM integrity, particularly the MF as a dynamic stabilizer modulating vertebral rotation [\u003cspan additionalcitationids=\"CR13 CR14\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. While Kiram et al. revealed correlations between PSM degeneration and coronal imbalance [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Loss of MF muscle function may cause abnormal. However, the relationship between PSM degeneration and VRS has yet to be determined.\u003c/p\u003e \u003cp\u003eThis study presents novel investigation focused on the phenomenon of diagonal paraspinal sarcopenia in VRS. While previous reports have documented enhanced PSM degeneration in VRS cohorts, particularly affecting spinal extensors and flexors [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e], our findings align with Ferrero et al.'s volumetric analysis demonstrating comparable CSA between RS and non-RS groups [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. Notably, our FI% quantification complements previous observations of elevated muscular degeneration in VRS. Both concave and convex measurements confirmed significantly higher FI% in VRS, corroborating Ferrero's 3D volumetric evidence of preferential fat deposition over absolute muscle loss as a hallmark of rotational instability.\u003c/p\u003e \u003cp\u003eWe noted the inverse Ro FI% (concave/convex) across VRS levels: \u0026lt;1 at RS\u0026thinsp;+\u0026thinsp;1 versus \u0026gt;\u0026thinsp;1 at RS-1, indicating inverse severity of fat infiltration around the VRS level. This spatial inversion of degeneration patterns echoes the Parallelogram Effect described in apical vertebral degeneration [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e], though occurring at distinct anatomical locations - a divergence potentially attributable to our specific focus on VRS. Histological validation confirmed enhanced FI% in convex RS\u0026thinsp;+\u0026thinsp;1 level and concave RS-1 level musculature, establishing concordance between imaging analysis and tissue-level degeneration. Fat infiltration results in decreased contractile composition of muscle, which in turn leads to the decline of musculature power production[\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. Thus, the asymmetric fat inflation in bilateral paraspinal muscle generates uncompensated muscle power sheer. Specifically, diagonal fat infiltration across VRS may cause inversed muscle force, which may accelerate spinal instability and the VRS, and we collectively concluded this phenomenon as diagonal degeneration.\u003c/p\u003e \u003cp\u003eThe relationship between PSM degeneration and vertebral rotation were assessed. Xie et al found that apical vertebral rotation and lateral vertebral translation can aggravate the asymmetric degree of PSM [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Our study found the asymmetrical changes in PSM were associated with the degree of vertebral rotation and lateral displacement. Recently, Schonnagel L et al. demonstrated a significant and independent association between lumbar spinal stenosis and the composition of the posterior paraspinal musculature, patients with lumbar spinal stenosis might be especially susceptible to axial muscle wasting, which could worsen lumbar spinal stenosis due to increased spinal instability, leading to a positive feedback loop [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. Likewise, VRS may result in intervertebral foraminal stenosis and neural impingement and leading to the positive feedback mentioned above. Our study indicated that PSM diagonal degeneration at different disc levels would allow increased lateral instability and proposed that this was responsible for VRS in DLS.\u003c/p\u003e \u003cp\u003eLow HU value may exacerbate spinal instability. Multiple studies have found that osteoporosis may contribute to DLS [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e, \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. Our findings showed that the RS group demonstrated lower HU values than those of Non-RS group on multiple lumbar levels, especially on L1. Vibhu et al. demonstrated that upper lumbar HU measurements show stronger correlations with bone mineral density [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The observed HU variations could be attributed to degenerative alterations in lower lumbar vertebrae, including osteophyte formation, subchondral bone involvement, and trabecular microdamage. Weishi Li et al. emphasize that osteoporosis evaluated by HU value could increase the asymmetrical vertebral degeneration [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. The transition zone between the main curve and fractional curve undergoes concave-convex side transformation. The vertebral body in this area bears the largest gravitational load, and patients with low HU values are more prone to wedge collapse of the vertebral body in this area. The gravitational load is decomposed into vertical and lateral stress, exacerbating lumbar instability.\u003c/p\u003e \u003cp\u003eIn conclusion, diagonal paraspinal sarcopenia and osteoporosis contribute to the occurrence and development process of VRS. As VRS was important in evaluating curve progression and quality of life, a careful analysis of lumbar MRI and CT images in patients with initial degenerative scoliosis would be required to determine PSM-bone quality and thus potential VRS, as well as predicting the possible natural history of scoliosis.\u003c/p\u003e \u003cp\u003eThere are several limitations in this study. Firstly, this is a retrospective study with a relatively small sample size. Second, 2D axial measurements of CSA and FI% lack volumetric accuracy; future studies employing 3D musculoskeletal modeling could mitigate measurement biases arising from positional variability. Thirdly, the cross-sectional nature prevents causal conclusions regarding paraspinal sarcopenia and VRS, highlighting the need for longitudinal studies for validation.\u003c/p\u003e "},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003e(I) Conception and design: Z Liu; (II) Administrative support: Y Qiu; (III) Provision of study materials or patients: A Kiram, M Wang, Q Liu; (IV) Collection and assembly of data: M Wang, A Kiram; (V) Data analysis and interpretation: M Wang, A Kiram, P Li, Z Tian, Z Liu, Z Zhu, Y Qiu; (VI) Manuscript writing: All authors; (VII) Final approval of manuscript: All authors.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eFund program:\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003col\u003e\n \u003cli\u003eSupported by the National Natural Science Foundation of China (NSFC) (No. 82272545).\u003c/li\u003e\n \u003cli\u003eSpecial Fund of Science and Technology Plan of Jiangsu Province (No.BE2023658).\u003c/li\u003e\n \u003cli\u003eChina Postdoctoral Science Foundation (No. 2024M751403).\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eTrammell TR, Schroeder RD, Reed DB. 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Spine (Phila Pa 1976). 2014 Dec 15;39(26 Spec No.):B45-51.\u003c/li\u003e\n\u003cli\u003eWang H, Zou D, Sun Z, et al. Hounsfield Unit for Assessing Vertebral Bone Quality and Asymmetrical Vertebral Degeneration in Degenerative Lumbar Scoliosis. Spine (Phila Pa 1976). 2020 Nov 15;45(22):1559-1566.\u003c/li\u003e\n\u003cli\u003eHodges PW, Danneels L. Changes in Structure and Function of the Back Muscles in Low Back Pain: Different Time Points, Observations, and Mechanisms. J Orthop Sports Phys Ther. 2019 Jun;49(6):464-476.\u003c/li\u003e\n\u003cli\u003eDeng X, Zhu Y, Wang S, et al. CT and MRI Determination of Intermuscular Space within Lumbar Paraspinal Muscles at Different Intervertebral Disc Levels. PLoS One. 2015;10(10):e0140315.\u003c/li\u003e\n\u003cli\u003ePeng X, Li X, Xu Z, et al. Age-related fatty infiltration of lumbar paraspinal muscles: a normative reference database study in 516 Chinese females. Quant Imaging Med Surg. 2020 Aug;10(8):1590-1601.\u003c/li\u003e\n\u003cli\u003eWard SR, Kim CW, Eng CM, et al. Architectural analysis and intraoperative measurements demonstrate the unique design of the multifidus muscle for lumbar spine stability. J Bone Joint Surg Am. 2009 Jan;91(1):176-85.\u003c/li\u003e\n\u003cli\u003eJun HS, Kim JH, Ahn JH, et al. The Effect of Lumbar Spinal Muscle on Spinal Sagittal Alignment: Evaluating Muscle Quantity and Quality. Neurosurgery. 2016 Dec;79(6):847-855.\u003c/li\u003e\n\u003cli\u003eGoubert D, Oosterwijck JV, Meeus M, et al. Structural Changes of Lumbar Muscles in Non-specific Low Back Pain: A Systematic Review. Pain Physician. 2016 Sep-Oct;19(7):E985-E1000.\u003c/li\u003e\n\u003cli\u003eHiyama A, Katoh H, Sakai D, et al. The correlation analysis between sagittal alignment and cross-sectional area of paraspinal muscle in patients with lumbar spinal stenosis and degenerative spondylolisthesis. BMC Musculoskelet Disord. 2019 Jul 31;20(1):352.\u003c/li\u003e\n\u003cli\u003eYeung KH, Man GCW, Shi L, et al. Magnetic Resonance Imaging-Based Morphological Change of Paraspinal Muscles in Girls With Adolescent Idiopathic Scoliosis. Spine (Phila Pa 1976). 2019 Oct 1;44(19):1356-1363.\u003c/li\u003e\n\u003cli\u003eKiram A, Hu Z, Man GC, et al. The role of paraspinal muscle degeneration in coronal imbalance in patients with degenerative scoliosis. Quant Imaging Med Surg. 2022 Nov;12(11):5101-5113.\u003c/li\u003e\n\u003cli\u003eZhou M, Liu L, Chen Z, et al. Characteristics of paraspinal muscle degeneration in patients with adult degenerative scoliosis. Eur Spine J. 2023 Nov;32(11):4020-4029.\u003c/li\u003e\n\u003cli\u003ePerie D, Curnier D, de Gauzy JS. Correlation between nucleus zone migration within scoliotic intervertebral discs and mechanical properties distribution within scoliotic vertebrae. Magn Reson Imaging. 2003 Nov;21(9):949-53.\u003c/li\u003e\n\u003cli\u003eAaro S, Dahlborn M. Estimation of vertebral rotation and the spinal and rib cage deformity in scoliosis by computer tomography. Spine (Phila Pa 1976). 1981 Sep-Oct;6(5):460-7.\u003c/li\u003e\n\u003cli\u003eViswanathan VK, Shetty AP, Rai N, et al. What is the role of CT-based Hounsfield unit assessment in the evaluation of bone mineral density in patients undergoing 1- or 2-level lumbar spinal fusion for degenerative spinal pathologies? A prospective study. Spine J. 2023 Oct;23(10):1427-1434.\u003c/li\u003e\n\u003cli\u003ePickhardt PJ, Pooler BD, Lauder T, et al. Opportunistic screening for osteoporosis using abdominal computed tomography scans obtained for other indications. Ann Intern Med. 2013 Apr 16;158(8):588-95.\u003c/li\u003e\n\u003cli\u003eLee JC, Cha JG, Kim Y, et al. Quantitative analysis of back muscle degeneration in the patients with the degenerative lumbar flat back using a digital image analysis: comparison with the normal controls. Spine (Phila Pa 1976). 2008 Feb 1;33(3):318-25.\u003c/li\u003e\n\u003cli\u003eXie D, Zhang J, Ding W, et al. Abnormal change of paravertebral muscle in adult degenerative scoliosis and its association with bony structural parameters. Eur Spine J. 2019 Jul;28(7):1626-1637.\u003c/li\u003e\n\u003cli\u003eKobayashi T, Atsuta Y, Takemitsu M, et al. A prospective study of de novo scoliosis in a community based cohort. Spine (Phila Pa 1976). 2006 Jan 15;31(2):178-82.\u003c/li\u003e\n\u003cli\u003eLee JS, Shin JK, Goh TS. Interleukin 6 gene polymorphism in patients with degenerative lumbar scoliosis: a cohort study. Eur Spine J. 2018 Mar;27(3):607-612.\u003c/li\u003e\n\u003cli\u003eYagi M, Hosogane N, Watanabe K, et al. The paravertebral muscle and psoas for the maintenance of global spinal alignment in patient with degenerative lumbar scoliosis. Spine J. 2016 Apr;16(4):451-8.\u003c/li\u003e\n\u003cli\u003eWatanuki A, Yamada H, Tsutsui S, et al. Radiographic features and risk of curve progression of de-novo degenerative lumbar scoliosis in the elderly: a 15-year follow-up study in a community-based cohort. J Orthop Sci. 2012 Sep;17(5):526-31.\u003c/li\u003e\n\u003cli\u003eGardner RO, Torrie PA, Bertram W, et al. A Radiological Evaluation of Lateral Vertebral Subluxation Associated With Spinal Stenosis in the Lumbar Spine in Degenerative Scoliosis. Spine Deform. 2013 Sep;1(5):365-370.\u003c/li\u003e\n\u003cli\u003eMoal B, Bronsard N, Raya JG, et al. Volume and fat infiltration of spino-pelvic musculature in adults with spinal deformity. World J Orthop. 2015 Oct 18;6(9):727-37.\u003c/li\u003e\n\u003cli\u003eFerrero E, Skalli W, Lafage V, et al. Relationships between radiographic parameters and spinopelvic muscles in adult spinal deformity patients. Eur Spine J. 2020 Jun;29(6):1328-1339.\u003c/li\u003e\n\u003cli\u003eSun XY, Kong C, Zhang TT, et al. Correlation between multifidus muscle atrophy, spinopelvic parameters, and severity of deformity in patients with adult degenerative scoliosis: the parallelogram effect of LMA on the diagonal through the apical vertebra. J Orthop Surg Res. 2019 Aug 28;14(1):276.\u003c/li\u003e\n\u003cli\u003eFidler MW, Jowett RL. Muscle imbalance in the aetiology of scoliosis. J Bone Joint Surg Br. 1976 May;58(2):200-1.\u003c/li\u003e\n\u003cli\u003eSchonnagel L, Zhu J, Camino-Willhuber G, et al. Relationship between lumbar spinal stenosis and axial muscle wasting. Spine J. 2024 Feb;24(2):231-238.\u003c/li\u003e\n\u003cli\u003eGillespy T, 3rd, Gillespy T, Jr., Revak CS. Progressive senile scoliosis: seven cases of increasing spinal curves in elderly patients. Skeletal Radiol. 1985;13(4):280-6.\u003c/li\u003e\n\u003cli\u003eVanderpool DW, James JI, Wynne-Davies R. Scoliosis in the elderly. J Bone Joint Surg Am. 1969 Apr;51(3):446-55.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Table 2 to 5","content":"\u003cp\u003eTable 2 to 5 are available in the Supplementary Files section.\u003c/p\u003e\n"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"european-spine-journal","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"esjo","sideBox":"Learn more about [European Spine Journal](http://link.springer.com/journal/586)","snPcode":"586","submissionUrl":"https://submission.springernature.com/new-submission/586/3","title":"European Spine Journal","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"paraspinal sarcopenia, osteoporosis, vertebral rotational subluxation, degenerative lumbar scoliosis","lastPublishedDoi":"10.21203/rs.3.rs-6202643/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6202643/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eThis study aims to investigate the potential association between paraspinal sarcopenia, osteoporosis, and vertebral rotational subluxation (VRS) in patients with degenerative lumbar scoliosis (DLS).\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eThis retrospective study analyzed standing anteroposterior radiographs to assess coronal (Cobb angle, CA; coronal balance distance, CBD; lateral translation, LT) and sagittal parameters (thoracic kyphosis, TK; lumbar lordosis, LL; sagittal vertical axis, SVA). Patients were categorized into Rotatory Subluxation (RS, LT\u0026thinsp;\u0026ge;\u0026thinsp;5mm) and Non-RS groups, with the RS group further subdivided into single and double level subgroups based on the frequency of RS occurrence. Bilateral paraspinal muscle (PSM) cross-sectional area (CSA) and fat infiltration rate (FI%) at L1-S1 were evaluated via lumbar MRI. Vertebral rotation angles and Hounsfield units (HU) were quantified using reconstructed axial CT images, with osteoporosis defined as L1 HU\u0026thinsp;\u0026le;\u0026thinsp;110. Ratios of convex-to-concave measurements (Ro FI%, Ro CSA, Ro HU) were calculated. Spearman correlation and logistic regression analyses explored associations among paraspinal sarcopenia, osteoporosis, and VRS. Intraoperative multifidus muscle (MF) samples from RS-1 (upper RS level) and RS\u0026thinsp;+\u0026thinsp;1 (below RS level) in DLS patients underwent histological analysis to assess regional fat infiltration and muscle atrophy.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003e166 patients were included in this study, 90 (54.2%) with VRS and 76 without. The apex vertebrae were predominantly at the RS-1 level (67%). Both single level and double level RS groups showed significantly higher FI% of PSM (erector spine, ES and MF) compared to the Non-RS group at various levels (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Patients with VRS generally exhibited osteoporosis. The HU value for both single level and double level RS patients were significantly lower than those in the Non-RS group at multiple levels (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Notably, the FI% of bilateral MF and HU value in RS group showed more severe asymmetry at multiple levels compared to the Non-RS group (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Both Ro HU and Ro FI% of MF muscle were generally\u0026thinsp;\u0026lt;\u0026thinsp;1 above the RS level, while\u0026thinsp;\u0026gt;\u0026thinsp;1 below the RS level, suggesting that asymmetric paraspinal sarcopenia and osteoporosis above and below the RS level was reversed. Logistic regression analysis showed that VRS was significantly associated with the Ro FI% above RS (odds ratio, 0.021; 95% confidence interval, 0.001\u0026ndash;0.147; P\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and Ro FI% below RS (odds ratio, 1.956; 95% confidence interval, 0.930\u0026ndash;4.114; P\u0026thinsp;=\u0026thinsp;0.007). Cobb angle and osteoporosis were additional independent factors associated with VRS.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eVRS in DLS is characterized by diagonal paraspinal sarcopenia patterns and vertebral osteoporosis. The reversed sarcopenia-osteoporosis gradient across subluxation levels suggests a biomechanical coupling mechanism driving curve progression. Preoperative quantification of these parameters may stratify progression risk and guide targeted rehabilitation.\u003c/p\u003e","manuscriptTitle":"Diagonal Paraspinal Sarcopenia and Osteoporosis contribute to the Rotatory Subluxation in patients with Degenerative Lumbar Scoliosis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-04-17 10:41:00","doi":"10.21203/rs.3.rs-6202643/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-04-20T21:08:22+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-13T22:56:55+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-08T12:30:01+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"131420031953392345700144035085896641184","date":"2025-04-01T16:20:47+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"336547266755568208627499559890833461077","date":"2025-03-30T11:52:09+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-03-28T11:48:57+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-03-17T13:40:31+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-03-17T13:34:45+00:00","index":"","fulltext":""},{"type":"submitted","content":"European Spine Journal","date":"2025-03-11T11:39:54+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"european-spine-journal","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"esjo","sideBox":"Learn more about [European Spine Journal](http://link.springer.com/journal/586)","snPcode":"586","submissionUrl":"https://submission.springernature.com/new-submission/586/3","title":"European Spine Journal","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"472507c5-5bd8-49e8-ba2a-d2c37e4f1db5","owner":[],"postedDate":"April 17th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-09-01T16:02:53+00:00","versionOfRecord":{"articleIdentity":"rs-6202643","link":"https://doi.org/10.1007/s00586-025-09292-z","journal":{"identity":"european-spine-journal","isVorOnly":false,"title":"European Spine Journal"},"publishedOn":"2025-08-27 15:58:06","publishedOnDateReadable":"August 27th, 2025"},"versionCreatedAt":"2025-04-17 10:41:00","video":"","vorDoi":"10.1007/s00586-025-09292-z","vorDoiUrl":"https://doi.org/10.1007/s00586-025-09292-z","workflowStages":[]},"version":"v1","identity":"rs-6202643","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6202643","identity":"rs-6202643","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}