Atrophy and Fat Infiltration of Contralateral Lumbar M uscles Correlate with the Severity of Osteonecrosis of the Femoral Head

Atrophy and Fat Infiltration of Contralateral Lumbar M uscles Correlate with the Severity of Osteonecrosis of the Femoral Head | 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 Article Atrophy and Fat Infiltration of Contralateral Lumbar M uscles Correlate with the Severity of Osteonecrosis of the Femoral Head Yang Huibao, Long Dawei, Wang Shuo, Kuang Xueao, Wei Shuailong, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8177991/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Objective :To investigate the correlation between the cross-sectional area and fat infiltration degree of the multifidus muscle in the lumbar core muscle group and the ARCO staging of femoral head necrosis. Methods :Ninety patients with ONFH diagnosed between March 2019 and March 2025 were included and divided into Stage II, Stage III, and Stage IV groups according to ARCO staging, with 30 patients in each group. Additionally, 30 healthy volunteers were included as a control group. All subjects underwent lumbosacral 3.0T MRI examination. The cross-sectional area and fat infiltration rate of the bilateral multifidus (MF) and erector spinae (LT) muscles were measured on axial images at the L4/L5 intervertebral disc level. One-way ANOVA was used to compare differences between groups, and Spearman correlation analysis was used to assess the relationship between muscle indicators and ARCO staging. Results : Compared with the control group, the cross-sectional area of the MF and LT on the healthy side in ONFH patients significantly decreased with increasing ARCO stage, while the fat infiltration rate significantly increased. In the same ONFH patient, the cross-sectional area of the multifidus and erector spinae muscles on the affected side was significantly larger than that on the healthy side, and the fat infiltration rate was significantly lower than that on the healthy side. Spearman correlation analysis showed that ARCO staging was negatively correlated with the cross-sectional area of the MF and LT on the healthy side and positively correlated with the fat infiltration rate on the healthy side. Conclusion :Atrophy and fat infiltration of the core muscles on the healthy side of the lower back are significantly correlated with the severity of ONFH. This indicates that the pathological changes in ONFH patients are not limited to the hip joint but also involve alterations in lumbopelvic compensation mechanisms, providing imaging evidence for the assessment of core muscles and rehabilitation intervention. Health sciences/Anatomy Health sciences/Diseases Health sciences/Health care Health sciences/Medical research Femoral head necrosis Multifidus muscle Erector spinae muscle Cross-sectional area Fat infiltration Figures Figure 1 Background Osteonecrosis of the femoral head (ONFH) is a disabling disease, and its pathological progression is typically described using the ARCO or Ficat staging systems [ 1 , 2 ] Clinical observations have found that patients with mid-to-late stage ONFH often experience refractory lumbosacral pain and knee pain [ 3 , 4 ] in addition to hip joint pain and limited mobility, the mechanisms of which remain unclear. Current research has mostly focused on changes in the perihip muscles (such as the gluteus medius) and thigh muscles, overlooking the potential role of the lumbar core muscle group [ 5 ] The lumbar core muscle group, including the multifidus and longissimus thoracis muscles, is key to maintaining lumbar stability and pelvic balance[ 6 ]. We hypothesize that the pain and limping gait caused by ONFH disrupt the lumbopelvic-hip biomechanical balance, leading to compensatory overuse or disuse changes in the lumbar muscles. These changes may manifest as muscle atrophy and fat infiltration and be correlated with the disease stage [ 7 ] This study aims to use MRI to quantitatively analyze the morphological changes of the lumbar core muscles in ONFH patients at different ARCO stages and to explore their correlation with disease staging, providing a theoretical basis for the comprehensive assessment and rehabilitation treatment of ONFH. 1 Materials and Methods 1.1 Clinical Data Ninety ONFH patients from March 2019 to March 2025 were included, and an additional 30 healthy volunteers matched for age, sex, and body mass index were recruited. Two senior orthopedic physicians independently staged all ONFH patients according to the ARCO staging system based on imaging data. Disagreements were resolved through consensus. The patients were ultimately divided into three groups: ARCO Stage II group (n = 30), Stage III group (n = 30), Stage IV group (n = 30), and 30 healthy volunteers were included as the control group. 1.2 Inclusion and Exclusion Criteria Inclusion ① Meeting the diagnostic criteria for ARCO staging; ② Age 18–65 years; ③ The patient and guardian agreed to participate in this study and signed an informed consent form. Exclusion ① History of lumbar spine surgery, lumbar disc herniation, lumbar spondylolisthesis, neurological diseases, severe scoliosis, or other conditions causing the disease; ② Severe impairment of heart, liver, kidney function, or coagulation function; ③ Severe cardiovascular and cerebrovascular diseases; ④ Patients with comorbid mental illness. 1.3 Measurement Methods and Observation Indicators A 3.0T MRI scanner was used, with sequences including T1-weighted and T2-weighted sequences. The scanning range was from the upper edge of the L2 vertebral body to the lower edge of the S1 vertebral body. Measurements were performed on axial T2-weighted images at the center level of the L4/L5 intervertebral disc. ① Cross-sectional area measurement (CSA): The contours of the bilateral MF muscles were manually outlined using medical image analysis software Image J, and the software automatically calculated the cross-sectional area. ② Fat infiltration assessment: A quantitative method based on signal intensity was used, placing regions of interest within the muscle contours to calculate the fat infiltration rate. ③ Visual Analog Scale (VAS) pain score was used for the hip joint, with a maximum score of 10, where higher scores indicate more severe pain. Harris Hip Score was used, with a maximum score of 100, where higher scores indicate better function. 1.5 Statistical Analysis SPSS 26.0 statistical software was used for processing and analysis. Measurement data are expressed as mean ± standard deviation (x̄ ± s). If normality and homogeneity of variance were met, one-way ANOVA was used; if not, median (interquartile range) [M (Q1, Q3)] was used, and non-parametric tests (U test, rank test, H test) were used for comparison. A P value < 0.05 was considered statistically significant. Spearman correlation analysis was used to assess the relationship between muscle indicators and ARCO staging. P < 0.05 was considered statistically significant. 2 Results 2.1 Comparison of Baseline Data, VAS Score, and Harris Score. There were no statistically significant differences in age, BMI, or sex between the groups (P > 0.05); there were statistically significant differences in Harris score and VAS score between the groups (P < 0.05). See Table 1 . Table 1 Comparison of Baseline Data, VAS Score, and Harris Score Group n Age Male/Female BMI Harris Score VAS Score Control 30 51.80 ± 11.72 16/14 21.31 ± 2.22 - - Stage Ⅱ 30 53.80 ± 8.67 15/15 21.01 ± 2.48 81.7 ± 4.55 5(5,6) Stage Ⅲ 30 48.16 ± 12.57 16/14 22.27 ± 2.72 66.90 ± 4.29 6(5,7) Stage Ⅳ 30 52.73 ± 9.50 17/13 21.56 ± 2.35 51.30 ± 4.86 6(6,7) Statistic - F = 1.557 χ 2 = 0.268 F = 1.403 F = 424.62 F = 815.89 P value - P >0.05(0.204) P >0.05(0.966) P >0.05(0.246) P <0.01 P <0.01 2.2 Comparison of Lumbar Muscle Cross-Sectional Area and Fat Infiltration Rate. The cross-sectional area of the lumbar muscles on the healthy side in Stage IV ONFH patients was significantly lower than that in the control group, and the cross-sectional area on the healthy side in each group was significantly lower than that on the affected side (except the control group). The differences were statistically significant (all P < 0.05); the fat infiltration rate of the lumbar muscles on the healthy side in Stage IV ONFH patients was significantly higher than that in the control group, and the fat infiltration rate on the healthy side in each group was significantly higher than that on the affected side (except the control group). The differences were statistically significant (all P < 0.05). See Table 2 and Table 3 . Table 2 Comparison of Cross-Sectional Area (CSA cm²) Group n Healthy Side MF Affected Side MF Healthy Side LT Affected Side LT Control 30 10.77 ± 2.09 10.47 ± 2.43 22.10 ± 3.84 24.20 ± 4.34 Stage Ⅱ 30 9.59 ± 1.21 10.04 ± 2.40 19.10 ± 4.06 24.43 ± 4.38 Stage Ⅲ 30 8.18 ± 2.07 10.07 ± 2.20 13.79 ± 4.14 24.78 ± 4.51 Stage Ⅳ 30 7.59 ± 1.72 9.88 ± 2.45 8.70 ± 2.45 22.58 ± 4.43 Statistic - F = 18.671 F = 0.346 F = 77.149 F = 1.471 P value - P 0.05(0.792) P 0.05(0.226) Table 3 Comparison of Fat Infiltration Rate (FI %) Group n Healthy Side MF Affected Side MF Healthy Side LT Affected Side LT Control 30 9.93 ± 2.30 9.72 ± 1.77 8.92 ± 2.04 9.07 ± 2.05 Stage Ⅱ 30 19.12 ± 5.00 9.37 ± 2.32 16.11 ± 5.22 8.23 ± 1.62 Stage Ⅲ 30 32.28 ± 8.01 9.40 ± 1.91 23.34 ± 7.74 8.26 ± 1.79 Stage Ⅳ 30 39.46 ± 7.49 9.55 ± 2.06 30.24 ± 8.42 8.51 ± 1.81 Statistic F = 139.01 F = 0.186 F = 62.487 F = 1.390 P value P 0.05(0.906) P 0.05(0.249) 2.3 Correlation Analysis between Lumbar Muscle Indicators and ARCO Staging. Spearman correlation analysis showed that the cross-sectional area (CSA) of the lumbar muscles on the healthy side was negatively correlated with the ARCO staging of femoral head necrosis. The fat infiltration rate (FI) of the lumbar muscles on the healthy side was positively correlated with the ARCO staging of femoral head necrosis. The results were statistically significant (all P < 0.05). See Table 4 . Table 4 Correlation between Lumbar Muscles and ARCO Staging Muscle /Staging Healthy Side MF CSA Affected Side MF CSA Healthy Side MF FI Affected Side MF FI Healthy Side LT CSA Affected Side LT CSA Healthy Side LT FI Affected Side LT FI Correlation Coefficient (r) -0.568 -0.061 0.895 -0.025 -0.819 -0.106 0.803 -0.134 P value P <0.01 P = 0.51 P <0.01 P = 0.79 P <0.01 P = 0.25 P <0.01 P = 0.14 2.4 Typical Imaging Processing Before and After Illustration. Figure 1 a and e show the cross-sectional views of the lumbar muscles at the L4/L5 level in the control group before and after processing, respectively; b and f show the cross-sectional views of the lumbar muscles at the L4/L5 level in the ARCO stage II group before and after processing, respectively; c and g show the cross-sectional views of the lumbar muscles at the L4/L5 level in the ARCO stage III group before and after processing, respectively; d and h show the cross-sectional views of the lumbar muscles at the L4/L5 level in the ARCO stage IV group before and after processing, respectively. 3 Discussion This study systematically analyzed the morphological changes of the paraspinal core muscles (erector spinae and multifidus) in patients with femoral head necrosis (ONFH) at different stages through quantitative imaging measurements. Our core finding is that the lumbar core muscles in ONFH patients exhibit progressive atrophy and fat infiltration closely related to disease severity (ARCO staging). As the ARCO stage progressed from stage I to stage IV, the cross-sectional area (CSA) of the erector spinae and multifidus muscles measured at the L4 level in patients significantly decreased, while the fat infiltration percentage (FI%) significantly increased. This result indicates that the pathological process of ONFH is not an isolated hip joint event [ 8 ] but is accompanied by significant degenerative changes in the core stabilizing muscles of the spine-pelvis-hip complex. This provides a new perspective and important theoretical basis for understanding the systemic functional disability caused by ONFH. 3.1 Mechanism and Factor Analysis of Core Muscle Degeneration The lumbar core muscles, especially the multifidus, play an irreplaceable role in maintaining segmental spinal stability. They act as precise "segmental stabilizers," finely adjusting the position of each intervertebral joint through coordinated contractions, effectively preventing abnormal micromotion and shear forces between vertebrae. Simultaneously, their rich proprioceptors provide the central nervous system with accurate postural feedback, forming the neurocontrol basis for normal gait and dynamic balance [ 9 ]. Furthermore, studies have shown that fat infiltration in paraspinal muscles is associated with low back pain [ 10 , 11 ]. In the pathological context of ONFH, this delicate system is severely disrupted. Firstly, biomechanical compensation mechanisms are the direct pathway leading to muscle group changes. Pain forces patients to adopt a compensatory gait, such as shortening the stance phase on the affected side and tilting the trunk towards the healthy side during the gait cycle [ 12 ]. When the center of gravity shifts to the healthy side, the erector spinae and multifidus muscles on the affected side should eccentrically contract to control trunk flexion, but the abnormal posture alters the load pattern of these muscles. As the disease worsens, the usage of the affected hip further decreases, requiring the affected side muscle groups to cooperate with the quadratus lumborum and gluteal muscles to lift the pelvis to compensate for lower limb function. This is not only an important reason for pelvic tilt in mid-to-late stage patients but also leads to long-term abnormal activation and fatigue of the core muscles. Secondly, neurogenic inhibition mechanisms are equally critical. According to the "arthrogenic muscle inhibition" theory [ 13 ], a large amount of nociceptive input generated by intra-articular lesions (such as increased intra-articular pressure and synovitis) in the hip joint can inhibit motor neurons innervating the periarticular and even paraspinal muscles through reflex arcs at the spinal level. This inhibitory effect leads to "under-activation" of the core muscles when force is required, directly causing disuse atrophy over the long term [ 14 ] and potentially affecting muscle protein anabolic metabolism, accelerating its catabolic process. In addition to the above secondary mechanisms, we must recognize that many primary etiologies leading to ONFH are themselves causes of myopathy. The most typical is the long-term or high-dose use of glucocorticoids [ 15 ] While exerting anti-inflammatory effects, glucocorticoids have a clear myopathic effect. They promote muscle protein degradation by activating the ubiquitin-proteasome pathway and inhibit anabolic signals such as insulin-like growth factor-1, leading to rapid atrophy primarily of type II muscle fibers. Concurrently, corticosteroids can induce the differentiation of mesenchymal stem cells into adipocytes, directly promoting fat infiltration within muscle tissue [ 16 ]. Similarly, chronic alcoholism, as another major cause of ONFH [ 17 ], has direct toxicity to muscle cells through its metabolites, interfering with mitochondrial function, inducing oxidative stress, and also promoting muscle atrophy and fatty degeneration [ 18 ]. Therefore, in ONFH patients caused by hormones or alcohol, the observed degeneration of paraspinal muscles may be the result of the parallel development and mutual exacerbation of ONFH and primary myopathy driven by common etiologies. Furthermore, other factors such as aging (leading to decreased muscle cell activity and regeneration capacity), postmenopausal sex hormone level changes (affecting fat distribution and metabolism), obesity, and insulin resistance (causing dysregulation of adipokine secretion and fat metabolism imbalance) [ 19 ] collectively exacerbate the process of muscle atrophy and fat infiltration, forming a complex multifactorial interactive system. 3.2 Clinical Implications and Research Prospects The findings of this study have certain clinical translational value. Firstly, it proposes a new assessment strategy. Traditional ONFH assessment primarily relies on hip joint imaging and functional scores (such as the Harris Hip Score). While these indicators can reflect the degree of local joint destruction, they have limitations in assessing the functional status of the overall musculoskeletal system. This study confirms that the cross-sectional area and fat infiltration rate of the erector spinae and multifidus muscles can serve as objective imaging biomarkers for assessing the overall muscle involvement in ONFH patients. For patients with both severe femoral head collapse and significant core muscle degeneration, their degree of functional disability, rehabilitation difficulty, and long-term prognosis may be far worse than those with only imaging changes but well-preserved core muscles. Therefore, in clinical practice, consider incorporating spinal MRI or specialized core muscle ultrasound into the routine examination system for ONFH patients, or perform secondary analysis on lumbar MRI already taken for other reasons (such as low back pain), thereby achieving a multi-dimensional and holistic assessment of the condition. Secondly, this study provides a new direction for rehabilitation therapy. For early-stage patients (ARCO I-II), the rehabilitation goals should not be limited to maintaining hip joint range of motion and strengthening perihip muscle strength; the assessment and training of lumbar core muscles must be elevated to a core position. After effective pain management (such as physical therapy, medication) to reduce arthrogenic inhibition, targeted and precise core stability training and control training (such as supine/side-lying leg raises, prone "superman" exercises) should be initiated as early as possible to awaken and strengthen the deep stabilizing muscles, delay or even partially reverse early muscle atrophy, and improve neuromuscular control, thereby creating a more favorable biomechanical environment for hip preservation therapy. For end-stage patients requiring total hip arthroplasty, the status of the core muscles can serve as an important basis for preoperative prehabilitation and individualized postoperative rehabilitation. Patients with severe core muscle atrophy before surgery are more prone to persistent low back pain and abnormal gait after surgery [ 20 ] Therefore, promoting the concept of "prehabilitation," i.e., assessing core muscle strength and implementing strengthening training before surgery, is expected to enhance the patient's stress tolerance to surgery, optimize postoperative functional outcomes, and accelerate the recovery process. Postoperative rehabilitation plans must also be individualized. For patients with weak core muscles, a more intensive and progressive lumbopelvic core training plan needs to be designed to truly achieve the treatment goal from joint replacement to overall functional reconstruction. 3.3 Study Limitations Certainly, this study also has several limitations. Firstly, although we infer a causal path from ONFH progression to core muscle degeneration based on existing theory and findings, this study is cross-sectional in design and cannot fully establish causality. The possibility that some patients inherently have weak core muscles, leading to a worse prognosis after the disease, cannot be excluded. Secondly, we only performed two-dimensional measurements at the L4/5 level. Although this level is a commonly used representative plane for assessing the lumbar core muscles, it cannot accurately reflect the three-dimensional volumetric changes of the entire lumbosacral muscle group (especially the multifidus) and their differences in the craniocaudal direction. Future research using MRI-based three-dimensional volumetric segmentation techniques will provide more precise and comprehensive data. Furthermore, although we made efforts to control for common confounding factors such as age, sex, and BMI, there may still be some unmeasured or inadequately controlled variables, such as the patient's specific daily activity level, precise duration and intensity of pain, use of analgesic medications, and subgroup differences in ONFH etiologies (steroid-induced or alcohol-induced). These factors may all influence muscle morphology. Finally, this study primarily focused on morphological changes and did not simultaneously collect functional indicators such as gait analysis, isokinetic muscle strength testing, or patient-reported outcome scores for all patients. This makes the direct quantitative link between morphological changes and the degree of specific functional disability still insufficient, which is a key area for improvement in future research. 4 Conclusion In summary, this study discovered and confirmed a significant correlation between the staging of femoral head necrosis and the degree of atrophy and fat infiltration of the erector spinae and multifidus muscles. This indicates that ONFH is not an isolated hip joint disease but a systemic functional disorder affecting the entire spine-pelvis-hip kinetic chain. The underlying mechanisms involve pain-mediated neural inhibition, abnormal biomechanical compensation, and possible common etiological effects. The morphological changes of the paraspinal core muscles are an important component of the disease burden in ONFH and may, in turn, affect the patient's pain experience, functional disability, and rehabilitation prognosis. Therefore, in the clinical diagnosis, treatment, and rehabilitation practice of ONFH, we should adopt a holistic concept, making the assessment and intervention of core muscles an indispensable part, thereby providing new ideas and approaches for the ultimate goal of maximizing patient function. Declarations Acknowledgements Not applicable. Author contributions Y.HB, L.DW, and W.S. designed the study; K.XA. and W.SL collected the data. Y.HB, W.ZZ, and G.TX analyzed the data; Y.HB and L.DW drafted the manuscript. All authors reviewed and approved the submitted manuscript. Funding No funding was received for conducting this study. Data availability statement The datasets used and/or analysed during the current study available from the corresponding author on reasonable request Ethical approval This study is a prospective study based on data obtained for clinical purposes, and has been approved by the Institutional Review Board of The Seventh Affiliated Hospital of Anhui University of Chinese Medicine, Anhui Province, China. Informed consent was obtained from all participants and their legal guardians, and all research procedures were conducted in strict accordance with the ethical principles of the Declaration of Helsinki. Consent for publication Not applicable. Informed consent Written informed consent was obtained from each patient for publication of this study. Statement of human and animal rights There are no experimental procedures involving animals or humans and statement of human or animal rights is not applicable. Competing interests The authors declare no competing interests. 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16:28:44","extension":"xml","order_by":5,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":73481,"visible":true,"origin":"","legend":"","description":"","filename":"2b319fcebab641b7886348a91c43dfda1structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8177991/v1/e4b7acf7dd493f2483196d66.xml"},{"id":99188414,"identity":"8d206d5b-7cfb-4a9e-b49f-def5d95ee28e","added_by":"auto","created_at":"2025-12-30 00:18:48","extension":"html","order_by":6,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":83696,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8177991/v1/ca88b640fae1e319a198e169.html"},{"id":99188413,"identity":"537ad80d-bf68-48b6-b59e-feaf19cb354b","added_by":"auto","created_at":"2025-12-30 00:18:48","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":737470,"visible":true,"origin":"","legend":"\u003cp\u003ea and e show the cross-sectional views of the lumbar muscles at the L4/L5 level in the control group before and after processing, respectively; b and f show the cross-sectional views of the lumbar muscles at the L4/L5 level in the ARCO stage II group before and after processing, respectively; c and g show the cross-sectional views of the lumbar muscles at the L4/L5 level in the ARCO stage III group before and after processing, respectively; d and h show the cross-sectional views of the lumbar muscles at the L4/L5 level in the ARCO stage IV group before and after processing, respectively.\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8177991/v1/0877c2f1963561794f5a4cae.jpeg"},{"id":99323491,"identity":"7fb86808-6483-4995-92f3-f14ddde6a9dd","added_by":"auto","created_at":"2025-12-31 16:45:33","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1700132,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8177991/v1/801a1be2-6aa7-4bf5-8468-c66389e5ea9b.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Atrophy and Fat Infiltration of Contralateral Lumbar M uscles Correlate with the Severity of Osteonecrosis of the Femoral Head","fulltext":[{"header":"Background","content":"\u003cp\u003eOsteonecrosis of the femoral head (ONFH) is a disabling disease, and its pathological progression is typically described using the ARCO or Ficat staging systems [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] Clinical observations have found that patients with mid-to-late stage ONFH often experience refractory lumbosacral pain and knee pain [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] in addition to hip joint pain and limited mobility, the mechanisms of which remain unclear. Current research has mostly focused on changes in the perihip muscles (such as the gluteus medius) and thigh muscles, overlooking the potential role of the lumbar core muscle group [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] The lumbar core muscle group, including the multifidus and longissimus thoracis muscles, is key to maintaining lumbar stability and pelvic balance[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. We hypothesize that the pain and limping gait caused by ONFH disrupt the lumbopelvic-hip biomechanical balance, leading to compensatory overuse or disuse changes in the lumbar muscles. These changes may manifest as muscle atrophy and fat infiltration and be correlated with the disease stage [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] This study aims to use MRI to quantitatively analyze the morphological changes of the lumbar core muscles in ONFH patients at different ARCO stages and to explore their correlation with disease staging, providing a theoretical basis for the comprehensive assessment and rehabilitation treatment of ONFH.\u003c/p\u003e"},{"header":"1 Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e1.1 Clinical Data\u003c/h2\u003e \u003cp\u003eNinety ONFH patients from March 2019 to March 2025 were included, and an additional 30 healthy volunteers matched for age, sex, and body mass index were recruited. Two senior orthopedic physicians independently staged all ONFH patients according to the ARCO staging system based on imaging data. Disagreements were resolved through consensus. The patients were ultimately divided into three groups: ARCO Stage II group (n\u0026thinsp;=\u0026thinsp;30), Stage III group (n\u0026thinsp;=\u0026thinsp;30), Stage IV group (n\u0026thinsp;=\u0026thinsp;30), and 30 healthy volunteers were included as the control group.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e1.2 Inclusion and Exclusion Criteria\u003c/h2\u003e \u003cp\u003e \u003cstrong\u003eInclusion\u003c/strong\u003e \u003cp\u003e① Meeting the diagnostic criteria for ARCO staging; ② Age 18\u0026ndash;65 years; ③ The patient and guardian agreed to participate in this study and signed an informed consent form.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eExclusion\u003c/strong\u003e \u003cp\u003e① History of lumbar spine surgery, lumbar disc herniation, lumbar spondylolisthesis, neurological diseases, severe scoliosis, or other conditions causing the disease; ② Severe impairment of heart, liver, kidney function, or coagulation function; ③ Severe cardiovascular and cerebrovascular diseases; ④ Patients with comorbid mental illness.\u003c/p\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e1.3 Measurement Methods and Observation Indicators\u003c/h2\u003e \u003cp\u003eA 3.0T MRI scanner was used, with sequences including T1-weighted and T2-weighted sequences. The scanning range was from the upper edge of the L2 vertebral body to the lower edge of the S1 vertebral body. Measurements were performed on axial T2-weighted images at the center level of the L4/L5 intervertebral disc.\u003c/p\u003e \u003cp\u003e① Cross-sectional area measurement (CSA): The contours of the bilateral MF muscles were manually outlined using medical image analysis software Image J, and the software automatically calculated the cross-sectional area.\u003c/p\u003e \u003cp\u003e② Fat infiltration assessment: A quantitative method based on signal intensity was used, placing regions of interest within the muscle contours to calculate the fat infiltration rate.\u003c/p\u003e \u003cp\u003e③ Visual Analog Scale (VAS) pain score was used for the hip joint, with a maximum score of 10, where higher scores indicate more severe pain. Harris Hip Score was used, with a maximum score of 100, where higher scores indicate better function.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e1.5 Statistical Analysis\u003c/h2\u003e \u003cp\u003eSPSS 26.0 statistical software was used for processing and analysis. Measurement data are expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (x̄ \u0026plusmn; s). If normality and homogeneity of variance were met, one-way ANOVA was used; if not, median (interquartile range) [M (Q1, Q3)] was used, and non-parametric tests (U test, rank test, H test) were used for comparison. A P value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant. Spearman correlation analysis was used to assess the relationship between muscle indicators and ARCO staging. P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"2 Results","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Comparison of Baseline Data, VAS Score, and Harris Score.\u003c/h2\u003e \u003cp\u003eThere were no statistically significant differences in age, BMI, or sex between the groups (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05); there were statistically significant differences in Harris score and VAS score between the groups (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). See Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of Baseline Data, VAS Score, and Harris Score\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGroup\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAge\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMale/Female\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eBMI\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eHarris Score\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eVAS Score\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eControl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e51.80\u0026thinsp;\u0026plusmn;\u0026thinsp;11.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e16/14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e21.31\u0026thinsp;\u0026plusmn;\u0026thinsp;2.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStage Ⅱ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e53.80\u0026thinsp;\u0026plusmn;\u0026thinsp;8.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e15/15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e21.01\u0026thinsp;\u0026plusmn;\u0026thinsp;2.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e81.7\u0026thinsp;\u0026plusmn;\u0026thinsp;4.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e5(5,6)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStage Ⅲ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e48.16\u0026thinsp;\u0026plusmn;\u0026thinsp;12.57\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e16/14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e22.27\u0026thinsp;\u0026plusmn;\u0026thinsp;2.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e66.90\u0026thinsp;\u0026plusmn;\u0026thinsp;4.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e6(5,7)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStage Ⅳ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e52.73\u0026thinsp;\u0026plusmn;\u0026thinsp;9.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e17/13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e21.56\u0026thinsp;\u0026plusmn;\u0026thinsp;2.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e51.30\u0026thinsp;\u0026plusmn;\u0026thinsp;4.86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e6(6,7)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStatistic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1.557\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eχ\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u0026thinsp;\u003cem\u003e=\u003c/em\u003e\u0026thinsp;0.268\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1.403\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u0026thinsp;=\u0026thinsp;424.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u0026thinsp;=\u0026thinsp;815.89\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026gt;0.05(0.204)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026gt;0.05(0.966)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026gt;0.05(0.246)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026lt;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026lt;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Comparison of Lumbar Muscle Cross-Sectional Area and Fat Infiltration Rate.\u003c/h2\u003e \u003cp\u003eThe cross-sectional area of the lumbar muscles on the healthy side in Stage IV ONFH patients was significantly lower than that in the control group, and the cross-sectional area on the healthy side in each group was significantly lower than that on the affected side (except the control group). The differences were statistically significant (all P\u0026thinsp;\u0026lt;\u0026thinsp;0.05); the fat infiltration rate of the lumbar muscles on the healthy side in Stage IV ONFH patients was significantly higher than that in the control group, and the fat infiltration rate on the healthy side in each group was significantly higher than that on the affected side (except the control group). The differences were statistically significant (all P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). See Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of Cross-Sectional Area (CSA cm\u0026sup2;)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGroup\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHealthy Side MF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAffected Side MF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eHealthy Side LT\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eAffected Side LT\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eControl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10.77\u0026thinsp;\u0026plusmn;\u0026thinsp;2.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10.47\u0026thinsp;\u0026plusmn;\u0026thinsp;2.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e22.10\u0026thinsp;\u0026plusmn;\u0026thinsp;3.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e24.20\u0026thinsp;\u0026plusmn;\u0026thinsp;4.34\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStage Ⅱ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9.59\u0026thinsp;\u0026plusmn;\u0026thinsp;1.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10.04\u0026thinsp;\u0026plusmn;\u0026thinsp;2.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e19.10\u0026thinsp;\u0026plusmn;\u0026thinsp;4.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e24.43\u0026thinsp;\u0026plusmn;\u0026thinsp;4.38\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStage Ⅲ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8.18\u0026thinsp;\u0026plusmn;\u0026thinsp;2.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10.07\u0026thinsp;\u0026plusmn;\u0026thinsp;2.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e13.79\u0026thinsp;\u0026plusmn;\u0026thinsp;4.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e24.78\u0026thinsp;\u0026plusmn;\u0026thinsp;4.51\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStage Ⅳ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.59\u0026thinsp;\u0026plusmn;\u0026thinsp;1.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9.88\u0026thinsp;\u0026plusmn;\u0026thinsp;2.45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8.70\u0026thinsp;\u0026plusmn;\u0026thinsp;2.45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e22.58\u0026thinsp;\u0026plusmn;\u0026thinsp;4.43\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStatistic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u0026thinsp;=\u0026thinsp;18.671\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.346\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u0026thinsp;=\u0026thinsp;77.149\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1.471\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026lt;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026gt;0.05(0.792)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026lt;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026gt;0.05(0.226)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of Fat Infiltration Rate (FI %)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGroup\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHealthy Side MF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAffected Side MF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eHealthy Side LT\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eAffected Side LT\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eControl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9.93\u0026thinsp;\u0026plusmn;\u0026thinsp;2.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9.72\u0026thinsp;\u0026plusmn;\u0026thinsp;1.77\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8.92\u0026thinsp;\u0026plusmn;\u0026thinsp;2.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e9.07\u0026thinsp;\u0026plusmn;\u0026thinsp;2.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStage Ⅱ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e19.12\u0026thinsp;\u0026plusmn;\u0026thinsp;5.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9.37\u0026thinsp;\u0026plusmn;\u0026thinsp;2.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e16.11\u0026thinsp;\u0026plusmn;\u0026thinsp;5.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e8.23\u0026thinsp;\u0026plusmn;\u0026thinsp;1.62\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStage Ⅲ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e32.28\u0026thinsp;\u0026plusmn;\u0026thinsp;8.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9.40\u0026thinsp;\u0026plusmn;\u0026thinsp;1.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e23.34\u0026thinsp;\u0026plusmn;\u0026thinsp;7.74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e8.26\u0026thinsp;\u0026plusmn;\u0026thinsp;1.79\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStage Ⅳ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e39.46\u0026thinsp;\u0026plusmn;\u0026thinsp;7.49\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9.55\u0026thinsp;\u0026plusmn;\u0026thinsp;2.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e30.24\u0026thinsp;\u0026plusmn;\u0026thinsp;8.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e8.51\u0026thinsp;\u0026plusmn;\u0026thinsp;1.81\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStatistic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eF\u0026thinsp;=\u0026thinsp;139.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eF\u0026thinsp;=\u0026thinsp;0.186\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eF\u0026thinsp;=\u0026thinsp;62.487\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eF\u0026thinsp;=\u0026thinsp;1.390\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026lt;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026gt;0.05(0.906)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026lt;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026gt;0.05(0.249)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Correlation Analysis between Lumbar Muscle Indicators and ARCO Staging.\u003c/h2\u003e \u003cp\u003eSpearman correlation analysis showed that the cross-sectional area (CSA) of the lumbar muscles on the healthy side was negatively correlated with the ARCO staging of femoral head necrosis. The fat infiltration rate (FI) of the lumbar muscles on the healthy side was positively correlated with the ARCO staging of femoral head necrosis. The results were statistically significant (all P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). See Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCorrelation between Lumbar Muscles and ARCO Staging\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMuscle /Staging\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHealthy Side MF\u003c/p\u003e \u003cp\u003eCSA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAffected Side MF CSA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHealthy Side MF FI\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAffected Side MF FI\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eHealthy Side LT CSA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eAffected Side LT CSA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eHealthy Side LT FI\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eAffected Side LT FI\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCorrelation Coefficient (r)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.568\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.061\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.895\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-0.025\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-0.819\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-0.106\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.803\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e-0.134\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026lt;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026lt;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026lt;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026lt;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.14\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Typical Imaging Processing Before and After Illustration.\u003c/h2\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\u003cp\u003eFigure 1 a and e show the cross-sectional views of the lumbar muscles at the L4/L5 level in the control group before and after processing, respectively; b and f show the cross-sectional views of the lumbar muscles at the L4/L5 level in the ARCO stage II group before and after processing, respectively; c and g show the cross-sectional views of the lumbar muscles at the L4/L5 level in the ARCO stage III group before and after processing, respectively; d and h show the cross-sectional views of the lumbar muscles at the L4/L5 level in the ARCO stage IV group before and after processing, respectively.\u003c/p\u003e"},{"header":"3 Discussion","content":"\u003cp\u003eThis study systematically analyzed the morphological changes of the paraspinal core muscles (erector spinae and multifidus) in patients with femoral head necrosis (ONFH) at different stages through quantitative imaging measurements. Our core finding is that the lumbar core muscles in ONFH patients exhibit progressive atrophy and fat infiltration closely related to disease severity (ARCO staging). As the ARCO stage progressed from stage I to stage IV, the cross-sectional area (CSA) of the erector spinae and multifidus muscles measured at the L4 level in patients significantly decreased, while the fat infiltration percentage (FI%) significantly increased. This result indicates that the pathological process of ONFH is not an isolated hip joint event [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] but is accompanied by significant degenerative changes in the core stabilizing muscles of the spine-pelvis-hip complex. This provides a new perspective and important theoretical basis for understanding the systemic functional disability caused by ONFH.\u003c/p\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Mechanism and Factor Analysis of Core Muscle Degeneration\u003c/h2\u003e \u003cp\u003eThe lumbar core muscles, especially the multifidus, play an irreplaceable role in maintaining segmental spinal stability. They act as precise \"segmental stabilizers,\" finely adjusting the position of each intervertebral joint through coordinated contractions, effectively preventing abnormal micromotion and shear forces between vertebrae. Simultaneously, their rich proprioceptors provide the central nervous system with accurate postural feedback, forming the neurocontrol basis for normal gait and dynamic balance [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Furthermore, studies have shown that fat infiltration in paraspinal muscles is associated with low back pain [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. In the pathological context of ONFH, this delicate system is severely disrupted. Firstly, biomechanical compensation mechanisms are the direct pathway leading to muscle group changes. Pain forces patients to adopt a compensatory gait, such as shortening the stance phase on the affected side and tilting the trunk towards the healthy side during the gait cycle [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. When the center of gravity shifts to the healthy side, the erector spinae and multifidus muscles on the affected side should eccentrically contract to control trunk flexion, but the abnormal posture alters the load pattern of these muscles. As the disease worsens, the usage of the affected hip further decreases, requiring the affected side muscle groups to cooperate with the quadratus lumborum and gluteal muscles to lift the pelvis to compensate for lower limb function. This is not only an important reason for pelvic tilt in mid-to-late stage patients but also leads to long-term abnormal activation and fatigue of the core muscles. Secondly, neurogenic inhibition mechanisms are equally critical. According to the \"arthrogenic muscle inhibition\" theory [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e], a large amount of nociceptive input generated by intra-articular lesions (such as increased intra-articular pressure and synovitis) in the hip joint can inhibit motor neurons innervating the periarticular and even paraspinal muscles through reflex arcs at the spinal level. This inhibitory effect leads to \"under-activation\" of the core muscles when force is required, directly causing disuse atrophy over the long term [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] and potentially affecting muscle protein anabolic metabolism, accelerating its catabolic process.\u003c/p\u003e \u003cp\u003eIn addition to the above secondary mechanisms, we must recognize that many primary etiologies leading to ONFH are themselves causes of myopathy. The most typical is the long-term or high-dose use of glucocorticoids [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] While exerting anti-inflammatory effects, glucocorticoids have a clear myopathic effect. They promote muscle protein degradation by activating the ubiquitin-proteasome pathway and inhibit anabolic signals such as insulin-like growth factor-1, leading to rapid atrophy primarily of type II muscle fibers. Concurrently, corticosteroids can induce the differentiation of mesenchymal stem cells into adipocytes, directly promoting fat infiltration within muscle tissue [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Similarly, chronic alcoholism, as another major cause of ONFH [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], has direct toxicity to muscle cells through its metabolites, interfering with mitochondrial function, inducing oxidative stress, and also promoting muscle atrophy and fatty degeneration [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Therefore, in ONFH patients caused by hormones or alcohol, the observed degeneration of paraspinal muscles may be the result of the parallel development and mutual exacerbation of ONFH and primary myopathy driven by common etiologies. Furthermore, other factors such as aging (leading to decreased muscle cell activity and regeneration capacity), postmenopausal sex hormone level changes (affecting fat distribution and metabolism), obesity, and insulin resistance (causing dysregulation of adipokine secretion and fat metabolism imbalance) [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] collectively exacerbate the process of muscle atrophy and fat infiltration, forming a complex multifactorial interactive system.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Clinical Implications and Research Prospects\u003c/h2\u003e \u003cp\u003eThe findings of this study have certain clinical translational value. Firstly, it proposes a new assessment strategy. Traditional ONFH assessment primarily relies on hip joint imaging and functional scores (such as the Harris Hip Score). While these indicators can reflect the degree of local joint destruction, they have limitations in assessing the functional status of the overall musculoskeletal system. This study confirms that the cross-sectional area and fat infiltration rate of the erector spinae and multifidus muscles can serve as objective imaging biomarkers for assessing the overall muscle involvement in ONFH patients. For patients with both severe femoral head collapse and significant core muscle degeneration, their degree of functional disability, rehabilitation difficulty, and long-term prognosis may be far worse than those with only imaging changes but well-preserved core muscles. Therefore, in clinical practice, consider incorporating spinal MRI or specialized core muscle ultrasound into the routine examination system for ONFH patients, or perform secondary analysis on lumbar MRI already taken for other reasons (such as low back pain), thereby achieving a multi-dimensional and holistic assessment of the condition. Secondly, this study provides a new direction for rehabilitation therapy. For early-stage patients (ARCO I-II), the rehabilitation goals should not be limited to maintaining hip joint range of motion and strengthening perihip muscle strength; the assessment and training of lumbar core muscles must be elevated to a core position. After effective pain management (such as physical therapy, medication) to reduce arthrogenic inhibition, targeted and precise core stability training and control training (such as supine/side-lying leg raises, prone \"superman\" exercises) should be initiated as early as possible to awaken and strengthen the deep stabilizing muscles, delay or even partially reverse early muscle atrophy, and improve neuromuscular control, thereby creating a more favorable biomechanical environment for hip preservation therapy. For end-stage patients requiring total hip arthroplasty, the status of the core muscles can serve as an important basis for preoperative prehabilitation and individualized postoperative rehabilitation. Patients with severe core muscle atrophy before surgery are more prone to persistent low back pain and abnormal gait after surgery [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] Therefore, promoting the concept of \"prehabilitation,\" i.e., assessing core muscle strength and implementing strengthening training before surgery, is expected to enhance the patient's stress tolerance to surgery, optimize postoperative functional outcomes, and accelerate the recovery process. Postoperative rehabilitation plans must also be individualized. For patients with weak core muscles, a more intensive and progressive lumbopelvic core training plan needs to be designed to truly achieve the treatment goal from joint replacement to overall functional reconstruction.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Study Limitations\u003c/h2\u003e \u003cp\u003eCertainly, this study also has several limitations. Firstly, although we infer a causal path from ONFH progression to core muscle degeneration based on existing theory and findings, this study is cross-sectional in design and cannot fully establish causality. The possibility that some patients inherently have weak core muscles, leading to a worse prognosis after the disease, cannot be excluded. Secondly, we only performed two-dimensional measurements at the L4/5 level. Although this level is a commonly used representative plane for assessing the lumbar core muscles, it cannot accurately reflect the three-dimensional volumetric changes of the entire lumbosacral muscle group (especially the multifidus) and their differences in the craniocaudal direction. Future research using MRI-based three-dimensional volumetric segmentation techniques will provide more precise and comprehensive data. Furthermore, although we made efforts to control for common confounding factors such as age, sex, and BMI, there may still be some unmeasured or inadequately controlled variables, such as the patient's specific daily activity level, precise duration and intensity of pain, use of analgesic medications, and subgroup differences in ONFH etiologies (steroid-induced or alcohol-induced). These factors may all influence muscle morphology. Finally, this study primarily focused on morphological changes and did not simultaneously collect functional indicators such as gait analysis, isokinetic muscle strength testing, or patient-reported outcome scores for all patients. This makes the direct quantitative link between morphological changes and the degree of specific functional disability still insufficient, which is a key area for improvement in future research.\u003c/p\u003e \u003c/div\u003e"},{"header":"4 Conclusion","content":"\u003cp\u003eIn summary, this study discovered and confirmed a significant correlation between the staging of femoral head necrosis and the degree of atrophy and fat infiltration of the erector spinae and multifidus muscles. This indicates that ONFH is not an isolated hip joint disease but a systemic functional disorder affecting the entire spine-pelvis-hip kinetic chain. The underlying mechanisms involve pain-mediated neural inhibition, abnormal biomechanical compensation, and possible common etiological effects. The morphological changes of the paraspinal core muscles are an important component of the disease burden in ONFH and may, in turn, affect the patient's pain experience, functional disability, and rehabilitation prognosis. Therefore, in the clinical diagnosis, treatment, and rehabilitation practice of ONFH, we should adopt a holistic concept, making the assessment and intervention of core muscles an indispensable part, thereby providing new ideas and approaches for the ultimate goal of maximizing patient function.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eY.HB, L.DW, and W.S. designed the study; K.XA. and W.SL collected the data. Y.HB, W.ZZ, and G.TX analyzed the data; Y.HB and L.DW drafted the manuscript. All authors reviewed and approved the submitted manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo funding was received for conducting this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability statement\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analysed during the current study available from the corresponding author on reasonable request\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study is a prospective study based on data obtained for clinical purposes, and has been approved by the Institutional Review Board of The Seventh Affiliated Hospital of Anhui University of Chinese Medicine, Anhui Province, China. Informed consent was obtained from all participants and their legal guardians, and all research procedures were conducted in strict accordance with the ethical principles of the Declaration of Helsinki.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInformed consent\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWritten informed consent was obtained from each patient for publication of this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatement of human and animal rights\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThere are no experimental procedures involving animals or humans and statement of human or animal rights is not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eKonarski, W. et al. Avascular Necrosis of Femoral Head-Overview and Current State of the Art. \u003cem\u003eInt J. Environ. Res. Public. Health\u003c/em\u003e \u003cb\u003e19\u003c/b\u003e(12). (2022).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHines, J. T. et al. Osteonecrosis of the Femoral Head: an Updated Review of ARCO on Pathogenesis, Staging and Treatment. \u003cem\u003eJ. Korean Med. Sci.\u003c/em\u003e \u003cb\u003e36\u003c/b\u003e (24), e177 (2021).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNakamura, J. et al. Distribution of hip pain in patients with idiopathic osteonecrosis of the femoral head. \u003cem\u003eMod. Rheumatol.\u003c/em\u003e \u003cb\u003e27\u003c/b\u003e (3), 503\u0026ndash;507 (2017).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOsawa, Y. et al. 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Are MRI-defined fat infiltrations in the multifidus muscles associated with low back pain? \u003cem\u003eBMC Med.\u003c/em\u003e \u003cb\u003e5\u003c/b\u003e, 2 (2007).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTeichtahl, A. J. et al. Fat infiltration of paraspinal muscles is associated with low back pain, disability, and structural abnormalities in community-based adults. \u003cem\u003eSpine J.\u003c/em\u003e \u003cb\u003e15\u003c/b\u003e (7), 1593\u0026ndash;1601 (2015).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSvarnas, G., Popa, V., Patsiou, T. S., Schwab, J. M. \u0026amp; Tannast, M. Postoperative muscle atrophy and fatty degeneration with respect to surgical approaches in total hip arthroplasty. \u003cem\u003eArch. Orthop. Trauma. Surg.\u003c/em\u003e \u003cb\u003e145\u003c/b\u003e (1), 177 (2025).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLepley, A. S. \u0026amp; Lepley, L. K. Mechanisms of Arthrogenic Muscle Inhibition. \u003cem\u003eJ. Sport Rehabil\u003c/em\u003e. \u003cb\u003e31\u003c/b\u003e (6), 707\u0026ndash;716 (2022).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGabel, C. P., Mokhtarinia, H. R. \u0026amp; Melloh, M. The Politics of Chronic LBP: Can We Rely on a Proxy-Vote? Linking Multifidus Intra-Myo-Cellular Lipid (IMCL) Fatty Infiltration With Arthrogenic Muscle Inhibition (AMI)-induced Chronic Nonspecific Low Back Pain. \u003cem\u003eSpine (Phila Pa. 1976)\u003c/em\u003e. \u003cb\u003e46\u003c/b\u003e (2), 129\u0026ndash;130 (2021).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen, C. Y. et al. Glucocorticoid-induced loss of beneficial gut bacterial extracellular vesicles is associated with the pathogenesis of osteonecrosis. \u003cem\u003eSci. Adv.\u003c/em\u003e \u003cb\u003e8\u003c/b\u003e (15), eabg8335 (2022).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKwon, H. M. et al. Effect of Corticosteroid Use on the Occurrence and Progression of Osteonecrosis of the Femoral Head: A Nationwide Nested Case-Control Study. \u003cem\u003eJ. Arthroplasty\u003c/em\u003e. \u003cb\u003e39\u003c/b\u003e (10), 2496\u0026ndash;2505e2491 (2024).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHulse, J. L. et al. Mineralocorticoid Receptors Mediate Diet-Induced Lipid Infiltration of Skeletal Muscle and Insulin Resistance. \u003cem\u003eEndocrinology\u003c/em\u003e \u003cb\u003e163\u003c/b\u003e(11). (2022).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen, W., Qing, L., Wu, P. \u0026amp; Tang, J. [Progress of pathogenesis and genetics of alcohol-induced osteonecrosis of femoral head]. \u003cem\u003eZhongguo Xiu Fu Chong Jian Wai Ke Za Zhi\u003c/em\u003e. \u003cb\u003e36\u003c/b\u003e (11), 1420\u0026ndash;1427 (2022).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSimon, L., Bourgeois, B. L. \u0026amp; Molina, P. E. Alcohol and Skeletal Muscle in Health and Disease. \u003cem\u003eAlcohol Res.\u003c/em\u003e \u003cb\u003e43\u003c/b\u003e (1), 04 (2023).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHe, K. et al. The Implications of Paraspinal Muscle Atrophy in Low Back Pain, Thoracolumbar Pathology, and Clinical Outcomes After Spine Surgery: A Review of the Literature. \u003cem\u003eGlobal Spine J.\u003c/em\u003e \u003cb\u003e10\u003c/b\u003e (5), 657\u0026ndash;666 (2020).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"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":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Femoral head necrosis, Multifidus muscle, Erector spinae muscle, Cross-sectional area, Fat infiltration","lastPublishedDoi":"10.21203/rs.3.rs-8177991/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8177991/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eObjective\u003c/strong\u003e:To investigate the correlation between the cross-sectional area and fat infiltration degree of the multifidus muscle in the lumbar core muscle group and the ARCO staging of femoral head necrosis.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e:Ninety patients with ONFH diagnosed between March 2019 and March 2025 were included and divided into Stage II, Stage III, and Stage IV groups according to ARCO staging, with 30 patients in each group. Additionally, 30 healthy volunteers were included as a control group. All subjects underwent lumbosacral 3.0T MRI examination. The cross-sectional area and fat infiltration rate of the bilateral multifidus (MF) and erector spinae (LT) muscles were measured on axial images at the L4/L5 intervertebral disc level. One-way ANOVA was used to compare differences between groups, and Spearman correlation analysis was used to assess the relationship between muscle indicators and ARCO staging.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e: Compared with the control group, the cross-sectional area of the MF and LT on the healthy side in ONFH patients significantly decreased with increasing ARCO stage, while the fat infiltration rate significantly increased. In the same ONFH patient, the cross-sectional area of the multifidus and erector spinae muscles on the affected side was significantly larger than that on the healthy side, and the fat infiltration rate was significantly lower than that on the healthy side. Spearman correlation analysis showed that ARCO staging was negatively correlated with the cross-sectional area of the MF and LT on the healthy side and positively correlated with the fat infiltration rate on the healthy side.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion\u003c/strong\u003e:Atrophy and fat infiltration of the core muscles on the healthy side of the lower back are significantly correlated with the severity of ONFH. This indicates that the pathological changes in ONFH patients are not limited to the hip joint but also involve alterations in lumbopelvic compensation mechanisms, providing imaging evidence for the assessment of core muscles and rehabilitation intervention.\u003c/p\u003e","manuscriptTitle":"Atrophy and Fat Infiltration of Contralateral Lumbar M uscles Correlate with the Severity of Osteonecrosis of the Femoral Head","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-30 00:18:43","doi":"10.21203/rs.3.rs-8177991/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-01-12T07:01:42+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-08T15:27:14+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-07T19:53:23+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"137147428162856199735762344871191605794","date":"2025-12-21T14:26:38+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"144101545450979686545313822020874880468","date":"2025-12-19T10:24:09+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-12-19T09:43:26+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-12-13T12:12:47+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-12-02T12:58:09+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-12-02T07:10:06+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-12-02T06:56:50+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"89065618-faf0-45d9-97e1-eedd3292a77b","owner":[],"postedDate":"December 30th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":60021342,"name":"Health sciences/Anatomy"},{"id":60021343,"name":"Health sciences/Diseases"},{"id":60021344,"name":"Health sciences/Health care"},{"id":60021345,"name":"Health sciences/Medical research"}],"tags":[],"updatedAt":"2026-04-16T10:54:27+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-30 00:18:43","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8177991","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8177991","identity":"rs-8177991","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}