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Background: People with knee osteoarthritis (OA) may have more thigh intermuscular and intramuscular adipose tissue (interMAT and intraMAT, respectively) compared to those without knee OA. Literature has not considered differences in body mass index (BMI) in the context of comparing intraMAT and interMAT between individuals with and without knee OA, matched for BMI (± 1 kg/m²). This study aims to compare interMAT and intraMAT, along with physical function (including knee extension strength), between individuals with and without knee osteoarthritis, matched by BMI. Methods: Participants aged ≥ 40 years with symptomatic and radiological knee OA group (grade 2 and 3 on the Kellgren and Lawrence (KL) scale) were included in the affected group, while those with no knee pain and no radiological knee OA changes were included in the unaffected group. No participants were lost to assessment, ensuring complete data analysis for all participants. We used independent t-test and mean difference (95% CI) to compare thigh intraMAT and interMAT volume, self-reported measures (WOMAC questionnaire), physical function measures, and knee extension strength between groups. Results: Forty-six participants were analyzed (23 in each group). The affected group had significantly higher intraMAT compared to the unaffected group (p < 0.05), but no differences were observed for interMAT. Self-reported outcomes and physical function measures were worse in the affected group, as was knee extension strength. Conclusion: People with knee OA present higher levels of intraMAT and poorer physical function compared to those without knee OA. These findings highlight the need for further research to explore the clinical significance of intraMAT and its potential impact on physical function in this population. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to assess clinical and radiological outcome in patients after proximal hamstring tendon repair. We hypothesized that there is a significant correlation among subjective clinical outcome and interlimb asymmetries in muscle strength, fatty infiltration, and hamstring volume. Methods: This retrospective monocentric case series included patients with surgical repair after proximal hamstring tendon rupture. Clinical outcome was assessed utilizing: Healthy Days Core Module (CDC HRQOL-4), numeric pain rating scale (NRS), modified Harris Hip Score (mHHS), Tegner Activity Scale (TAS), return to pre-injury activity level (RTPA), and patient satisfaction score. Postoperative hamstring strength was measured using a handheld dynamometer and radiological outcome was determined by postoperative magnetic resonance imaging (MRI). Results: Twenty-seven patients with a mean age of 51.2 (± 12.6) years were available for follow-up at a mean of 41.11 (± 18.4) months. Patients state a mean of 10.6 (± 11.5) days in the unhealthy days (UHD) index and 88.9% show “good health” in the simple summary score (SSS). Mean subjective outcome scores were as follows: NRS 1.1 (± 2.4), mHHS 90.3 (± 14.8) and TAS 5.7 (± 2.2). A total of 59.3% RTPA and 88.9% state to be somewhat or very satisfied with their surgery. Mean interlimb strength ratio was 0.88 (± 0.21). MRI demonstrated a fully restored muscle–tendon unit, significantly greater fatty infiltration in the injured hamstrings (p = 0.009, d = 0.558), and a mean interlimb hamstring volume ratio of 0.94 (± 0.11). With respect to the 10% benchmark, patients had no significant asymmetries in muscle strength (p = 0.677, d = 0.084) or hamstring volume (p = 0.102, d = − 0.34). Correlation analysis revealed moderate correlation among asymmetries in strength and volume (p = 0.073, r = 0.373). In patients with the operated side inferior to the healthy side (n = 15), there was strong correlation among asymmetries in strength and volume (p = 0.002, r = 0.725). Statistically significant correlation was found between interlimb muscle volume atrophy and increase in fatty infiltration (p = 0.015, r = 0.481). Conclusion: Proximal hamstring repair results in good clinical outcome with satisfactory recovery of hamstring strength and volume. Interlimb asymmetries, in terms of muscle strength, fatty infiltration, and hamstring volume do not correlate with clinical outcome. Study Type: Retrospective cohort study; Level of evidence, 3. [ABSTRACT FROM AUTHOR]

Background: Multiple factors, such as muscle fatty infiltration (FI), tendon collagen content, and collagen arrangement, determine bone-tendon interface (BTI) healing after rotator cuff (RC) repair. Purpose: To evaluate the effects of systemic administration of ezetimibe-atorvastatin (EZE/ATZ) combination on muscle FI and tendon collagen density and arrangement in an RC repair rat model. Study design: Controlled laboratory study. Methods: A total of 26 male Sprague-Dawley rats were randomly divided equally into control and EZE/ATZ groups and subjected to RC tendon repair surgery. Postoperatively, the EZE/ATZ group rats received a combination of EZE (10 mg/kg/d) and ATZ (20 mg/kg/d) for 4 weeks, after which they were sacrificed. Oil Red O staining was used to assess FI in the supraspinatus muscle. The expression of biomarkers related to muscle atrophy and FI was measured using quantitative real-time polymerase chain reaction. For the qualitative and quantitative analysis of FI-related biomarkers, immunohistochemical staining was performed. Biomechanical and histological analyses were performed to evaluate the quality of BTI healing after RC repair. Results: The EZE/ATZ group showed significantly lower FI compared with the control group (P <.001) and significantly downregulated expression of gene markers related to muscle atrophy and FI. On histological analysis, the EZE/ATZ group exhibited increased collagen type I contents, consistent collagen arrangement (P =.005), and significantly higher collagen density (P =.003) compared with the control group. Biomechanical analysis of the BTI healing revealed that the EZE/ATZ group had significantly increased ultimate strength (P =.006) compared with the control group. Conclusion: Systemic EZE/ATZ administration suppressed supraspinatus FI by downregulating muscle atrophy–related and FI-related genes after RC repair. Additionally, EZE/ATZ use improved collagen biosynthesis, density, and arrangement at the BTI and significantly increased tensile strength. Clinical Relevance: The results of the current study strongly advocate the use of EZE/ATZ to improve shoulder function and tendon healing after RC repair. [ABSTRACT FROM AUTHOR]

Fatty infiltration (FI) and muscle atrophy (MA) in the rotator cuff muscles following rotator cuff tears (RCT) persist postrepair, increasing the risk of re-tears. Brown adipocyte-like "beige adipocytes" are expected to have a therapeutic effect on intramuscular FI and MA due to their lipolytic activity and the muscle regenerative effects of their secreted factors. However, whether parathyroid hormone (PTH) ameliorates the already advanced FI and MA remains unknown. Therefore, this study aimed to clarify whether PTH promotes the expression of beige adipocytes and ameliorates advanced FI and MA following chronic RCT in rats. Supraspinatus muscles were harvested from rats with chronic RCT after 4 or 8 weeks of PTH treatment and compared to those in the control group or to those at the start of treatment. FI was assessed by Oil Red O staining, and the staining area was evaluated as a percentage of the muscle cross-sectional area. MA was evaluated by measuring muscle wet weight and cross-sectional area of muscle fiber. Beige adipocyte expression was evaluated by immunostaining for uncoupling protein 1 (UCP1). Fibro-adipogenic progenitors (FAPs) were separated from muscle-injured mice. We assessed whether PTH could diminish fat droplet accumulation by promoting the differentiation of FAPs into beige adipocytes. After 4 weeks, PTH reduced the area fraction of FI in the rat supraspinatus muscle following chronic RCT compared with that at the beginning of treatment (P =.028). In addition, PTH increased wet muscle mass (P <.001), and muscle fiber cross-sectional area (P =.018) compared with measurements at the start of treatment. PTH administration promoted the expression of UCP1, a beige adipocyte marker, in the supraspinatus muscle (P =.019). PTH increased gene expression of beige adipocyte-related markers and suppressed fat droplet accumulation even after adipogenic differentiation of FAPs (P =.004) but did not reduce fat droplets that had already accumulated in in vitro experiments. PTH facilitated beige adipocyte expression and reversibly ameliorated muscle quality and atrophy following chronic RCT by hindering fat droplet accumulation and facilitating muscle regeneration. Therefore, PTH may be a medical treatment for FI and MA following RCT, leading to expanded rotator cuff repair indications. [ABSTRACT FROM AUTHOR]

Introduction: Increased fatty infiltration of the paraspinal muscles (PM) has been recognized as a sign of decreased muscle quality in patients with degenerative disc disease. However, whether fatty infiltration is a consequence of a neurogenic process due to spinal nerve root compression has not yet been determined. Objective: To investigate the correlation between fatty infiltration of the paraspinal muscles (PM) and neurogenic remodeling of motor unit action potentials (MUAPs) in patients with lumbar radiculopathy. Materials and methods: 58 adult patients (32 women) with L5 radiculopathy caused by an L4-L5 herniated disc were examined. We compared the neurological status, EMG data of the PM at the L5 level on the affected side and the L4 level on the opposite side of the spine, and the severity of fatty infiltration of the PM assessed on axial T2-weighted magnetic resonance imaging (MRI) scans. Results: We did not find any correlation between the degree of fatty infiltration and neurogenic remodeling of MUAPs in the PM. Conclusion: The lack of correlation between the degree of fatty infiltration and the presence of neurogenic remodeling of MUAPs in the PM suggests that fatty infiltration and neuropathic changes in muscles may be considered as separate processes requiring further research. [ABSTRACT FROM AUTHOR]

Muscle atrophy, fibrosis, and fatty infiltration are commonly seen in rotator cuff tears (RCTs), which are critical factors that directly determine the clinical outcomes for patients with this injury. Therefore, improving muscle quality after RCT is crucial in improving the clinical outcome of tendon repair. In recent years, it has been discovered that adults have functional beige/brown adipose tissue (BAT) that can secrete batokines to promote muscle growth. PRDM16, a PR-domain-containing protein, was discovered with the ability to determine the brown fat cell fate and stimulate its development. Thus, the goal of this study was to discover the role of PRDM16 in improving muscle function after massive tendon tears using a transgenic mouse model with an elevated level of PRDM16 expression. Transgenic aP2-driven PRDM16-overexpressing mice and C57BL/6J mice underwent unilateral supraspinatus (SS) tendon transection and suprascapular nerve transection (TTDN) as described previously (n = 8 in each group). DigiGait was performed to evaluate forelimb function at 6 weeks post the TTDN injury. Bilateral SS muscles, interscapular brown fat, epididymal white fat, and inguinal beige fat were harvested for analysis. The expression of PRDM16 in adipose tissue was detected by Western blot. Masson Trichrome staining was conducted to evaluate the muscle fibrosis, and Oil Red O staining was used to determine the fat infiltration. Muscle fiber type was determined by major histocompatibility complex (MHC) expression via immunostaining. All data were presented in the form of mean ± standard deviation. t test and 2-way analysis of variance was performed to determine a statistically significant difference between groups. Significance was considered when P <.05. Western blot data showed an increased expression of PRDM16 protein in both white and brown fat in PRDM16-overexpressing mice compared with wild-type (WT) mice. Even though PRDM16 overexpression had no effect on increasing muscle weight, it significantly improved the forelimbs function with longer brake, stance, and stride time and larger stride length and paw area in mice after RCT. Additionally, PRDM16-overexpressing mice showed no difference in the amount of fibrosis when compared to WT mice; however, they had a significantly reduced area of fatty infiltration. These mice also exhibited abundant MHC-IIx fiber percentage in the supraspinatus muscle after TTDN. Overexpression of PRDM16 significantly improved muscle function and reduced fatty infiltration after rotator cuff tears. Promoting BAT activity is beneficial in improving rotator cuff muscle quality and shoulder function after RCT. [ABSTRACT FROM AUTHOR]

The degree of atrophy and fatty infiltration of rotator cuff muscle belly is a key predictor for cuff repairability. Traditionally, Goutallier grading of fatty infiltration is assessed at sagittal scapular Y-view. Massive rotator cuff tears are associated with tendon retraction and medial retraction of cuff musculature, resulting in medialization of the muscle bulk. Thus, standard Y-view can misrepresent the region of interest and may misguide clinicians when assessing repairability. It is hypothesized that by assessing the muscle belly with multiple medial sagittal magnetic resonance imaging (MRI) sections at the medial scapular body, the Medial Scapular Body–Goutallier Classification (MSB-GC) will improve reliability and repeatability, giving a more representative approximation to the degree of fatty infiltration, as compared with the original Y-view. Fatty infiltration of the rotator cuff muscles were classified based on the Goutallier grade (0-4) at 3 defined sections: section 1, original Y-view; section 2, level of suprascapular notch; and section 3, 3 cm medial to the suprascapular notch on MRI scans. Six subspecialist fellowship-trained shoulder surgeons and 3 musculoskeletal radiologists independently evaluated deidentified MRI scans of included patients. Of 80 scans, 78% (n = 62) were massive cuff tears involving the supraspinatus, infraspinatus, and subscapularis tendons. Interobserver reliability (consistency between observers) for Goutallier grade was excellent for all 3 predefined sections (range: 0.87-0.95). Intraobserver reliability (repeatability) for Goutallier grade was excellent for all 3 sections and 4 rotator cuff muscles (range: 0.83-0.97). There was a moderate to strong positive correlation of Goutallier grades between sections 1 and 3 and between sections 2 and 3 and these were statistically significant (P <.001). There was a reduction in the severity of fatty infiltration on the Goutallier classification from sections 1 to 3 across all muscles: 42.5% of both supraspinatus and infraspinatus were downgraded by 1, 20% of supraspinatus and 3.8% of infraspinatus were downgraded by 2, and 2.5% of supraspinatus were downgraded by 3. This study found that applying the Goutallier classification to more medial MRI sections (MSB-GC) resulted in assignment of lower grades for all rotator cuff muscles. Additionally, this method demonstrated excellent test-retest reliability and repeatability. Inclusion of a more medial view or whole scapula on MRI, especially in advanced levels of tear retraction, could be more reliable and representative for assessment of the degree of fatty infiltration within the muscle bulk that could help predict tear repairability and therefore improve clinical decision making, which should be studied further in clinical studies. [ABSTRACT FROM AUTHOR]

Abstract Failure rate after chronic rotator cuff repair is considerably high. Moreover, diabetes mellitus is known as a compromising factor of rotator cuff tear. The effect of Polydeoxyribonucleotide (PDRN) and polynucleotide (PN) on tendon healing and fatty infiltration is unclear as tissue regeneration activator in diabetic state. Therefore, a diabetic rat model with chronic rotator cuff tear was made for mechanical, histologic and blood tests. In the animal study using a diabetic rat cuff repair model, the administration of PDRN and PN increased the load to failure of repaired cuffs and improved tendon healing and decreased fatty infiltration. Also, the plasma levels of vascular endothelial growth factor and fibroblast growth factor were elevated in PDRN and PN administrated groups. We concluded that PDRN and PN appear to boost tendon recovery and reduce the presence of fatty infiltration following cuff repair in diabetic state. Also, PN showed a later onset and a longer duration than PDRN associated with the mean plasma growth factors.

Objective To evaluate the degeneration patterns of paraspinal muscles in double-level degenerative lumbar spondylolisthesis (dl-DLS) versus single-level degenerative lumbar spondylolisthesis (sl-DLS). Methods A total of 67 dl-DLS and 73 sl-DLS patients were included. Multifidus (MF), erector spinae (ES), and psoas major (PM)’s fatty infiltration (FI) and relative cross-sectional area (rCSA) were measured. Sagittal parameters such as lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS) were also assessed. Comparisons and correlation analysis were performed between the 2 groups. Results MF atrophy is worse in dl-DLS patients from L3–4 to L5–S1, with higher FI from L1–2 to L5–S1 compared to sl-DLS patients. ES atrophy and FI are more pronounced in dl-DLS patients from L1–2 to L5–S1. PM atrophy is more significant in dl-DLS patients at L2–3 to L5–S1, with heavier FI from L1–2 to L3–4, though no difference in FI from L4–5 to L5–S1. The rCSA and FI of MF and ES show significant differences between adjacent segments in both groups, except for MF rCSA between L3–4 and L4–5 in dl-DLS. In dl-DLS, PM rCSA negatively correlates with PT from L4–5 to L2–3, while FI of MF and ES in L5–S1 positively correlates with LL. In sl-DLS, PM FI in L4–5 and L5–S1 negatively correlates with LL. Conclusion Degeneration of MF, ES, and PM is more severe in dl-DLS patients, particularly at the spondylolisthesis level. Severe paraspinal muscle degeneration can lead to spinal force imbalance and progression from sl-DLS to dl-DLS. The degradation of PM and ES correlates negatively with PT and SVA, indicating a link to pelvic decompensation and SVA abnormalities, potentially causing disproportionate degenerative changes in dl-DLS patients.

BACKGROUND: Rotator cuff muscle degeneration (muscle atrophy, fibrosis and fatty infiltration) is a common condition after rotator cuff tears, which seriously affects shoulder function and surgical outcomes. Ginsenoside Rg1 has biological effects such as anti-oxidation, anti-apoptosis and lipid-lowering. However, the effect of ginsenoside Rg1 on muscle degeneration after rotator cuff tear has not been reported. OBJECTIVE: To investigate the effect of ginsenoside Rg1 on muscle degeneration after massive rotator cuff tear in mice. METHODS: Sixty C57BL/6J mice were randomly divided into sham group, model group, ginsenoside Rg1 low dose group and ginsenoside Rg1 high dose group, with 15 mice in each group. The skin of the right shoulder of mice in the sham group was cut and sutured. Massive rotator cuff tear mouse models of the right shoulder were established in the other three groups. Supraspinatus tendon and suprascapular nerve compression were administrated. Mice in the sham and model groups were intraperitoneally injected with 0.5 mL of saline after operation, while those in the ginsenoside Rg1 low and high dose groups were intraperitoneally injected with ginsenoside Rg1 30 and 60 mg/kg respectively, once a day, for 6 weeks. Mice were assessed for limb function by gait analysis the day after the last injection. After euthanasia, the supraspinatus muscle on the operated side was taken to measure the muscle atrophy rate and muscle contractility. Muscle tissue was stained with oil red O and Masson. RT-PCR was used to detect the expression of atrophy, fibrosis, and fatty infiltration related genes. RESULTS AND CONCLUSION: Compared with the model group, low- and high-dose ginsenoside Rg1 significantly increased paw print area and step length (P < 0.05). Compared with the model group, low- and high-dose ginsenoside Rg1 significantly increased myofiber cross-sectional area and supraspinatus contractility (P < 0.05), and significantly decreased wet muscle mass reduction ratio, fatty infiltration area ratio, and collagen fiber area ratio (P < 0.05). Compared with the model group, low- and high-dose ginsenoside Rg1 significantly decreased the expression of atrophy, fibrosis, and fatty infiltration related genes (P < 0.05). There was no significant difference in paw print area, supraspinatus muscle contractility, and myofiber cross-sectional area between ginsenoside Rg1 low and high dose groups (P > 0.05), and all other indexes were better in the ginsenoside Rg1 high dose group than in the ginsenoside Rg1 low dose group (P < 0.05). To conclude, ginsenoside Rg1 could significantly reduce muscle atrophy, fibrosis and fatty infiltration following massive rotator cuff tear in mice, which is beneficial to improve muscle strength and limb function. [ABSTRACT FROM AUTHOR]

Osteoporosis is a disease characterized by severe imbalance in bone metabolism, progressive reduction of bone mineral density, and increased risk of fractures, which poses a serious threat to human health and quality of life. The paravertebral muscles are an important stabilizing device of the human spine and play a vital role in the upright body of the human body. With the deepening of the study of paravertebral muscles, it is found that the paravertebral muscles are closely related to the bone mineral density of the lumbar vertebrae and even the bone mineral density of the whole body. This is highly consistent with the theory of incompatibility of flesh and blood in traditional Chinese medicine. This paper discusses the combination of various physical and chemical properties of paravertebral muscles with bone mineral density, and correlates them with the theory of incompatibility of flesh and blood, aiming to provide new insights for the diagnosis and treatment of osteoporosis. [ABSTRACT FROM AUTHOR]

Lumbar spine disorders often cause lower back pain, lower limb radiating pain, restricted movement, and neurological dysfunction, which seriously affect the quality of life of middle-aged and older people. It has been found that pathological changes in the spine often cause changes in the morphology and function of the paraspinal muscles (PSMs). Fatty infiltration (FI) in PSMs is closely associated with disc degeneration and Modic changes. And FI causes inflammatory responses that exacerbate the progression of lumbar spine disease and disrupt postoperative recovery. Magnetic resonance imaging can better distinguish between fat and muscle tissue with the threshold technique. Three-dimensional magnetic resonance imaging multi-echo imaging techniques such as water-fat separation and proton density are currently popular for studying FI. Muscle fat content obtained based on these imaging sequences has greater accuracy, visualization, acquisition speed, and utility. The proton density fat fraction calculated from these techniques has been shown to evaluate more subtle changes in PSMs. Magnetic resonance spectroscopy can accurately reflect the relationship between FI and the degeneration of PSMs by measuring intracellular and extracellular lipid values to quantify muscle fat. We have pooled and analyzed published studies and found that patients with spinal disorders often exhibit FI in PSMs. Some studies suggest an association between FI and adverse surgical outcomes, although conflicting results exist. These suggest that clinicians should consider FI when assessing surgical risks and outcomes. Future studies should focus on understanding the biological mechanisms underlying FI and its predictive value in spinal surgery, providing valuable insights for clinical decision-making. [ABSTRACT FROM AUTHOR]

Background/Objectives: Pancreatic cancer remains one of the deadliest malignancies worldwide with a pressing need for early detection and intervention strategies. Emerging evidence has suggested a potential link between pancreas steatosis, characterized by excessive pancreatic fat accumulation, and an increased risk of pancreatic cancer development. This retrospective imaging study aims to elucidate the association between pancreatic steatosis and the subsequent development of pancreatic cancer. In the study, we aimed to determine the characteristics of pancreatic cancer with pancreatic steatosis. Methods: During the period of January 2022 to December 2022, we conducted a retrospective study, collecting 101 newly diagnosed pancreas cancer cases from the available image datasets. A comprehensive database of retrospective abdominal imaging studies, comprising computed tomography (CT) and magnetic resonance imaging (MRI), was established from a diverse patient population and subsequently analyzed. Inclusion criteria encompassed patients having available baseline imaging data, allowing for the assessment of pancreatic fat content. Pancreatic fat content was quantified using validated radiological techniques, while demographic, clinical, and histopathological data were all collected. The clinical data and patient characteristics were collected from medical records and analyzed. Results: Preliminary analysis revealed a significant correlation between elevated pancreatic fat content and an increased incidence of subsequent pancreatic cancer. Moreover, subgroup analysis based on age, gender, and comorbidities provided valuable insight into potential risk factors associated with this progression. Additionally, the study identified novel radiological markers that may serve as early indicators of pancreatic cancer development in individuals with pancreatic steatosis. Conclusions: In the imaging study, approximately 30% (30/101) of pancreatic cancer patients presented with pancreatic steatosis. Chronic pancreatitis emerged as the primary factor contributing to pancreatic steatosis in these patients. Importantly, pancreatic steatosis did not significantly impact the prognosis of pancreatic cancer. Follow-up data revealed no significant differences in survival duration between patients with or without pancreatic steatosis. Additionally, no association was found between pancreatic steatosis and hepatic steatosis. [ABSTRACT FROM AUTHOR]

The purpose of this study was to establish consensus statements via a modified Delphi process on the definition of shoulder pseudoparalysis and pseudoparesis. A consensus process on the definition of a diagnosis of pseudoparalysis utilizing a modified Delphi technique was conducted, and 26 shoulder/sports surgeons from 11 countries, selected based on their level of expertise in the field, participated in these consensus statements. Consensus was defined as achieving 80%–89% agreement, whereas strong consensus was defined as 90%–99% agreement, and unanimous consensus was indicated by 100% agreement with a proposed statement. Three statements regarding the diagnosis of pseudoparalysis reached strong (>89%) consensus: passive range of motion should be unaffected, the passive range of abduction should not be considered, and diagnosis should be excluded if lidocaine injection produces a substantial improvement in range of motion. Additionally, consensus (>79%) was reached that the active range of external rotation should not be considered for diagnosis, pain as a cause of restricted motion must be excluded, and that distinctions between restricted active flexion and external rotation should be made by range of motion rather than tear characteristics. No consensus could be reached on statements regarding the size, number of tendons or chronicity of cuff tears. Nor was there agreement on the active range of flexion permitted or on the difference between pseudoparalysis and pseudoparesis. A modified Delphi process was utilized to establish consensus on the definition of shoulder pseudoparalysis and pseudoparesis. Unfortunately, almost half of the statements did not reach consensus, and agreement could not be reached across all domains for a unifying definition for the diagnosis of pseudoparalysis in the setting of rotator cuff tears. Furthermore, it was not agreed how or whether pseudoparalysis should be differentiated from pseudoparesis. Based on the lack of a consensus for these terms, studies should report explicitly how these terms are defined when they are used. [ABSTRACT FROM AUTHOR]

Background: Fatty infiltration (FI) of the supraspinatus is commonly seen in chronic large-to-massive rotator cuff tears. Evaluating FI in patients with severe muscle atrophy can be confusing. Purpose/Hypothesis: The purpose of this study was to investigate the anatomic relationship between the suprascapular artery and supraspinatus muscle on magnetic resonance imaging (MRI) to provide a method for defining the border of the supraspinatus muscle on Y-view MRI. It was hypothesized that the branches of the suprascapular artery would encircle the supraspinatus muscle on Y-view and adjacent MRI slices and could be used for defining the supraspinatus outline on oblique sagittal images. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: A total of 172 shoulders that had undergone arthroscopic repair for large-to-massive rotator cuff tears were retrospectively included. Two methods, one based on the supraspinous fossa and trapezius (SF method) and the other based on the region bounded by the branches of the suprascapular artery (SA method), were used for defining the supraspinatus outline on Y-view MRI for the assessment of FI. Preoperative supraspinatus FI grade and tangent sign and postoperative tendon integrity were evaluated. Shoulder function was assessed using the American Shoulder and Elbow Surgeons (ASES) score and active range of motion. Results: The branches of the suprascapular artery encircled the supraspinatus in all shoulders, with the diameter of the branches ranging from 0.5 to 3 mm. The agreement in supraspinatus FI grading between the SF and SA methods was 65.12%. When limited to the 61 shoulders with a positive tangent sign, the agreement dropped to 22.95% (κ = 0.032). The group (FI grade 2 by SA method and ≥3 by SF method) showed no significant difference in postoperative outcomes compared with the 2-vs-2 group but had significantly better postoperative ASES scores (P =.001) and active range of motion in forward elevation (P =.020) compared with the ≥3-vs-≥3 group. The tangent sign was positive in 92.16% of the 2-vs-≥3 group. Conclusion: The suprascapular artery is a reliable reference for the evaluation of supraspinatus FI. When a positive tangent sign presents, supraspinatus FI is likely to be overestimated if the hyperintensity outside the region bounded by the branches of the suprascapular artery is mistaken as FI. [ABSTRACT FROM AUTHOR]

Failure rate after chronic rotator cuff repair is considerably high. Moreover, diabetes mellitus is known as a compromising factor of rotator cuff tear. The effect of Polydeoxyribonucleotide (PDRN) and polynucleotide (PN) on tendon healing and fatty infiltration is unclear as tissue regeneration activator in diabetic state. Therefore, a diabetic rat model with chronic rotator cuff tear was made for mechanical, histologic and blood tests. In the animal study using a diabetic rat cuff repair model, the administration of PDRN and PN increased the load to failure of repaired cuffs and improved tendon healing and decreased fatty infiltration. Also, the plasma levels of vascular endothelial growth factor and fibroblast growth factor were elevated in PDRN and PN administrated groups. We concluded that PDRN and PN appear to boost tendon recovery and reduce the presence of fatty infiltration following cuff repair in diabetic state. Also, PN showed a later onset and a longer duration than PDRN associated with the mean plasma growth factors. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the degeneration patterns of paraspinal muscles in double-level degenerative lumbar spondylolisthesis (dl-DLS) versus single-level degenerative lumbar spondylolisthesis (sl-DLS). Methods: A total of 67 dl-DLS and 73 sl-DLS patients were included. Multifidus (MF), erector spinae (ES), and psoas major (PM)'s fatty infiltration (FI) and relative cross-sectional area (rCSA) were measured. Sagittal parameters such as lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS) were also assessed. Comparisons and correlation analysis were performed between the 2 groups. Results: MF atrophy is worse in dl-DLS patients from L3–4 to L5–S1, with higher FI from L1–2 to L5–S1 compared to sl-DLS patients. ES atrophy and FI are more pronounced in dl-DLS patients from L1–2 to L5–S1. PM atrophy is more significant in dl-DLS patients at L2–3 to L5–S1, with heavier FI from L1–2 to L3–4, though no difference in FI from L4–5 to L5–S1. The rCSA and FI of MF and ES show significant differences between adjacent segments in both groups, except for MF rCSA between L3–4 and L4–5 in dl-DLS. In dl-DLS, PM rCSA negatively correlates with PT from L4–5 to L2–3, while FI of MF and ES in L5–S1 positively correlates with LL. In sl-DLS, PM FI in L4–5 and L5–S1 negatively correlates with LL. Conclusion: Degeneration of MF, ES, and PM is more severe in dl-DLS patients, particularly at the spondylolisthesis level. Severe paraspinal muscle degeneration can lead to spinal force imbalance and progression from sl-DLS to dl-DLS. The degradation of PM and ES correlates negatively with PT and SVA, indicating a link to pelvic decompensation and SVA abnormalities, potentially causing disproportionate degenerative changes in dl-DLS patients. [ABSTRACT FROM AUTHOR]

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Background: Lumbar disc herniation (LDH) is a prevalent cause of low back pain. LDH patients commonly experience paraspinal muscle atrophy and fatty infiltration (FI), which further exacerbates the symptoms of low back pain. Magnetic resonance imaging (MRI) is crucial for assessing paraspinal muscle condition. Our study aims to develop a dual‐model for automated muscle segmentation and FI annotation on MRI, assisting clinicians evaluate LDH conditions comprehensively. Methods: The study retrospectively collected data diagnosed with LDH from December 2020 to May 2022. The dataset was split into a 7:3 ratio for training and testing, with an external test set prepared to validate model generalizability. The model's performance was evaluated using average precision (AP), recall and F1 score. The consistency was assessed using the Dice similarity coefficient (DSC) and Cohen's Kappa. The mean absolute percentage error (MAPE) was calculated to assess the error of the model measurements of relative cross‐sectional area (rCSA) and FI. Calculate the MAPE of FI measured by threshold algorithms to compare with the model. Results: A total of 417 patients being evaluated, comprising 216 males and 201 females, with a mean age of 49 ± 15 years. In the internal test set, the muscle segmentation model achieved an overall DSC of 0.92 ± 0.10, recall of 92.60%, and AP of 0.98. The fat annotation model attained a recall of 91.30%, F1 Score of 0.82, and Cohen's Kappa of 0.76. However, there was a decrease on the external test set. For rCSA measurements, except for longissimus (10.89%), the MAPE of other muscles was less than 10%. When comparing the errors of FI for each paraspinal muscle, the MAPE of the model was lower than that of the threshold algorithm. Conclusion: The models demonstrate outstanding performance, with lower error in FI measurement compared to thresholding algorithms. [ABSTRACT FROM AUTHOR]

IntroductionIncreased fatty infiltration of the paraspinal muscles (PM) has been recognized as a sign of decreased muscle quality in patients with degenerative disc disease. However, whether fatty infiltration is a consequence of a neurogenic process due to spinal nerve root compression has not yet been determined.ObjectiveTo investigate the correlation between fatty infiltration of the paraspinal muscles (PM) and neurogenic remodeling of motor unit action potentials (MUAPs) in patients with lumbar radiculopathy.Materials and methods58 adult patients (32 women) with L5 radiculopathy caused by an L4-L5 herniated disc were examined. We compared the neurological status, EMG data of the PM at the L5 level on the affected side and the L4 level on the opposite side of the spine, and the severity of fatty infiltration of the PM assessed on axial T2-weighted magnetic resonance imaging (MRI) scans.ResultsWe did not find any correlation between the degree of fatty infiltration and neurogenic remodeling of MUAPs in the PM.ConclusionThe lack of correlation between the degree of fatty infiltration and the presence of neurogenic remodeling of MUAPs in the PM suggests that fatty infiltration and neuropathic changes in muscles may be considered as separate processes requiring further research.

Objective Multiple‐level Intervertebral disc degeneration (IDD) in patients with lumbar disc herniation (LDH) is related to postoperative re‐herniation and low back pain. Although many investigators believed that there is an interdependence between paraspinal muscles degeneration and IDD, few studies focused on the fatty infiltration of paraspinal muscles on single‐ and multiple‐level IDD in patients with LDH. This study aims to investigate the difference on the fatty infiltration of paraspinal muscles between single‐ and multiple‐levels IDD in patients with LDH. and to explore in patients with LDH whether fatty infiltration is a potential risk factor for multiple‐level IDD. Methods This study was conducted as a retrospective observational analysis of 82 patients with LDH from January 1, 2020 to December 30, 2020 in our hospital were enrolled. Twenty‐seven cases had single‐level IDD (Group A), and 55 cases had multiple‐level IDD (Group B). We measured the mean computed tomography (CT) density value of the paraspinal muscles, including multifidus (MF), erector spinae (ES) and psoas muscle (PM) at each disc from L1 to S1. Subgroups were set to further analyze the odds ratio (OR) of fatty infiltration of paraspinal muscles in different sex and BMI groups. We measured sagittal angles and analyzed the relationships between these angles and IDD. Finally, we use logistic regression, adjusted for other confounding factors, to investigate whether fatty infiltration is an independent risk factor for multi‐level IDD. Results The average age in multi‐level IDD (51.40 ± 15.47 years) was significantly higher than single‐level IDD (33.37 ± 7.10 years). The mean CT density value of MF, ES and PM in single‐level IDD was significantly higher than multi‐level IDD (all ps 24.0 kg/m2) or normal, patients with low mean muscle CT density value of MF and ES are significantly easier to suffer from multiple‐level IDD. In the pure model, the average CT density value of the MF, ES and PM is all significantly associated with the occurrence of multi‐IDD. However, after adjusting for various confounding factors, only the OR of the average CT density value for MF and ES remains statistically significant (OR = 0.810, 0.834, respectively). Conclusions In patients with LDH, patients with multiple‐level IDD have more severe fatty infiltration of MF and ES than those with single‐level IDD. Fatty infiltration of MF and ES are independent risk factors for multiple‐level IDD in LDH patients.

Abstract Objective In chronic low back pain (CLBP), the relationship between spinal pathologies and paraspinal muscles fat infiltration remains unclear. This study aims to evaluate the relationship between MRI findings and paraspinal muscles morphology and fat infiltration in CLBP patients by quantitative MRI. Methods All the CLBP patients were enrolled from July 2021 to December 2022 in four medical institutions. The cross-sectional area (CSA) and proton density fat fraction (PDFF) of the multifidus (MF) and erector spinae (ES) muscles at the central level of the L4/5 and L5/S1 intervertebral discs were measured. MRI findings included degenerative lumbar spondylolisthesis (DLS), intervertebral disc degeneration (IVDD), facet arthrosis, disc bulge or herniation, and disease duration. The relationship between MRI findings and the paraspinal muscles PDFF and CSA in CLBP patients was analyzed. Results A total of 493 CLBP patients were included in the study (198 females, 295 males), with an average age of 45.68 ± 12.91 years. Our research indicates that the number of MRI findings are correlated with the paraspinal muscles PDFF at the L4/5 level, but is not significant. Moreover, the grading of IVDD is the primary factor influencing the paraspinal muscles PDFF at the L4-S1 level (BES at L4/5=1.845, P

Background: To quantify fatty infiltration and degree of paraspinal muscle degeneration in patients submitted to tubular microdiscectomy and conventional open microdiscectomy. Methods: A prospective cohort of patients was submitted to microdiscectomy for lumbar disc herniation after failure of conservative treatment. Selection of the technique was based on the surgeon’s preference. Analysis of the multifidus muscle was performed using the Goutallier system and the percentage of fat in the muscle. Preoperative and 1-year postoperative T2-weighted magnetic resonance imaging was used, and statistical analysis was carried out using the Wilcoxon test and Spearman correlation test using a significance level of 5%. Results: Thirty-two patients were included in the study. The percentage of fatty infiltration in the muscle increased on both sides of the spine 1 year after surgery, although only the ipsilateral side presented statistical significance in patients submitted to conventional microdiscectomy (43.3% preoperative and 57.8% postoperative). Muscular degeneration increased significantly ipsilateral to the disc herniation according to the Goutallier classification (grades 1–2) for both interventions. No statistically significant difference was found for fatty infiltration scores or for the degree of muscular degeneration of the multifidus in the comparative analysis of the methods. Conclusions: Muscular damage resulting from surgery of lumbar disc herniation significantly increases fatty infiltration and degeneration of the multifidus. Muscular degeneration was associated with worsening back pain. Clinical Relevance: While no significant difference was found between the techniques, the tubular minimally invasive approach shows a tendency for less muscle damage. These findings highlight the importance of minimizing muscle injury during surgery to improve postoperative recovery and long-term outcomes. [ABSTRACT FROM AUTHOR]

Objective: Multiple‐level Intervertebral disc degeneration (IDD) in patients with lumbar disc herniation (LDH) is related to postoperative re‐herniation and low back pain. Although many investigators believed that there is an interdependence between paraspinal muscles degeneration and IDD, few studies focused on the fatty infiltration of paraspinal muscles on single‐ and multiple‐level IDD in patients with LDH. This study aims to investigate the difference on the fatty infiltration of paraspinal muscles between single‐ and multiple‐levels IDD in patients with LDH. and to explore in patients with LDH whether fatty infiltration is a potential risk factor for multiple‐level IDD. Methods: This study was conducted as a retrospective observational analysis of 82 patients with LDH from January 1, 2020 to December 30, 2020 in our hospital were enrolled. Twenty‐seven cases had single‐level IDD (Group A), and 55 cases had multiple‐level IDD (Group B). We measured the mean computed tomography (CT) density value of the paraspinal muscles, including multifidus (MF), erector spinae (ES) and psoas muscle (PM) at each disc from L1 to S1. Subgroups were set to further analyze the odds ratio (OR) of fatty infiltration of paraspinal muscles in different sex and BMI groups. We measured sagittal angles and analyzed the relationships between these angles and IDD. Finally, we use logistic regression, adjusted for other confounding factors, to investigate whether fatty infiltration is an independent risk factor for multi‐level IDD. Results: The average age in multi‐level IDD (51.40 ± 15.47 years) was significantly higher than single‐level IDD (33.37 ± 7.10 years). The mean CT density value of MF, ES and PM in single‐level IDD was significantly higher than multi‐level IDD (all ps < 0.001). There was no significant difference of the mean value of angles between the two groups. No matter being fat (body mass index [BMI] > 24.0 kg/m2) or normal, patients with low mean muscle CT density value of MF and ES are significantly easier to suffer from multiple‐level IDD. In the pure model, the average CT density value of the MF, ES and PM is all significantly associated with the occurrence of multi‐IDD. However, after adjusting for various confounding factors, only the OR of the average CT density value for MF and ES remains statistically significant (OR = 0.810, 0.834, respectively). Conclusions: In patients with LDH, patients with multiple‐level IDD have more severe fatty infiltration of MF and ES than those with single‐level IDD. Fatty infiltration of MF and ES are independent risk factors for multiple‐level IDD in LDH patients. [ABSTRACT FROM AUTHOR]

Objective: In chronic low back pain (CLBP), the relationship between spinal pathologies and paraspinal muscles fat infiltration remains unclear. This study aims to evaluate the relationship between MRI findings and paraspinal muscles morphology and fat infiltration in CLBP patients by quantitative MRI. Methods: All the CLBP patients were enrolled from July 2021 to December 2022 in four medical institutions. The cross-sectional area (CSA) and proton density fat fraction (PDFF) of the multifidus (MF) and erector spinae (ES) muscles at the central level of the L4/5 and L5/S1 intervertebral discs were measured. MRI findings included degenerative lumbar spondylolisthesis (DLS), intervertebral disc degeneration (IVDD), facet arthrosis, disc bulge or herniation, and disease duration. The relationship between MRI findings and the paraspinal muscles PDFF and CSA in CLBP patients was analyzed. Results: A total of 493 CLBP patients were included in the study (198 females, 295 males), with an average age of 45.68 ± 12.91 years. Our research indicates that the number of MRI findings are correlated with the paraspinal muscles PDFF at the L4/5 level, but is not significant. Moreover, the grading of IVDD is the primary factor influencing the paraspinal muscles PDFF at the L4-S1 level (BES at L4/5=1.845, P < 0.05); DLS was a significant factor affecting the PDFF of MF at the L4/5 level (B = 4.774, P < 0.05). After including age, gender, and Body Mass Index (BMI) as control variables in the multivariable regression analysis, age has a significant positive impact on the paraspinal muscles PDFF at the L4-S1 level, with the largest AUC for ES PDFF at the L4/5 level (AUC = 0.646, cut-off value = 47.5), while males have lower PDFF compared to females. BMI has a positive impact on the ES PDFF only at the L4/5 level (AUC = 0.559, cut-off value = 24.535). Conclusion: The degree of paraspinal muscles fat infiltration in CLBP patients is related to the cumulative or synergistic effects of multiple factors, especially at the L4/L5 level. Although age and BMI are important factors affecting the degree of paraspinal muscles PDFF in CLBP patients, their diagnostic efficacy is moderate. [ABSTRACT FROM AUTHOR]

Fatty infiltration denotes the anomalous accrual of adipocytes in non-adipose tissue, thereby generating toxic substances with the capacity to impede the ordinary physiological functions of various organs. With aging, the musculoskeletal system undergoes pronounced degenerative alterations, prompting heightened scrutiny regarding the contributory role of fatty infiltration in its pathophysiology. Several studies have demonstrated that fatty infiltration affects the normal metabolism of the musculoskeletal system, leading to substantial tissue damage. Nevertheless, a definitive and universally accepted generalization concerning the comprehensive effects of fatty infiltration on the musculoskeletal system remains elusive. As a result, this review summarizes the characteristics of different types of adipose tissue, the pathological mechanisms associated with fatty infiltration in bone, muscle, and the entirety of the musculoskeletal system, examines relevant clinical diseases, and explores potential therapeutic modalities. This review is intended to give researchers a better understanding of fatty infiltration and to contribute new ideas to the prevention and treatment of clinical musculoskeletal diseases. [ABSTRACT FROM AUTHOR]

The role of lumbar paraspinal muscle health in back pain (BP) is not straightforward. Challenges in this field have included the lack of tools and large, heterogenous datasets to interrogate the association between muscle health and BP. Computer-vision models have been transformative in this space, enabling the automated quantification of muscle health and the processing of large datasets. To investigate the associations between lumbar paraspinal muscle health and age, sex, BMI, physical activity, and BP in a large, heterogenous dataset using an automated computer-vision model. Cross-sectional study. Participants from the UK Biobank with abdominal Dixon fat-water MRI (N=9,564) were included (41.8% women, mean [SD] age: 63.5 [7.6] years, BMI: 26.4 [4.1] kg/m2) of whom 6,953 reported no pain, 930 acute BP, and 1,681 chronic BP. Intramuscular fat (IMF) and average cross-sectional area (aCSA) were automatically derived using a computer-vision model for the left and right lumbar multifidus (LM), erector spinae (ES), and psoas major (PM) from the L1 to L5 vertebral levels. Two-tailed partial Pearson correlations were generated for each muscle to assess the relationships between the muscle measures (IMF and aCSA) and age (controlling for BMI, sex, and physical activity), BMI (controlling for age, sex, and physical activity), and physical activity (controlling for age, sex, and BMI). One-way ANCOVA was used to identify sex differences in IMF and aCSA for each muscle while controlling for age, BMI, and physical activity. Similarly, one-way ANCOVA was used to identify between-group differences (no pain, acute BP, and chronic BP) for each muscle and along the superior-inferior expanse of the lumbar spine while controlling for age, BMI, sex, and physical activity (α=0.05). Females had higher IMF (LM mean difference [MD]=11.1%, ES MD=10.2%, PM MD=0.3%, p<.001) and lower aCSA (LM MD=47.6 mm2, ES MD=350.0 mm2, PM MD=321.5 mm2, p<.001) for all muscles. Higher age was associated with higher IMF and lower aCSA for all muscles (r≥0.232, p<.001) except for LM and aCSA (r≤0.013, p≥.267). Higher BMI was associated with higher IMF and aCSA for all muscles (r≥0.174, p<.001). Higher physical activity was associated with lower IMF and higher aCSA for all muscles (r≥0.036, p≤.002) except for LM and aCSA (r≤0.010, p≥.405). People with chronic BP had higher IMF and lower aCSA than people with no pain (IMF MD≤1.6%, aCSA MD≤27.4 mm2, p<.001) and higher IMF compared to acute BP (IMF MD≤1.1%, p≤.044). The differences between people with BP and people with no pain were not spatially localized to the inferior lumbar levels but broadly distributed across the lumbar spine. Paraspinal muscle health is associated with age, BMI, sex, and physical activity with the exception of the association between LM aCSA and age and physical activity. People with BP (chronic>acute) have higher IMF and lower aCSA than people reporting no pain. The differences were not localized but broadly distributed across the lumbar spine. When interpreting measures of paraspinal muscle health in the research or clinical setting, the associations with age, BMI, sex, and physical activity should be considered. [ABSTRACT FROM AUTHOR]

Although previous studies have reported fatty infiltration of the gastrocnemius–soleus complex, little is known about the volumetric distribution and patterns of fatty infiltration. The purpose of this anatomical study was to document and quantify the frequency, distribution, and pattern of fatty infiltration of the gastrocnemius–soleus complex. One hundred formalin‐embalmed specimens (mean age 78.1 ± 12.3 years; 48F/52M) were serially dissected to document the frequency, distribution, and pattern of fatty infiltration in the medial and lateral heads of gastrocnemius and soleus muscles. Fatty infiltration was found in 23% of specimens, 13 unilaterally (8F/5M) and 10 (5M/5F) bilaterally. The fatty infiltration process was observed to begin medially from the medial aspect of the medial head of gastrocnemius and medial margin of soleus and then progressed laterally throughout the medial head of gastrocnemius and the marginal, anterior, and posterior soleus. The lateral head of gastrocnemius remained primarily muscular in all specimens. Microscopically, the pattern of infiltration was demonstrated as intramuscular with intact aponeuroses, and septa. The remaining endo‐, peri‐, and epimysium preserved the overall contour of the gastrocnemius–soleus complex, even in cases of significant fatty replacement. Since the external contour of the calf is preserved, the presence of fatty infiltration may be underdiagnosed in the clinic without imaging. Myosteatosis is associated with gait and balance challenges in the elderly, which can impact quality of life and result in increased risk of falling. The findings of the study have implications in the rehabilitation management of elderly patients with sarcopenia and myosteatosis. [ABSTRACT FROM AUTHOR]

Background: Previous research has emphasized the effect of prognostic factors on arthroscopic rotator cuff repair (ARCR) success, but a specific focus on subscapularis (SSC) tendon repair healing is lacking. Purpose: To identify prognostic factors for SSC healing after ARCR and develop the Subscapularis Healing Index (SSC-HI) by incorporating these factors. Study Design: Case-control study; Level of evidence, 3. Methods: This was a retrospective study using prospectively maintained data collected from patients with isolated or combined SSC tears who underwent ARCR between 2011 and 2021 at a single institution with a minimum 2-year follow-up. Functional outcomes were assessed using the American Shoulder and Elbow Surgeons (ASES) score, Subjective Shoulder Value (SSV), and visual analog scale (VAS) pain scale. SSC tendon healing was evaluated via ultrasound at the final follow-up. Multivariate logistic regression analysis was performed to determine the factors affecting SSC healing, and based on these factors, the SSC-HI, which ranges from 0 to 15 points, was developed using odds ratios (ORs). Results: Among 1018 ARCR patients, 931 met the inclusion criteria; 279 returned voluntarily for postoperative SSC ultrasound assessment. The overall healing failure rate was 10.8% (30/279). Risk factors for healing failure included female sex (P =.008; OR, 3.119), body mass index (BMI) ≥30 (P =.053; OR, 2.323), supraspinatus fatty infiltration ≥3 (P =.033; OR, 3.211), lower SSC fatty infiltration ≥2 (P =.037; OR, 3.608), and Lafosse classification ≥3 (P =.007; OR, 3.224). A 15-point scoring system comprised the following: 3 points for female sex, 2 points for BMI ≥30, 3 points for supraspinatus fatty infiltration ≥3, 4 points for lower SSC fatty infiltration ≥2, and 3 points for Lafosse classification ≥3. Patients with ≤4 points had a 4% healing failure rate, while those with ≥9 points had a 55% rate of healing failure. Patients with a healed SSC reported significantly higher ASES (healed SSC: ΔASES, 44.7; unhealed SSC: ΔASES, 29; P <.01) and SSV (healed SSC: ΔSSV, 52.9; unhealed SSC: ΔSSV, 27.5; P <.01) and lower VAS (healed SSC: ΔVAS, –4.2; unhealed SSC: ΔVAS, –3; P <.01) scores compared with those with an unhealed SSC. Conclusion: The SSC-HI scoring system integrates clinical and radiological factors to predict SSC healing after surgical repair. Successful SSC healing was found to be associated with enhanced functional outcomes, underscoring the clinical relevance of SSC healing prediction in the management of these tears. [ABSTRACT FROM AUTHOR]

Purpose of Review: Increasingly, massive irreparable rotator cuff tears present a treatment challenge due to their high re-tear rates. The reparability of such tears depends on factors like tear size, the number of involved tendons, tendon retraction extent, muscular atrophy, fatty infiltration, and the presence or absence of arthritis. There are non-surgical and several surgical treatment options described each with their specific indications, contraindications, pros, and cons. Bridging reconstruction restores the superior rotator cuff tissue and arrests humeral head superior migration. The purpose of his review is to explore the existing literature on interpositional graft mechanics, indications, surgical technique, and clinical outcomes. It aims to understand how these parameters can facilitate the incorporation of bridging reconstruction using interpositional grafts into a surgeon's practice for managing massive irreparable rotator cuff tears. Recent Findings: Interpositional grafts for irreparable massive rotator cuff tears can either be auto-, allo-, xenografts, or synthetic material and are best suited for patients who are relatively younger, no glenohumeral arthritis, and minimal to no fatty infiltration and muscle atrophy. Short to medium term outcome studies available report good functional, clinical, and radiological improvements with bridging reconstruction utilizing acellular dermal matrix allograft. Summary: Interpositional grafts for management of irreparable posterosuperior cuff tears provides improved clinical and radiological outcomes with minimal complications and thus a viable and valuable surgical technique for a shoulder surgeon's armamentarium. [ABSTRACT FROM AUTHOR]

Purpose: The relationship between functional shoulder deficits in children with neonatal brachial plexus palsy (NBPP) and magnetic resonance imaging (MRI) shoulder abnormalities was evaluated. Methods: Shoulder function was assessed in 16 children (mean age: 5.8 years; range: 3–12 years) with NBPP based on shoulder rotator muscle strength, as measured using an isokinetic dynamometer and the modified Mallet score. The thickness and fatty infiltration of the subscapularis and infraspinatus muscles, and the morphology of the glenoid on MRI, were also determined. Results: The highest subscapularis fatty infiltration subgroup of NBPP patients promoted the highest alteration muscle thickness and modified Mallet score. Conclusions: In NBPP children, subscapularis impairments play a major role in the functional limitations. This study of pediatric NBPP patients highlighted the value of adding an examination of the muscles to routine MRI assessment of bone parameters in the shoulders of NBPP children. Trial registration: NCT03440658. [ABSTRACT FROM AUTHOR]

Fatty infiltration of the rotator cuff muscles is very common following rotator cuff tears and is one of the most important factors in determining treatment. Current clinical practice relies on subjective evaluation of fatty infiltration through categorical scoring based on the Goutallier classification system. The Dixon magnetic resonance imaging (MRI) sequence provides flexibility in selecting echo times for water–fat separation. The Dixon method, therefore, has the potential to provide robust and high-quality fat quantification that allows for more accurate calculation of fat fraction (%Fat) of the rotator cuff muscles than the Goutallier classification system. However, significant variance exists in sequencing and post-processing methodology within the recent application of Dixon sequences to quantify rotator cuff fatty infiltration. In this paper, we conducted a systematic review to synthesize the relevant literature utilizing Dixon sequencing for the quantification of rotator cuff fatty infiltration. The literature search was extracted from 1094 articles, with 12 studies included in the final review. Regardless of the varying sequencing pattern and post-processing techniques among studies, the findings suggest the Dixon method is reliable for quantitatively calculating the fat fraction of the rotator cuff muscles, even at very low levels of fatty infiltration. In addition, a quantitative difference in fat fraction was observed between participants with different degrees of tear vs. those without any shoulder pathologies. Multi-point Dixon imaging has the potential to be utilized clinically to objectively quantify fatty infiltration and may lead to improved clinical decision making for patients with rotator cuff tears. [ABSTRACT FROM AUTHOR]

Purpose: This study examines the influence of preoperative fatty infiltration (FI) of the subscapularis tendon (SBS) on outcomes following reverse total shoulder arthroplasty (rTSA) with SBS repair. Methods: A cohort of 161 rTSA patients with SBS repair, followed for a mean of 45.3 months, was divided into three groups based on FI: Group A (intact upper and lower portions, n = 85), Group B (intact lower portions, n = 44), and Group C (fatty infiltrated in both portions, n = 32). The mean age was 74.5 years (range: 65–95). Results: Preoperative FI displayed significant disparity among the groups: Group A (1.18 ± 0.60), Group B (2.95 ± 0.56), and Group C (4.0 ± 0.00) (p <.001). Group A exhibited a more positive trend in activities of daily living, particularly in toileting ability (81% in Group A, 68% in Group B, and 72% in Group C), although without statistical significance (p = 0.220). Complication rates varied: Group A had seven acromial fractures (8%), three cases of instability (3%), and six instances of scapular notching (7%). Group B experienced four acromial fractures (9%) and four cases of scapular notching (9%), while Group C had only one case of scapular notching (3%) (p = 0.733). Conclusion: In cases characterized by favorable preoperative SBS quality, there was an elevation in functional internal rotation (IR) post-surgery, accompanied by an increased incidence of postoperative complications. Hence, careful consideration is advised when determining the necessity for SBS repair. Level of Evidence: Level III, retrospective comparative study. [ABSTRACT FROM AUTHOR]

Background: The effect of local corticosteroid (CS) injections on rotator cuff muscles remains poorly defined, despite the significance of muscle quality as a crucial prognostic factor for patients with rotator cuff tears (RCTs). Purpose: To compare alterations in gene and protein expression patterns in the rotator cuff muscles of patients with RCTs who received frequent joint CS injections with alterations in those without a history of CS injections. Study Design: Controlled laboratory study. Methods: A total of 24 rotator cuff muscle samples with medium-sized tears from 12 patients with a frequent joint CS injection history (steroid group; 7 men and 5 women who had received ≥5 injections with at least 1 within the previous 3 months; mean age, 63.0 ± 7.2 years) and 12 age- and sex-matched control patients without a history of CS injections (no-steroid group) were acquired. Alterations in the expression of genes and proteins associated with adipogenesis, myogenesis, inflammation, and muscle fibrosis were compared between the groups using quantitative reverse transcription–polymerase chain reaction, Western blotting, and immunohistochemistry. Statistical analysis included comparison of group means using the Mann-Whitney U test, chi-square test, or Fisher exact test and logistic regression for multivariate analysis. Results: In the steroid group, the mRNA expression levels of adipogenic CCAAT/enhancer-binding protein alpha (C/EBPα; P =.008) and muscle atrophy–related genes (atrogin; P =.019) were significantly higher, and those of myogenic differentiation 1 (MyoD; P =.035), inflammatory interleukin 6 (IL-6; P =.035), and high mobility group box 1 (P =.003) were significantly lower compared with the no-steroid group. In addition, MyoD (P =.041) and IL-6 (P =.026) expression were decreased in the steroid versus no-steroid group. Immunohistochemistry revealed increased expression of C/EBPα and atrogin and decreased expression of MyoD and IL-6 in the steroid versus no-steroid group. Conclusion: Patients with RCTs and a history of frequent CS injections exhibited an upregulation of adipogenic and muscle atrophy–related genes and proteins within the rotator cuff muscles and a downregulation in the expression of myogenic and inflammatory genes and proteins in the same muscles. Clinical Relevance: These altered gene and protein expressions by frequent local CS injections may cause poor outcomes in patients with RCTs. [ABSTRACT FROM AUTHOR]

ObjectivesTo identify risk factors for tendon healing failure following arthroscopic rotator cuff repair (ARCR) in patients with small to medium-sized rotator cuff tears (RCTs).MethodsA retrospective study was conducted on 320 patients with RCTs who underwent arthroscopic repair between June 2018 and June 2021. All patients had at least 2 years of postoperative follow-up, with MRI scans at the final assessment. Based on MRI results, patients were categorized into the healing success group (Group A: types I–III) or the healing failure group (Group B: types IV–V). Variables associated with rotator cuff healing, including patient characteristics, baseline symptoms, imaging data, and surgery-related factors, were analyzed using univariate and multivariate logistic regression.ResultsHealing failure occurred in 54 of the 320 patients (16.9%). Functional status improved significantly across all patients (P

BackgroundGoutallier’s fatty infiltration of the supraspinatus muscle is a critical condition in degenerative shoulder disorders. Deep learning research primarily uses manual segmentation and labeling to detect this condition. Employing unsupervised training with a hybrid framework of segmentation and classification could offer an efficient solution.AimTo develop and assess a two-step deep learning model for detecting the region of interest and categorizing the magnetic resonance image (MRI) supraspinatus muscle fatty infiltration according to Goutallier’s scale.Materials and methodsA retrospective study was performed from January 1, 2019 to September 20, 2020, using 900 MRI T2-weighted images with supraspinatus muscle fatty infiltration diagnoses. A model with two sequential neural networks was implemented and trained. The first sub-model automatically detects the region of interest using a U-Net model. The second sub-model performs a binary classification using the VGG-19 architecture. The model’s performance was computed as the average of five-fold cross-validation processes. Loss, accuracy, Dice coefficient (CI. 95%), AU-ROC, sensitivity, and specificity (CI. 95%) were reported.ResultsSix hundred and six shoulders MRIs were analyzed. The Goutallier distribution was presented as follows: 0 (66.50%); 1 (18.81%); 2 (8.42%); 3 (3.96%); 4 (2.31%). Segmentation results demonstrate high levels of accuracy (0.9977 ± 0.0002) and Dice score (0.9441 ± 0.0031), while the classification model also results in high levels of accuracy (0.9731 ± 0.0230); sensitivity (0.9000 ± 0.0980); specificity (0.9788 ± 0.0257); and AUROC (0.9903 ± 0.0092).ConclusionThe two-step training method proposed using a deep learning model demonstrated strong performance in segmentation and classification tasks.

Abstract Background Lumbar disc herniation (LDH) is a prevalent cause of low back pain. LDH patients commonly experience paraspinal muscle atrophy and fatty infiltration (FI), which further exacerbates the symptoms of low back pain. Magnetic resonance imaging (MRI) is crucial for assessing paraspinal muscle condition. Our study aims to develop a dual‐model for automated muscle segmentation and FI annotation on MRI, assisting clinicians evaluate LDH conditions comprehensively. Methods The study retrospectively collected data diagnosed with LDH from December 2020 to May 2022. The dataset was split into a 7:3 ratio for training and testing, with an external test set prepared to validate model generalizability. The model's performance was evaluated using average precision (AP), recall and F1 score. The consistency was assessed using the Dice similarity coefficient (DSC) and Cohen's Kappa. The mean absolute percentage error (MAPE) was calculated to assess the error of the model measurements of relative cross‐sectional area (rCSA) and FI. Calculate the MAPE of FI measured by threshold algorithms to compare with the model. Results A total of 417 patients being evaluated, comprising 216 males and 201 females, with a mean age of 49 ± 15 years. In the internal test set, the muscle segmentation model achieved an overall DSC of 0.92 ± 0.10, recall of 92.60%, and AP of 0.98. The fat annotation model attained a recall of 91.30%, F1 Score of 0.82, and Cohen's Kappa of 0.76. However, there was a decrease on the external test set. For rCSA measurements, except for longissimus (10.89%), the MAPE of other muscles was less than 10%. When comparing the errors of FI for each paraspinal muscle, the MAPE of the model was lower than that of the threshold algorithm. Conclusion The models demonstrate outstanding performance, with lower error in FI measurement compared to thresholding algorithms.

PurposeThe purpose of this study was to evaluate the agreement between paraspinal muscle composition measurements obtained from fat-water images using % fat-signal fraction (%FSF) in comparison to those obtained from T2-weighted magnetic resonance images (MRI) using a thresholding method.MethodsA sample of 35 subjects (19 females, 16 males; 40.26 ± 11.3 years old) was selected from a cohort of patients with chronic low back pain (LBP). Axial T2-weighted and IDEAL (Lava-Flex, 2 echo sequence) fat and water MR images were obtained using a 3.0 Tesla GE scanner. Multifidus, erector spinae, and psoas major muscle composition measurements were acquired bilaterally at L4-L5 and L5-S1 using both imaging sequences and related measurement methods. All measurements were obtained by the same rater, with a minimum of 7 days between each method. Intra-class correlation coefficients (ICCs) were calculated to assess intra-rater reliability. Pearson Correlation and Bland-Altman 95% limits of agreement were used to assess the agreement between both measurement methods.ResultsThe intra-rater reliability was excellent for all measurements with ICCs varying between 0.851 and 0.997. Strong positive correlations indicating a strong relationship between composition measurements were obtained from fat-water and T2-weighted images for bilateral multifidus and erector spinae muscles at both spinal levels and the right psoas major muscle at L4-L5, with correlation coefficient r ranging between 0.67 and 0.92. Bland-Altman plots for bilateral multifidus and erector spinae muscles at both levels revealed excellent agreement between the two methods, however, systematic differences between both methods were evident for psoas major fat measurements.ConclusionOur findings suggest that utilizing fat-water and T2-weighted MR images are comparable for quantifying multifidus and erector spinae muscle composition but not of the psoas major. While this suggests that both methods could be used interchangeably for the multifidus and erector spinae, further evaluation is required to expand and confirm our findings to other spinal levels.

BackgroundLumbar spine pathology is a common feature of lower back and/or lower extremity pain and is associated with observable degenerative changes in the lumbar paraspinal muscles that are associated with poor clinical prognosis. Despite the commonly observed phenotype of muscle degeneration in this patient population, its underlying molecular mechanisms are not well understood. The aim of this study was to investigate the relationships between groups of genes within the atrophic, myogenic, fibrogenic, adipogenic, and inflammatory pathways and multifidus muscle health in individuals undergoing surgery for lumbar spine pathology.MethodsMultifidus muscle biopsies were obtained from patients (n = 59) undergoing surgery for lumbar spine pathology to analyze 42 genes from relevant adipogenic/metabolic, atrophic, fibrogenic, inflammatory, and myogenic gene pathways using quantitative polymerase chain reaction. Multifidus muscle morphology was examined preoperatively in these patients at the level and side of biopsy using T2-weighted magnetic resonance imaging to determine whole muscle compartment area, lean muscle area, fat cross-sectional areas, and proportion of fat within the muscle compartment. These measures were used to investigate the relationships between gene expression patterns and muscle size and quality.ResultsRelationships between gene expression and imaging revealed significant associations between decreased expression of adipogenic/metabolic gene (PPARD), increased expression of fibrogenic gene (COL3A1), and lower fat fraction on MRI (r = -0.346, p = 0.018, and r = 0.386, p = 0.047 respectively). Decreased expression of myogenic gene (mTOR) was related to greater lean muscle cross-sectional area (r = 0.388, p = 0.045).ConclusionFibrogenic and adipogenic/metabolic genes were related to pre-operative muscle quality, and myogenic genes were related to pre-operative muscle size. These findings provide insight into molecular pathways associated with muscle health in the presence of lumbar spine pathology, establishing a foundation for future research that addresses how these changes impact outcomes in this patient population.

Aims: Rotator cuff (RC) injuries are characterized by tendon rupture, muscle atrophy, retraction, and fatty infiltration, which increase injury severity and jeopardize adequate tendon repair. Epigenetic drugs, such as histone deacetylase inhibitors (HDACis), possess the capacity to redefine the molecular signature of cells, and they may have the potential to inhibit the transformation of the fibro-adipogenic progenitors (FAPs) within the skeletal muscle into adipocyte-like cells, concurrently enhancing the myogenic potential of the satellite cells. Methods: HDACis were added to FAPs and satellite cell cultures isolated from mice. The HDACi vorinostat was additionally administered into a RC injury animal model. Histological analysis was carried out on the isolated supra- and infraspinatus muscles to assess vorinostat anti-muscle degeneration potential. Results: Vorinostat, a HDACi compound, blocked the adipogenic transformation of muscle-associated FAPs in culture, promoting myogenic progression of the satellite cells. Furthermore, it protected muscle from degeneration after acute RC in mice in the earlier muscle degenerative stage after tenotomy. Conclusion: The HDACi vorinostat may be a candidate to prevent early muscular degeneration after RC injury. Cite this article: Bone Joint Res 2024;13(4):169–183.

Objectives Osteoporotic vertebral fractures (OVFs) are a critical public health concern requiring urgent attention, and severe OVFs impose substantial health and economic burdens on patients and society. Analysis of the risk factors for severe OVF is imperative to actively prevent the occurrence of this degenerative disorder. This study aimed to investigate the risk factors associated with the severity of OVF, with a specific focus on changes in the paraspinal muscles. Methods A total of 281 patients with a first‐time single‐level acute OVF between January 2016 and January 2023 were enrolled in the study. Clinical and radiological data were collected and analyzed. The cross‐sectional area (CSA) and degree of fatty infiltration (FI) of the paraspinal muscles, including the multifidus muscles (MFMs), erector spinae muscles (ESMs), and psoas major muscles (PSMs), were measured by magnetic resonance imaging (MRI) of the L4/5 intervertebral discs. According to the classification system of osteoporotic fractures (OF classification) and recommended treatment plan, OVFs were divided into a low‐grade OF group and a high‐grade OF group. Univariate and multivariate logistic regression analyse s were performed to identify risk factors associated with the severity of OVF. Results Ninety‐eight patients were included in the low‐grade OF group, and 183 patients were included in the high‐grade OF group. Univariate analysis revealed a significantly higher incidence of a high degree of FI of MFMs (OR = 1.71, p = 0.002) and ESMs (OR = 1.56, p = 0.021) in the high‐grade OF group. Further multivariate logistic regression analysis demonstrated that a high degree of FI of the MFMs (OR = 1.71, p = 0.002) is an independent risk factor for the severity of OVF. Conclusion A high degree of FI of the MFMs was identified as an independent risk factor for the severity of OVF. Decreasing the degree of FI in the MFMs might lower the incidence of the severity of OVF, potentially reducing the necessity for surgical intervention in OVF patients.

The physiological loss of muscle mass and strength with aging is referred to as "sarcopenia", whose combined effect with osteoporosis is a serious threat to the elderly, accounting for decreased mobility and increased risk of falls with consequent fractures. In previous studies, we observed a high degree of inter-individual variability in paraspinal muscle fatty infiltration, one of the most relevant indices of muscle wasting. This aspect led us to develop a computerized method to quantitatively characterize muscle fatty infiltration in aging and diseases. Magnetic resonance images of paraspinal muscles from 58 women of different ages (age range of 23–85 years) and physio-pathological status (healthy young, pre-menopause, menopause, and osteoporosis) were used to set up a method based on fractal-derived texture analysis of lean muscle area (contractile muscle) to estimate muscle fatty infiltration. In particular, lacunarity was computed by parameter β from the GBA (gliding box algorithm) curvilinear plot fitted by our hyperbola model function. Succolarity was estimated by parameter µ, for the four main directions through an algorithm implemented with this purpose. The results show that lacunarity, by quantifying muscle fatty infiltration, can discriminate between osteoporosis and healthy aging, while succolarity can separate the other three groups showing similar lacunarity. Therefore, fractal-derived features of contractile muscle, by measuring fatty infiltration, can represent good indices of sarcopenia in aging and disease. [ABSTRACT FROM AUTHOR]

Purpose: To explore degeneration and fatty infiltration (FI) of lumbar paraspinal muscles in patients with dynamic sagittal imbalance (DSI) and the relationship between lumbar paraspinal muscles degeneration, fatty infiltration and severity of the disease. Methods: We recruited 41 DSI patients and selected 22 lumbar spinal stenosis (LSS) patients without osphyalgia as controls. All patients received magnetic resonance imaging (MRI) scan and DSI patients also received pre-walk and post-walk X-rays. DSI patients were divided into 2 subgroups according to their symptom improvement after conservative treatment. We calculated rmCSA and FI of the lumbar paraspinal muscles. The rmCSA and FI between DSI and control and between DSI subgroups were compared by t test. The regression analysis was used to explore the risk factors influencing disease severity. Receiver operating characteristic (ROC) curves and area under curves (AUCs) were used to evaluate the severity of the disease. Results: In comparison of rmCSA and FI between DSI and control, there are significant differences of most muscles. In comparison of rmCSA between two subgroups, there are significant differences of most muscles, while in comparison of FI, only muscles in L4 segment have significant different. In logistic regression analysis, total rmCSA and total FI are risk factors influencing disease severity. ROC curves shows that total rmCSA and total FI both achieve an AUC greater than 0.7. Conclusion: Compared with control, DSI patients have degeneration and fatty infiltration of the lumbar paraspinal muscles. The degeneration and fatty infiltration are risk factors influencing disease severity. The total rmCSA and total FI can be used as an indicator to determine whether a patient has severe DSI. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to investigate the association between muscle density as an indicator of fatty infiltration of lower extremity muscles and physical activity (PA) after total hip arthroplasty (THA) and identify the patient characteristics with high postoperative PA. Methods: This study included 62 female patients who underwent THA for unilateral hip osteoarthritis. Muscle density of the gluteus maximus, gluteus medius, iliopsoas, and quadriceps muscles was measured using computed tomography (CT). PA was assessed using University of California, Los Angeles (UCLA) activity scores. CT and UCLA activity score were obtained before and 1 year after THA. The patients were divided into two groups, sufficient (score ≥ 6) and insufficient (score < 6) activity groups, based on their level of PA as determined by their UCLA activity score 1 year after THA. The association of PA with the amount of changes in muscle density was examined with Spearman's rank correlation coefficient. Logistic regression analysis was performed to identify postoperative factors determining PA at 1 year after THA. Results: Spearman's rank correlation coefficient showed a significantly positive association between recovery in PA and an increase in muscle density of the gluteus maximus, gluteus medius, iliopsoas, and quadriceps muscles. Additionally, logistic regression analysis confirmed that postoperative muscle densities of the gluteus maximus and quadriceps muscles were variables determining the PA 1 year after THA. Conclusion: The findings of this study indicated that the improvement of fatty infiltration in lower limb muscles, especially in the gluteus maximus and quadriceps, is likely to promote the increase in postoperative PA. [ABSTRACT FROM AUTHOR]

Structural muscle changes, including muscle atrophy and fatty infiltration, follow rotator cuff tendon tear and are associated with a high repair failure rate. Despite extensive research efforts, no pharmacological therapy is available to successfully prevent both muscle atrophy and fatty infiltration after tenotomy of tendomuscular unit without surgical repair. Poly(ADP-ribose) polymerases (PARPs) are identified as a key transcription factors involved in the maintenance of cellular homeostasis. PARP inhibitors have been shown to influence muscle degeneration, including mitochondrial hemostasis, oxidative stress, inflammation and metabolic activity, and reduced degenerative changes in a knockout mouse model. Tenotomized infraspinatus were assessed for muscle degeneration for 16 weeks using a Swiss Alpine sheep model (n = 6). All sheep received daily oral administration of 0.5 mg Talazoparib. Due to animal ethics, the treatment group was compared with three different controls from prior studies of our institution. To mitigate potential batch heterogeneity, PARP-I was evaluated in comparison with three distinct control groups (n = 6 per control group) using the same protocol without treatment. The control sheep were treated with an identical study protocol without Talazoparib treatment. Muscle atrophy and fatty infiltration were evaluated at 0, 6 and 16 weeks post-tenotomy using DIXON-MRI. The controls and PARP-I showed a significant (control p < 0.001, PARP-I p = 0.01) decrease in muscle volume after 6 weeks. However, significantly less (p = 0.01) atrophy was observed in PARP-I after 6 weeks (control 1: 76.6 ± 8.7%; control 2: 80.3 ± 9.3%, control 3: 73.8 ± 6.7% vs. PARP-I: 90.8 ± 5.1% of the original volume) and 16 weeks (control 1: 75.7 ± 9.9; control 2: 74.2 ± 5.6%; control 3: 75.3 ± 7.4% vs. PARP-I 93.3 ± 10.6% of the original volume). All experimental groups exhibited a statistically significant (p < 0.001) augmentation in fatty infiltration following a 16-week period when compared to the initial timepoint. However, the PARP-I showed significantly less fatty infiltration (p < 0.003) compared to all controls (control 1: 55.6 ± 6.7%, control 2: 53.4 ± 9.4%, control 3: 52.0 ± 12.8% vs. PARP-I: 33.5 ± 8.4%). Finally, a significantly (p < 0.04) higher proportion and size of fast myosin heavy chain-II fiber type was observed in the treatment group. This study shows that PARP-inhibition with Talazoparib inhibits the progression of both muscle atrophy and fatty infiltration over 16 weeks in retracted sheep musculotendinous units. [ABSTRACT FROM AUTHOR]