Examining mechanisms involved in the mutual regulation between the muscular system and the skeletal system, elucidating the key issues responsible for loss of muscle and bone mass and strength, and thus halting the progression of these conditions are critical measures for reducing fractures caused by falls and subsequent disability and mortality.At present, most studies have treated the muscular system and the skeletal system separately, often ignoring the mutual regulation and connections between them.This article reviews the current research progress on the mechanisms of interaction between the two systems, aiming to provide a basis for the prevention, diagnosis and treatment of disuse-related diseases in the elderly population.

Objective:To explore the optimal index of rotational displacement of femoral neck fractures by modeling the axial rotational displacement of femoral neck fractures after reduction and based on X-ray projections.Methods:Six dry human femur specimens, comprising 2 males and 4 females, were utilized in the study. Design and manufacture a proximal femur ortholateral and oblique X-ray casting jigs and mounts. The femoral neck fracture was modeled on the femoral specimen, with Pauwells 30°, 50°, and 70° models (2 each) made according to Pauwells typing. The fractures were manually repositioned with residual anterior 20°, 40° and 60° axial rotational displacements. Each fracture model was projected at different angles (pedicled 40°, pedicled 20°, vertical 0°, cephalad 20°, and cephalad 40°), and the trabecular angle and Garden's alignment index of the model were measured to observe the imaging characteristics of the fracture line on the medial oblique and lateral oblique radiographs.Results:In the presence of a 20° and 40° anterior rotational displacement following reduction of a femoral neck fracture, the trabecular angle in the rotationally displaced group was not significantly different from that of the anatomically repositioned group in various projection positions. However, when a residual rotational displacement of 60° was present, the trabeculae appeared blurred at most projection angles in the Pauwells 30° and 50° models, failing to measure trabecular angles. In the Pauwells 70° fracture model, the trabecular angle in the rotational displacement group was significantly different from that in the anatomical reduction group. In anteroposterior radiographs, when the anterior rotation displacement was 60° in the Pauwells 70° group, Garden's contralateral index showed an unsatisfactory restoration (150°, 142°), whereas all rotationally displaced models in the Pauwells 30° and Pauwells 50° groups had a Garden's contralateral index of >155°, which achieved an acceptable restoration. In lateral radiographs, all rotational displacement models with Garden's alignment index>180° failed to achieve acceptable repositioning, and the larger the Pauwells angle the greater the Garden's alignment index at the same rotational displacement. In the internal oblique position with a bias towards the foot side, the image showed partial overlap between the femoral head and the shaft, making it difficult to assess the quality of the reduction. Conversely, when projected cephalad, the femoral neck appeared longer, particularly at a projection angle of 40° cephalad, allowing for clear observation of the fracture line and the anatomy of the proximal femur. The trabeculae were not well visualized in the external oblique position.Conclusion:There are limitations in applying the trabecular angle to assess the axial rotational displacement of the femoral head after reduction of femoral neck fractures. The Pauwells 70° with residual rotational anterior displacement of 60° was the only way to detect axial rotational displacement of the femoral head on anteroposterior radiographs Garden's alignment index. For the determination of axial rotational displacement of the femoral head, the Garden's alignment index on lateral radiographs provides higher reliability.

Objective: To explore mental health status of vocational college students and its association with physical exercise and exercise motivation, so as to provide data support for the promotion of physical exercise, exercise motivation theory and the protection of mental health among vocational college students. Methods: From June 2 to July 2, 2023, a convenience sampling method was used to select 1 763 college students from three vocational colleges in Sichuan, Chongqing, and Guizhou for the survey. Physical Activity Rating Scale (PARS-3), Motives for Physical Activities Measure-Revised (MPAM-R), Patient Health Questionnaire-9 (PHQ-9) and Flourishing Scale (FS) were used to assess physical exercise, exercise motivation, depressive symptoms and flourishing levels of vocational college students. Multiple linear regression analysis was conducted to examine the relationship between physical exercise, exercise motivation, depression as the negative indicator of mental health and flourishing as the positive indicator of mental health. Results: There were negative correlations between physical exercise, exercise motivation and their five factors with depression scores among vocational college students ( r=-0.162--0.133, P <0.01). Physical exercise, health motivation and pleasure motivation were positively correlated with flourishing and its eight factors among vocational college students ( r= 0.054 -0.099, P <0.05). Depression scores and flourishing scores varied significantly across students with different levels of physical exercise and exercise motivation ( F=11.18-15.69, 2.80-16.05, P <0.05). Multiple linear regression analysis indicated that physical exercise, health motivation, and total exercise motivation scores were negatively correlated with depressive symptoms ( β = -0.02 , -0.11, -0.35), and physical exercise, health motivation, pleasure motivation, and total exercise motivation scores were positively correlated with flourishing ( β =0.31, 0.32, 0.50, 0.30) ( P <0.05). Conclusions Physical exercise and exercise motivation are significantly associated with mental health of vocational college students. Enhancing physical exercise and increasing exercise motivation in aspects of health and pleasure can promote mental health of vocational college students.

Osteoporosis is an emerging threat characterized by systemic damage to bone mass and microarchitecture leading to fragility fractures.Exosomes are nanosized vesicular particles secreted by cells into the extracellular compartment with biological activities similar to those of their cell of origin and play an important role in intercellular communication processes.Exosomes from multiple cell sources are involved in the regulation of bone-related cell proliferation and differentiation during bone metabolism,and have the advantages of high stability,non-immunogenicity and strong targeting ability,which make up for the shortcomings of traditional drug and stem cell therapies.Exosomes secreted from bone marrow mesenchymal stem cells(MSCs)can promote bone regeneration and improve morphology,biomechanics and histological damage,and exosomes derived from bone marrow mesenchymal stem cells(BMSCs)in the mechanical microenvironment are more effective in inducing osteogenesis,significantly enhancing the osteogenic effect of BMSCs and promoting bone regeneration.Therefore,this article provides a review on the mechano-sensitivity of MSCs,mechanical responsive functionalized exosomes of MSCs,and explores their potential role in the treatment of osteoporosis.

The surgical reduction and fixation of subtrochanteric femoral fractures are challenging due to its particular anatomical and biomechanical characteristics. Intramedullary nailing is the golden standard for its treatment, but postoperative bone nonunion is a common complication, resulting in limb pain and decreased mobility, which requires a second operation and greatly affects the patients′ life quality. At present, there are many studies on the risk factors of bone nonunion after intramedullary nail fixation, but the risk factors with strong correlation remain unclear and the subsequent treatment plans are diverse, without consensus. Further identification of risk factors can help to select treatment plans. To this end, the authors reviewed the research progress in the risk factors and treatment methods of bone nonunion after intramedullary nailing of subtrochanteric femoral fractures to provide references for its clinical treatment.

Shape memory materials are intelligent materials that have the effect of remembering and recovering their original shape in response to external stimuli. The preparation methods include heat treatment and laser sintering for alloy-based memory materials, and thermoplastic methods for polymer-based and composite shape memory materials. Shape memory materials have shown great application value in the field of orthopaedics, such as fracture treatment, bone tissue engineering repair, spinal correction and joint replacement. Shape memory materials have excellent biomechanical properties, providing sustained and effective compression, support and torsion resistance during fracture treatment, as well as the advantage of reducing stress masking in internal fixation of fractures. The sustained stress exerted on the surrounding bone tissue due to environmental changes provides continuous corrective force for spinal deformity correction, and improves the durability of prostheses in arthroplasty. Shape memory materials exhibit good biocompatibility and the performance of inducing cell proliferation, making them suitable for fabricating self-adapting" scaffolds for tissue engineering. When precisely filling bone defect sites, they apply mechanical forces to the autogenous bone, stimulate the proliferation and differentiation of osteoblasts, guide bone regeneration and accelerate bone repair. Moreover, shape memory materials can be used as carriers for drug delivery and release, controlling drug release by adjusting temperature, stress and environmental factors to achieve targeted therapy. With the development of 4D printing technology, shape memory materials have extensive potential in the fields of personalized orthopaedic diagnosis and treatment as well as individualized medical device customization.

Objective:To explore the role and mechanism of miR-485-5p targeted regulation of WNT7B in regulating osteogenic differentiation of bone marrow mesenchymal stem cell (BMSC). Methods:15 osteoporotic patients who underwent hip replacement due to hip fracture in Tianjin Hospital from January to October 2023 were collected, and bone tissues in the femoral head in the area of reduced bone density detected by the dual-energy X-ray absorptiometry (DXA) method were collected (osteoporosis group); 15 patients who underwent joint replacement due to osteoarthritis were matched according to their age and body mass index, and bone tissues in the femoral head in the area of normal bone density were collected (no osteoporosis group). MiR-485-5p and WNT7B were detected using qRT-PCR technology; the target genes and potential mechanisms of miR-485-5p were predicted using bioinformatics technology, and the relationship between miR-485-5p and WNT7B was analyzed by dual luciferase reporter system. The miR-485-5p overexpression (mimic) and inhibitor (inhibitor) were constructed and divided into control, miR-485-5p group and miR-485-5p inhibitor group. After alkaline phosphatase staining (ALP) and alizarin red staining (ARS), osteogenesis-related proteins were detected by Western blot (ALP, BMP-2, Runx2, OPN, OCN); expression of osteogenic proteins was detected by transfection of miR-485-5p inhibitor and WNT7B siRNA into BMSC. Results:The relative expression of miR-485-5p in the osteoporosis group was 7.54±0.49, which was higher than that in the no-osteoporosis group with significant difference ( t=4.11, P<0.001), while the relative expression of WNT7B was significantly lower ( t=3.38, P<0.001), which was negatively correlated with miR-485-5p; bioinformatics analysis found that miR-485-5p targeted 666 genes, miR-485-5p could bind the 3'UTR of WNT7B, and the main mechanism was related to the Wnt/β-catenin signaling pathway; ALP activity and calcium deposition were reduced in the miR-485-5p group compared with the control group, and ALP, BMP-2, Runx2, OPN, OCN, WNT7B and β-catenin proteins were 0.78±0.13, 0.68±0.16, 0.59±0.19, 0.54±0.14, 0.74±0.12, 0.49±0.17, 0.52±0.19, respectively, which were significantly reduced compared with the control group ( t=3.214, P<0.001; t=3.637, P<0.001; t=3.479, P<0.001; t=4.062, P<0.001; t=4.271, P<0.001; t=4.164, P<0.001; t=4.621, P<0.001), and ALP activity, calcium deposition were reduced; ALP, BMP-2, Runx2, OPN, OCN in miR-485-5p inhibition group, WNT7B and β-catenin protein relative expression were 1.29±0.21, 1.24±0.19, 1.16±0.24, 1.31±0.27, 1.45±0.25, 1.05±0.19, 1.41±0.26, respectively, which were significantly higher compared with the control group ( t=3.156, P<0.001; t=3.645, P<0.001; t=3.473, P<0.001; t=3.954, P<0.001; t=4.006, P<0.001; t=3.889, P<0.001; t=4.513, P<0.001). The relative expression of OPN, WNT7B and β-catenin proteins in the miR-485-5p inhibition group were 1.42±0.21, 1.38±0.32, 1.16±0.2.ALP activity was significantly lower in the miR-485-5p inhibition+WNT7Bi group, with lighter ARS staining, fewer bone deposits, and reduced bone-forming related proteins OPN, WNT7B and β-catenin relative expression of 1.08±0.19, 0.71±0.22, and 0.84±0.25, which were all significantly reduced ( t=3.675, P<0.001; t=3.401, P<0.001; t=3.354, P<0.001). Conclusion:MiR-485-5p overexpression slowed down the process of osteogenic differentiation and caused down-regulation of the expression of related proteins, whereas miR-485-5p inhibition promoted osteogenic differentiation and was negatively correlated with WNT7B in the bone tissues of osteoporosis patients. MiR-485-5p binds to the WNT7B mRNA target, which in turn influences the expression of related proteins of WNT7B, and the mechanism of its action is that miR-485-5p targeted to regulate WNT7B-mediated Wnt/β-catenin signalling pathway inhibits BMSC osteogenic differentiation.

Objective:To propose a method to measure the femoral anteversion angle based on the three-dimensional model of femur.Methods:From January 2019 to December 2023, a total of 50 patients (100 femurs) with patellar instability who underwent full-length CT examination of both lower limbs in Tianjin Hospital were retrospectively analyzed, including 16 males and 34 females, aged 28.5±11.9 years (range, 16-57 years). All patients underwent CT examination of both lower limbs, and the imaging data were imported into Mimics 21.0 software as DICOM format files. The femur was extracted by the threshold segmentation function, and the 3D model of the femur was reconstructed by appropriate trimming and smoothing. Three-dimensional models of the femur from 30 patients (60 femurs) were selected and imported into 3-matic 13.0 software for labeling of anatomical points and drawing of axes. The angle between the axis of the distal femur and the axis of the proximal femur was the femoral anteversion angle. Two observers positioned the spatial coordinates of the intercondylar fossa apex, the greater trochanter apex, the center of the femoral head, the femoral through-condylar axis and the posterior condylar tangent marker points on a 3D model of the femur to compare the differences between the groups. The femoral anteversion angles measured by different three-dimensional measurement methods were compared with the clinically reported femoral anteversion angles.Results:The difference between the femoral head center and intercondylar fossa apex coordinate data of 30 patients (60 femurs) measured by the two observers was not statistically significant ( P>0.05), whereas the data for the Y-axis coordinate of the greater trochanter apex were 25.77±23.21 and 22.08±25.73, respectively, and the difference was statistically significant ( t=2.906, P=0.017). The difference between the data of femoral through condylar and posterior condylar tangential coordinates of 30 patients (60 femurs) measured by the two observers was not statistically significant ( P>0.05). Using the femoral mechanical axis as the projection direction, the angle between the transcondylar axis and the posterior condylar tangent line was 5.97°±2.02° (range, 1.48°-12.08°). The anterior tilt of the femur measured by the two observers in the femoral neck cylinder fitting method was 23.35°±7.45° and 24.94°±9.01°, respectively, and the difference was statistically significant ( t=-2.147, P=0.040). The anterior inclination of the femur measured by the two observers in the femoral head ball enlargement method was 24.63°±7.66° and 25.12°±8.84°, the difference was not statistically significant ( t=-0.820, P=0.419). Using the femoral head ball expansion method to locate the proximal femoral axis, two observers measured the anterior tilt angle of the femur in 50 patients (100 femurs) according to the method described above, which was 23.30°±9.41° and 23.57°±9.97°, respectively, without a statistically significant difference ( t=-0.664, P=0.508), both smaller than the 29.56°±8.74° measured based on two-dimensional images in the imaging report, and the difference was statistically significant ( P<0.05). Conclusion:The femoral anteversion angle measured by the angle between the axis of the femoral condyle and the axis of the femoral neck based on the three-dimensional model is accurate and effective, and the measured value is smaller than that based on the two-dimensional images in clinical practice.

In recent years, with the advancement of diagnostic and treatment technology, lumbosacral extra-canal nerve root entrapment has gradually attracted attention. Patients often have hypertrophy of the transverse process, high iliac spine, proliferation of the articular process joints and iliopsoas ligaments, and extreme lateral herniation of the intervertebral disc, mostly classified as type 1-2 in the lumbosacral triangle, because of which misdiagnosis is not uncommon in clinic. Diffusion tensor imaging and magnetic resonance neurography can display the compressed nerve root. The main purpose of surgical treatment is to fully relieve nerve compression and thus appropriate surgical techniques should be selected based on the site of compression and the classification of the lumbosacral triangle, including paraspinal or Wiltse approach TLIF, micro foraminotomy, and endoscopic decompression. Direct introduction of a co-axis endoscopic tube into the narrow space may compress or damage the nerve root; while foramen fenestration or extra-foraminal biportal endoscopy can be used to sufficiently decompress the nerve root with floating tube.

Osteotomy around the knee includes medial opening wedge high tibial osteotomy (HTO), lateral closing wedge HTO, lateral opening wedge distal femoral osteotomy (DFO), medial opening wedge DFO, and double-site osteotomy. Osteotomy redistributes the knee joint pressure by correcting the lower limb alignment, which can effectively delay the progression of knee osteoarthritis. Currently, three methods are used to determine the intraoperative osteotomy angle: the pre-drilling method, wedge block insertion method, and angle-guided linkage method. Coronal plane accuracy is evaluated using the hip-knee-ankle (HKA) angle, medial proximal tibial angle (MPTA), and ratio of lower limb weight-bearing line, while sagittal plane accuracy is assessed by measuring the posterior tibial slope (PTS). Individualized osteotomy guide plate can enhance osteotomy accuracy. The preparation process includes: (1) importing low-dose CT data of both lower limbs in DICOM format into reconstruction software to establish a 3D model of both lower limbs; (2) determining the osteotomy plane and distraction angle through threshold segmentation, importing the plate model, and establishing the length and position of each screw; (3) using fused deposition modeling to layer materials through a nozzle to create the 3D object. Individualized osteotomy guide plate in osteotomy around the knee can not only improve the accuracy of surgery, but also reduce the intraoperative fluoroscopy times and the incidence of complications. The operation efficiency and postoperative rehabilitation are better than those of traditional surgery. With the continuous upgrading of new materials and the improvement of design concepts, the accuracy and efficiency of individualized osteotomy guide will be further improved. Future research will focus on improving the degree of personalization of guide plate design and simplifying the manufacturing process.