Objective To study the effects of natural walking on human plantar pressure and surface electromyogrphy (sEMG) of lower limbs.Methods 28 healthy male volunteers were enrolled,and their plantar pressure and surface electromyogrphy related parameters were measured before and after 30 min natural walking.These parameters not only include plantar peak pressure and peak impulse,but also include time domain parameter (integral electromyogrphy,iEMG) and frequency domain parameter (mean power frequency,MPF) of tibial anterior muscle,gastrocnemius,femoral rectus,and biceps femoris muscle.The correlations between peak pressure and height as well as weight were analyzed.Results The feature parameters showed significant difference between left and right foot before and after 30 min natural walking (all P＜0.05).The differences of peak pressure and peak impulse values between left and right limb were found in different plantar areas.In the metatarsal areas M3,M4 and M5,the pressure parameters of left side were larger than those of right side (all P＜0.05).The values of iEMG and sEMG of left limb were larger than those of right side in tibialis anterior,gastrocnemius,rectus femoris and biceps femoris (all P＜ 0.05).The MPF values of sEMG of left limb were larger than those of right side in tibialis anterior and gastrocnemius (all P＜0.05).After 30 min natural walking,the peak pressures in right toe2-5 areas were decreased (all P＜0.05),the differences of iEMG of sEMG in all muscles were not significantly,and the MPF value of sEMG in left rectus femoris was decreased.Weak correlations were observed between peak pressure and height as well as weight.Conclusions The differences of left and right lower limbs were found in plantar pressure and sEMG values during natural walking.The results showed that 30 min natural walking did not cause significant stress-related fatigue in plantar areas.Therefore,the stability of gait can be maintained for a 30 min natural walking.However,that may lead to fatigue of the femoris rectus in the left limb.

Objective:To observe the effects of continuous light exposure on skeletal muscle fiber type transformation and lipid metabolism, and to explore its internal relationship.Methods:Mice were randomly divided into normal light group and 24-hour continuous light group by random number table. The serum and skeletal muscle lipid content and urine 6-sulfatoxymelatonin(6-SML)level were detected by ELISA. The expression of circadian clock and lipid metabolism related genes mRNA were observed by realtime PCR. The muscle fiber type and lipid deposition were evaluated by tissue immunofluorescence as well as oil red O staining.Results:Compared with the normal light group, the level of 6-SML in urine at night decreased( P<0.05), and the expression level and rhythm of brain and muscle ARNT-like protein 1(Bmal1), circadian locomotor output cycles protein kaput(Clock), and period 2(Per2)mRNA in the skeletal muscle changed in continuous light group. In addition, the body weight, blood lipid, free fatty acid, and triglyceride contents of skeletal muscle in continuous light group increased significantly( P<0.05 or P<0.01), the expression of carnitine palmitoyltransferase 1b (Cpt1b)mRNA, the key enzyme of fatty acid oxidation, decreased significantly( P<0.05), while the expression of stearoyl-CoA desaturase(Scd1)mRNA, a lipid synthesis related gene, increased significantly( P<0.01). Further immunofluorescence analysis showed that the proportion of slow muscle fibers decreased and that of fast muscle fibers increased in continuous light group(both P<0.05). Conclusion:The process of ectopic deposition of lipid in skeletal muscle in mice induced by continuous light exposure may be related to the remodeling of skeletal muscle fibers.

A 3D printed patient-specific surgical guide plate is an auxiliary device made with the help of computer-aided design and 3D printing technology according to a surgical plan. It is used in reduction and internal fixation of fracture and specific corrective osteotomy as well. It is very adaptive as it has been widely used in trauma surgery, joint surgery and spine surgery, as well as in surgical treatment of bone tumors. Digital orthopedic technology is an important means to realize orthopedic precision medicine. This paper reviews the technical advantages, applications, main problems and future prospects of 3D printed patient-specific surgical guide plates in the field of orthopedics based on the recent literature.

As a pandemic metabolic disease, obesity has become a worldwide problem, which endangering human health. The change in body weight reflects the energy imbalance. And the homeostasis regulation of the central and peripheral melanocortin system may maintain the energy balance and then affect the body weight. Recent studies have found that melanocortin receptor-4 ( MC4R) plays an important role in energy homeostasis and body weight changes, but its specific mechanism needs further elucidation. In this paper, we reviewed the research progress of MC4R in body weight and energy regulation, so as to provide a theoretical basis for further exploring the potential role of MC4R in improving energy metabolism imbalance and obesity.

Posttraumatic ankle arthritis caused by trauma, a common articular disease, mainly destroys the biomechanical balance of the ankle joint and results in degeneration of the joint.It often occurs in young people, leading to articular pain and stiffness and other symptoms which may deteriorate to end-stage posttrau-matic ankle arthritis with no intervention.At present, a variety of therapies are available for the disease. However, no domestic literature has addressed the choice and application of its treatment methods.To be useful in clinic, this review deals with the etiology, diagnosis and treatment (including choice, efficacy, indications and contraindications) of the disease.

The sources of common knee valgus deformities were classified in order to better plan the orthopedic methods, matching prostheses and soft tissue repair of knee valgus deformities.Based on the analysis of typical clinical cases and the operability of classification standards in practical clinical practice, it is of great significance to establish a reasonable morphological classification of knee valgus deformity, in order to grasp the characteristics and patterns of the onset of valgus deformity. According to the origin of the deformity and the tension of the medial and lateral collateral ligaments, the classification of the genu valgus deformity can be divided into the classification of the traditional Genu valgum deformity origin and the classification of the new Genu valgum deformity origin. Although both of them highlight the skeletal characteristics and soft tissue conditions of the valgus deformity, they are quite different. Traditional classification is based on femoral tibial angle, valgus angle, etc; The new classification is divided into mechanical angle, anatomical angle, distal condylar angle, etc. The origin of Genu valgum deformity is generally complex. The traditional classification cannot fully reflect the origin of valgus deformity and the tension state of soft tissue. The new classification, especially based on the classification of anatomical angle valgus deformity, can not only reflect the morphological and anatomical details of knee valgus deformity, but also reflect the tension state of the medial and lateral collateral ligaments and local soft tissue stress state that determine the stability of the knee joint. At present, the commonly used surgical methods for valgus deformity of the knee include periarticular osteotomy of the knee and total knee Joint replacement. The former focuses on correcting extraarticular deformity without over repairing ligaments, and the latter focuses on force line correction, which is the final treatment for terminal valgus deformity. The application of digital technology in clinical orthopedics can improve the accuracy of implant placement. Implant placement needs to be based on the patient's bone characteristics and degree of deformity. For patients with severe deformity, the application of digital technology can improve the accuracy of implant placement and assist in the treatment of knee valgus deformity.

Objective To observe the changes in the subfoveal choroidal thickness(SFCT)of children and adoles-cents with different refractive states using optical coherence tomography angiography.Methods A total of 171 children and adolescents were followed.They were divided into the lower primary school group(6-8 years old),upper primary school group(9-11 years old),and junior high school group(12-14 years old)according to their age at the time of en-rollment.Dioptric examinations(including best corrected visual acuity,diopter,intraocular pressure,corneal curvature,axial length and SFCT)were performed,data collection was conducted twice in half a year(initial examination and review after half a year),and the eyeball parameters and changes in eyeball parameters after half a year among all groups were compared.Results The axial length and SFCT of subjects had significant differences among all groups(both P＜0.05).In children and adolescents,the axial length gradually lengthened and SFCT gradually thickened with age,while intraocular pressure and corneal curvature were not associated with age(both P＞0.05).In the initial examination and review after half a year,there was no significant difference in intraocular pressure,corneal curvature and SFCT of subjects with differ-ent refractive states in all groups(all P＞0.05),while the axial length of myopic subjects was greater than that of non-my-opic subjects in all groups(all P＜0.05).In the review after half a year,the SFCT of non-myopic subjects in the lower pri-mary school group and upper primary school group was significantly thickened(P＜0.001,P=0.003),while there was no significant difference in SFCT of myopic subjects in all groups compared with the value half a year ago(all P＞0.05).The axial length of all subjects showed a positive correlation with the SFCT in the initial examination and review after half a year(r=0.354,0.228,P＜0.05).Conclusion Myopia affects the increase in SFCT in children and adolescents.

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.

Sarcopenia, referred to as myopenia, is a systemic syndrome characterized by decreased muscle mass and muscle strength, and decline of motor function.The elderly are a high incidence group of myopenia.With the aging of the world's population becoming increasingly severe, the incidence rate of sarcopenia has also increased, which has brought a heavy burden to the elderly family and society, and has become an important social health problem for the elderly.At present, there are more and more researches on sarcopenia, but the pathogenic factors of sarcopenia are complex and diverse.The prevention and treatment of sarcopenia still need to be further explored and studied.The establishment of an ideal animal model is the key premise and basis for the related research of sarcopenia.In this paper, the different modeling methods, advantages and disadvantages as well as the scope of application of sarcopenia animal models are described, which can provide reference and help for the subsequent animal experimental research of sarcopenia.

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.