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.

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.

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.

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.

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 establish a risk assessment system focusing on surgical and anesthesian-related indicators for the incidence of complications and mortality of hip fracture surgery in senile patients, and to evaluate its prediction accuracy, sensitivity and specificity.Methods:From January 2020 to February 2021, a total of 1 086 elderly patients (493 males and 593 females) aged 76±5 years (ranging from 60 to 94 years) underwent hip fracture surgery in Tianjin Hospital were collected. A total of 543 patients were randomly selected for the establishment of the hip fracture scoring system in senile patients, including 253 males and 290 females, aged 75±6 years (ranging from 60 to 92 years). With the preoperative physiological factor score and surgical risk factor score as independent variables and the occurrence of complications and death as dependent variables, binary logistic regression analysis was performed to establish a surgical risk scoring system for hip fracture in senile patients. The remaining 543 patients, including 240 males and 303 females, aged 74±7 years (range 60-94 years), their data were used to compare AUC, sensitivity, specificity, and compliance of the physiological and operative severity score for the enumeration of mortality and morbidity (POSSUM), Daping orthopedics operative risk scoring system for senile patient (DORSSSP), and our surgical risk scoring system for hip fracture in senile patients through receiver operating characteristic (ROC) curves, and to compare the predictive value of these systems for complication incidence and mortality.Results:The predictive model equation of the elderly hip fracture scoring system is: ln R1/ (1- R1) =-7.13+0.112× PS+0.148× OS; ln R2/ (1- R2) =-6.14+0.124× PS+0.136× OS; [ R1 is the incidence of complications, R2 is the mortality, PS (physiology score) is the score of preoperative physiological factors, and OS (operation score) is the score of surgical risk factors]. Among the 543 patients whose data were used to compared with the hip fracture scoring system, POSSUM and DORSSSP, 72 actually developed complications and 36 died. The complication rate predicted by surgical risk scoring system for hip fracture in senile patients was 12.05%±6.34% (range 6.18%-61.29%), and 64 cases were predicted to have complications. The predicted mortality was 6.05%±3.26% (range 2.45%-58.36%), and 29 cases were predicted to die. The complication rate predicted by POSSUM was 25.36%±13.95% (range 9.16%-76.34%), and 126 cases were predicted to have complications. The predicted mortality rate was 10.46%±5.31% (range 6.23%-59.34%), and 54 deaths were predicted. The predicted complication rate of DORSSSP was 19.34%±9.67% (range 8.36%-70.85%), and 99 cases were predicted to have complications. The predicted mortality was 10.12%±5.16% (range 7.35%-57.54%), and 52 deaths were predicted. In predicting the incidence of complications, the AUC of surgical risk scoring system for hip fracture in senile patients, POSSUM and DORSSSP were 0.95, 0.82 and 0.75, the sensitivity was 0.89, 0.83 and 0.85, the specificity was 0.80, 0.86 and 0.92, and the compliance rate was 0.94, 0.93 and 0.94, respectively. In the prediction of mortality, the AUC of surgical risk scoring system for hip fracture in senile patients, POSSUM and DORSSSP were 0.87, 0.67 and 0.71, the sensitivity was 0.85, 0.69 and 0.75, the specificity was 0.73, 0.94, 0.95, and the compliance rate was 0.94, 0.93 and 0.94, respectively. Conclusion:Compared with POSSUM and DORSSSP, hip fracture scoring system in elderly patients has improved its ability to predict surgical risk, and can accurately predict the incidence of complications and mortality in elderly patients undergoing hip surgery.

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 compare the differences in kinematic parameters and plantar pressures for two types of knee varus with tibial and femoral origins in gait analysis, so as to provide biomechanical theoretical basis for different types of genu varus. Methods Twenty-six patients with unilateral knee osteoarthritis (KOA) varus genu were enrolled, with 13 from femoral and 13 from tibial sources. Using Noraxon MyoMotion three-dimensional (3D) motion capture system and Footscan plantar pressure test system, the gait of the subjects during natural walking was measured, the temporal and spatial parameters of the gait, the kinematics parameters of lower limb joints and plantar pressures were collected, to make comparative analysis between the two groups. Results The range of knee flexion and extension of tibial varus, the peak of hip abduction, the range of motion (ROM) of hip adduction and abduction and the peak of ankle pronation were larger than those of femoral lateral genu varus. The peak of knee flexion and hip adduction was smaller than that of femoral lateral genu varus. Compared with femoral varus, subjects with tibial varus had increased stress time and peak pressure on the plantar of the 4th and 5th metatarsals (P<0.05). In the 3rd metatarsal region, the impulse of healthy femoral limb was greater than that of healthy limb with tibial deformity. While in the medial calcaneal region, the impulse of healthy femoral limb was smaller (P<0.05). Conclusions There are some differences in kinematic parameters and plantar pressures between two different types of unilateral genu varus patients. The results of this study are helpful to understand the abnormal gait caused by genu varus, and provide reliable reference for postoperative rehabilitation and limb exercise for different types of genu varus.