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.

Femoral fracture is a common type of fracture in clinical practice, and poor fracture reduction may lead to malunion and dysfunction. At present, traditional reduction with manipulation and intramedullary nailing are the mainstream treatments, but there exist problems such as X-ray exposure or poor reduction. Fracture reduction robots are of positive significance in improving the safety of surgical treatment of femur fracture, avoiding repetitive operations and poor alignment, and shortening the patients′ postoperative recovery time. Navigation algorithm is the key to achieve the function of femoral repositioning. Understanding the advantages and disadvantages that various types of navigation algorithms demonstrated in femoral reduction applications is important for giving full play to the value of fracture reduction robots in femoral reduction. Therefore, the authors reviewed the research progress in existing robot navigation algorithms applied in femoral fracture repositioning from the following four aspects, including image alignment algorithm, algorithm for establishing the target pose of femoral repositioning, algorithm for compensating the mechanical error, and algorithm for path planning, hoping to provide a reference for the application and research of navigation algorithms of fracture reduction robots.

Bone defects, often accompanied by osteomyelitis, soft tissue contusions, etc, are facing lengthy treatment process and slow healing, seriously jeopardizing the structural integrity of the human bone tissue. Currently, the main treatment for bone defects involves autologous or allogeneic bone transplant. However, autologous bone transplant poses problems, including long surgical duration, increased pain and complications such as infections. Additionally, immune rejection reactions also limit the effectiveness of allogeneic bone transplant of the same species. Bone scaffolds have become a potential alternative for bone transplant, but problems such as sharp edges of the scaffolds and poor compatibility with human tissues exist. Triply periodic minimal surface (TPMS), with an average curvature of zero has lower levels of stress concentration and the ability to be precisely expressed with mathematical formulas, compared with other structures. Its application in bone scaffolds attracts much attention, but there is currently a lack of comprehensive understanding of the impacts of different types of TPMS on the performance of bone scaffolds. With this purpose, the authors reviewed the research progress in the impacts of different types of TPMS on the performance of bone scaffolds, providing a reference for the construction of bone scaffolds.

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.

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 investigate biomechanical characteristics of femoral neck fracture with different reduction qualities. Methods Three cases of Sawbones artificial femoral models were selected, and two cases of Pauwel III femoral neck fracture were modeled. Three cannulated screws were inserted into the models in the form of inverted triangle to fix the fracture. Two cases maintained different reduction qualities (defined as Model 1 and Model 2). In the 3 third case, no modeling operation was performed (defined as intact model). Then the strain gauges were respectively pasted on regions of interest of the 3 femoral models. Finally, the femur model was applied with the vertical load on mechanical testing machine. Results When the displacement of femoral head reached 4 mm, the average load of intact model, Model 1 and Model 2 was (236.30±5.35), (196.57±3.56), (69.50±2.95) N, showing significant differences. When the displacement of femoral head reached 5 mm, the average load of intact model, Model 1 and Model 2 was (276.7±3.40)，(232.93±2.64)，(80.83±4.54) N, showing significant differences. Conclusions The lower the reduction quality of the femoral neck fracture, the weaker the ability of the femur to bear stress, the higher the probability of nonunion, re-fracture and femoral head necrosis in the process of postoperative rehabilitation.

OBJECTIVE: To review the research progress of design of bone scaffolds with different single cell structures. METHODS: The related literature on the study of bone scaffolds with different single cell structures at home and abroad in recent years was extensively reviewed, and the research progress was summarized. RESULTS: The single cell structure of bone scaffold can be divided into regular cell structure, irregular cell structure, cell structure designed based on topology optimization theory, and cell structure designed based on triply periodic minimal surface. Different single cell structures have different structural morphology and geometric characteristics, and the selection of single cell structure directly determines the mechanical properties and biological properties of bone scaffold. It is very important to choose a reasonable cell structure for bone scaffold to replace the original bone tissue. CONCLUSION Bone scaffolds have been widely studied, but there are many kinds of bone scaffolds at present, and the optimization of single cell structure should be considered comprehensively, which is helpful to develop bone scaffolds with excellent performance and provide effective support for bone tissue.
Bone and Bones ; Tissue Scaffolds

OBJECTIVE: To summarize the influence of microstructure on performance of triply-periodic minimal surface (TPMS) bone scaffolds. METHODS: The relevant literature on the microstructure of TPMS bone scaffolds both domestically and internationally in recent years was widely reviewed, and the research progress in the imfluence of microstructure on the performance of bone scaffolds was summarized. RESULTS: The microstructure characteristics of TPMS bone scaffolds, such as pore shape, porosity, pore size, curvature, specific surface area, and tortuosity, exert a profound influence on bone scaffold performance. By finely adjusting the above parameters, it becomes feasible to substantially optimize the structural mechanical characteristics of the scaffold, thereby effectively preempting the occurrence of stress shielding phenomena. Concurrently, the manipulation of these parameters can also optimize the scaffold's biological performance, facilitating cell adhesion, proliferation, and growth, while facilitating the ingrowth and permeation of bone tissue. Ultimately, the ideal bone fusion results will obtain. CONCLUSION The microstructure significantly and substantially influences the performance of TPMS bone scaffolds. By deeply exploring the characteristics of these microstructure effects on the performance of bone scaffolds, the design of bone scaffolds can be further optimized to better match specific implantation regions.
Tissue Scaffolds/chemistry* ; Tissue Engineering/methods* ; Bone and Bones ; Porosity