Objective To establish a refined model of trunk composed of different lumbar segments, lumped thoracic spine and pelvis, analyze the kinematic differences between patients with lumbar disc herniation (LDH) and healthy people during three daily activities, and to compare the refined trunk model with the simplified trunk model adopting the whole lumbar segment, and discuss the necessity of using the refined trunk model for kinematic analysis of LDH patients. Methods Motion capture system NDI was used to collect kinematic parameters of each segment from 15 healthy people and 7 male LDH patients during level walking, trunk flexion and contralateral pickup, then the kinematic differences between patients and healthy people by the two models were compared respectively. Results During level walking, the rotation of the thoracic segment and pelvis for LDH patients increased, while no significant change was found in motion angle of the whole lumbar segment, and the rotation angle of L4-5 segment significantly reduced. During trunk flexion, the flexion angles of all lumbar segments for LDH patients were reduced by varying degrees, and the flexion angle of L3-4 segment was significantly different from that of healthy people. During contralateral pickup, the performance on the sagittal plane was similar to that during flexion. However, the lateral bending angles of L3-4 segment and L4-5 segment for LDH patients were significantly lower than those for healthy people. ConclusionsLDH patients mainly restrict the motion of injured lumbar segments in daily activities. During some motions, only refined model can discover the abnormal motion of injured lumbar segments. Therefore, it is necessary to subdivide the lumbar spine into 5 independent segments for analyzing the kinematic characteristics of LDH patients.

In recent years, with the growth of social development, the incidence of lumbar vertebrae diseases has increased year by year, and many surgical methods have been developed. These treatment methods mark the accumulation of surgical experience and the development of medical technology. However, a new issue appears, i.e. how to evaluate the degree of lumbar disease and postoperative rehabilitation. There is an urgent need to establish a quantitative index of preoperative examination and postoperative rehabilitation criteria for lumbar disease from both doctors’ and patients’ perspectives. The current studies show that the measurement of the center of rotation (COR) for lumbar vertebrae and surface electromyography (sEMG) can reduce the error in the evaluation of clinical curative effect for treating lumbar disease and can be applied widely. This review summarizes the relationship between COR and lumbar disease, as well as the role of COR and sEMG joint evaluation in clinical operation and postoperative rehabilitation.

Total lumbar disc replacement is an alternative to interbody fusion for the effective treatment of symptomatic degenerative disc disease. This paper reviewed the history of ball-on-socket type artificial lumbar disc (ALD) prosthesis, which is a typical ALD prosthesis and summarized the ALD prosthesis research progress, according to different materials such as metal-on-metal, metal-on-polymer, and polymer-on-polymer prosthesis. The structural design factors of ball-on-socket type ALD prosthesis were analyzed and its prospect of development was also presented. The purpose of this paper is to provide a theoretical reference for the design of the ball-on-socket ALD prosthesis by reviewing the current state of ball-on-socket type ALD prosthesis.

Objective To study the biomechanical properties of porous titanium cages used for different lumbar interbody fusion surgeries. Methods The three-dimensional (3D) finite element model of the lumbar spine was constructed, and mechanical parameters of porous materials were obtained by mechanical test. The biomechanical properties of porous titanium cages in anterior lumbar interbody fusion (ALIF), posterior lumbar interbody fusion (PLIF), transforaminal lumbar interbody fusion (TLIF), direct lateral interbody fusion (DLIF) were compared. Results After lumbar interbody surgery, the predicted range of motion (ROM) and the maximum stress in cage of DLIF model and ALIF model were substantially lower than those of PLIF model and TLIF model. The maximum stress in endplate of DLIF model, ALIF model and TLIF model were obviously lower than that of PLIF model. Conclusions DLIF with the porous cage showed advantages in biomechanical properties, which was simple to operate and suitable for minimally invasive surgery in clinical practice. DLIF performed the superior comprehensive properties.

Objective: To investigate the effect of allogeneic red blood cell transfusion on T lymphocyte subsets and natural killer (NK) cells in peripheral blood of patients with gastric cancer during perioperative period. Methods: 50 patients with gastric cancer in our hospital from January 2017 to December 2017 were randomly divided into control group (n=25) and observation group (n=25). Perioperative allogeneic erythrocyte transfusion was performed in the observation group, while no allogeneic erythrocyte transfusion was performed in the control group. Blood samples were taken from two groups before and after operation 3 d, and serum T lymphocyte subsets (CD3⁺, CD4⁺, CD8⁺, CD4⁺ /CD8⁺ ) and NK cell levels were measured. T cell subsets and NK cell levels of patients in observation group, control group and observation group at different clinical stages before and after operation were counted. According to blood transfusion volume, the patients in the observation group were divided into <4 U group and <4 U group. T cell subsets and NK cell levels before and after operation were compared between the two groups. Results: There was no significant difference in CD3⁺, CD4⁺, CD8⁺, CD4⁺ /CD8⁺, NK cells between the two groups before operation (P>0.05). The levels of CD3⁺, CD4⁺, CD4⁺ /CD8⁺, NK cells in the two groups after operation were lower than those before operation and CD8⁺ levels were higher than those before operation. The levels of CD3⁺, CD4⁺, CD4⁺ /CD8⁺, NK cells in the observation group were lower than those in the control group, and the levels of CD8⁺ in the observation group were higher than those in the control group (P<0.05). The levels of CD3⁺, CD4⁺, CD8⁺, CD4⁺ /CD8⁺, NK cells in patients with stage Ⅰ-Ⅱ and stage Ⅲ-Ⅳ had no significant difference before operation (P>0.05). After operation, the levels of CD3⁺, CD4⁺, CD4⁺ /CD8⁺, NK cells in the two groups were lower and CD8⁺ levels were higher than those before operation. The levels of CD3⁺, CD4⁺, CD4⁺ /CD8⁺, NK cells in stage Ⅰ-Ⅱ patients were higher than those in stage Ⅲ-Ⅳ patients, and CD8⁺ levels were lower than those in stage Ⅲ-Ⅳ patients (P< 0.05); There was no significant difference in the levels of CD3⁺, CD4⁺, CD8⁺, CD4⁺ /CD8⁺, NK cells between the <4 U group and <4 U group before operation (P>0.05). After operation, the levels of CD8⁺ in the two groups were higher than those before operation, while the levels of CD3⁺, CD4⁺, CD4⁺ /CD8⁺, NK cells were lower than those before operation; The levels of CD3⁺, CD4⁺, CD4⁺ /CD8⁺, NK cells in the <4 U group were higher than those in >4 U group, and CD8⁺ levels were lower than those in >4 U group (P<0.05). Conclusions Perioperative allogeneic red blood cell transfusion can affect T cell subsets and NK cell content in peripheral blood of patients with gastric cancer, and there are some differences in the effects of different clinical stages of gastric cancer patients, which can cause the suppression of cellular immune function.

The mechanical properties of artificial intervertebral disc (AID) are related to long-term reliability of prosthesis. There are three testing methods involved in the mechanical performance evaluation of AID based on different tools: the testing method using mechanical simulator, specimen testing method and finite element analysis method. In this study, the testing standard, testing equipment and materials of AID were firstly introduced. Then, the present status of AID static mechanical properties test (static axial compression, static axial compression-shear), dynamic mechanical properties test (dynamic axial compression, dynamic axial compression-shear), creep and stress relaxation test, device pushout test, core pushout test, subsidence test, etc. were focused on. The experimental techniques using specimen testing method and testing results of available artificial discs were summarized. The experimental methods and research status of finite element analysis were also summarized. Finally, the research trends of AID mechanical performance evaluation were forecasted. The simulator, load, dynamic cycle, motion mode, specimen and test standard would be important research fields in the future.

Aiming at the background and significance of biomechanical researches on lumbar interbody fusion, the research progress of interbody cage and interbody fusion was reviewed and its prospect was forecasted. The related work was summarized, including research method of lumbar biomechanics, biomechanics of interbody cage, and biomechanics of lumbar interbody fusion. The main research directions on biomechanical study of lumbar interbody fusion were: modeling refinement of finite element method， geometrical optimization of traditional fusion device, clinical application of new porous fusion device, and diversification of the supplemented fixation method. Finally, the prospect of biomechanics of lumbar interbody fusion was discussed. The review and prospect on biomechanics of lumbar interbody fusion will provide references for clinical treatment of lumbar spine diseases.

The research progress of finite element method (FEM) applied in biomechanics of lumbar fusion and artificial lumbar disc replacement was reviewed and its prospect was forecasted. The main research directions of FEM are optimal selection of operation plans before the surgery, performance evaluation of implanted devices and prediction of postoperative outcomes. Based on the recent research progress, the application prospects of FEM in simulation of personalized surgery, evaluation of elastic implants and postoperative prediction of novel operation method were discussed. By reviewing and prospecting the application of FEM in biomechanical research of lumbar fusion and artificial lumbar disc replacement, the purpose of this paper is to provide theoretical references and practical guidance for the treatment of lumbar diseases in clinic.

This article reviews the progress of biomechanical studies on anterior cervical fusion and non-fusion surgery in recent years. The similarities and differences between animal and human cervical spines as well as the major three biomechanical test methods are introduced. Major progresses of biomechanical evaluation in anterior cervical fusion and non-fusion devices, hybrid surgery, coupled motion and biomechanical parameters, such as the instant center of rotation, are classified and summarized. Future development of loading method, multilevel hybrid surgery and coupling character are also discussed.
Animals ; Biomechanical Phenomena ; Cervical Vertebrae ; surgery ; Humans ; Rotation ; Spinal Fusion ; methods

Hepatic perfusion parameters play an important role in detecting and diagnosing diffusion diseases of liver. Based on a hemodynamic model. In this study, we described a fast and accurate method to calculate the perfusion parameters. First, we used a dual-input one-compartment kinetics model to illustrate the distribution of the contrast agent concentration among the body. Then, we used the Gaussian function to fit the scatter concentration data of portal vein and aorta, to obtain a liver agent concentration on function of time. Finally, we solved the model parameters by using Levenberg-Marquardt algorithm, and calculated the perfusion parameters. The results showed that the method proposed in this study could calculate the parameters precisely, and had a prosperous future application possibility.
Algorithms ; Contrast Media ; Hemodynamics ; Humans ; Liver ; physiology ; Models, Biological ; Perfusion