A through understanding of the biomechanics of the cervical spine is necessary to apply its knowledge to management of cervical disorders intelligently. In this article authors tried to fully review the biomechnics of cervical spine by, first, going over the basic anatomical and physiological characteristics of the cervical spine. Then, with these in mind, related kinemtics are reviewed with discussion of some of important clinical applications related to these facts. Finally, diagnostic points of cervical instability are stressed which can be used some of the guidelines in management of such patients in actual clinical situations.
Biomechanical Phenomena ; Humans ; Spine*

OBJECTIVE: To study the self-tapping performance test method of self-tapping bone screws based on the YY/T 1505 standard. METHODS: With reference to the method of YY/T 1505, various factors affecting the self-tapping force test was optimised, and the self-tapping force judgment method was improved. RESULTS: The experimental results showed that the self-tapping force obtained by the improved self-tapping force judgment method has good repeatability and high stability of the experimental data. At the same time, the test results of other influencing factors indicated that the manufacturer should fully consider the test material and the size of the pre-drilled hole. CONCLUSIONS An improved method for judging the self-tapping force is helpful for the repeatability and stability of the test data. This study has certain significance referring to the self-tapping performance test of self-tapping bone screws.
Biomechanical Phenomena ; Bone Screws

Background: Hamstring strain injury (HSI) is the most common cause of missing practices and sporting events among running-related athletes. The incidence rate of recurrence in individuals with HSI ranges from 12% to 63%. While various risk factors for HSI have been identified, the alterations and role of biomechanical factors as potential causes of injury have been largely overlooked. Objectives: To report the critical biomechanical parameters assessed among running-related athletes with a recurrent HSI and to present common testing protocols in assessing the biomechanical parameters among running-related athletes with a recurrent HSI. Methods: Eligibility Criteria: Included studies investigated biomechanical parameters assessed among collegiate or elite running-related athletes with recurrent HSI. Sources of Evidence: This scoping review was registered in OSF and was conducted based on PRISMA-ScR. Six electronic databases were systematically searched from 1993 to May 2022. Charting Methods: The reviewers created a data charting tool for the scoping review. Results: Out of 874 articles, a total of 10 articles were included in the scoping review. The critical biomechanical parameters assessed include trunk flexion, hip flexion, and knee extension angles (kinematic variables), flight and stance times and velocity (spatiotemporal variables), and EMG activity of biceps femoris, semitendinosus, semimembranosus, vastus lateralis, and rectus femoris, knee flexion and extension angle peak joint torque (kinetic variables). The most common running test protocols used were the 30-meter overground repeated sprint test, a percentage of maximum running velocity (treadmill), and repeated sprints on a non-motorized treadmill. The most common protocols for isokinetic muscle testing were 60 degrees (concentric), 300 degrees (concentric), and 180 degrees (eccentric) per second angular velocities. Conclusion The review demonstrated a need for more research on this topic, leading to only limited biomechanical parameters being discussed in the literature. This underscores the need for more rigorous research that could have practical applications for athletes and coaches.
Biomechanical Phenomena ; Athletes

Splint fixation is an external fixation system,composed of retainer, splint, paper pad and traction. Pressure under retainer is the power source of splint fixation in treatment of fractures. Now we have a review literature about the progress of type and biomechanics of fixation retainer of splint, to offer the scientific parameters for modern reform of fixation retainer of splint.
Biomechanical Phenomena ; Humans ; Splints ; classification

The kinematic model parameter deviation is the main factor affecting the positioning accuracy of neurosurgical robots. To obtain more realistic kinematic model parameters, this paper proposes an automatic parameters identification and accuracy evaluation method. First, an identification equation contains all robot kinematics parameter was established. Second, a multiple-pivot strategy was proposed to find the relationship between end-effector and tracking marker. Then, the relative distance error and the inverse kinematic coincidence error were designed to evaluate the identification accuracy. Finally, an automatic robot parameter identification and accuracy evaluation system were developed. We tested our method on both laboratory prototypes and real neurosurgical robots. The results show that this method can realize the neurosurgical robot kinematics model parameters identification and evaluation stably and quickly. Using the identified parameters to control the robot can reduce the robot relative distance error by 33.96% and the inverse kinematics consistency error by 67.30%.
Biomechanical Phenomena ; Robotic Surgical Procedures

OBJECTIVETo determine the biomechanical characteristics of mandibular fractures in different site.

METHODSNine adult mandibular specimens were measured precisely. The data was used to establish a three-dimensional model. When mandibular was under functional loading, the bending and torsion moment as well as shear force of angle, body and symphyseal fracture was calculated. The data were analyzed by Origin 6.0 software.

RESULTSAngle fracture had relatively high positive bending moment and high shear force. Body fracture had positive as well as negative bending moment and the highest torsion moments. Symphyseal fracture had only negative bending moment and relatively low shear force.

CONCLUSIONAngle, body and symphyseal fractures each have a biomechanics characteristic. These biomechanics characteristic should have an important meaning in the treatment of mandibular fractures and instructing patient how to bite correctly.

Kinematical alignment during total knee arthroplasty is an emerging process, and draws more and more attentions from scholars. Knee joint is close to normal joint after TKA through kinematical alighment, which has good clinical results and functional scores, and not increase failure probility. Thus, it may increase joint stress of patella-femur joint, lead to patellar maltracking and increase abrasion. The paper summarized defination and basical principle, operative method, clinical outcomes and deficiency of kinematical alignment during total knee arthroplasty, in order to choose a better way for kinematical alignment during total knee arthroplasty.
Arthroplasty, Replacement, Knee ; methods ; Biomechanical Phenomena ; Humans

Forensic biomechanics is the science of proof, which applies the biomechanical theory and technology to resolve problems related to mechanics in the process of expert witness. It belongs to the realm of a new subject combining biomechanics and forensics. Forensic biomechanics is a new branch of modern biomechanics and at the same time a new important branch of forensics, and it is one of the most potential research areas in forensics of injury. In this paper, the task of forensic biomechanics expert witness, the procedure of expert witness, and the forensic biomechanics research methods and cases are reviewed.
Biomechanical Phenomena ; Expert Testimony ; Forensic Medicine ; Humans

OBJECTIVE: The potential of a low-cost, novel Kinect?-based markerless motion analysis system as a tool to measure temporospatial parameters, joint and muscle kinematics, and hand trajectory patterns during the propulsion and recovery phase of wheelchair propulsion (WCP) was determined.

METHODS:Twenty (20) adult male track and field paralympians,(mean age = 36 ± 8.47) propelled themselves on a wheelchair ergometer system while their upper extremity motion was recorded by two Kinect? cameras and processed.

RESULTS: The temporospatial parameters, joint kinematics, and hand trajectory patterns during the propulsion and recovery phase of each participant's WCP cycle were determined and averaged. Average cycle time was 1.45s ± 0.19, average cadence was 0.70 cycles/s ± 0.09, and average speed was 0.76m/s ± 0.32. Average shoulder flexion was 30.99° ± 28.38, average elbow flexion was 24.23° ± 12.25, and average wrist flexion was 12.82° ± 26.78. Eighty five percent (85%) of the participants used a semicircular hand trajectory pattern.

CONCLUSION: The low-cost, novel Kinect?-based markerless motion analysis system had the potential to obtain measurable values during independent wheelchair propu
Biomechanical Phenomena ; Ergometry ; Track and Field ; Para-Athletes

As a representative part of the oral system and masticatory robot system, the modeling method of the dental model is an important factor influencing the accuracy of the multi-body dynamic model. Taking the right first molars of the masticatory robot as the research object, an equivalent model, point-contact higher kinematic pair composed of v-shaped surface and sphere surface, was proposed. Firstly, the finite element method was used to analyze the occlusal dynamics of the original model in three static contact cases (intrusive contact, centric occlusion, and extrusive contact) and one dynamic chewing case, and the expected bite force was obtained. Secondly, the Hertz contact model was adopted to establish the analytical expression of the bite force of the equivalent model in three static contact cases. The normal vectors and contact stiffness in the expression were designed according to the expected bite force. Finally, the bite force performance of the equivalent model in three static contact cases and one dynamic chewing case was evaluated. The results showed that the equivalent model could achieve the equivalent bite force of 8 expected items in the static contact cases. Meanwhile, the bite force in the early and late stages of the dynamic chewing case coincides well with the original model. In the middle stage, a certain degree of impact is introduced, but it can be weakened by subsequent trajectory planning. The equivalent modeling scheme of the dental model proposed in this paper further improves the accuracy of the dynamic model of the multi-body system. It provides a new idea for the dynamic modeling of other complex human contacts.
Biomechanical Phenomena ; Bite Force ; Humans ; Mastication ; Molar