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

OBJECTIVE: To explore the effect of chitosan (CS) hydrogel loaded with tendon-derived stem cells (TDSCs; hereinafter referred to as TDSCs/CS hydrogel) on tendon-to-bone healing after rotator cuff repair in rabbits. METHODS: TDSCs were isolated from the rotator cuff tissue of 3 adult New Zealand white rabbits by Henderson step-by-step enzymatic digestion method and identified by multidirectional differentiation and flow cytometry. The 3rd generation TDSCs were encapsulated in CS to construct TDSCs/CS hydrogel. The cell counting kit 8 (CCK-8) assay was used to detect the proliferation of TDSCs in the hydrogel after 1-5 days of culture in vitro, and cell compatibility of TDSCs/CS hydrogel was evaluated by using TDSCs alone as control. Another 36 adult New Zealand white rabbits were randomly divided into 3 groups ( n=12): rotator cuff repair group (control group), rotator cuff repair+CS hydrogel injection group (CS group), and rotator cuff repair+TDSCs/CS hydrogel injection group (TDSCs/CS group). After establishing the rotator cuff repair models, the corresponding hydrogel was injected into the tendon-to-bone interface in the CS group and TDSCs/CS group, and no other treatment was performed in the control group. The general condition of the animals was observed after operation. At 4 and 8 weeks, real-time quantitative PCR (qPCR) was used to detect the relative expressions of tendon forming related genes (tenomodulin, scleraxis), chondrogenesis related genes (aggrecan, sex determining region Y-related high mobility group-box gene 9), and osteogenesis related genes (alkaline phosphatase, Runt-related transcription factor 2) at the tendon-to-bone interface. At 8 weeks, HE and Masson staining were used to observe the histological changes, and the biomechanical test was used to evaluate the ultimate load and the failure site of the repaired rotator cuff to evaluate the tendon-to-bone healing and biomechanical properties. RESULTS: CCK-8 assay showed that the CS hydrogel could promote the proliferation of TDSCs ( P<0.05). qPCR results showed that the expressions of tendon-to-bone interface related genes were significantly higher in the TDSCs/CS group than in the CS group and control group at 4 and 8 weeks after operation ( P<0.05). Moreover, the expressions of tendon-to-bone interface related genes at 8 weeks after operation were significantly higher than those at 4 weeks after operation in the TDSCs/CS group ( P<0.05). Histological staining showed the clear cartilage tissue and dense and orderly collagen formation at the tendon-to-bone interface in the TDSCs/CS group. The results of semi-quantitative analysis showed that compared with the control group, the number of cells, the proportion of collagen fiber orientation, and the histological score in the TDSCs/CS group increased, the vascularity decreased, showing significant differences ( P<0.05); compared with the CS group, the proportion of collagen fiber orientation and the histological score in the TDSCs/CS group significantly increased ( P<0.05), while there was no significant difference in the number of cells and vascularity ( P>0.05). All samples in biomechanical testing failed at the repair site during the testing process. The ultimate load of the TDSCs/CS group was significantly higher than that of the control group ( P<0.05), but there was no significant difference compared to the CS group ( P>0.05). CONCLUSION TDSCs/CS hydrogel can induce cartilage regeneration to promote rotator cuff tendon-to-bone healing.
Rabbits ; Animals ; Rotator Cuff/surgery* ; Chitosan ; Hydrogels ; Rotator Cuff Injuries/surgery* ; Wound Healing ; Tendons/surgery* ; Collagen ; Stem Cells ; Biomechanical Phenomena

OBJECTIVE: To review the biomechanical research progress of internal fixation of tibial plateau fracture in recent years and provide a reference for the selection of internal fixation in clinic. METHODS: The literature related to the biomechanical research of internal fixation of tibial plateau fracture at home and abroad was extensively reviewed, and the biomechanical characteristics of the internal fixation mode and position as well as the biomechanical characteristics of different internal fixators, such as screws, plates, and intramedullary nails were summarized and analyzed. RESULTS: Tibial plateau fracture is one of the common types of knee fractures. The conventional surgical treatment for tibial plateau fracture is open or closed reduction and internal fixation, which requires anatomical reduction and strong fixation. Anatomical reduction can restore the normal shape of the knee joint; strong fixation provides good biomechanical stability, so that the patient can have early functional exercise, restore knee mobility as early as possible, and avoid knee stiffness. Different internal fixators have their own biomechanical strengths and characteristics. The screw fixation has the advantage of being minimally invasive, but the fixation strength is limited, and it is mostly applied to Schatzker typeⅠfracture. For Schatzker Ⅰ-Ⅳ fracture, unilateral plate fixation can be used; for Schatzker Ⅴand Ⅵ fracture, bilateral plates fixation can be used to provide stronger fixation strength and avoid the stress concentration. The intramedullary nails fixation has the advantages of less trauma and less influence on the blood flow of the fracture end, but the fixation strength of the medial and lateral plateau is limited; so it is more suitable for tibial plateau fracture that involves only the metaphysis. Choosing the most appropriate internal fixation according to the patient's condition is still a major difficulty in the surgical treatment of tibial plateau fractures. CONCLUSION Each internal fixator has good fixation effect on tibial plateau fracture within the applicable range, and it is an important research direction to improve and innovate the existing internal fixator from various aspects, such as manufacturing process, material, and morphology.
Humans ; Biomechanical Phenomena ; Bone Plates ; Fracture Fixation, Internal ; Fracture Fixation, Intramedullary ; Tibial Fractures/surgery* ; Tibial Plateau Fractures

OBJECTIVE: To design customized titanium alloy lunate prosthesis, construct three-dimensional finite element model of wrist joint before and after replacement by finite element analysis, and observe the biomechanical changes of wrist joint after replacement, providing biomechanical basis for clinical application of prosthesis. METHODS: One fresh frozen human forearm was collected, and the maximum range of motions in flexion, extension, ulnar deviation, and radialis deviation tested by cortex motion capture system were 48.42°, 38.04°, 35.68°, and 26.41°, respectively. The wrist joint data was obtained by CT scan and imported into Mimics21.0 software and Magics21.0 software to construct a wrist joint three-dimensional model and design customized titanium alloy lunate prosthesis. Then Geomagic Studio 2017 software and Solidworks 2017 software were used to construct the three-dimensional finite element models of a normal wrist joint (normal model) and a wrist joint with lunate prosthesis after replacement (replacement model). The stress distribution and deformation of the wrist joint before and after replacement were analyzed for flexion at and 15°, 30°, 48.42°, extension at 15°, 30°, and 38.04°, ulnar deviation at 10°, 20°, and 35.68°, and radial deviation at 5°, 15°, and 26.41° by the ANSYS 17.0 finite element analysis software. And the stress distribution of lunate bone and lunate prosthesis were also observed. RESULTS: The three-dimensional finite element models of wrist joint before and after replacement were successfully constructed. At different range of motion of flexion, extension, ulnar deviation, and radial deviation, there were some differences in the number of nodes and units in the grid models. In the four directions of flexion, extension, ulnar deviation, and radial deviation, the maximum deformation of wrist joint in normal model and replacement model occurred in the radial side, and the values increased gradually with the increase of the range of motion. The maximum stress of the wrist joint increased gradually with the increase of the range of motion, and at maximum range of motion, the stress was concentrated on the proximal radius, showing an overall trend of moving from the radial wrist to the proximal radius. The maximum stress of normal lunate bone increased gradually with the increase of range of motion in different directions, and the stress position also changed. The maximum stress of lunate prosthesis was concentrated on the ulnar side of the prosthesis, which increased gradually with the increase of the range of motion in flexion, and decreased gradually with the increase of the range of motion in extension, ulnar deviation, and radialis deviation. The stress on prosthesis increased significantly when compared with that on normal lunate bone. CONCLUSION The customized titanium alloy lunate prosthesis does not change the wrist joint load transfer mode, which provided data support for the clinical application of the prosthesis.
Humans ; Lunate Bone/surgery* ; Finite Element Analysis ; Titanium ; Wrist Joint/surgery* ; Artificial Limbs ; Range of Motion, Articular ; Biomechanical Phenomena

The shoulder joint is the most flexible joint in the body with the largest range of motion, and the movement pattern is more complex. Accurate capture of three-dimensional motion data of the shoulder joint is crucial for biomechanical evaluation. Optical motion capture systems offer a non-invasive and radiation-free method to capture shoulder joint motion data during complex movements, enabling further biomechanical analysis of the shoulder joint. This review provides a comprehensive overview of optical motion capture technology in the context of shoulder joint movement, including measurement principles, data processing methods to reduce artifacts from skin and soft tissues, factors influencing measurement results, and applications in shoulder joint disorders.
Humans ; Shoulder ; Motion Capture ; Biomechanical Phenomena ; Upper Extremity ; Shoulder Joint ; Movement ; Range of Motion, Articular

PURPOSE: Child head injury under impact scenarios (e.g. falls, vehicle crashes, etc.) is an important topic in the field of injury biomechanics. The head of piglet was commonly used as the surrogate to investigate the biomechanical response and mechanisms of pediatric head injuries because of the similar cellular structures and material properties. However, up to date, piglet head models with accurate geometry and material properties, which have been validated by impact experiments, are seldom. We aim to develop such a model for future research. METHODS: In this study, first, the detailed anatomical structures of the piglet head, including the skull, suture, brain, pia mater, dura mater, cerebrospinal fluid, scalp and soft tissue, were constructed based on CT scans. Then, a structured butterfly method was adopted to mesh the complex geometries of the piglet head to generate high-quality elements and each component was assigned corresponding constitutive material models. Finally, the guided drop tower tests were conducted and the force-time histories were ectracted to validate the piglet head finite element model. RESULTS: Simulations were conducted on the developed finite element model under impact conditions and the simulation results were compared with the experimental data from the guided drop tower tests and the published literature. The average peak force and duration of the guide drop tower test were similar to that of the simulation, with an error below 10%. The inaccuracy was below 20%. The average peak force and duration reported in the literature were comparable to those of the simulation, with the exception of the duration for an impact energy of 11 J. The results showed that the model was capable to capture the response of the pig head. CONCLUSION This study can provide an effective tool for investigating child head injury mechanisms and protection strategies under impact loading conditions.
Animals ; Swine ; Finite Element Analysis ; Skull/injuries* ; Craniocerebral Trauma/diagnostic imaging* ; Brain ; Biomechanical Phenomena ; Scalp

OBJECTIVE: To study the mechanical properties related to the typical functional failure modes of non-absorbable suture anchor in clinical use, and to support product design, development and verification. METHODS: By retrieving the database of relevant adverse events, the typical functional failure modes of non-absorbable suture anchor were summarized, and the influencing factors of functional failure were further analyzed by studying the mechanical properties related to functional failure. The publicly available test data was retrieved for verification and provided reference for the researchers. RESULTS: The typical functional failure modes of non-absorbable suture anchor include anchor failure, suture failure, fix loosening, inserter failure, which are related to the mechanical properties of products, such as screw-in torque and break torque of screw-in anchors, insertion force of knock-in anchors, suture strength, pull-out force before and after system fatigue test and elongation of sutures after fatigue test. CONCLUSIONS Enterprises should pay attention to improving the mechanical performance level of products through material, structural design and the suture weaving process to ensure the safety and effectiveness of products.
Suture Anchors ; Suture Techniques ; Sutures ; Absorbable Implants ; Biomechanical Phenomena ; Materials Testing

This study briefly introduces the revised content of Guidance for Registration of Metallic Bone Plate Internal Fixation System (Revised in 2021) compared to the original guidance, mainly including the principles of dividing registration unit, main performance indicators of standard specification, physical and mechanical performance research, and clinical evaluation. At the same time, in order to provide some references for the registration of metallic bone plate internal fixation system, this study analyzes the main concerns in the review process of these products based on the accumulation of experience combining with the current review requirements.
Bone Plates ; Fracture Fixation, Internal ; Biomechanical Phenomena

Stress, Mechanical ; Biomechanical Phenomena ; Head ; Brain

A novel structural dynamics test method and device were designed to test the biomechanical effects of dynamic axial loading on knee cartilage and meniscus. Firstly, the maximum acceleration signal-to-noise ratio of the experimental device was calculated by applying axial dynamic load to the experimental device under unloaded condition with different force hammers. Then the experimental samples were divided into non-specimen group (no specimen loaded), sham specimen group (loaded with polypropylene samples) and bovine knee joint specimen group (loaded with bovine knee joint samples) for testing. The test results show that the experimental device and method can provide stable axial dynamic load, and the experimental results have good repeatability. The final results confirm that the dynamic characteristics of experimental samples can be distinguished effectively by this device. The experimental method proposed in this study provides a new way to further study the biomechanical mechanism of knee joint structural response under axial dynamic load.
Animals ; Cattle ; Biomechanical Phenomena ; Knee Joint/physiology* ; Meniscus ; Mechanical Phenomena ; Weight-Bearing