Multi-directional one-handed strength assessments using AnyBody Modeling Systems

Biomechanical mechanisms of anterior cruciate ligament injury in the jerk dip phase of clean and jerk: A case study of an injury event captured on-site

Background

Weightlifting exposes athletes to significant loads, potentially placing the knee joint in an abnormal mechanical environment and leading to anterior cruciate ligament (ACL) injuries. Once an ACL injury occurs, it can affect athletes' competitive ability to varying degrees and even prematurely end their career. Understanding the biomechanical mechanisms of ACL injuries in weightlifters helps in comprehensively understanding the stress patterns and degrees on ACL during human movement, and identifying potential injury-causing factors, thereby enabling the implementation of appropriate preventive measures to reduce the occurrence of injuries. This study aimed to explore the biomechanical mechanisms of ACL injuries during the jerk dip phase of clean and jerk in weightlifters, providing a theoretical basis for the prevention of ACL injuries in weightlifting sports.

Methods

This study utilized the German SIMI Motion 10.2 movement analysis system and the AnyBody simulation system to analyze the kinematic and dynamic parameters of a 109 kg + class weightlifter (height: 191 cm, age: 22 years, weight: 148 kg, athletic level: elite) performing a 205 kg clean and jerk (non-injured) and a 210 kg clean and jerk (ACL injury occurred). The differences in kinematic and dynamic indicators of lower limb joints under injured and non-injured jerk dip conditions were investigated.

Results

Knee joint torque during non-injured clean and jerk was consistently positive (i.e., external rotation) but turned from positive to negative (i.e., from external rotation to internal rotation) during injured clean and jerk and reached a maximum internal rotation torque of 21.34 Nm at the moment of injury. At every moment, the muscle activation and simulated muscle force of the quadriceps and gastrocnemius during the injured clean and jerk were higher than those during the non-injured clean and jerk. By contrast, the muscle activation and simulated muscle force of the semitendinosus, semimembranosus, biceps femoris, and soleus during non-injured clean and jerk were higher than those during injured clean and jerk. The knee joint internal rotation angle during injured clean and jerk first increased and then declined, reaching a peak at 46.93° at the moment of injury, whereas it gradually increased during non-injured clean and jerk. The proximal tibia on the left side during the injured clean and jerk moved forward faster by 0.76 m/s compared with that during the non-injured clean and jerk.

Conclusions

The small muscle activation and simulated muscle force of the hamstring and soleus could not resist timely and effectively the large muscle activation and simulated muscle force of the quadriceps (especially the medial quad) and gastrocnemius. As such, the force applied to the ACL could exceed its ultimate load-bearing capacity. Kinematic indicators in the athlete's injured lift demonstrated certain disparities from those in their non-injured lift. Knee internal rotation and tibial anterior translation during the jerk dip phase of weightlifting might be the kinematic characteristics of ACL injuries.

A neuromusculoskeletal modelling approach to bilateral hip mechanics due to unexpected lateral perturbations during overground walking

BACKGROUND

Current studies on how external perturbations impact gait dynamics have primarily focused on the changes in the body's center of mass (CoM) during treadmill walking. The biomechanical responses, in particular to the multi-planar hip joint coordination, following perturbations in overground walking conditions are not completely known.

METHODS

In this study, a customized gait-perturbing device was designed to impose controlled lateral forces onto the subject's pelvis during overground walking. The biomechanical responses of bilateral hips were simulated by subject-specific neuromusculoskeletal models (NMS) driven by in-vivo motion data, which were further evaluated by statistical parameter mapping (SPM) and muscle coactivation index (CI) analysis. The validity of the subject-specific NMS was confirmed through comparison with measured surface electromyographic signals.

RESULTS

Following perturbations, the sagittal-plane hip motions were reduced for the leading leg by 18.39° and for the trailing leg by 8.23°, while motions in the frontal and transverse plane were increased, with increased hip abduction for the leading leg by 10.71° and external rotation by 9.06°, respectively. For the hip kinetics, both the bilateral hip joints showed increased abductor moments during midstance (20%-30% gait cycle) and decreased values during terminal stance (38%-48%). Muscle CI in both sagittal and frontal planes was significantly decreased for perturbed walking (p < 0.05), except for the leading leg in the sagittal plane.

CONCLUSION

The distinctive phase-dependent biomechanical response of the hip demonstrated its coordinated control strategy for balance recovery due to gait perturbations. And the changes in muscle CI suggested a potential mechanism for rapid and precise control of foot placement through modulation of joint stiffness properties. These findings obtained during actual overground perturbation conditions could have implications for the improved design of wearable robotic devices for balance assistance.

Dynamics analysis of the anterior cruciate ligament reconstruction surgery based on magnetic resonance imaging

In clinical practice, anterior cruciate ligament (ACL) rupture is always repaired by the single-beam reconstruction method. Before the surgery, the surgeon made the diagnosis based on medical images, such as CT (computerized tomography) and MR (magnetic resonance) images. However, little is known about how biomechanics governs the biological nature for femoral tunnel position. In the present study, three volunteers' motion trails were captured by six cameras when they were doing squat movement. The medical image can reconstruct the structure of the ligaments and bones and a left knee model was reconstructed by MIMICS by MRI data of DICOM format. Finally, the effects of different femoral tunnel positions on ACL biomechanics were characterized by the inverse dynamic analysis method. The results showed that there were significant differences in the direct mechanical effects of the anterior cruciate ligament at different locations of the femoral tunnel (p < 0.05), the peak stress of ACL in the low tension area was 1097.24 ± 25.55 N, and the peak stress of ACL in the distal femur was 356.81 ± 15.39 N, both of which were much higher than that in the direct fiber area (118.78 ± 20.68 N).

Dynamic effect of three locking plates fixated to humeral fracture based on multibody musculoskeletal model

OBJECTIVE

This study attempts to analyse the biomechanical effect of internal fixation (plated in parallel or plated vertically) on the basis of distal humeral fractures on musculoskeletal multibody dynamics using AnyBody in Finite Element Method.

METHOD

Humeral 3D models were reconstructed by MIMICS after volunteers' CT image input in *.dicom format, and processed by Geomagic Studio for surfaces, while locking plates and screws were then designed by Pro-E. A humeral model of T-type fracture was created and assembled in Hypermesh, to integrate fixtures (e.g., MPL/PML/ML), to grid the mesh and then assign materials. A musculoskeletal model of the upper limb was established by AnyBody to simulate elbow flexion and extension. They were finally imported to Abaqus for boundary conditions and dynamic analysis.

RESULT

In terms of Von Mises stress, its maximum increased and then decreased gradually during the joint motion, but p > 0.05 in SPSS suggests no significant difference for all three fixtures. In terms of displacement, when the elbow was at 90°, each motional pattern reached its peak as follows: ML180° = 0.28 mm, MPL90° = 0.49 mm & PML90° = 0.54 mm during flexion; ML180° = 0.073 mm, MPL90° = 0.10 mm & PML90° = 0.12 mm during extension. p < 0.05 suggests a significant difference for the displacements of all three fixations. p = 0.007 < 0.01667 suggests the significant difference between the two fixations, for example, PML90° and ML180°, indicating that the peak displacement of ML180° is less than that of PML90°.

CONCLUSION

After generally analysed in musculoskeletal dynamics, the biomechanical property of the fixtures was presented as follows: the displacement of the parallel plate was less than that of the vertical, and the parallel plate may optimise the clinical reduction anatomically.

Dynamics analysis for flexion and extension of elbow joint motion based on musculoskeletal model of Anybody

PURPOSE

Little is known about how biomechanics governs the biological nature for humeral motion dynamically. Elbow motion ought to be investigated based on a musculoskeletal model and evidence the physiologic principle of upper limbs.

METHOD

A humeral model was reconstructed by MIMICS after CT images input in *.dicom format, it was processed by Geomagic Studio for Surfaces, then gridded mesh and assigned materials by Hypermesh. On the other hand, a musculoskeletal model was built by AnyBody, physical motions were then simulated to export boundary condition and myodynamia during flexion and extension. Finally, all the humeral model and boundary were imported to Abaqus for finite element analysis.

RESULT

During the simulative motion of flexion, the primary muscles are brachii biceps, brachialis anticus and teretipronator, their myodynamia increased and then decreased gradually, and reached its peak value at 30°; During extension, the main muscles are triceps brachii and brachialis anticus, their myodynamia increased and then decreased gradually too, and reached peak at 50°; In these two cases, their strain and displacement distributed at the middle of humerus.

CONCLUSION

AnyBody is a novel modelling system to simulate physical motion, for example flexion and extension. Biceps brachii and brachialis anticus are functional for flexion, and triceps brachii plays a key role in extension critically. This simulation confirms the physiologic rule for sport event, humeral fixation and postoperative healing with clinical significance that minimizing joint forces from injury onset may promote pain-free ways.

Maximal isometric force exertion predicted by the force feasible set formalism: application to handbraking

The aim of this study was to test the capacity of the force feasible set formalism to predict maximal force exertion during isometric handbraking. Maximal force exertion and upper-limb posture were measured with a force sensor embedded in a handbrake and an optoelectronic system, respectively. Eleven subjects participated in the experiment which consisted of exerting the maximal force in isometric conditions considering five hand brake positions relative to the seat H-point. Then, maximal force was predicted by the force feasible set obtained from an upper-limb musculoskeletal model. The root-mean-square (RMS) of the angle between measured and predicted forces was 8.4° while the RMS error (RMSE) for amplitude prediction was 95.4 N. However, predicted, and measured force amplitudes were highly correlated (r = 0.88, p < 0.05, slope = 0.97, intercept = 73.3N) attesting the capacity of the model to predict force exertion according to the subject's posture. The implications in the framework of ergonomics are then discussed. Practitioner summary: Maximal force exertion is of paramount importance in digital human modelling. We used the force feasible set formalism to predict maximal force exertion during handbraking from posture and anthropometric data. The predicted and measured force orientation showed a RMS of 8.4° while amplitude presented a RMSE of 95.4 N with a strong correlation (r = 0.88, p < 0.05, slope 0.97, intercept 77.3 N).