Finite element (FE) modeling is widely used to study the biomechanical effect of material properties, surgical procedures, and loading and boundary conditions on the lumbar spine. Since several ...studies have presented FE analyses of the lumbar spine in relation to spine biomechanics, soft tissue modeling, intervertebral discs, facet joints, load-sharing behaviors of lumbar motion segments, and FE modeling methods, detailed analyses of disc degeneration or muscle force prediction have been little considered. This study focused on recent developments in FE modeling of the lumbar spine, including disc degeneration, muscle force prediction, and clinical applications. Modeling and analysis from the bone to soft tissue and muscle forces, as well as the validation and application of these models were provided and discussed with material properties, element types, loading and boundaries, geometric parameters, and muscle force modeling. Experimental data was summarized for validation of the FE model. Application studies were briefly reviewed, in which the majority of FE models focused on spinal degeneration diseases and surgical instrumentation techniques. Although muscle force prediction and optimization are challenging with FE modeling due to their complexity and redundancy, several studies have predicted muscle activation and spinal forces for injury prevention assessments and treatment strategies. The level of modeling prediction and representation can be improved with subject-specific data, and integration of FE and musculoskeletal models could generate a comprehensive analysis of the lumbar spine in clinical applications.
The human cervical spine is a complex structure that is the most frequently injured site among all spinal injuries. Therefore, understanding of the cervical spine injury and dysfunction, and also ...biomechanical response to external stimuli is important. Finite element (FE) modeling can help researchers to access the internal stresses and strains in the bones, ligaments and soft tissues more realistically, and it has been widely adopted for spine biomechanics research. Although in recent years numerous techniques have been developed, there are no recent literature reviews on FE models of the cervical spine. Our objective was to present recent advances in FE modeling of the human cervical spine in terms of component modeling, material properties, and validation procedures. Model applications and further development are also discussed. The integration of new technologies will allow us to generate more accurate and comprehensive model of the cervical spine, which can increase efficiency and model applicability. Finally, the FE modeling can help to facilitate diagnosis, treatment, and prevention technologies for cervical spine injuries.
There are several widely used devices for controlled contusion of the spinal cord, including the Ohio State University device, the University of British Columbia multi-mechanisms injury device, the ...New York University (NYU) impactor, and the Infinite Horizon (IH) impactor. Although various devices and protocols have been used to generate consistent injury severities, further investigation of the relationship between the key parameters of different spinal cord injury (SCI) contusion devices (e.g., drop height in the NYU impactor and impact force in the IH impactor) will improve our understanding of SCI mechanisms. A three-dimensional finite element model of the rat spinal cord from T9 to T10 that included the white and gray matters, dura mater, and cerebrospinal fluid was developed to investigate the von-Mises stress, maximum principal strain, and maximum displacement of the spinal cord for the drop height in the NYU impactor and the impact force in the IH impactor. A quantitative relationship was established as a conversion equation between two key parameters--i.e., the drop height and the impact force--in the NYU and IH impactors from regression equations for peak von-Mises stress, peak maximum principal strain, and maximum displacement in the spinal cord with respect to drop height and impact force with very high coefficients of determination. The consistent correlation was represented as a simple equation (Force = (28.2 ± 3.2) · Height((0.83 ± 0.07))) under the experimental conditions of a 10-g rod in the NYU impactor and an impact velocity of 125 mm/sec in the IH impactor. Thus, the key biomechanical parameter for a contusion device can be converted or translated to that of another device to analyze experimental results from multiple contusion devices.
This study aimed to analyze and compare the hip, knee, and elbow joint movements during the double poling (DP) technique in cross-country skiing using a wearable inertial measurement unit (IMU) ...sensor on a real snow skiing track. Six national players (NP) and five college players (CP) participated in this study. The joints angles were calculated using the data from IMU sensors on a 145 m skiing course with 10° slope using the DP technique. In addition, the parameters of the DP phase were estimated. Then, all parameters were compared between the NP and CP groups. The hip and knee joint angles in the NP groups were significantly larger than the CP groups. However, there was no intergroup difference in elbow joint range of motion (ROM). Moreover, the cycle length and cycle velocity was higher in the NP group than the CP group. The results showed that the NP group had higher speed and longer cycle length with greater flexion angles in the hip and knee joints. The wearable IMU sensor was used to analyze the motions during DP skiing on the snow skiing slope, which can provide more realistic detailed analysis of the skiing movements. This study provides the comparison analysis of the main parameters between the two different skilled skiers groups, which may help coaches and players improve skiing performance.
For golf swing, the soft tissue structure resisting joint compression and internal rotation of the knee at low flexion angle may be susceptible for a lead knee injury. Therefore, anterior cruciate ...ligament (ACL) rupture is one of the potential injuries that may occur from repeated stress during golf. The current study was purposed to investigate the biomechanical factors that lead to high ACL load in the lead knee during golf swing. The joint kinematic data of the lead leg and trunk, joint kinetic data of the lead knee, ground reaction force, and the external knee moments were compared between the low and high ACL loading groups. The results demonstrated an increased amount of frontal plane moment arm and external knee adduction (varus) moment just after ball impact for the high ACL loading group. These observations were associated with a characteristic difference in the upper body motion and were the main contributors to the elevated ACL force of the lead knee. The mechanism that generates a high amount of ACL loading during golf swing, which involves the application of external knee adduction moment just after ball impact, may differ from conventional non-contact ACL injury mechanisms that associated with dynamic valgus loading during injury circumstance.
In clinical settings, examining the range of motion (ROM) of trunk rotation and functional tasks is commonly employed as part of musculoskeletal assessments to diagnose low back pain (LBP) cases. ...This study compared trunk kinematics during functional activities between individuals with and without non-specific LBP. A total of 45 LBP patients and 45 healthy participants were recruited for this research. The Xsens wearable motion capture system was utilized to record movements during axial trunk rotations and activities such as single-leg standing, walking, hurdle steps, squats, and box lifting. During functional tasks, individuals with LBP displayed larger trunk ROMs, except for rotation in the transverse plane (TP) during single-leg standing. Statistically significant differences were observed between the two groups in trunk extension-flexion in the frontal plane (FP) and TP, trunk bending in TP, trunk rotation in FP and TP, single-leg standing in the sagittal plane (SP), walking in SP and FP, hurdle step in TP, and squat in the FP plane (p < 0.05). Individuals with LBP exhibited smaller trunk ROMs during simple trunk rotation movements, whereas larger ROMs were observed during functional tests. These findings shed light on the particular alterations observed in trunk movement and function experienced by individuals with LB.
Instability of the distal radioulnar joint (DRUJ) is a common clinical problem due to a fall on the outstretched hand or unexpected forcible wrist rotations. Although there are many surgical ...treatments available for DRUJ instabilities, many of injuries can be managed conservatively, such as the wrist-wearing DRUJ stabilizer to provide the stability of the joint. However, there is a lack of research regarding use of the stabilizer on wrist joint biomechanics. In this study, a finite element (FE) model of the forearm was developed to investigate the effects of the stabilizer on DRUJ stability. The effect of the stabilizer on joint stability was quantified by laxity and rotation tests. Our results showed that use of a stabilizer may help to provide stability for the joint by reducing dorsal-volar translation of the radius and ulna, which might be helpful to prevent reoccurrence of a wrist joint injury related with instability.
Swing tempo, rhythm and swing plane are shown to be important in maintaining the performance. However, nearly all studies utilized optical motion capture system for the planar behavior of golf swings ...and the movement of the club. The primary aim of this study was to develop inertial measurement unit sensor-based swing motion analysis algorithm, and validate against an optical motion camera system by comparing the estimated clubhead trajectories during the golf swing. Then, the tempo, rhythm and functional swing plane were investigated using a validated wearable inertial sensor. Fourteen male golfers performed repeated swings for three clubs (driver, 7-iron, and wedge) and at three distances (30 m, 50 m, and 70 m using the wedge). The swing tempo of all the participants was consistent across different clubs. The swing rhythm tends to decrease for club types with less carrying distance. The functional swing plane slope tends to decrease for club types with greater carrying distance. Our study demonstrated a potential application of a wearable inertial measurement unit system for analyzing golf performance parameters.
Joint loading, such as join forces and moments, needs to be investigated as fundamental information for prediction and analysis of skating-related musculoskeletal injuries. However, there is a lack ...of previous biomechanical studies due to technical difficulties in measuring three-dimensional motion data and ground reaction force data in the ice rink. A wearable motion analysis system with inertial sensors and in-shoe pressure sensors was recently developed. In this study, the knee joint kinematics and kinetics during shorttrack speed skating were investigated based on the data obtained from the wearable motion analysis system. The magnitudes of the estimated joint force and moment results were compared with those in the side-step cutting motion, in which non-contact anterior cruciate ligament (ACL) injury is common. The result indicates that the knee valgus moments in the gliding phase and push-off phase were similar to that in the side-step cutting motion. The knee internal rotational moment during the gliding phase and push-off phase were much higher than that measured during side-step cutting. It is necessary to note the high internal rotational moments during the skating in order to prevent any possibility of ACL injury.
Abstract Ossification of the posterior longitudinal ligament (OPLL) and ossification of the ligamentum flavum (OLF) have been recognized as causes of myelopathy due to thickening of the ligaments ...resulting in narrowing of the spinal canal and compression of the spinal cord. However, few studies have focused on predicting stress distribution under conditions of OPLL and OLF based on clinical aspects such as the relationship between level of stress and severity of neurologic symptoms because direct in vivo measurement of stress is very restrictive. In this study, a three-dimensional finite element model of the spinal cord in T12-L1 was developed based on MR images. The von-Mises stresses in the cord and the cross-sectional area of the cord were investigated for various grades and shapes of spinal cord compression in OPLL and OLF. Substantial increases in maximum stresses resulting in the manifestation of spinal cord symptoms occurred when the cross-sectional area was reduced by 30–40% at 60% compression of the antero-posterior diameter of the cord in OPLL and at 4 mm compression in OLF. These results indicate that compression greater than these thresholds may induce spinal symptoms, which is consistent with clinical observations.
