Discrete element and finite element methods provide similar estimations for hip joint contact mechanics during walking gait

Biomechanical study of the effect of traction on elbow joint capsule contracture

Dynamic orthoses have a significant effect on the treatment of elbow capsular contracture. Because of the lack of quantitative research on traction forces, determining the appropriate traction force to help stretch soft tissues and maintain the joint's range of motion is a challenge in the rehabilitation process. We developed a human elbow finite element (FE) model incorporating the activity behavior of the muscles and considering different capsular contracture locations, including total, anterior and posterior capsular contractures, to analyze the internal biomechanical responses of different capsular contracture models during flexion (30 to 80 degrees). Traction loads of 10, 20, 30 and 40 N were applied to the ulna and radius at the maximum flexion angle (80 degrees) to explore the appropriate traction loads at week 4 after a joint capsule injury. We observed a significant increase in posterior capsule stress with anterior capsular contracture (ACC), and the maximum peak stress was 1.3 times higher than that in the healthy model. During the fourth week after elbow capsule injury, the appropriate traction forces for total capsule contracture (TCC), ACC and posterior capsule contracture (PCC) were 20, 10 and 20 N, respectively; these forces maintained a stable biomechanical environment for the elbow joint and achieved a soft tissue pulling effect, thus increasing elbow mobility. The results can be used as a quantitative guide for the rehabilitation physicians to determine the traction load for a specific patient.

Hip joint contact pressure and force: a scoping review of in vivo and cadaver studies

Aims

Research on hip biomechanics has analyzed femoroacetabular contact pressures and forces in distinct hip conditions, with different procedures, and used diverse loading and testing conditions. The aim of this scoping review was to identify and summarize the available evidence in the literature for hip contact pressures and force in cadaver and in vivo studies, and how joint loading, labral status, and femoral and acetabular morphology can affect these biomechanical parameters.

Methods

We used the PRISMA extension for scoping reviews for this literature search in three databases. After screening, 16 studies were included for the final analysis.

Results

The studies assessed different hip conditions like labrum status, the biomechanical effect of the cam, femoral version, acetabular coverage, and the effect of rim trimming. The testing and loading conditions were also quite diverse, and this disparity limits direct comparisons between the different researches. With normal anatomy the mean contact pressures ranged from 1.54 to 4.4 MPa, and the average peak contact pressures ranged from 2 to 9.3 MPa. Labral tear or resection showed an increase in contact pressures that diminished after repair or reconstruction of the labrum. Complete cam resection also decreased the contact pressure, and acetabular rim resection of 6 mm increased the contact pressure at the acetabular base.

Conclusion

To date there is no standardized methodology to access hip contact biomechanics in hip arthroscopy, or with the preservation of the periarticular soft-tissues. A tendency towards improved biomechanics (lower contact pressures) was seen with labral repair and reconstruction techniques as well as with cam correction.

Neonatal Hip Loading in Developmental Dysplasia: Finite Element Simulation of Proximal Femur Growth and Treatment

Background

Abnormal prenatal hip joint loading can lead to compromised hip joint function. Early intervention is crucial for favorable outcomes.

Purpose

This study investigates the impact of treatment timing (initiation and duration) on cartilage growth and ossification in the proximal femur of infants with developmental dysplasia of the hip, a condition affecting newborns.

Methods

We used a mechanobiological model to simulate proximal femur growth during treatment durations of 3 months, 6 months, and a late-start treatment.

Results

The findings indicate that the timing of treatment initiation is crucial, while a longer treatment duration does not contribute to improved morphological development of the hip joint.

Conclusions

Mechanobiological models of growth can be used to develop treatments and therapies that correct loading conditions. Growing bone is particularly sensitive to loading conditions, and altered loading during growth can affect bone shape and functionality.

A combined experimental and finite element analysis of the human elbow under loads of daily living

Elbow trauma is often accompanied by a loss of independence in daily self-care activities, negatively affecting patients' quality of life. Finite element models can help gaining profound knowledge about native human joint mechanics, which is crucial to adequately restore joint functionality after severe injuries. Therefore, a finite element model of the elbow is required that includes both the radio-capitellar and ulno-trochlear joint and is subjected to loads realistic for activities of daily living. Since no such model has been published, we aim to fill this gap. For comparison, 8 intact cadaveric elbows were subjected to loads of up to 1000 N, after they were placed in an extended position. At each load step, the displacement of the proximal humerus relative to the distal base plate was measured with optical tracking markers and the joint pressure was measured with a pressure mapping sensor. Analogously, eight finite element models were created based on subject-specific CT scans of the corresponding elbow specimens. The CT scans were registered to the positions of tantalum beads in the experiment. The optically measured displacements were applied as boundary conditions. We demonstrated that the workflow can predict the experimental contact pressure distribution with a moderate correlation, the experimental peak pressures in the correct joints and the experimental stiffness with moderate to excellent correlation. The predictions of peak pressure magnitude, contact area and load share on the radius require improvement by precise representation of the cartilage geometry and soft tissues in the model, and proper initial contact in the experiment.

Automated 3D Analysis of Clinical Magnetic Resonance Images Demonstrates Significant Reductions in Cam Morphology Following Arthroscopic Intervention in Contrast to Physiotherapy

Purpose

To obtain automated measurements of cam volume, surface area, and height from baseline (preintervention) and 12-month magnetic resonance (MR) images acquired from male and female patients allocated to physiotherapy (PT) or arthroscopic surgery (AS) management for femoroacetabular impingement (FAI) in the Australian FASHIoN trial.

Methods

An automated segmentation pipeline (CamMorph) was used to obtain cam morphology data from three-dimensional (3D) MR hip examinations in FAI patients classified with mild, moderate, or major cam volumes. Pairwise comparisons between baseline and 12-month cam volume, surface area, and height data were performed within the PT and AS patient groups using paired t-tests or Wilcoxon signed-rank tests.

Results

A total of 43 patients were included with 15 PT patients (9 males, 6 females) and 28 AS patients (18 males, 10 females) for premanagement and postmanagement cam morphology assessments. Within the PT male and female patient groups, there were no significant differences between baseline and 12-month mean cam volume (male: 1269 vs 1288 mm³, t[16] = −0.39; female: 545 vs 550 mm,³t[10] = −0.78), surface area (male: 1525 vs 1491 mm², t[16] = 0.92; female: 885 vs 925 mm,²t[10] = −0.78), maximum height (male: 4.36 vs 4.32 mm, t[16] = 0.34; female: 3.05 vs 2.96 mm, t[10] = 1.05) and average height (male: 2.18 vs 2.18 mm, t[16] = 0.22; female: 1.4 vs 1.43 mm, t[10] = −0.38). In contrast, within the AS male and female patient groups, there were significant differences between baseline and 12-month cam volume (male: 1343 vs 718 mm³, W = 0.0; female: 499 vs 240 mm³, t[18] = 2.89), surface area (male: 1520 vs 1031 mm², t(34) = 6.48; female: 782 vs 483 mm², t(18) = 3.02), maximum-height (male: 4.3 vs 3.42 mm, W = 13.5; female: 2.85 vs 2.24 mm, t(18) = 3.04) and average height (male: 2.17 vs 1.52 mm, W = 3.0; female: 1.4 vs 0.94 mm, W = 3.0). In AS patients, 3D bone models provided good visualization of cam bone mass removal postostectomy.

Conclusions

Automated measurement of cam morphology from baseline (preintervention) and 12-month MR images demonstrated that the cam volume, surface area, maximum-height, and average height were significantly smaller in AS patients following ostectomy, whereas there were no significant differences in these cam measures in PT patients from the Australian FASHIoN study.

Level of Evidence

Level II, cohort study.

Changes in hip joint contact stress during a gait cycle based on the individualized modeling method of "gait-musculoskeletal system-finite element"

OBJECTIVE

To construct a comprehensive simulation method of "gait-musculoskeletal system (MS)-finite element (FE)" for analysis of hip joint dynamics characteristics and the changes in the contact stress in the hip throughout a gait cycle.

METHODS

Two healthy volunteers (male and female) were recruited. The 3D gait trajectories during normal walking and the CT images including the hip and femur of the volunteers were obtained. CT imaging data in the DICOM format were extracted for subjected 3D hip joint reconstruction. The reconstructed 3D model files were used to realize the subject-specific registration of the pelvis and thigh segment of general musculoskeletal model. The captured marker trajectory data were used to drive subject-specific musculoskeletal model to complete inverse dynamic analysis. Results of inverse dynamic analysis were exported and applied as boundary and load settings of the hip joint finite element in ABAQUS. Finally, the finite element analysis (FEA) was performed to analyze contact stress of hip joint during a gait cycle of left foot.

RESULTS

In the inverse dynamic analysis, the dynamic changes of the main hip-femoral muscle force with respect to each phase of a single gait cycle were plotted. The hip joint reaction force reached a maximum value of 2.9%BW (body weight) and appeared at the end of the terminal stance phase. Twin peaks appeared at the initial contact phase and the end of the terminal stance phase, respectively. FEA showed the temporal changes in contact stress in the acetabulum. In the visual stress cloud chart, the acetabular contact stress was mainly distributed in the dome of the acetabulum and in the anterolateral area at the top of the femoral head during a single gait cycle. The acetabular contact area was between 293.8 and 998.4 mm², and the maximum contact area appear at the mid-stance phase or the loading response phase of gait. The maximum contact stress of the acetabulum reached 6.91 MPa for the model 1 and 6.92 MPa for the model 2 at the terminal stance phase.

CONCLUSIONS

The "Gait-MS-FE" technology is integrated to construct a comprehensive simulation framework. Based on human gait trajectories and their CT images, individualized simulation modeling can be achieved. Subject-specific gait in combination with an inverse dynamic analysis of the MS provides pre-processing parameters for FE simulation for more accurate biomechanical analysis of hip joint.