Displacement of the Hip Center of Rotation After Arthroplasty of Crowe III and IV Dysplasia A Radiological and Biomechanical Study

To study the direction and biomechanical consequences of hip center of rotation (HCOR) migration in Crowe type III and VI hips after total hip arthroplasty, post-operative radiographs and CT scans of several unilaterally affected hips were evaluated. Using a three-dimensional model of the human hip, the HCOR was moved in all directions, and joint reaction force (JRF) and abductor muscle force (AMF) were calculated for single-leg stance configuration. Comparing to the normal side, HCOR had displaced medially and inferiorly by an average of 23.4% and 20.8%, respectively, of the normal femoral head diameter. Significant decreases in JRF (13%) and AMF (46.13%) were observed in a presumptive case with that amount of displacement. Isolated inferior displacement had a small, increasing effect on these forces. In Crowe type III and IV hips, the HCOR migrates inferiorly and medially after THA, resulting in a decrease in JRF, AMF, and abductor muscle contraction force.

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A Three-Dimensional Printed Foot Orthosis for Flexible Flatfoot: An Exploratory Biomechanical Study on Arch Support Reinforcement and Undercut

Materials ◽

10.3390/ma14185297 ◽

2021 ◽

Vol 14 (18) ◽

pp. 5297

Author(s):

Ka-Wing Cheng ◽

Yinghu Peng ◽

Tony Lin-Wei Chen ◽

Guoxin Zhang ◽

James Chung-Wai Cheung ◽

...

Keyword(s):

Peak Pressure ◽

Reaction Force ◽

Three Dimensional ◽

Biomechanical Study ◽

Rank Test ◽

Arch Height ◽

Vertical Ground Reaction Force ◽

Flexible Flatfoot ◽

Arch Support ◽

Foot Orthosis

The advancement of 3D printing and scanning technology enables the digitalization and customization of foot orthosis with better accuracy. However, customized insoles require rectification to direct control and/or correct foot deformity, particularly flatfoot. In this exploratory study, we aimed at two design rectification features (arch stiffness and arch height) using three sets of customized 3D-printed arch support insoles (R+U+, R+U−, and R−U+). The arch support stiffness could be with or without reinforcement (R+/−) and the arch height may or may not have an additional elevation, undercutting (U+/−), which were compared to the control (no insole). Ten collegiate participants (four males and six females) with flexible flatfoot were recruited for gait analysis on foot kinematics, vertical ground reaction force, and plantar pressure parameters. A randomized crossover trial was conducted on the four conditions and analyzed using the Friedman test with pairwise Wilcoxon signed-rank test. Compared to the control, there were significant increases in peak ankle dorsiflexion and peak pressure at the medial midfoot region, accompanied by a significant reduction in peak pressure at the hindfoot region for the insole conditions. In addition, the insoles tended to control hindfoot eversion and forefoot abduction though the effects were not significant. An insole with stronger support features (R+U+) did not necessarily produce more favorable outcomes, probably due to over-cutting or impingement. The outcome of this study provides additional data to assist the design rectification process. Future studies should consider a larger sample size with stratified flatfoot features and covariating ankle flexibility while incorporating more design features, particularly medial insole postings.

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Figure 10.1 Illustration of the forces acting on the forearm while holding a ball weighing W in the hand. The biceps muscle force, B, acts upward on the ulna. The joint reaction force, R, and weight of the forearm, G, act downward. The vector sum of these forces must be zero to maintain static equilibrium. Similarly, the net moment about the joint centre must also be zero. These two conditions can be written algebraically as Equations 10.1 and 10.2.

Biomechanics in Ergonomics ◽

10.4324/9780203016268-42 ◽

1999 ◽

pp. 214-215

Keyword(s):

Muscle Force ◽

Reaction Force ◽

Static Equilibrium ◽

Biceps Muscle ◽

Joint Reaction Force ◽

Vector Sum ◽

Joint Reaction

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Experimental Analysis of the Quadriceps Muscle Force and Patello-Femoral Joint Reaction Force for Various Activities

Acta Orthopaedica Scandinavica ◽

10.3109/17453677208991251 ◽

1972 ◽

Vol 43 (2) ◽

pp. 126-137 ◽

Cited By ~ 268

Author(s):

Donald T. Reilly ◽

Marc Martens

Keyword(s):

Experimental Analysis ◽

Muscle Force ◽

Reaction Force ◽

Quadriceps Muscle ◽

Joint Reaction Force ◽

Joint Reaction

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CONTRIBUTION OF MUSCLE TENSION FORCE TO MEDIAL KNEE CONTACT FORCE AT FAST WALKING SPEED

Journal of Mechanics in Medicine and Biology ◽

10.1142/s0219519415500025 ◽

2015 ◽

Vol 15 (01) ◽

pp. 1550002 ◽

Cited By ~ 2

Author(s):

S. OGAYA ◽

H. NAITO ◽

Y. OKITA ◽

A. IWATA ◽

Y. HIGUCHI ◽

...

Keyword(s):

Contact Force ◽

Muscle Force ◽

Walking Speed ◽

Reaction Force ◽

Muscle Tension ◽

Moderate Increase ◽

Joint Reaction Force ◽

Medial Knee ◽

Fast Walking ◽

Second Peak

Fast walking is considered as a factor that causes pain in patients suffering from knee disorders. This study examined the effect of walking speed on the medial knee contact force and identified contributions to the muscle tension on the medial knee contact force during fast walking using musculoskeletal simulation analysis. The muscle contribution to the medial knee contact force was calculated based on the joint angles and ground reaction force for the normal and fast walking experiments of seven subjects. The muscle force and joint reaction force were used to estimate the medial knee contact force. Results showed, in average, 70% increase in medial knee contact force at the first peak and 34% increase at the second peak with a fast walking speed, compared to when they walked at a normal walking speed. The remarkable increase in the first peak was mainly contributed by the increase in the quadriceps force resisting the external knee flexion moment. In contrast, the moderate increase of second peak was contributed by the increase in the gastrocnemius muscle force. These results suggest that the increase in medial knee contact force at fast walking speeds is caused by the increased muscle force.

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Gait Design and Analysis of Quadruped Crawling Robot Climbing Over the Raised Terrain of Slope

Recent Patents on Mechanical Engineering ◽

10.2174/2212797614666210413145741 ◽

2021 ◽

Vol 14 ◽

Author(s):

Peng Wang ◽

Renquan Dong ◽

Tiecheng Sun ◽

Qiong Tang

Keyword(s):

Ground Reaction Force ◽

Reaction Force ◽

Kinematic Model ◽

Impact Resistance ◽

Three Dimensional ◽

Position Vector ◽

Displacement Curve ◽

Three Dimensional Model ◽

Tripod Gait ◽

The Impact

Background: It is a challenge that quadruped crawling robots face when working in the raised terrain of slope. The robot is affected by gravity and gait under this terrain, the ground reaction force on its hind legs is relatively large. This has strict requirements for the structure and gait planning of the quadruped crawling robot. Objective: Aiming at that the ground reaction force on the hind legs of quadruped crawling robot is relatively large when the robot climbing over the raised terrain of slope, a slope-triangular gait walking strategy for quadruped robots based on a layered CGP gait generation method is proposed. Methods: Three-dimensional model of the quadruped crawling robot is created in SOLIDWORKS. The kinematic model is established, and the foot position vector is obtained. Consider the characteristics of the raised terrain of slope, slope tripod gait and hierarchical CPG slope tripod gait generator are proposed. Comparative simulation of sloped tripod gait and flat tripod gait, the slope tripod gait with and without the gait generator is carried out by Adams programming. Results: Compared the centroid displacement curve, foot speed curve, and foot contact force curve of slope tripod gait and flat tripod gait. Compare the posture angle curves of the fuselage with and without the slope tripod gait generator. The result proves that the tripod gait walking strategy is feasible. Conclusion: The slope tripod gait walking strategy can improve the impact resistance of the quadruped crawling robot on sloped high ground. The gait design and motion analysis process of the robot can provide a reference for other quadruped crawling robot device.v

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