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Is the human acetabulofemoral joint spherical?
Abstract
The human acetabulofemoral joint is commonly modelled as a pure ball-and-socket joint, but there has been no quantitative assessment of this assumption in the literature. Our aim was to test the limits and validity of this hypothesis. We performed experiments on four adult cadavers. Cortical pins, each equipped with a marker cluster, were implanted in the pelvis and the femur. Movements were recorded using stereophotogrammetry while an operator rotated the cadaver’s acetabulofemoral joint, exploiting the widest possible range of movement. The functional consistency of the acetabulofemoral joint as a pure spherical joint was assessed by comparing the magnitude of the translations of the hip joint centre as obtained on cadavers, with the centre of rotation of two metal segments linked through a perfectly spherical hinge. The results showed that the radii of the spheres containing 95% of the positions of the estimated centres of rotation were separated by less than 1 mm for both the acetabulofemoral joint and the mechanical spherical hinge.
Therefore, the acetabulofemoral joint can be modelled as a spherical joint within the considered range of movement (flexion/extension 20° to 70°; abduction/adduction 0° to 45°; internal/external rotation 0° to 30°).
... According to research conducted in the field of rehabilitation medicine [29][30], this section proposes the notion that movements occurring in the sagittal plane exert a more profound influence compared to those in the coronal and horizontal planes during regular walking. As a result, the analysis of the dynamics of the lowerlimb exoskeleton rehabilitation robot solely considers alterations in the sagittal plane. ...
The utilization of the LLE offers a highly effective means of enhancing walking ability for individuals with permanent leg weakness, surpassing that of a wheelchair. For individuals experiencing permanent leg weakness, the utilization of the LLE represents a highly effective means to enhance their walking ability, The joint's actuator model is developed using the Matlab system identification technique. The actuators are interconnected with the LLE and payload, enabling an examination of the LLE's dynamics. A three-dimensional model of the LLE is fabricated using Solidworks software, and a simulation approach is implemented using SimMechanics.. Afterwards, the model is verified through simulation, incorporated with a Matlab-Simulink control model, and subjected to testing in both payload and non-payload conditions.The results demonstrate that the model can be effectively employed in simulation to verify the controller performance for tracking the trajectory of LLE walking. The RMS error of the joint angle is minimal and closely approximates the desired input of the joint with high velocity in the absence of payload, while in the presence of payload, the torque of the joint adapts well under high load. This behavior is highly logical during walking. The implementation of the PID controller enhances system stability by reducing the step response of the joint position, thereby providing accurate angles in less time and with reduced vibration.
... AlphaPose, OpenPose) ( [5], [16]- [18]), not necessarily gait, and training relies on reference data not based on clinical gait analysis standards [29] (e.g. clear and anatomical/functional rules for joint centers definition [30]). Furthermore, original training data sets do not include people with impaired gait and, therefore, methods performance is not optimized and clinical validity is not established. ...
Clinical gait analysis is a diagnostic tool often used for identifying and quantifying gait alterations in cerebral palsy (CP) patients. To date, 3D clinical gait analysis protocols based on motion capture systems featuring multiple infrared cameras and retroreflective markers to be attached to the subject’s skin are considered the gold standard. However, the need for fully dedicated personnel and space in addition to the inconvenient requirement of multiple markers attached on the patient’s body limit their use in the clinical practice. To shorten the time necessary to setup the patient and to limit his/her discomfort motion tracking performed using markerless technologies may offer a promising alternative to marker-based motion capture. This study aims at proposing and validating on 18 CP patients, an original markerless clinical gait analysis protocol based on a single RGB-D camera. Accuracy and reliability of the spatial-temporal parameters and sagittal lower limb joint kinematics were assessed based on a 3D marker-based clinical gait analysis protocol. The smallest percent mean absolute errors were obtained for stride duration (2%), followed by the step and stride length (2.2% and 2.5%, respectively) and by gait speed (3.1%). The average angular offset values between the two protocols were 8° for the ankle, 6° for the knee and 7° for the hip joint. The smallest root mean square error values were found for the knee joint kinematics (3.2°), followed by the hip (3.5°) and the ankle (4.5°). Both protocols showed a good-to-excellent reliability. Thus, this study demonstrated the technical validity of a markerless single-camera protocol for clinical gait analysis in CP population. The dataset containing markerless data from 10 CP patients along with the MATLAB codes have been made available.
... According to research conducted in the field of rehabilitation medicine [29][30], this section proposes the notion that movements occurring in the sagittal plane exert a more profound influence compared to those in the coronal and horizontal planes during regular walking. As a result, the analysis of the dynamics of the lowerlimb exoskeleton rehabilitation robot solely considers alterations in the sagittal plane. ...
The utilization of the LLE offers a highly effective means of enhancing walking ability for individuals with permanent leg weakness, surpassing that of a wheelchair. For individuals experiencing permanent leg weakness, the utilization of the LLE represents a highly effective means to enhance their walking ability, The joint's actuator model is developed using the Matlab system identification technique. The actuators are interconnected with the LLE and payload, enabling an examination of the LLE's dynamics. A three-dimensional model of the LLE is fabricated using Solidworks software, and a simulation approach is implemented using SimMechanics.. Afterwards, the model is verified through simulation, incorporated with a Matlab-Simulink control model, and subjected to testing in both payload and non-payload conditions.The results demonstrate that the model can be effectively employed in simulation to verify the controller performance for tracking the trajectory of LLE walking. The RMS error of the joint angle is minimal and closely approximates the desired input of the joint with high velocity in the absence of payload, while in the presence of payload, the torque of the joint adapts well under high load. This behavior is highly logical during walking. The implementation of the PID controller enhances system stability by reducing the step response of the joint position, thereby providing accurate angles in less time and with reduced vibration.
... Andersen et al., 2009;Duprey et al., 2010;Reinbolt et al., 2005) : n'autorise qu'une rotation autour d'un seul axe prédéfini (un degré de liberté) et aucune translation • Rotule à doigt, ellipsoïde et joint de cardan(Andersen et al., 2009;Duprey et al., 2010;Reinbolt et al., 2005) : autorise la rotation autour de deux axes (deux degrés de liberté) et aucune translation.• Rotule ou sphéroïde(Cereatti et al., 2010) : autorise les trois rotations dans l'espace (3 degrés de liberté), mais aucune translation.• Sphère sur plan ou ponctuelle (Parenti-Castelli et al., 2004) : autorise les trois rotations et deux translations sur le plan (cinq degrés de liberté). ...
L’analyse du mouvement humain est un paramètre clé pour comprendre les différentes problématiques de la locomotion humaine. Qui plus est, il est nécessaire que ces analyses soient effectuées au plus proche de la locomotion réelle. L’essor de la miniaturisation des capteurs et des technologies sans fil a permis d’offrir la possibilité d’utiliser les centrales inertielles sur le terrain. Mais différentes problématiques existent encore pour obtenir la cinématique des membres inférieurs avec les centrales inertielles.La première étude de ce manuscrit aborde une comparaison des différents calibrages centrale-à-segment pour définir le passage entre l’orientation de la centrale inertielle et le segment sous-jacent. Nous avons mis en avant une méthode qui valide ces critères au mieux et ne demande que deux postures et un dispositif simple. Mais la cinématique obtenue reste entachée d’erreurs qui pourraient être dues à la présence d’artefacts de tissu mou.C’est pourquoi dans une seconde partie nous étudions la possibilité de diminuer ces effets par l’intermédiaire de l’optimisation multisegmentaire. Ainsi nous avons pu mettre en avant la nécessité de bien paramétrer le modèle derrière l’optimisation sans pour autant présenter un apport significatif. Enfin, en dernière partie, nous proposons d’appliquer la méthodologie de traitement de la cinématique articulaire sur une population pathologique, en collaboration avec le laboratoire de cinésiologie Willy Taillard des HUG et de l’Université de Genève. En conclusion cette thèse propose un processus méthodologique et des recommandations pour développer des analyses de la cinématique en milieu écologique avec des centrales inertielles.
... The joints of a lower limb can be modeled as a spherical joint within the considered range of movement. 36 Referring to the fundamental and basic axes defined in the anatomy, the basic forms of joint motion can be classified into three categories: flexion/extension (FE) around the frontal axis, abduction/adduction (AA) around the sagittal axis, and internal/external (IE) around the vertical axis. Degrees of freedom (DOF) is used as a term to describe the freedom of motion. ...
The lower limb exoskeleton robot is capable of providing assisted walking and enhancing exercise ability of humans. The coupling human–machine model has attracted a lot of research efforts to solve the complex dynamics and nonlinearity within the system. This study focuses on an approach of gait trajectory optimization of lower limb exoskeleton coupled with human through genetic algorithm. The human–machine coupling system is studied in this article through multibody virtual simulation environment. Planning of the motion trajectory is carried out by the genetic algorithm, which is iteratively generated under optimization of a set of specially designed fitness functions. Human motion captured data are used to guide the evolution of gait trajectory generation method based on genetic algorithm. Experiments are carried out using the MATLAB/Simulink Multibody physical simulation engine and genetic algorithm-toolbox to generate a more natural gait trajectory, the results show that the proposed gait trajectory generation method can provide an anthropomorphic gait for lower limb exoskeleton device.
The femoral neck axis (FNA) is an important reference in femoral neck rotational osteotomy, which is a hip preservation procedure. The purpose of this study was to propose a method for determining the FNA with high accuracy and reliability and to evaluate the effect of FNA determination accuracy on the stress and strain distribution in the proximal femur. Femoral computed tomography data from 50 patients were reconstructed, and the FNA was fitted by the centroid iterative method. The fitting accuracy was evaluated in terms of the distance between the femoral head centre and the FNA. The reliability was assessed by intraclass correlation coefficient (ICC). Stress–strain distributions of the native femur model and rotational osteotomy models with accurate FNA and deviated FNA were simulated by finite element analysis and digital image correlation methods. The distance between the femoral head centre and the FNA was 1.24 ± 0.35 mm. The intra- and interobserver reliability was high, with ICC values of 0.960 and 0.924, respectively. The maximum von Mises stress was 25.76 MPa, 50.82 MPa, and 93.24 MPa for the native femur model, accurate FNA model, and deviated FNA model, respectively. The finite element strain distributions were linearly correlated with digital image correlation results. The centroid iterative method for FNA fitting has high accuracy and reliability. Accurate determination of the FNA reduces stress concentration in the proximal femur and decreases the risk of subsequent fracture and non-union of the osteotomy surface.
Conventional assistive and rehabilitative robotic systems often overlook human biomechanics, particularly muscular forces, as they predominantly operate in joint or task space and focus on position and exchanged forces. Similarly, traditional manual rehabilitation techniques employed by physiotherapists struggle to obtain quantitative measurements and make precise modifications to key human variables, resulting in predominantly qualitative methods and outcomes. In response to these limitations, this article introduces an innovative assistive robot controller that operates in the muscular space, targeting specific muscles in the lower limb, and distinguishing itself from existing solutions that focus primarily on joint or task space. A key innovation of our approach is the real-time measurement of muscular forces during dynamic tasks, obtained from a calibrated musculoskeletal model. These measurements enable the establishment of a multistep closed-loop controller, with the outer loop precisely tracking the desired muscular forces. Implemented within a configurable viscous environment, the controller provides a natural response for the user. Experimental evaluations conducted using a parallel robot designed for rehabilitation demonstrate the controller’s efficacy. Incorporating the outer loop reduced the median relative error of the tracked muscular force by nearly 80% and decreased the variability of this error by over 85% compared to a pure viscous environment defined as the baseline. These findings highlight the potential applications of this control framework in areas, such as assistive robotics and precision rehabilitation. By achieving objective measurement and control, the system may enhance rehabilitation outcomes, offering tailored exercises that match the individual needs, capabilities, and engagement of each patient.
Childbirth is a complex physiological process in which a foetal neuromusculoskeletal model is of great importance to develop realistic delivery simulations and associated complication analyses. However, the estimation of hip joint centre (HJC) in foetuses remains a challenging issue. Thus, this paper aims to propose and evaluate a new approach to locate the HJC in foetuses. Hip CT-scans from 25 children (F = 11, age = 5.5 ± 2.6 years, height = 117 ± 21 cm, mass = 26 kg ± 9.5 kg) were used to propose and evaluate the novel acetabulum sphere fitting process to locate the HJC. This new approach using the acetabulum surface was applied to a population of 57 post-mortem foetal CT scans to locate the HJC as well as to determine associated regression equations using multiple linear regression. As results, the average distance between the HJC located using acetabulum sphere fitting and femoral head sphere fitting in children was 1.5 ± 0.7 mm. The average prediction error using our developed foetal HJC regression equations was 3.0 ± 1.5 mm, even though the equation for the x coordinate had a poor value of R2 (R2 for the x coordinate = 0.488). The present study suggests that the use of the acetabulum sphere fitting approach is a valid and accurate method to locate the HJC in children, and then can be extrapolated to get an estimation of the HJC in foetuses with incomplete bone ossification. Therefore, the present paper can be used as a guideline for foetus specific neuromusculoskeletal modelling.
Purpose:
In the setting of acetabular dysplasia, the increased translational motion of the femur may damage the labrum and cartilage, as well as stretch the capsule. The purpose of the study was to investigate the relationship between the acetabular coverage and the capsular stiffness by assessing the distension of anterior and posterior joint recesses on the hip computed tomography arthrography.
Methods:
One hundred thirty-three patients (138 hips) with a median age of 36 years (range 18-50 years) who received the computed tomography arthrography for evaluation of nonarthritic hip pain in our institute between 2015 and 2017 were retrospectively reviewed. The maximal distance between the anterior/posterior capsule and the anterior femoral head-neck junction/posterior femoral head on the axial imaging of computed tomography arthrography was defined as the width of anterior/posterior joint recess. The width of anterior/posterior joint recess was adjusted with the diameter of the femoral head and was then compared between acetabular dysplasia (lateral center-edge angle < 25°), normal acetabulum (lateral center-edge angle between 25 and 39°), and deep acetabulum (lateral center-edge angle > 39°). In addition, the standard univariate linear regression analysis was used to investigate the relationship between the adjusted width of anterior/posterior joint recess and anterior/posterior coverage of the hip, determined by the anterior/posterior wall index.
Results:
The adjusted width of posterior joint recess was significantly greater in the acetabular dysplasia group than the normal acetabulum and deep acetabulum groups (p < 0.01 and p = 0.02, respectively). There was no significant difference of the adjusted width of anterior joint recess between the groups (n.s.). The adjusted width of posterior joint recess had a significant but weak negative correlation with the anterior wall index (r = - 0.25, p < 0.001), and no correlation with the posterior wall index (r = - 0.0004, n.s.). There was no significant correlation between the adjusted width of anterior joint recess and the anterior/posterior wall index (r = 0.05, n.s./r = 0.07, n.s.).
Conclusions:
The distension of posterior capsule on the computed tomography arthrography was significantly greater in acetabular dysplasia. In addition, there was a significant but weak negative correlation between the distension of posterior capsule and the anterior coverage of the hip. It indicated a looser posterior capsule was observed in a dysplastic hip. The relevance of posterior capsular laxity to clinical outcomes warrants further investigation. Given the fact that the distension of anterior capsule was not significantly higher in acetabular dysplasia, the need of anterior capsular plication in a dysplastic hip should be carefully evaluated.
Level of evidence:
Level III.
Pre-operative computerised three-dimensional planning was carried out in 223 patients undergoing total hip replacement with a cementless acetabular component and a cementless modular-neck femoral stem. Components were chosen which best restored leg length and femoral offset. The post-operative restoration of the anatomy was assessed by CT and compared with the pre-operative plan.
The component implanted was the same as that planned in 86% of the hips for the acetabular implant, 94% for the stem, and 93% for the neck-shaft angle. The rotational centre of the hip was restored with a mean accuracy of 0.73 mm (sd 3.5) craniocaudally and 1.2 mm (sd 2) laterally. Limb length was restored with a mean accuracy of 0.3 mm (sd 3.3) and femoral offset with a mean accuracy of 0.8 mm (sd 3.1).
This method appears to offer high accuracy in hip reconstruction as the difficulties likely to be encountered when restoring the anatomy can be anticipated and solved pre-operatively by optimising the selection of implants. Modularity of the femoral neck helped to restore the femoral offset and limb length.
Three-dimensional kinematics of the tibiofemoral joint were studied during normal walking. Target markers were fixed to tibia and femur by means of intra-cortical traction pins. Radiographs of the lower limb were obtained to compute the position of the target markers relative to internal anatomical structures. High-speed cine cameras were used to measure three-dimensional coordinates of the target markers in five subjects walking at a speed of 1.2 m s-1. Relative motion between tibia and femur was resolved according to a joint coordinate system (JCS). The measurements have identified that substantial angular and linear motions occur about and along each of the JCS axes during walking. The results do not, however, support the traditional view that the so-called 'screw home' mechanism of the knee joint operates during gait.
This paper reports a discussion on the heuristic and applicative objectives of gait analysis and on the experimental and analytical methods used in this context. In particular, the use of an effective method of description of joint kinematics and kinetics i.e., joint function, as applied to the lower limb joints during normal walking is reported. A methodological hypothesis for the evaluation of gait, as an integrated phenomenon is presented and supported by experimental data concerning normal and pathological walking and sportive gaits.
In a 12- to 18-year radiographic follow-up study of 95 Charnley low-friction total hip arthroplasties (THA), there was a statistically significant correlation between location of the center of rotation of the total hip prosthesis (notably the element horizontal distance cup to tear-drop) and long-term, unfavorable, radiographic signs, such as acetabular and stem demarcation, cup wear, cup migration, subsidence of the stem, and calcar resorption. Small differences, as little as 2 mm, in the placement of the cup in relation to anatomic landmarks were responsible for these findings
The Standardization and Terminology Committee (STC) of the International Society of Biomechanics (ISB) proposes a general reporting standard for joint kinematics based on the Joint Coordinate System (JCS), first proposed by Grood and Suntay for the knee joint in 1983 (J. Biomech. Eng. 105 (1983) 136). There is currently a lack of standard for reporting joint motion in the field of biomechanics for human movement, and the JCS as proposed by Grood and Suntay has the advantage of reporting joint motions in clinically relevant terms.In this communication, the STC proposes definitions of JCS for the ankle, hip, and spine. Definitions for other joints (such as shoulder, elbow, hand and wrist, temporomandibular joint (TMJ), and whole body) will be reported in later parts of the series. The STC is publishing these recommendations so as to encourage their use, to stimulate feedback and discussion, and to facilitate further revisions.For each joint, a standard for the local axis system in each articulating bone is generated. These axes then standardize the JCS. Adopting these standards will lead to better communication among researchers and clinicians.
The human hip joint is normally represented as a spherical hinge and its centre of rotation is used to construct femoral anatomical axes and to calculate hip joint moments. The estimate of the hip joint centre (HJC) position using a functional approach is affected by stereophotogrammetric errors and soft tissue artefacts. The aims of this study were (1) to assess the accuracy with which the HJC position can be located using stereophotogrammetry and (2) to investigate the effects of hip motion amplitude on this accuracy. Experiments were conducted on four adult cadavers. Cortical pins, each equipped with a marker cluster, were implanted in the pelvis and femur, and eight skin markers were attached to the thigh. Recordings were made while an operator rotated the hip joint exploiting the widest possible range of motion. For HJC determination, a proximal and a distal thigh skin marker cluster and two recent analytical methods, the quartic sphere fit (QFS) method and the symmetrical centre of rotation estimation (SCoRE) method, were used. Results showed that, when only stereophotogrammetric errors were taken into account, the analytical methods performed equally well. In presence of soft tissue artefacts, HJC errors highly varied among subjects, methods, and skin marker clusters (between 1.4 and 38.5 mm). As expected, larger errors were found in the subject with larger soft tissue artefacts. The QFS method and the distal cluster performed generally better and showed a mean HJC location accuracy better than 10mm over all subjects. The analysis on the effect of hip movement amplitude revealed that a reduction of the amplitude does not improve the HJC location accuracy despite a decrease of the artefact amplitude.
Hip resurfacing is a technically demanding procedure in which accurate positioning of the femoral component is critical to the avoidance of early implant failures. The purpose of this study was to assess the accuracy of computer-assisted placement of the femoral component and to evaluate the impact of computer-assisted surgery on the learning curve associated with this procedure.
The accuracy of positioning the femoral component was analyzed radiographically in hips undergoing resurfacing procedures performed by surgeons assigned to four different study groups: Group 1, in which the operations were performed with use of computer-assisted surgery by a fellowship-trained surgeon who was experienced in performing resurfacing arthroplasty (surgical experience, more than 250 hip resurfacings); Group 2, in which the operations were performed with use of computer-assisted surgery by senior residents who were inexperienced in performing resurfacing arthroplasty and who were closely supervised by faculty; Group 3, in which the operations were performed with use of conventional instruments by fellowship-trained faculty members; and Group 4, in which the operations were performed with use of computer-assisted surgery by a lesser experienced fellowship-trained faculty member (surgical experience, more than forty but less than seventy-five hip resurfacings) from Group 3.
The range of error in varus or valgus angulation that was observed for navigated procedures was 6 degrees in Group 1, 7 degrees in Group 2, and 5 degrees in Group 4. Compared with the preoperative neck-shaft angle value, the mean postoperative stem-shaft angle value increased by a mean of 4.7 degrees in Group 1, 7.2 degrees in Group 2, 6.5 degrees in Group 3, and 11.6 degrees in Group 4. When compared with the use of standard instrumentation, the use of computer-assisted surgery reduced the number of outliers and facilitated valgus insertion.
In the present study, computer-assisted surgery resulted in improved accuracy and precision in positioning the femoral component. In addition, computer-assisted surgery led to a reduction in the length of the learning curve for beginners in hip resurfacing and improved the surgeon's ability to perform this procedure safely.
The sphericity of a limited area of the surface of the human femoral head has been assessed using the Talyrond roundness-measuring
instrument. It is argued that this area approximates sufficiently closely to the load-bearing surface during standing and
walking to allow conclusions to be drawn as to the sphericity of the whole head. The degree of sphericity is less than that
reported byWalmsley (1928), but asphericity does frequently exist. The exis of any ovality is highly variable in this range of specimens, and
the significance of this in relation to other published work is briefly discussed.