Joint Mechanics Research Articles

Gait asymmetry persists following unilateral and bilateral total ankle arthroplasty.

Total ankle arthroplasty (TAA) improves gait symmetry in patients with unilateral end-stage ankle arthritis but has not been studied in patients undergoing bilateral TAA (B-TAA), and few studies compare TAA patients to control subjects. The purpose of this study was to compare gait symmetry in U-TAA and B-TAA patients and healthy controls. Using prospective databases, 19 unilateral and 19 bilateral ankle arthritis patients undergoing TAA were matched to 19 control subjects by age, sex, and BMI. The Normalized Symmetry Index (NSI) was determined for joint mechanics and ground reaction forces (GRF) during walking trials at a single visit for controls and preoperatively and 1 to 2 years postoperatively for TAA patients. Data was analyzed using linear mixed-effects models to determine differences among time points and cohorts at a significance of α = 0.05. Following surgery, B-TAA and U-TAA experienced improved peak plantarflexion moment symmetry (p = 0.017) but remained less symmetric than controls. B-TAA patients had more symmetry than U-TAA patients during peak weight acceptance GRF (p = 0.002), while U-TAA patients had greater peak dorsiflexion symmetry than B-TAA patients. TAA patients demonstrated more asymmetry compared to control subjects for all outcome measures. There was no significant impact of TAA on gait symmetry for GRF or peak ankle angles, and neither U-TAA nor B-TAA was consistently associated with higher gait symmetry. These results indicate that TAA improves symmetry during peak plantarflexion moment, and that significant gait asymmetry persists for B-TAA and U-TAA patients compared to healthy participants.

Influence of Prophylactic Ankle Bracing on Knee Joint Moments and Ground Reaction Forces during Side-step Cutting Tasks

OBJECTIVES Prophylactic ankle bracing is widely used to prevent ankle sprains, but its effects on knee joint mechanics, particularly regarding ACL injury risk, are less understood. This study aimed to investigate the influence of ankle bracing on knee joint kinetics and ground reaction forces (GRFs) during a 90° side-step cutting task.METHODS Thirty physically active participants (15 males, 15 females) performed cutting trials under braced and unbraced conditions. Knee flexion, abduction, and internal rotation moments, along with mediolateral, anteroposterior, and vertical GRFs, were measured using a motion analysis system and a force plate. Paired t tests were conducted to compare the knee joint moments and GRFs between the two conditions.RESULTS The results showed that while ankle bracing did not significantly affect GRFs, it significantly increased knee internal rotation moment (<i>p</i> = 0.003). No significant differences were observed in knee flexion or abduction moments.CONCLUSIONS Ankle bracing, though beneficial for ankle stability, may elevate the risk of ACL injuries during dynamic activities like cutting by increasing knee internal rotation moments. Clinicians and coaches should weigh the benefits of ankle bracing against potential risks to knee health and consider alternative injury prevention strategies focused on neuromuscular control and strength training.

Heat‐Treatment and Water Immersion Effect on the Mechanical Properties and Joint Strength of 3D‐Printed Polylactic Acid Parts

ABSTRACTThis paper investigates the effect of short‐time water immersion (WI) and heat‐treatment (HT) post‐processes on the mechanical properties and joint strength of printed polylactic acid (PLA) parts with various raster angles. Using these post‐processing methods to enhance the joint strength of printed PLA parts could be deemed as the novelty and the contribution of the current study. The WI and HT of the tensile test specimens and the adherends of the bonded joints were carried out at 21°C and 90°C, respectively. Depending on the raster angle, the tensile strength of the heat‐treated specimens was about 11%–43% higher than that of the untreated specimens. Interestingly, it was found that WI had a more significant effect on the strength of printed parts than HT. In the case of WI, the tensile strength was increased by about 27%–57% as compared to the untreated specimens. Joint tests revealed that HT and WI exerted a similar positive effect on the strength of the joints. The findings highlighted that short‐time WI is at least as effective as HT in increasing the tensile and joint strengths of 3D‐printed PLA parts.

The lateral approach for total knee arthroplasty in valgus osteoarthritis provides similar clinical and radiological results compared with the medial approach.

In total knee arthroplasty (TKA), valgus deformities require special approaches to achieve precise mechanical axis correction and joint stability. This study aimed to determine whether the lateral approach without tibial tubercle osteotomy allows mechanical axis correction in valgus knee osteoarthritis (OA), which is at least as effective as the medial approach, while also assessing whether it provides clinically comparable results and complications. A total of 204 patients undergoing TKA for valgus knee OA were included in this retrospective comparative study, with 131 patients in the lateral approach group and 73 patients in the medial approach group. The surgical goal was to achieve stability with a neutral axis based on mechanical alignment. Detailed pre- and postoperative clinical and radiographic data were obtained, including measurements of the hip-knee-ankle angle (HKAA) and patella tilt angle. Functional status was determined based on the Oxford Knee Score (OKS). Age, body mass index, sex and preoperative HKAA were adjusted between both groups using propensity score matching (n = 45 per group). In the propensity score-matched cohort, the postoperative HKAA did not show differences when comparing the lateral and the medial approach at a mean follow-up of 19.7 months (p = 0.385). The achieved correction of the patella tilt angle was higher in the lateral approach group in the overall (p < 0.001) and matched cohort (p < 0.001). No differences were detected regarding the postoperative OKS and complications. However, wound healing disorders showed a tendency to be more prevalent in patients who underwent the lateral approach in the overall cohort (6.1%, n = 8 vs. 0.0%, n = 0, p = 0.053) but not in the propensity score-matched cohort (p = 0.494). This study demonstrated that for pronounced valgus OA, the lateral approach achieves favourable results in HKAA correction, patellar tilt and complications comparable to the medial approach. However, the risk of wound healing disorders appears higher with severe valgus deformity. Level III therapeutic study.

Investigation on the failure mechanism of friction-based self-centering timber beam-column joint considering bolt bearing effect: Experimental study and theoretical analyses

For friction-based self-centering timber structures, the bearing between friction bolts and the edge of holes is inevitable, due to machining inaccuracies and significant deformations at the beam-column joints. However, this issue has yet to be addressed in existing research. A limit state investigation was conducted on these friction-based self-centering timber beam-column joints under extensive deformation to analyze the failure mechanism and the loss of pretension force throughout the loading process. The influence of bolt bearing behavior on the residual deformation, loading capacity, energy dissipation capacity, and stiffness of the joint was studied. Finally, a theoretical prediction model considering single bolt and multi bolts bearing was proposed incorporating theoretical analysis and experimental results. The results indicate that the damage of the joint is concentrated on the compression deformation at the edge of bolt holes in friction pads and timber beams. The joint ultimately fails due to the end face of the column being crushed by the anchor used to fix post-tensioned (PT) strands. The joint exhibits good hysteresis characteristics within a 4 % drift and still demonstrates good recoverability within a 6 % drift. The loss rate of pretension force is below 15 % when the drift is lower than 4 %, but it increases significantly after the drift exceeds 5 %. When the drift is less than 4 %, the joints primarily exhibit single bolt bearing mode, resulting in only a slight increase in stiffness for the joints. When the drift exceeds 8 %, the joints primarily exhibit a multi bolt bearing mode, resulting in a maximum increase of approximately 64.5 % in joint stiffness. The theoretical bolt bearing model derived can better predict the position of bolts bearing the edge of holes and the damage state of friction-based self-centering timber beam-column joints.

Experimental and numerical study of dissimilar fiber laser welding of martensitic AISI 1060 carbon steel with different configuration with austenitic 304 and ferritic 420 stainless steel

Welding with fiber laser for two distinct stainless steel types was performed to join with the martensitic carbon steel (AISI 1060) in order to assess the effect of laser welding operating parameters for two dissimilar materials on the weld characterization thorough experimental design method and numerical investigation. A full central composite design (CCD) matrix in accordance with the response surface methodology (RSM) was developed to represent the responses variations by equations including quadratic and nonlinear interaction terms. Different laser welding parameters were taken into account, such as laser power, linear speed of welding, focal distance of the beam, and beam deviation. The responses considered were the temperature field next to the melt pool border line, the maximum penetration depth of the fusion zone and the ultimate tensile strength of the dissimilar weld joint. Additionally, the variation of the microstructure fusion zone and adjacent areas and failure mechanism of the weld joint were evaluated. The experimental results indicate that the temperature field measured at the vicinity of the melt pool fusion line with both 304 and 420 stainless steel which primarily influenced by the incident power of the laser and linear velocity of beam, respectively. Additionally, the numerical simulation results are in good agreement with temperature experimental results at vicinity of fusion line where the temperature measured, experimentally. Apart from this, at the center of the fusion zone, the temperature clearly predicts via numerical simulation results which is not possible to assess experimentally. A clear comparison between the temperature distribution with different joint configuration illustrates that distinct relation between the temperature variation rate and different thermal conductivity coefficient of AISI 1060 with different AISI 304 and 420 joint configuration resulted different temperature distribution. The weld joint microstructure for 420 stainless steel–AISI 1060 steel joint at fusion boundary zone consists of columnar dendrites and skeletal columnar ferrite. At the center of fusion zone, a cellular-type structure is seen. For 304 stainless steel joint, the fusion zone has composed of a remarkable part of skeletal delta-ferrite and dendritic microstructure at austenite matrix microstructure. The fracture section of 304 steel has a ductile fracture and the depth of fracture dimples and cavities toward 304 stainless steel are higher than AISI 1060 steel.

Creep Behavior and Fracture Mechanisms of the Dissimilar Inertia Friction Welded Joints of Deformed and Powder Metallurgy Ni‐Based Superalloys

ABSTRACTIn this research, the microstructure and precipitate characteristics of the dissimilar inertia friction welded (IFW) joints of deformed and powder metallurgy (PM) nickel‐based superalloys were studied using optical, scanning electron, and transmission electron microscopy. In addition, several creep tests were conducted. The high‐temperature mechanical properties of the IFW joints were systematically analyzed. Under the creep testing condition of 680°C, the specimens exhibited creep fracture at the thermomechanically affected zone (TMAZ) of the PM superalloys. Further, the failure lifetime is enhanced with a reduction in the applied creep loading. Owing to the IFW process, various γ′ precipitates and carbide distributions were observed in the various zones of a dissimilar IFW joint. Undissolved powder particle boundary (PPB) defects in the TMAZ of the PM superalloy initiated creep cracks under creep loading. Based on the experimental results and theoretical analysis, the creep fracture mechanisms of the dissimilar IFW joints were revealed. Thus, the findings of this study provide guidance for controlling the microstructures and properties of dissimilar deformed/PM nickel‐based superalloy IFW joints.

Fatigue Fracture Mechanism and Life Prediction of TA1 Titanium Alloy Clinched Joints

ABSTRACTThis study investigated the fatigue fracture mechanisms and life prediction of clinched joints made from titanium alloy TA1. The fatigue tests revealed that TA1 titanium alloy clinched joints exhibited failure characterized by fracture of the lower plate at three distinct fatigue load levels. Additionally, finite element analysis indicated that cold work hardening enhanced the fatigue performance of these joints. Observations of fracture surfaces using scanning electron microscopy identified the crack source and its propagation path, which correlated with the location of maximum principal stress from the finite element simulations. Fretting wear was also observed in this critical region. Furthermore, fatigue life predictions for TA1 titanium alloy clinched joints were made using Paris' law and the local strain approach. Both methods closely matched experimental results across different fatigue life intervals. Overall, the local strain approach exhibited superior predictive capability compared to Paris' law, taking into account various influencing factors.

Analysis of Geometrical Accuracy and Surface Quality of Threaded and Spline Connections Manufactured Using MEX, MJ and VAT Additive Technologies

This paper presents the process of manufacturing mechanical joint components using additive manufacturing (AM) techniques such as Material Extrusion (Fused Deposition Modelling (FDM)), Material Jetting (PolyJet), and Vat Photopolymerization (VAT)/Stereolithography (SLA). Using the PolyJet technique and a photopolymer resin, spline and threaded joint components were produced. For comparative analysis, the threaded joint was also fabricated using FDM and SLA techniques. PLA material was used for the FDM technique, while photopolymer resin was utilized for the SLA process. The components produced underwent a surface analysis to evaluate the accuracy of the dimensions in relation to the nominal dimensions. For the spline connection components, the dimensional deviations recorded by a 3D scanner ranged from −0.11 to +0.18 mm for the shaft and up to 0.24 mm for the sleeve. Measurements of screw and nut diameters showed the highest accuracy for screws produced using the PolyJet technique, while the nuts exhibited the best accuracy when fabricated with the SLA method. The profile of the screw threads using a contour gauge revealed the most accurate thread profile on the screw manufactured with the PolyJet technique.

Study on the surface texture-microparticles synergistic lubrication mechanism of artificial joint

Abstract After total joint replacement surgery, frequent injection of lubricating substances is required due to lubrication failure caused by the absorption of lubricants by the human body, which will cause serious physiological and psychological burdens on patients. In this study, with the help of surface texture aggregation of particles, gelatin microgel particles with a diameter of about 4 µm were used as lubricating substances to achieve aggregation in the texture, thus improving the friction environment under low-concentration lubricants. The study found that the rectangular cross-section texture demonstrated the most effective anti-friction properties, resulting in a 26% reduction in friction coefficient compared to non-textured surfaces. Additionally, utilizing COMSOL for particle flow simulation, researchers observed the motion behavior of particles within the texture and clarified the mechanism of particle aggregation and the improvement of lubrication on the surface. This article confirms the beneficial effects of combining surface texture and particles on lubrication, thus providing valuable insight for improving lubrication in dilute particle solutions.

Joint passive beamforming and deployment design for active intelligent reflecting surface-assisted energy harvesting-cognitive radio sensor networks.

To prolong the network lifetime of energy harvesting-cognitive radio sensor networks (EH-CRSNs), this paper integrates active intelligent reflecting surface (IRS) to support both downlink EH and uplink data transmissions and formulates a constrained non-convex optimization problem that maximizes the net energy gain. To solve this problem, a joint passive beamforming and IRS deployment mechanism is proposed to determine the optimal deployment location of the active IRS and optimally configure the IRS reflection coefficient matrices. Specifically, the net energy gain maximization problem at a specified location is divided into two sub-problems according to its characteristics: maximizing the cumulative energy harvested by all CRSNs nodes in the downlink and minimizing the energy consumption of cluster heads in uplink data transmissions, with each sub-problem being solved independently. Furthermore, this paper explores how factors such as the number of active reflecting elements and the amplification power budget influence the optimal deployment location of the active IRS. The findings from this investigation can guide the design of active IRS-assisted EH-CRSNs under specified parameters. Simulation results confirm the aforementioned conclusions and highlight the benefits of the proposed joint mechanism in enhancing net energy gain over various benchmark mechanisms.

A Novel Normal Contact Stiffness Model of Bi-Fractal Surface Joints

The contact stiffness of the mechanical joint usually becomes the weakest part of the stiffness for the whole machinery equipment, which is one of the important parameters affecting the dynamic characteristics of the engineering machinery. Based on the three-dimensional Weierstrass–Mandelbrot (WM) function, the novel normal contact stiffness model of the joint with the bi-fractal surface is proposed, which comprehensively considers the effects of elastoplastic deformation of asperity and friction factor. The effect of various parameters (fractal dimension, scaling parameter, material parameter, friction factor) on the normal contact stiffness of the joint is analyzed by numerical simulation. The normal contact stiffness of the joint increases with an increase in the fractal dimension, normal load, and material properties and decreases with an increase in the scaling parameter. Meanwhile, the fractal parameters of the equivalent rough surface of the joint are calculated by the structural function method. The experimental results show that when the load is between 14 and 38 N∙m, the error of the model is within 20%. The normal contact stiffness model of the bi-fractal surface joint can provide a theoretical basis for the analysis of the dynamic characteristics of the whole machine at the design stage.

Laser-Induced Self-Limiting Welding of Ag Nanowires with High Mechanical and Electrical Performance.

The high-efficiency and high-precision welding technology of Ag nanowires is of great engineering significance for the integration of new-generation micro- and nanodevices, and the mechanical behavior of its interconnect joints is also essential for their reliable application, especially for some flexible device. In this paper, based on the nano-focusing and localized plasma enhancement properties of Ag nanowires under laser irradiation, Ag nanowire self-limiting joints with mechanical and electrical properties comparable to those of the base material are obtained. At the same time, the local plasma enhancement characteristics of Ag nanowire joints are scanned and analyzed with nanoscale resolution by using cathodoluminescence technology, and the local multi-physical field coupling regulation mechanism of Ag nanowire joints induced by different laser parameters is systematically investigated by combining theoretical simulations. Meanwhile, based on the in situ laser welding and nanomechanical tensile experiments, the mechanical properties of single Ag nanowires and their welded joints are systematically analyzed, and the characteristics of the interfacial atomic behaviors and the evolution process during the welding and tensile processes are investigated.

The shear performance of DSCW-RC joints with lap-spliced steel bars

The double steel plate concrete composite shear wall (DSCW) structure combines the advantages of steel and concrete, offering high strength, stiffness, and durability. The joint formed by the DSCW and reinforced concrete foundation (RC foundation) was often unavoidable in engineering practice. Research related to the mechanical behavior of the DSCW-RC foundation is limited. This paper investigated the shear performance of DSCW-RC joints with lap-spliced steel bars. A total of seven specimens were designed and tested. The influences of steel plate thickness, steel bar arrangement, and stud spacing on the shear behavior of the joints are elucidated. The test results indicate that the predominant failure mode of the specimens occurred in the upper part of the local steel plate, with reinforcement yielding. While steel bar diameter and stud spacing minimally affected the shear strength, they significantly influenced the failure displacement at the joint interface. The failure deformation increased with increasing steel bar diameter and decreased with increasing stud spacing. Moreover, the thickness of the steel plate profoundly impacted structural shear strength and deformation, with both deformation and bearing capacity increasing with plate thickness. In addition, this study explores the force-transferring mechanism of such joints under shear load, offering a crucial reference for subsequent analyses of the composite force mechanism of DSCW - RC foundation joints.

Physics-based digital twin updating and twin-based explainable crack identification of mechanical lap joint

The mechanical joints, including the lap joint, weld, bolt, and pin, are vulnerable to fatigue failure because of stress concentration and internal flaws. Digital twin (DTw) strategies were proposed to prevent catastrophic system failure by fatigue damage in mechanical joints. In previous studies, the data-driven approach, such as deep learning and machine learning were utilized to estimate severity of the damage. However, it needs to improve its prediction accuracy because of insufficient data and physical interpretability. In this study, the physics-based digital twin model updating and twin-based crack identification of fatigue damage in riveted lap joints were proposed using lamb waves with consideration of uncertain crack growth path. The proposed approach is based on three techniques; (i) Data pre-processing, including filtering and optimization-based signal synchronization, (ii) Lamb-wave propagation analysis with sensor dynamics model and uncertain crack path, and (iii) Optimization based physics-based model updating and inference. In data pre-processing, the excitation frequency magnitude and truncation time are estimated using the observed actuator signal in the Lamb-wave test. The sensor dynamic model and model parameters are updated using the Bayesian optimization method to minimize both the errors in the predicted (y^t) and observed (yt) wave signal and the errors in the inferred (l*) and observed (l) crack length. The crack growth path is sampled based on angular and spline schemes to consider uncertain crack propagation paths. The validity of the proposed method is demonstrated using an open data set (2019 PHM society data challenge). The results conclude that the proposed digital twin approach can improve estimation accuracy considering both the crack growth path and sensor dynamics model.

Physics-Informed Neural ODE with Heterogeneous control Inputs (PINOHI) for quality prediction of composite adhesive joints

Composite materials have long been used in various industries due to their superior properties such as high strength, light weight and corrosive resistance. Bonded composite joints are finding increasing applications, as they provide extensive structural benefits and design flexibility. On the other hand, the failure mechanism of composite adhesive joints is not fully understood. A model that bridges manufacturing parameters and final quality measures is highly desired for the design and optimization of the manufacturing process of composite adhesive joints. In this study, a novel framework of Physics-Informed Neural Ordinary Differential Equation (ODE) with Heterogeneous Control Input (PINOHI) is proposed, which links the heterogeneous manufacturing parameters to the final bonding quality of composite joints. The proposed model structure is heavily motivated by engineering knowledge, incorporating a calibrated mathematical physics model into the Neural ODE framework, which can significantly reduce the number of data samples required from costly experiments while maintaining high prediction accuracy. The proposed PINOHI model is implemented in the quality prediction of composite adhesive joints bonding problem. A set of experiments and associated data analytics are conducted to demonstrate the superior property of the PINOHI model by using both the leave-one-batch-out cross-validation and sensitivity analysis.

Kaplan fibers of iliotibial band: a comprehensive review of current literature.

This review highlights the pivotal role of Kaplan fibers (KFs) in knee stability, particularly in the anterolateral aspect. Studies reveal their complex anatomy with varying attachments to the distal femur, demonstrating a significant impact on knee joint mechanics across different populations. Investigations into the biomechanics of KFs show their crucial role in maintaining rotational stability of the knee, especially during rotational movements. Their synergistic function with other knee structures, like the anterolateral ligament, is emphasized, underscoring their importance in knee integrity and function. MRI emerges as a key tool in detecting KFs, with varying visibility and prevalence of injuries. The review discusses the development of MRI criteria for accurate diagnosis, highlighting the need for further research to refine these criteria and understand the interplay between KF injuries, anterior cruciate ligament (ACL) ruptures, and associated knee pathologies. The review covers various lateral extra-articular tenodesis (LET) techniques used to address residual laxity and instability following ACL reconstruction. Among them, the modified Lemaire technique, which resembles the anatomical and functional characteristics of distal KFs, shows effectiveness in reducing internal rotation and residual laxity. The review emphasizes the need for further research to understand the healing dynamics of KF injuries and the efficacy of different LET techniques. It suggests that a comprehensive approach, considering both biomechanical and clinical aspects, is crucial for advancing knee joint health and rehabilitation.

Lap joining of Ti6Al4V titanium alloy by vortex flow-based friction stir welding

The current study uses a novel vortex flow-based friction stir lap welding (VFSLW) process to weld 1.4 mm thick Ti6Al4V sheets, trying to replace the diffusion bonding in the superplastic forming/diffusion bonding process. The mechanical properties and joining mechanism of the VFSLW joint were investigated. Good weld formation was obtained at 300–350 rpm and 80 mm/min. No hook defect was formed in the lap interface. The lap joint fractured across the stir zone (SZ) in the top plate under the optimal parameters. The cracks initiated from the oxidation defect, where the oxides on the workpiece surface were involved in the SZ by the vortex during the welding. It suggests that a good argon shield is very important for the VFSLW of titanium alloy. The highest tensile strength reaches ~890 MPa, up to 95 % of the base material. The formation of an α + β lamellar structure in the SZ is due to the peak welding temperature exceeding the β-transus temperature. In the bonded zone (BZ), a very thin layer with ultrafine α grains was formed by dynamic recrystallization in the α phase field, although its two sides are α + β lamellar structures. This is because of the oxidation on the workpiece surface during the welding process and the O element is a strong α stabilizer.

Alignment rod and gap measurement methods achieve comparable alignment correction in opening wedge high tibial osteotomy for varus osteoarthritic knees.

To compare clinical and radiological outcomes of medial opening wedge high tibial osteotomy (MOWHTO) using two different alignment methods: the alignment rod (AR) versus the gap measurement (GM) method. The primary outcome was to report the surgical accuracy of coronal plane corrections in each method. Patients who underwent MOWHTO with either AR or GM method between 2014 and 2022 at a single institution, with a minimum of 2 years of follow-up, were included. The opening gap was gradually spread with an AR under fluoroscopic control in the AR group, whereas the osteotomy site was opened to the value of the measured gap distance in addition to the thickness of the bone saw in the GM group. Radiological assessment of geometric characteristics included hip-knee-ankle angle (HKA), medial proximal tibial angle (MPTA), mechanical lateral distal femoral angle and joint line convergence angle. Surgical accuracy, which is the deviation (Δ) between the intended and achieved correction, was compared between both methods. Clinical outcomes were assessed using the Knee Injury and Osteoarthritis Outcome Scores. A total of 110 patients (n = 110 knees) with a mean age of 54.1 ± 8.4 years were included in the study. Radiological parameters were significantly improved as reflected by HKA correction from 171.6° ± 2.0° to 181.1° ± 2.6° in the AR group and from 171.0° ± 2.3° to 181.1° ± 2.8° in the GM group at 2 years (Intergroup n.s). There was no significant intergroup difference for all radiological parameters and clinical outcomes. There was no intergroup difference in the surgical accuracy as evaluated by Δvalues and absolute Δvalues of both HKA and MPTA (n.s). Comparable correction accuracy was achieved in MOWHTO using either the AR or GM method. The GM method is simple and reliable in achieving the intended correction in MOWHTO. Ⅲ retrospective comparative study.

People With Marfan Syndrome Ambulate With Altered Joint Mechanics

People With Marfan Syndrome Ambulate With Altered Joint Mechanics