scholarly journals Subject-Specific Analysis of Joint Contact Mechanics: Application to the Study of Osteoarthritis and Surgical Planning

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Corinne R. Henak ◽  
Andrew E. Anderson ◽  
Jeffrey A. Weiss
Keyword(s):  
Contact Mechanics ◽  
Computational Models ◽  
Preoperative Planning ◽  
Patient Specific ◽  
Joint Mechanics ◽  
Imaging Data ◽  
Computational Biomechanics ◽  
Subject Specific ◽  
Joint Contact ◽  
Technical Considerations

Advances in computational mechanics, constitutive modeling, and techniques for subject-specific modeling have opened the door to patient-specific simulation of the relationships between joint mechanics and osteoarthritis (OA), as well as patient-specific preoperative planning. This article reviews the application of computational biomechanics to the simulation of joint contact mechanics as relevant to the study of OA. This review begins with background regarding OA and the mechanical causes of OA in the context of simulations of joint mechanics. The broad range of technical considerations in creating validated subject-specific whole joint models is discussed. The types of computational models available for the study of joint mechanics are reviewed. The types of constitutive models that are available for articular cartilage are reviewed, with special attention to choosing an appropriate constitutive model for the application at hand. Issues related to model generation are discussed, including acquisition of model geometry from volumetric image data and specific considerations for acquisition of computed tomography and magnetic resonance imaging data. Approaches to model validation are reviewed. The areas of parametric analysis, factorial design, and probabilistic analysis are reviewed in the context of simulations of joint contact mechanics. Following the review of technical considerations, the article details insights that have been obtained from computational models of joint mechanics for normal joints; patient populations; the study of specific aspects of joint mechanics relevant to OA, such as congruency and instability; and preoperative planning. Finally, future directions for research and application are summarized.

Accuracy of Cartilage Geometry Reconstruction From Volumetric CT Data: A Phantom Study

2007 ◽  
Author(s):  
Andrew E. Anderson ◽  
Benjamin J. Ellis ◽  
Christopher L. Peters ◽  
Jeffrey A. Weiss
Keyword(s):  
Articular Cartilage ◽  
Contrast Agent ◽  
Computational Models ◽  
Image Data ◽  
Cartilage Thickness ◽  
Patient Specific ◽  
Joint Spacing ◽  
Ct Arthrography ◽  
Diarthrodial Joints ◽  
Joint Contact

Segmentation of medical image data is often used for the construction of computational models to study the mechanics of diarthrodial joints such as the hip and knee. The analyst must demonstrate that the reconstructed geometry is an accurate representation of the true continuum to ensure model validity. This becomes especially important for computational modeling of joint contact, which requires accurate reconstruction of articular cartilage. Although volumetric computed tomography (CT) is often used to image diarthrodial joints, the lower bounds for detecting articular cartilage thickness and the influence of imaging parameters on the ability to image cartilage have not been reported. The use of contrast agent (CT arthrography) is necessary to visualize the surface of articular cartilage in live patients. Thus, it is of primary interest to quantify the accuracy of CT arthrography to demonstrate the feasibility of patient-specific modeling. The objectives of this study were to assess the accuracy and detection limits of CT for measuring simulated cartilage thickness using a phantom and to quantify changes in accuracy due to alterations in contrast agent concentration, imaging plane direction, spatial resolution and joint spacing.

scholarly journals Parkinsonian gait effects with DBS are associated with pallido-peduncular axis activation

2021 ◽  
Author(s):  
Mojgan Goftari ◽  
Chiahao Lu ◽  
Megan Schmidt ◽  
Remi Patriat ◽  
Tara Palnitkar ◽  
...  
Keyword(s):  
Computational Models ◽  
Positive Association ◽  
Step Length ◽  
Imaging Data ◽  
Significant Positive Association ◽  
Pathway Activation ◽  
Gait Dysfunction ◽  
Subject Specific ◽  
Specific Pathway ◽  
Stn Dbs

Background: Deep brain stimulation (DBS) targeting the subthalamic nucleus (STN) often shows variable outcomes on treating gait dysfunction in Parkinson's disease (PD). Such variability may stem from which specific neuronal pathways are modulated by DBS and the extent to which those pathways are modulated relative to one another. Objective: Leveraging ultra-high-field (7T) imaging data and subject-specific computational models, this study investigated how activation of seven distinct pathways in and around STN, including the pallidopeduncular and pedunculopallidal pathways, affect step length at clinically-optimized STN-DBS settings. Methods: Personalized computational models were developed for 10 subjects with a clinical diagnosis of PD and with bilateral STN-DBS implants. Results: The subject-specific pathway activation models showed a significant positive association between activation of the pedunculopallidal pathway and increased step length, and negative association on step length with pallidopeduncular pathway and hyperdirect pathway activation. Conclusions: The STN region includes multiple pathways, including fibers of passage to and from the mesencephalic locomotor area. Future clinical optimization of STN-DBS should consider these fibers of passage in the context of treating parkinsonian gait.

Toward Patient-Specific Computational Study of Aortic Diseases: A Population Based Shape Modeling Approach

2014 ◽  
Author(s):  
Kang Li ◽  
Xiaoping Qian ◽  
Caitlin Martin ◽  
Wei Sun
Keyword(s):  
Computational Models ◽  
Computational Study ◽  
Shape Representation ◽  
Aortic Disease ◽  
Patient Specific ◽  
Shape Correspondence ◽  
Imaging Data ◽  
Aortic Diseases ◽  
Training Set ◽  
Clinical Images

Patient-specific computational study of aortic disease provides a powerful means for diagnosis and pre-operative planning. However, creating patient-specific computational models can be time-consuming due to the fact that anatomical geometries extracted from clinical imaging data are often incomplete and noisy. This paper presents an approach for constructing statistical shape models (SSMs) for aortic surfaces with the eventual goal of mapping the mean aorta geometries to raw surface data obtained from the clinical images for each new patient so that patient-specific models can be automatically constructed. The input aortic models in this study come in the form of triangle meshes generated from CT scans on 6 patients. Statistical models with modes that characterize the variation pattern are found after optimizing the group-wise correspondence across the aorta training set. We use the direct reparametrization approach to efficiently manipulate shape correspondence. We use B-spline based differentiable shape representation for the training set and use the adjoint method for deriving analytical gradients in a gradient based approach for manipulating the shape correspondence to minimize the description length of the resulting SSM. Our numerical result shows that the evaluation measures of the optimized statistical model have been significantly enhanced.

scholarly journals High Tibial Osteotomy: Review of Techniques and Biomechanics

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Xiaoyu Liu ◽  
Zhenxian Chen ◽  
Yongchang Gao ◽  
Jing zhang ◽  
Zhongmin Jin
Keyword(s):  
Contact Mechanics ◽  
High Tibial Osteotomy ◽  
Cartilage Damage ◽  
Varus Deformity ◽  
Patient Specific ◽  
Tibial Osteotomy ◽  
Element Analysis ◽  
Term Survival ◽  
Joint Contact

High tibial osteotomy becomes increasingly important in the treatment of cartilage damage or osteoarthritis of the medial compartment with concurrent varus deformity. HTO produces a postoperative valgus limb alignment with shifting the load-bearing axis of the lower limb laterally. However, maximizing procedural success and postoperative knee function still possess many difficulties. The key to improve the postoperative satisfaction and long-term survival is the understanding of the vital biomechanics of HTO in essence. This review article discussed the alignment principles, surgical technique, and fixation plate of HTO as well as the postoperative gait, musculoskeletal dynamics, and contact mechanics of the knee joint. We aimed to highlight the recent findings and progresses on the biomechanics of HTO. The biomechanical studies on HTO are still insufficient in the areas of gait analysis, joint kinematics, and joint contact mechanics. Combining musculoskeletal dynamics modelling and finite element analysis will help comprehensively understand in vivo patient-specific biomechanics after HTO.

Effects of Surgical Repair or Reconstruction on Radiocarpal Mechanics From Wrists With Scapholunate Injury

2011 ◽  
Author(s):  
Joshua E. Johnson ◽  
Sang-Pil Lee ◽  
Terence E. McIff ◽  
E. Bruce Toby ◽  
Kenneth J. Fischer
Keyword(s):  
Contact Forces ◽  
Joint Mechanics ◽  
Imaging Data ◽  
Contact Patterns ◽  
Radiocarpal Joint ◽  
Joint Contact ◽  
Ligament Disruption ◽  
Joint Contact Pressure ◽  
Contact Pressures

Scapholunate dissociation (SL ligament disruption) due to trauma can cause changes in joint kinematics and contact patterns, which can lead to scapholunate advanced collapse (SLAC wrist) with secondary radiocarpal osteoarthritis (OA) [1]. The relationship between consequent abnormal mechanics and the onset of OA is not clearly understood, however elevated joint contact pressure is believed to be an associated factor. Knowing how injuries affect joint physiology and mechanics and how well surgical repairs restore the mechanics may improve surgical efficacy and help predict OA risk. Recently a method was proposed to measure joint contact mechanics from in vivo imaging data during functional loading [2]. The objective of this study was to compare radiocarpal joint mechanics (contact forces, contact areas, peak and average contact pressures) of injured and post-operative wrists to contralateral controls using MRI-based contact modeling. We hypothesized that average contact pressures and peak contact pressures would be higher in the injured wrists, and that these measures would decrease post-operatively.

scholarly journals A novel method for defining ligament characteristics in subject specific dynamic surgical planning

10.29007/mkjf ◽  
2018 ◽  
Author(s):  
Willy Theodore ◽  
Joseph Little ◽  
David Liu ◽  
Jonathan Bare ◽  
David Dickison ◽  
...  
Keyword(s):  
Knee Joint ◽  
Computational Model ◽  
Computational Models ◽  
Reference Strain ◽  
Knee Laxity ◽  
Patient Specific ◽  
X Rays ◽  
Anatomical Characteristics ◽  
Free Length ◽  
Subject Specific

Despite of the high success of TKA, 20% of recipients remain dissatisfied with their surgery. There is an increasing discordance in the literature on what is an optimal goal for component alignment. Furthermore, the unique patient specific anatomical characteristics will also play a role. The dynamic characteristics of a TKR is a product of the complex interaction between a patient’s individual anatomical characteristics and the specific alignment of the components in that patient knee joint. These interactions can be better understood with computational models. Our objective was to characterise ligament characteristics by measuring knee joint laxity with functional radiograph and with the aid of a computational model and an optimisation study to estimate the subject specific free length of the ligaments.Pre-operative CT and functional radiographs, varus and valgus stressed X-rays assessing the collateral ligaments, were captured for 10 patients. CT scan was segmented and 3D-2D pose estimation was performed against the radiographs. Patient specific tibio-femoral joint computational model was created. The model was virtually positioned to the functional radiograph positions to simulate the boundary conditions when the knee is stressed. The model was simulated to achieve static equilibrium. Optimisation was done on ligament free length and a scaling coefficient, flexion factor, to consider the ligaments wrapping behaviour.Our findings show the generic values for reference strain differ significantly from reference strains calculated from the optimised ligament parameters, up to 35% as percentage strain. There was also a wide variation in the reference strain values between subjects and ligaments, with a range of 37% strain between subjects. Additionally, the knee laxity recorded clinically shows a large variation between patients and it appears to be divorced from coronal alignment measured in CT. This suggest the ligaments characteristics vary widely between subjects and non-functional imaging is insufficient to determine its characteristics. These large variations necessitates a subject-specific approach when creating knee computational models and functional radiographs may be a viable method to characterise patient specific ligaments.

Full tractography for detecting the position of cranial nerves in preoperative planning for skull base surgery: technical note

2020 ◽  
Vol 132 (5) ◽  
pp. 1642-1652 ◽  
Author(s):  
Timothee Jacquesson ◽  
Fang-Chang Yeh ◽  
Sandip Panesar ◽  
Jessica Barrios ◽  
Arnaud Attyé ◽  
...  
Keyword(s):  
Skull Base ◽  
Preoperative Planning ◽  
Skull Base Surgery ◽  
Cranial Nerves ◽  
Patient Specific ◽  
Small Scale ◽  
Skull Base Tumor ◽  
Skull Base Tumors ◽  
Brain White Matter ◽  
Human Connectome Project

OBJECTIVEDiffusion imaging tractography has allowed the in vivo description of brain white matter. One of its applications is preoperative planning for brain tumor resection. Due to a limited spatial and angular resolution, it is difficult for fiber tracking to delineate fiber crossing areas and small-scale structures, in particular brainstem tracts and cranial nerves. New methods are being developed but these involve extensive multistep tractography pipelines including the patient-specific design of multiple regions of interest (ROIs). The authors propose a new practical full tractography method that could be implemented in routine presurgical planning for skull base surgery.METHODSA Philips MRI machine provided diffusion-weighted and anatomical sequences for 2 healthy volunteers and 2 skull base tumor patients. Tractography of the full brainstem, the cerebellum, and cranial nerves was performed using the software DSI Studio, generalized-q-sampling reconstruction, orientation distribution function (ODF) of fibers, and a quantitative anisotropy–based generalized deterministic algorithm. No ROI or extensive manual filtering of spurious fibers was used. Tractography rendering was displayed in a tridimensional space with directional color code. This approach was also tested on diffusion data from the Human Connectome Project (HCP) database.RESULTSThe brainstem, the cerebellum, and the cisternal segments of most cranial nerves were depicted in all participants. In cases of skull base tumors, the tridimensional rendering permitted the visualization of the whole anatomical environment and cranial nerve displacement, thus helping the surgical strategy.CONCLUSIONSAs opposed to classical ROI-based methods, this novel full tractography approach could enable routine enhanced surgical planning or brain imaging for skull base tumors.

scholarly journals Application of subject-specific adaptive mechanical loading for bone healing in a mouse tail vertebral defect

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Angad Malhotra ◽  
Matthias Walle ◽  
Graeme R. Paul ◽  
Gisela A. Kuhn ◽  
Ralph Müller
Keyword(s):  
Mechanical Loading ◽  
Bone Defect ◽  
Bone Healing ◽  
Three Dimensional ◽  
Patient Specific ◽  
Dependent Manner ◽  
Micro Computed Tomography ◽  
Computed Tomography Images ◽  
Bone Defect Healing ◽  
Subject Specific

AbstractMethods to repair bone defects arising from trauma, resection, or disease, continue to be sought after. Cyclic mechanical loading is well established to influence bone (re)modelling activity, in which bone formation and resorption are correlated to micro-scale strain. Based on this, the application of mechanical stimulation across a bone defect could improve healing. However, if ignoring the mechanical integrity of defected bone, loading regimes have a high potential to either cause damage or be ineffective. This study explores real-time finite element (rtFE) methods that use three-dimensional structural analyses from micro-computed tomography images to estimate effective peak cyclic loads in a subject-specific and time-dependent manner. It demonstrates the concept in a cyclically loaded mouse caudal vertebral bone defect model. Using rtFE analysis combined with adaptive mechanical loading, mouse bone healing was significantly improved over non-loaded controls, with no incidence of vertebral fractures. Such rtFE-driven adaptive loading regimes demonstrated here could be relevant to clinical bone defect healing scenarios, where mechanical loading can become patient-specific and more efficacious. This is achieved by accounting for initial bone defect conditions and spatio-temporal healing, both being factors that are always unique to the patient.

scholarly journals Minimally Invasive Mini-orbitozygomatic Approach for Clipping an Anterior Communicating Artery Aneurysm: Virtual Reality Surgical Planning

2020 ◽  
Author(s):  
Nicolás González Romo ◽  
Franco Ravera Zunino
Keyword(s):  
Virtual Reality ◽  
Minimally Invasive ◽  
Surgical Planning ◽  
Artery Aneurysm ◽  
Patient Specific ◽  
Anterior Communicating Artery ◽  
Imaging Data ◽  
Advantages And Disadvantages ◽  
Orbitozygomatic Approach ◽  
Skull Base Anatomy

AbstractVirtual reality (VR) has increasingly been implemented in neurosurgical practice. A patient with an unruptured anterior communicating artery (AcoA) aneurysm was referred to our institution. Imaging data from computed tomography angiography (CTA) was used to create a patient specific 3D model of vascular and skull base anatomy, and then processed to a VR compatible environment. Minimally invasive approaches (mini-pterional, supraorbital and mini-orbitozygomatic) were simulated and assessed for adequate vascular exposure in VR. Using an eyebrow approach, a mini-orbitozygomatic approach was performed, with clip exclusion of the aneurysm from the circulation. The step-by-step process of VR planning is outlined, and the advantages and disadvantages for the neurosurgeon of this technology are reviewed.

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