Validation and applications of discrete element analysis in the hip joint

Townsend, K

doi:10.17077/etd.2r2jrny5

Cited by 2 publications

(6 citation statements)

References 84 publications

(120 reference statements)

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“…iteratively repositions each vertex towards the average distance of its connected neighbors until the surface approaches sphericity [84]. It was found that five smoothing iterations created an articular cartilage representation approaching a nearly spherical surface ( Figure 10) [85]. The distance from this spherical cartilage surface to the subchondral bone varies over the joint surface and produces a non-uniform cartilage thickness, which has been shown by previous studies to be a more realistic cartilage representation [87][88][89][90].…”

Section: Purpose Of This Workmentioning

confidence: 71%

“…Changes in VAS pain scores significantly correlated with changes in maximum contact stress (R 2 = 0.6024, p < 0.001). Changes in SF-36 quality-of-life scores correlated well with changes in maximum contact stress (R 2 = 0.5239, p = 0.012), and changes in WOMAC functional scores correlated moderately with changes in maximum contact stress (R 2 = 0.373, p = 0.046) [85].…”

Section: Previous Work and Rationalementioning

confidence: 89%

“…While the cadaveric validation work supported the use of DEA to assess changes in the dysplastic hip joint following PAO, there were several limitations to note in the application of the methodology to the PAO patients studied in the previous work. Those results illustrated poor agreement between contact mechanics and outcome scores [85].…”

Section: Previous Work and Rationalementioning

confidence: 95%

“…Selecting parameters that accurately represent cartilage stiffness and thickness in the hip joint, in conjunction with applying appropriate loading conditions is crucial to developing a realistic computational model. In the previous work [85], a cartilage modulus of 8 MPa and a Poisson's ratio of 0.42 were selected based on values reported in the literature for average cartilage modulus when loading at rates similar to walking [91,92]. A uniform cartilage thickness of 1 mm was selected based on the mean acetabular and femoral cartilage thicknesses of the two cadaveric specimens studied [85].…”

Section: Materials Properties and Cartilage Thicknessmentioning

confidence: 99%

“…A total of 5 iterations was found to generate viii realistic articular cartilage surfaces that produce accurate contact stress distributions. Image taken from Townsend [85] Figure 12. Average hip contact force of all subjects and its components.…”

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confidence: 99%

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A computational investigation of patient factors contributing to contact stress abnormalities in the dysplastic hip joint

Thomas¹

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Theses and DissertationsFall 2017 A computational investigation of patient factors contributing to A computational investigation of patient factors contributing to contact stress abnormalities in the dysplastic hip joint contact stress abnormalities in the dysplastic hip joint ABSTRACT Acetabular dysplasia, a deformity characterized by the presence of a shallow acetabulum inadequately covering the femoral head, alters force transfer through a joint, causing early-onset hip pain and degeneration. Dysplasia is often treated surgically with a periacetabular osteotomy (PAO), which permits multiplanar acetabular reorientation to stabilize the joint and alleviate pain. PAO alters joint mechanics, including contact stress, which can be assessed via computational methods.This work sought to enhance a discrete element analysis (DEA) model for assessment of the dysplastic hip. The primary focus was on understanding how the gait parameters used to load a DEA model affect the computed contact stress. Several additional studies focused on understanding specific anatomic and demographic factors contributing to the contact stress evaluation were also performed.Implementation of a dysplastic gait pattern to load the DEA models resulted in more cases with improved contact stress and clinical measures after PAO, which concurred with clinical findings. Patient demographics and acetabular and femoral geometry all affected the computed contact stress distributions, emphasizing the importance of proper cohort categorization prior to interpretation of DEA-calculated contact stress. These results indicate that accurate modeling of the particular deformity in this cohort likely requires evaluation of both functional and anatomic differences.These studies improve the ability to realistically model and characterize dysplastic hip contact mechanics. DEA is a valuable tool for assessing contact stress in dysplastic joints, which has the potential to improve patient outcomes by guiding clinicians in nonoperative treatment, pre-operative PAO planning, and evaluating intraoperative success. iv PUBLIC ABSTRACTHip dysplasia is a deformity of the pelvic bone that results in a mechanically unstable hip joint. This can be painful and lead to development of arthritis at a young age.Treatment may involve surgery to change how the hip socket is positioned and oriented in the pelvis to improve hip stability and decrease the damaging, painful stresses on the hip socket. Success of this realignment is largely determined by the ability of the surgeon to determine hip function in 3D from 2D X-ray images that can be obtained during surgery.Computational modeling offers the opportunity for analysis of joint mechanical function in 3D, which provides a much more realistic assessment of the mechanical changes after surgery.The purpose of this work was to develop the best method for using a specific type of computational modeling to evaluate changes in the joint mechanics of dysplastic hips before and after corrective surgery. This involved an investigation of mo...

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Section: Purpose Of This Workmentioning

confidence: 71%

Section: Previous Work and Rationalementioning

confidence: 89%

Section: Previous Work and Rationalementioning

confidence: 95%

Section: Materials Properties and Cartilage Thicknessmentioning

confidence: 99%

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confidence: 99%

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A computational investigation of patient factors contributing to contact stress abnormalities in the dysplastic hip joint

Thomas¹

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Complementary models reveal cellular responses to contact stresses that contribute to post‐traumatic osteoarthritis

Martin

Anderson

Goetz

et al. 2016

Journal Orthopaedic Research

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Two categories of joint overloading cause post-traumatic osteoarthritis (PTOA): single acute traumatic loads/impactions and repetitive overloading due to incongruity/instability. We developed and refined three classes of complementary models to define relationships between joint overloading and progressive cartilage loss across the spectrum of acute injuries and chronic joint abnormalities: explant and whole joint models that allow probing of cellular responses to mechanical injury and contact stresses, animal models that enable study of PTOA pathways in living joints and pre-clinical testing of treatments, and patient-specific computational models that define the overloading that causes OA in humans. We coordinated methodologies across models so that results from each informed the others, maximizing the benefit of this complementary approach. We are incorporating results from these investigations into biomathematical models to provide predictions of PTOA risk and guide treatment. Each approach has limitations, but each provides opportunities to elucidate PTOA pathogenesis. Taken together, they help define levels of joint overloading that cause cartilage destruction, show that both forms of overloading can act through the same biologic pathways, and create a framework for initiating clinical interventions that decrease PTOA risk.

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Validation and applications of discrete element analysis in the hip joint

Cited by 2 publications

References 84 publications

A computational investigation of patient factors contributing to contact stress abnormalities in the dysplastic hip joint

A computational investigation of patient factors contributing to contact stress abnormalities in the dysplastic hip joint

Complementary models reveal cellular responses to contact stresses that contribute to post‐traumatic osteoarthritis

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