Date of Award

Spring 4-25-2022

Document Type

Thesis - Open Access

Degree Name

Master of Science in Mechanical Engineering

Department

Mechanical Engineering

Committee Chair

Victor Huayamave, PhD

First Committee Member

Alesha Fleming, DC

Second Committee Member

Jean-Michel Dhainaut, PhD

Abstract

Developmental Dysplasia of the Hip is the dysplasia or dislocation of an unstable femoral head in the acetabulum of the pelvis. This is a result of an abnormal or underdeveloped growth of the acetabulum and triradiate cartilages and/or an out of place and uncentered femoral head in the acetabulum. This underdevelopment, if not diagnosed and treated at an early age, may lead to abnormal and pain and osteoarthritis later in life. A common step in diagnosis is to perform a physical examination of the hip, one method is the Barlow maneuver.

The aim of the project is to use healthy and dysplastic hip Finite Element Models to predict the biomechanics of the Barlow maneuver. By modeling and studying the diagnostic maneuver, insight can be gained into the contact pressures magnitude and distribution over different infants’ acetabula and the infant Finite Element Modeling technique. This 3D model is segmented and created using cadaveric infant images from the Padua collection and accurately depicts the partially ossified features of the pelvis and femur. The different regions are broken into three homogenous materials: cartilage, cortical bone, and trabecular bone. The ligaments and muscles that may influence the biomechanics during the Barlow maneuver are also included in a sensitivity-tested Finite Element Model. To model the Barlow maneuver, a range of displacements are applied to simulate the movement applied during the maneuver to healthy and dysplastic hips in Abaqus. Different material properties are also tested to analyze the different contact pressures on the acetabulum and for a sensitivity analysis of the materials. The results of this analysis show an overall trend in the healthy and dysplastic hip models that the contact pressure distribution within the acetabulum focuses posteriorly showing concentrations close to the inner rim in the dysplastic hip’s acetabula. In addition, an inversely proportional relationship between the maximum contact pressure can be seen within the acetabulum to degree of adduction for the grade A and grade B dysplastic pelvis’s but a proportional relationship for the grade C pelvis.

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