Masters Theses

Date of Award

5-2009

Degree Type

Thesis

Degree Name

Master of Science

Major

Biomedical Engineering

Major Professor

Xiaopeng Zhao

Abstract

Today, children and adolescents are participating heavily in organized athletics year-round. Each year, approximately one third of these children will experience a serious injury requiring a doctor's or hospital visit. A large number of these are overuse injuries. Physeal, or growth plate fractures, are one such type of overuse injury commonly seen in adolescents. At the knee joint, overuse injuries in adolescents occur most often in the proximal region of the tibia. Conversely, in mature adults, overuse injuries manifest themselves more often at the middle/distal third junction of the tibia, or in the soft tissues of the knee joint. While the exact reasons for this difference have not been directly and definitively quantified, several hypotheses have been suggested. They include differences in mechanical movement strategies, changes in limb inertial and material properties, and the timing of these changes in relation to one another.In addition, the presence of an inherently weaker growth plate is present throughout growth, since the growth plate is the last portion of the bone to ossify. This renders the epiphyseal and metaphyseal; areas more susceptible to injury than the than the diaphysis, and loads that would typically cause damage or rupture to soft tissues like the ACL or MCL instead disrupt the weaker physeal plate. This thesis aims to compare the changes in and interaction of inertial properties and forces produced by the quadriceps via the patellar tendon and tibiofemoral contact before and after puberty. To this end, these forces were first determined using Kane's method of dynamics in conjunction with an isometric knee extension study yielding separate adult and youth data. These results were then utilized in the finite element software package Abaqus to load tibial models with varying material properties and investigate changes in stress and strain at the proximal tibia.Shortened patellar ligament and increased force at the ankle had the greatest effect on forces at the proximal tibia. The areas at greatest risk for fracture from the finite element analysis were the posterior and lateral/medial portions of the metaphysis.

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