DOI

10.17077/etd.92oy-stmy

Document Type

Dissertation

Date of Degree

Summer 2019

Degree Name

PhD (Doctor of Philosophy)

Degree In

Biomedical Engineering

First Advisor

Anderson, Donald D.

First Committee Member

Grosland, Nicole M.

Second Committee Member

Lim, Tae-Hong

Third Committee Member

Sander, Edward

Fourth Committee Member

Marsh, J. Lawrence

Abstract

Intra-articular fractures (IAFs) are challenging injuries to study and treat clinically. Following IAF, different joints and even different regions within joints have been shown to have varying degrees of tolerance to injury severity and surgical reduction accuracy. Therefore, to determine the true effects of surgical reduction accuracy on post-traumatic osteoarthritis (PTOA) development, more sensitive and objective measures of articular injury and restoration are needed. To that end, this work details the development of objective measures of injury severity and models of restoration. Two hypotheses were posed: that surgical reduction accuracy is correlated with injury severity, and that injury severity more greatly influences outcomes than the surgical reduction.

To quantify the effects of acute injury severity on PTOA development, objective measures of the energy involved in fracturing as well as the degree of damage to the articular surface were created. Differences in the area over which the damage was delivered were also accounted for as a normalization of the fracture energy to a given joint. Inclusion of this latter factor enabled more accurate study of damage to the important areas of the bone. From these measures, a combined severity score was created that could be applied to any IAF. It was demonstrated to be predictive of the degree of PTOA development in the hip, hindfoot, and ankle.

The effects of surgical reduction accuracy were measured through contact stress, a measure that detects when forces are concentrated over small areas. When these stresses are too high and persist over time, they are associated with chronic joint degeneration. Therefore, the exposure to the contact stresses during a simulated walking gait after fracture reconstruction was computed for each patient. The over-exposures computed over this gait cycle were strongly associated with PTOA development in all 3 joints studied.

By measuring injury severity and reduction accuracy on the same patients with IAFs of the hip, hindfoot, or ankle, relative contributions to PTOA risk were determined for each joint. Significant correlations between injury severity and reduction accuracy were found supporting our first hypothesis. The second hypothesis was refuted, as reduction accuracy was also significantly associated with PTOA development in all 3 joints. An overall model combining the injury severity and reduction accuracy measure for each case was created to assess the total mechanical contributions to PTOA. This model achieved 100% accuracy in the ankle, 88% in the calcaneus, and 91% in the acetabulum.

Keywords

Contact Stress, Fracture Energy, Injury severity, Osteoarthritis, Pathomechanical, Post-traumatic

Pages

xvi, 106 pages

Bibliography

Includes bibliographical references (pages 101-106).

Copyright

Copyright © 2019 Kevin Nathaniel Dibbern

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