Date of Award

1-1-2018

Document Type

Masters Thesis

Degree Name

M.S.

Organizational Unit

Daniel Felix Ritchie School of Engineering and Computer Science

First Advisor

Chadd W. Clary, Ph.D.

Second Advisor

Paul Rullkoetter

Third Advisor

Scott Barbee

Keywords

Cementless, Implants, Initial stability, Micromotion, Tibial BaseTray, Total Knee Replacement, TKR

Abstract

Initial stability of cementless total knee replacement (TKR) components is directly related to long-term fixation and success, as excess motion hinders bony ingrowth. To assess implant stability, there is a need for more physiologically accurate loading conditions, incorporating forces and displacements in all 6 degrees-of-freedom found in the knee joint, as well as understanding the impact of femoral flexion on conformity of tibiofemoral articulation. Understanding how different activities of daily living generate tibial micromotion yields insight into surgical technique considerations, and rehabilitation strategies post-operatively. ASTM F3141-15, which specifies knee flexion, Internal-External moment, Medial-Lateral, Anterior-Posterior and Superior-Inferior forces during gait and stair descent activities, supplemented with abduction-adduction moments, as well as varied surgical alignment, was used to create loading profiles. Deep knee bending loading was extracted from the Orthoload database utilizing the same methods. These activities were simulated on Depuy Attune, Stryker Triathlon and ZimmerBiomet NexGen cementless tibial base tray designs implanted into biphasic synthetic tibia using the accompanying femoral component mounted in an AMTI VIVO joint simulator. Micromotions were observed on the anterior lateral, center and medial aspect of the tray with respect to the cortical tibia using digital image correlation to track displacements throughout the full cycle of each variation of each activity. Results demonstrated increased tibial tray micromotions are primarily correlated with large femoral A-P translations coupled with high compressive loads, but not increased ad-ab moment, indicating initial fixation may be robust to frontal plane alignment of the implant. Gait and stair descent activities resulted in higher micromotions compared to deep knee bending activities, potentially indicating deep knee bending is not deleterious to initial fixation of cementless tibial trays. The findings of this experiment were used to create a validated finite element model to be used for pre-clinical implant development. Further work is currently under way to simulate the quadriceps muscle force, allowing for whole joint (tibiofemoral and patellofemoral) simulation. The addition of a muscle force driven mode represents a more anatomically accurate experimental method for evaluating native and implanted knee joint mechanics. The work presented in this thesis has strong medical device development and verification implications, as well as the ability to provide more clinically relevant information leading to increasingly successful patient outcomes.

Publication Statement

Copyright is held by the author. User is responsible for all copyright compliance.

Rights Holder

Hayden Wilson

Provenance

Received from ProQuest

File Format

application/pdf

Language

en

File Size

129 p.

Discipline

Biomechanics, Engineering

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