Date of Award


Degree Name

Doctor of Philosophy


Mechanical and Aerospace Engineering

First Advisor

Dr. Peter A. Gustafson

Second Advisor

Dr. Daniel Kujawski

Third Advisor

Dr. James W. Kamman

Fourth Advisor

Dr. Andrew Geeslin


Tendon injuries in orthopedic surgery and sports medicine are escalating; hence there is great interest in improving tendon repair. The integrity of tendon repair depends in part on a combination of suture material, suture size and knot configuration. Recent studies have indicated the failure of surgical knots as a failure mode during surgical repair. Further, there is still no consensus on the ideal (best/safest) surgical knot techniques. Also, this failure mode is related to stress concentrations, which cannot be easily established with traditional tensile testing. Most researchers have focused on the measurement and comparison of the gross structural response of non-knotted and knotted suture, without direct investigation of the governing mechanics. Therefore, the purpose of this study is to develop a finite element approach to analyze the mechanical behavior of surgical sutures. Also, this analysis is necessary to differentiate the responses of several knot configurations and be validated against experiments.

To achieve this purpose, experiments and finite element models are performed to analyze the mechanical behavior of two types of sutures: monofilament and multifilament. Fixtures are experimentally designed to test (non-knotted/ knotted) sutures under tensile load until failure. The knotted sutures are included single, two and three throws-knots. Non-knotted suture and a single throw-knot are modeled and analyzed. Finite element model and experimental results are presented using as-manufactured multifilament surgical suture: core and jacket. The experimental results indicate suture mechanical behavior is influenced by increasing number of throws; this effect is highly dependent on the suture constituents. The presence of a knot reduces failure load; thus rupture occurs consistently at the knot region. The finite element models predict maximum stress regions; the regions are correlated with experimental failures. This study also investigates the shear lag phenomenon of partially failed multifilament suture by analyzing the stress distribution under static and cyclic loading. Furthermore, a valid design for testing the knotless anchors is reported.

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