Session: Research Posters

Paper Number: 111960

111960 - Designing a Protocol to Determine the Impacts of Fatigue on Suture Knots 

At hospitals across the world, tying suture knots is a fundamental skill of any orthopedic surgeon. It is a skill that has been practiced and fine-tuned over the centuries. While static analysis of suture knots helps surgeons identify best practices for knot and suture selection, a gap exists in the knowledge of the effect of fatigue on knot security and ultimate tensile strength. There is a limited understanding of fatigue in suture knots that experience cyclic loading greater than 1,000 cycles.  Current modeling techniques make analysis of fatigue on knots a very complex problem to analyze.  Additionally, research into fatigue and abrasion are done on specimens that do not have a knot.  Through experimentation, a cheaper and easier methodology can be created to analyze fatigue trends for various knots and suture materials.  To help understand this problem, an experimental protocol for analyzing suture knots is required.

The purpose of this project was to develop an experimental protocol to analyze the impacts of cyclic loading greater than 1,000 cycles on suture knots.  Initial tests were conducted using Arthrex FiberWire^®, a multi-strand, long chain ultra-high molecular weight polyethylene (UHMWPE) core with a braided jacket of polyester and UHMWPE.  Suture loops of consistent diameter were prepared by trained orthopedic surgeons using the same surgical knot. The loops were then pre-loaded to a set tensile load to determine slippage.  Any slippage was noted and the test iteration was repeated.  Following the pre-load, the suture loop was exposed to a fluctuating cyclic tensile load on an Instron machine.  Loads applied to the suture loops mimicked loads experienced by postoperative orthopedic patients.  Failures due to knot slippage were recorded at the relevant number of cycles.  Following the application of the cyclic load, the ultimate tensile strength was determined and recorded.  The same orthopedic surgeon tied several knots so that the knots were consistent, and variation was reduced across the various cyclic loads.    

This research will set the conditions for assessing displacement and ultimate tensile strength of popular suture materials and various suture knots utilized by orthopedic surgeons.  Through testing, data trends can be analyzed for impacts of fatigue on knot strength and knot slippage.  Analysis into the impacts of various suture materials and knot geometries will help illuminate the impacts of fatigue on suture knots and will help inform orthopedic surgeon knot selection. Additionally, the experimental data obtained from this research will help validate computational models of knots.

Presenting Author: Madeleine Suh United States Military Academy

Presenting Author Biography: Madeleine is a cadet at the United States Military Academy, class of 2025. She is majoring in Mechanical Engineering and has an interest is biomedical research.

Authors:

Brandon Clumpner United States Military Academy
Madeleine Suh United States Military Academy
Benjamin Simonson United States Military Academy
Michael Donohue Keller Army Community Hospital