University of Pennsylvania Department of Bioengineering Objective To even force distribution over all stitches and thus increase force needed for system failure Attaining Uniform Force Distribution Across Sutures 102WB3 Hypothesis: There will be higher force at failure for sutures tied using a basic running stitch

University of Pennsylvania Department of Bioengineering Methods, Protocol & Equipment: Equipment Instron Model 4444 [1.5 inch wide clamps] Computer loaded with Virtual Instrument “Inston.VI” Methods Create 4 pairs of samples (1 x 1.25 in, width x length) Suture Tyvek cloths using pulley stitch and basic running stitch. Use 7 stitches per sample and maintain an even distance between samples. Test load until system fails (decrease in force) in Instron force vs. displacement data. Repeat testing on samples. Analyze load at failure data Use a one tailed t-test to compare mean load at failure of the two stitching methods to determine if significant difference exists Pulley Stitch Running Stitch

University of Pennsylvania Department of Bioengineering Proposed Results/Findings/Deliverables: Deliverables Force vs. Displacement Graph Force at Failure Table Statistical Analysis (t-test) Force Stitch MethodTrial 1Trial 2Trial 3Trial 4Mean + SD Pulley Stitch Basic Running Anticipated Results Systems with pulley stitch will fail at lower load than systems with basic running stitch Why? - Running stitch allows thread movement through holes resulting in more even force distribution - Pulley stitch resists any thread movement between stitches resulting in increased force on middle stitches

University of Pennsylvania Department of Bioengineering Potential Pitfalls: Human Error Pitfalls - Non-uniform sutures - Knot may slip through Other Pitfalls - Difference in load at failure may not be detectable (Type II Error)

University of Pennsylvania Department of Bioengineering Materials and Budget & Justification: Instron Model 4444 [1.5 inch width clamps] $0.00 Already present in lab Tyvek Cloth (8.5 x 11 inch, 500 sheets)$79.00 Nylon Thread (1 lb. spool)$12.00 Sewing Needle (6 pack)$1.45 Materials consumed Consultancy Fees (1 hr)$50.00 Instruction on Instron Use Instrument Set-Up Total:$142.45