redesigning intramedullary nail : to improve success rate october 14, 2005
DESCRIPTION
Problem Statement To improve the intramedullary nail in an effort to decrease misalignments that lead to the inability to secure the nail to the bone.TRANSCRIPT
Redesigning Intramedullary Nail: to improve success rate
October 14, 2005
Tissue Engineering Design TeamTeam Members Erik Yusko – Leader Tony Wampole – BSAC Anna Moeller- BSAC Jon Sass- BWIG Danielle Ebben – CommunicationsClient Tass Dueland- DVM Ray Vanderby- ProfessorAdvisor Professor William Murphy
Problem Statement
To improve the intramedullary nail in an effort to decrease misalignments that lead to the inability to secure the nail to the bone.
Background Intramedullary nails are used to repair long
bone fractures Nails are inserted into the marrow of the bone
and secured into place by screws on the proximal and distal parts of the fracture
Most effective for clean fractures
Background Extension piece attached to nail Nail inserted in bone Jig attached to extension piece Screws put in place by using jig guides
Motivation
Poor alignment of jig guide with nail screw holes results in complications with inserting screws
Distal screws miss more often 4% of screws miss the target Need to strengthen extension piece/nail
interface
Client/Design Requirements Implement in current surgical procedure Maintain nail integrity Consist of only biocompatible materials Easily sterilized Reduce distal hole failure rate
Design 1: Extra Bars Decrease the width of
threaded screw Add 2 rods that go into the
nail New rods perpendicular to
screw holes
Proximal Screw Holes
Design 1: Pros and Cons
Pros: Moment arm
perpendicular to jig reduced
Doesn’t allow rotation Still easy to use
Cons: Screw is smaller Likely allow more
movement parallel to jig
May effect integrity of rod
Design 2: Conical Connection Force distribution increased Key prevent rotation around long axis Two areas were forces are now
opposing motion
Design 2: Pros and Cons
Pros: Easily implemented
into surgical procedure
Leaves most components unaltered
Moments in all directions should be reduced
Cons: May be difficult to
machine
Design 3: Double-Sided Screw Jig has conical hole Top extension screws into
middle and also into nail Middle has hollow center to
allow double sided screw through
Nut attaches middle to nail H head and notch align
holesConceptual; not to scale
Design 3: Pros and Cons
Pros: Will reduce
movement around top joint
Still align holes Stability of nail not
reduced
Cons: Increased difficulty
with more pieces Might not reduce
movement in second joint
Lengthens amount of nail left out of bone
Design Matrix
Design Simplicity Integrationintoprocess
Cleaning Cost PotentialEffective-
ness
TOTAL
(1-5) (1-10) (1-5) (1-5) (1-10) (5-35)
Extra Bars 4 9 5 3 7 28
ConicalConnection 3 8 5 3 8 27
Double-sided
Screw 4 7 5 2 7 25
Future Work
Decide on Final Design Determine Design Parameters Build & Test Prototype
References Rassman, W., Bernstein, R., McClellan, R., Jones, R., Worton, E.,
Uyttendaele, H. 2002. Follicular Unit Extraction: Minimally Invasive Surgery for Hair Transplantation [Online] http://www.newhair.com/resources/p_2002_fue.asp.
Willis, B. 2001 Hair! [Online] http://www.wcsscience.com/hair/page.html. [Company] Chemical Treatment, Internal Document, Rev. B. Mattmiller, Brian. (1998, April). UW Biochemist solves riddle of collagen
stability. Retrieved October 4, 2004, University of Wisconsin,http://www.news.wisc.edu/releases/print.php?id=2995
Youngerman-Cole, Sydney. Repair of the Vaginal wall (Vaginal Vault Prolapse. [Online] Retrieved October 7, 2004.http://my.webmd.com/hw/womens_conditions/tv1559.asp