STABILIZATION OF LONG BONE FRACTURES Team Members: Robert - PowerPoint PPT Presentation

TWO-PIN EXTERNAL FIXATOR FOR TEMPORARY STABILIZATION OF LONG BONE FRACTURES Team Members: Robert Bjerregaard- Communicator Cole Drifka- BSAC Marc Egeland- BWIG Derek Klavas- Team Leader Advisor: Client: Wan-Ju Li Ph.D. Ken Noonan M.D.

OVERVIEW  Background  Motivation: 4-Pin vs. 2-Pin  Existing Devices  Client Requirements  This Semester’s Work  External Fixator Bar Design Options  Pin Support Design Options  Future Work  Acknowledgements

BACKGROUND  Multi-injury trauma patients often require temporary fixation of the femur  Temporary http://www.1-800-translate.com/TranslationBlog/wp- content/uploads/2010/06/emergencyroom.jpg immobilization of the upper leg for up to 48 hours  Patient may undergo bed-to-bed transfer, femur should remain stabilized throughout

MOTIVATION 4-Pin External 2-Pin External Fixation Fixation  4 terminally threaded  2 terminally threaded pins pins  2 proximal and 2 distal to  1 proximal and 1 distal to fracture site fracture site  Procedure must be  Procedure can be conducted in the conducted immediately Operating Room in the Emergency Room  Alignment of 4 pins is  Minimal time, only one time consuming, physician necessary requiring multiple physicians

EXISTING DEVICES Monutube Triax External Traction pin stabilization Fixus 99 External Fixation System Fixation System http://www.osteosynthesis.stryker.com/me http://emedicine.medscape.com/article/1 http://www.fixus.nl/fixus99.html dias/pdf/triax_optech_50752504a2806.p 270717-treatment df • There are currently no known two-pin fixation devices on the market

CLIENT REQUIREMENTS  Implemented in ER by a single resident or staff physician  Installation time must be at most twenty minutes  A maximum of two fixation pins must be used  Device must fit wide range of patients  External bar must be radiolucent, and entire device must be MRI compatible

CLIENT REQUIREMENTS  Implemented in ER by a single resident or staff physician  Installation time must be at most twenty minutes  A maximum of two fixation pins must be used  Device must fit wide range of patients  External bar must be radiolucent, and entire device must be MRI compatible Future Work

THIS SEMESTER’S WORK  Design a pin with increased rotational stability  Construct a temporary external fixator that is easy to apply http://www.engr.wisc.edu/alumni/perspective/34.3/gi ft03PeterTong.html

STANDARD FIXED BAR  External bar with no joints  Pros:  Easy to construct the bar  Streamlined design after installed  Cons:  Requires complicated clamp design  Fits a limited range of pin locations

SINGLE AXIS ROTATION  Joint allows for rotation along long axis of bar  Pros:  Fits a wider range of pin orientations  Extra degree of freedom  Less complicated clamp design – easier installation  Cons:  More complicated design

BALL-AND-SOCKET  Dual ball-and-socket allows for  Pros:  Fits the widest range of pin locations  Three degrees of freedom  Least complicated clamp design – easy installation  Cons:  Bulky and complex design

Fixation Bar Design Matrix Design gn Charact acter eristi stics cs Fix ixed Bar Sin ingl gle e Axis is Ball ll-and nd-Soc Socket Rota otation tion Ease of Installation (40) 20 35 40 Cost (10) 10 6 8 Ergonomics (20) 20 17 15 Manufacturability (10) 8 6 10 Adjustability (20) 10 18 20 Total (100) 68 82 93

MOLLY BOLT  Drill hole, slide in pin, screw to expand  Pros:  Greater stability than standard pin  Cons:  Potential damage to bone  Could be difficult to remove  Targets soft trabecular bone

EXPANSION PIN  Insert pin, screw in central bore  4 expandable segments grip cortical bone to increase stability  Pros:  Greater stability than standard pin  30% higher pullout strength than standard pin [2]  Cons:  Potential damage to bone and surrounding tissue  More difficult to manufacture

NEGATIVE FEEDBACK PIN  Reverse threading combined with external sleeve  Loosening of inside pin causes external sleeve to drive deeper into cortical bone  Pros:  Exceptional stability  Cons:  Bulky  Hard to manufacture

Support Pin Design Matrix Design gn Charact haracter eristi stics cs Moll lly Bolt lt Expansio nsion n Pin in Negati tive e fe feedbac back k Pin in Rotational Stability 28 35 30 PIN DESIGN MATRIX (40) Ease of Installation 12 12 10 (15) Manufacturability (10) 5 9 7 Potential Damage to 10 15 18 Tissue (25) Cost (10) 7 7 7 Total (100) 62 78 72

FINAL DESIGN

FUTURE WORK  Test stability of existing expansion pin in animal bone  Construct pins and fixation bar  Test stability of entire fixator  Design entire fixator to be MRI compatible  Design fixation bar to be radiolucent

ACKNOWLEDGEMENTS  Dr. Wan-Ju Li  Dr. Ken Noonan

REFERENCES  http://www.3dcontentcentral.com/Search.aspx?arg=femur  Cook et. a l. “Lumbosacral fixation using expandable pedicle screws: an alternative in reoperation and osteoporosis” . The Spine Journal. Vol. 1, Issue 2. 2001.

QUESTIONS?