1. Minimally Invasive Delivery System for Bone Graft Materials
Lauren Burdock (BME)
Jon Witten (BME)
Frank Zhao (BME)

2. The physiology of bone Severe loading effects cause fractures
Exploit the natural repair process
Design Project: minimally invasive bone graft delivery device

3. Bone composition and natural repair
Osteoblasts and osteoclasts mobilized
Reparative phase of healing
What is non-union?

4. Non-union and operative repair
Non-union occurs when fragments fail to unite
Introduce bone grafting material into fracture site
Autograft
Allograft
Xenograft
Synthetic compounds

5. Current Bone Graft Insertion Procedures
Previous bone grafting techniques require incisions and manual application of bone pastes and putties into the fracture site, followed by closing of the surgical site.
Open surgery is more prone to contamination and infection than less invasive procedures.

6. Goal
We want to reduce morbidity associated with current bone grafting procedures
To do this, a minimally invasive technique would be needed to replace the procedure that is currently in place
This is a proof-of-concept project. We intend to construct a prototype that could then be adopted by the industry

7. Broken Tibia set with fixation device using bone screws
Market Potential
6 million fractures per year in the US
1.5 million involves long bones
Cost to society: BILLION dollars
5-10% of fractures exhibit delayed healing and/or non-union
Approximately six million fractures occur each year in the United
States, of which 1.5 million involve long bones. These injuries
produce considerable morbidity and impairment in individuals of both
genders, all age groups and regardless of socioeconomic circumstances.
On an annual basis, fractures account for over 36 million lost days
from work, more than seven million days missed from school,
approximately 6.4 million days of hospitalization, nearly 9.4 million
visits to healthcare providers, and cost society an estimated $21
billion (Praemer, 1999). Among the most problematic and burdensome
fractures are those 5-10% that demonstrate delayed healing or
non-union (Connolly, 1991).
Broken Tibia set with fixation device using bone screws

8. Intended Targets Unstable fractures: Long bone fracture: Oblique
Comminuted
Spiral
Transverse
Long bone fracture:
Femur

9. Design Concept
External fixation device holds bone sections together to allow proper healing and alignment

10. Design Concept Hollow needle design
Diameter of lumen is determined by viscosity of bone graft material
Potentially attached to the external fixation device
Pin will be inserted into this area to fill the gap with bone graft materials.

11. Device Operation
Lumen (inlet port)
The pin is inserted in or near the fracture site to serve as a conduit for the application of a bone graft material.
The bone graft will then solidify and the pin will be removed.
Outlet port

12. Device Operation
Bone graft material will flow through the lumen of the pin, exit into the medullary cavity of long bones, and subsequently moves into the fracture area.

13. Potential Problems Contamination at inlet port
Viscosity of bone graft material  change diameter of lumen
Clogging of output port  experiment with size and position
Accurate delivery to fracture site  experiment with pin placement
Pin material must be biocompatible
Pin strength (a problem of lumen versus outer diameter size)
The range for each allowable change to the system is contributed to by the nature of minimally invasive surgical procedures. The outer diameter of the pin must be no larger than 6mm to be feasible for use in current fixation devices. The outer diameter limits the lumen diameter due to the desired structural integrity of the pin. The size and shape of the exit port may vary to accommodate the consistency of the bone graft material.

14. Work Accomplished Started learning AutoCAD
Discussed various designs and have made sketches
Extensive preliminary research underway
We are working with the Orthopaedic Lab at University of Louisville

15. Future Progress
Meet to discuss preliminary design ideas before moving into the design process
Use a QFD diagram to compare designs
Having moved into the design process, we want to a full set of schematics for prototype production
Initiate contact with the Department of Orthopedic Surgery at Vanderbilt University to discuss modern bone grafting techniques and surgical instruments involved