Minimally Invasive Delivery System for Bone Graft Materials

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. Market Potential • 6 million fractures per year in the US • 1.5 million involves long bones • Cost to society: 21 BILLION dollars • 5-10% of fractures exhibit delayed healing and/or non-union Broken Tibia set with fixation device using bone screws

8. Intended Targets • Unstable fractures: • 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)

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