1. Orthopedic Adaptor Oral Presentation #3
Kate Huddleston
Anna Duloy
Alexander Byall
Ashley Goodnight

2. Schematic of Femur and Tibia

3. Schematic of Knee with Prosthesis (pre-periprosthetic Fracture)

4. Schematic of Femur and Tibia post-Periprosthetic Fracture

5. Project Definition
To design an adaptor that will connect the nail inserted into the shaft of the femur to the knee prosthesis, in the event that a periprosthetic femoral fracture has occurred

6. List of Constraints
Hold the nail 5 degrees relative to the prosthetic joint
Universal
Maintain rigid structure
Irremovable knee prosthesis
Compatible with both right and left knee

7. Project Background Periprosthetic femoral fractures
These fractures occur:
when femur weakens during surgery
in patients with osteoporosis and rheumatoid arthritis
No current method to attach nail and prosthesis
Background: Periprosthetic fracture is described as "an age-sex-specific increase in the rate of fracture in a given anatomical location with the presence of a prosthetic implant." A periprosthetic femoral fracture is seen if the anterior femoral cortex is notched and weakened during surgery and in patients with osteoporosis, rheumatoid arthritis, poor flexion, revision arthroplasty, and neurological disorders. The management of periprosthetic femoral fractures is quite complex, and often involves surgery. A wide variety of surgical techniques are described to treat these types of injuries, including the use of a retrograde femoral nail.
As the number of implants placed increases, it is inevitable that associated fractures also become more common. Once a fracture occurs, treatment is complicated by osteoporosis, defects in the bone, and the presence of the implant. There are 300,000 total knee replacement surgeries performed per year. The incidence of a periprosthetic femoral fracture after total knee replacement is %. Using the average of 1.55% incidence rate, there are approximately 4,650 cases of the periprosthetic femoral fracture a year. This fracture can occur more than 10 years after joint replacement; thus, as the number of patients with replacements accumulates and life expectancy continues to grow, more fractures occur. The range of patients having this type of fracture ranges from early forties to early ninties with an average age of 68. They occur more so in women for a 2 to 1 ratio.

8. Importance
300,000 total knee replacements per year. Of these there are 4,650 cases of periprosthetic femoral fractures (Incidence rate 0.6%-2.5%)
Target population: average age of patient is about 68, but range lies anywhere from 42-92

9. Cost Cost of periprosthetic femoral fracture repair: Cost of adaptor:
$30,000 (physician, hospital stay, radiology)
Cost of adaptor:
Unknown at this point
Material decided, but specifications undecided

10. Attachment Mechanism Brainstorm on pros and cons of each
Practicality of design
Ease of use
Twist and lock was a possible mechanism:

11. Initial Adaptor Schematic

12. Current Adaptor Schematic

13. Adaptor Advantages Significantly quicker procedure
2 pins versus 4
Less surgical dissection
Less blood loss
Better way to maintain alignment between femur and prosthetic knee

14. Biomaterials Factors to consider:
Compatibility with nail (same material) and prosthetic material
Oxidation reactions, Galvanic corrosion
Strength
Expense
Availability
Chosen Material:
titanium (Grade 5 or 6-4) - nail and adaptor
cobalt chrome - knee

15. Current Status
Weekly meetings in Med Center Orthopedics Lab with Advisors
Attachment Mechanism
Details (dimensions)
Schematic
Specifications
Contacted Johnson & Johnson
Ordered retrograde femoral nail

16. Future Work Work out details of chosen design Draw design on CAD
Determine Stresses
Work on installation procedures
Continue meeting with advisors

17. Acknowledgements
We would like to thank the following people for their help:
Dr. Limbird
Jeff Gordon
Sue Larson
Mike Bailey
Dr. King

18. References http://www.emedicine.com/orthoped/topic254.htm