Orthopedic Adaptor Oral Presentation #4 Kate Huddleston Anna Duloy Alexander Byall Ashley Goodnight

Schematic of Femur and Tibia

Schematic of Knee with Prosthesis (pre-periprosthetic Fracture) 300,000 total knee replacements per year

Schematic of Femur and Tibia post- Periprosthetic Fracture 7,500 Periprosthetic Fractures Per Year

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

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

Project Background Periprosthetic femoral fractures These fractures occur: –when femur weakens during surgery –in patients with osteoporosis and rheumatoid arthritis Patent Search - no current method to attach nail and prosthesis

Importance 300,000 total knee replacements per year. Of these there are 7,500 cases of periprosthetic femoral fractures (Incidence rate 0.6%-2.5%) Target population: average age of patient is about 68, but age ranges from years

Cost Cost of periprosthetic femoral fracture repair: –$30,000 (physician, hospital stay, radiology) Cost of adaptor: –Exact price unknown at this point –Material decided as titanium, but specifications undecided

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

Initial Adaptor Schematic

2 nd Adaptor Schematic

Current Adaptor Schematic

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

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 Biomaterials

CAD Drawing for Current Schematic

CAD Drawing with Applied Stresses Analysis for 100 N applied to both sides The maximum stress is 1500 MPa. Yield stress for titanium 6-4 is 800 MPa, so our adaptor would break.

Difficulties Head of the screw – too big Waiting for exact dimensions of the retrograde femoral nail Difficultly measuring the prosthesis

Prototype Machine Shop: Cupples J&J Co., Inc. in Jackson, TN Contact: John Landrum Plastic prototype not possible Titanium prototype wired with EDM Not to cost over $200

Current Status Weekly meetings in Med Center Orthopedics Lab with Advisors Attachment Mechanism –Details (dimensions) –Schematic –Specifications –CAD Drawing, Solidworks Contacted Johnson & Johnson Waiting retrograde femoral nail

Future Work Determine stresses on prototype Continue work on CAD Research mechanical properties of titanium 6-4 Work on installation procedures Continue meeting with advisors Set up meeting with Dr. King for needs

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

References pic254.htmhttp:// pic254.htm lm/Orthtkrperiprosthfrac.htmhttp:// lm/Orthtkrperiprosthfrac.htm dical/fracture_plate_intro.htmhttp:// dical/fracture_plate_intro.htm