1. Total Hip Arthroplasty BME 181 By: Erik Walder

2. What is total hip arthroplasty? Total Hip Replacement Bone is sheared away and an artificial hip is implanted Osteoarthritis, trauma, and overuse make people candidates

3. How does the implant work? The ‘stem’ is drilled into the femur The ‘ball’, also known as the bearing, acts as the femoral head The ‘liner’ acts as the acetabulum

4. Cemented vs. Un-cemented Implants Cemented ▫Liner is permanently attached to the pelvis Un-cemented ▫Liner is only temporarily attached ▫Liner consists of porous material compatible for bone growth ▫Bone grows and secures liner in place

5. Metal Ball with Polyethylene Liner Wear Rate: 0.1 mm/yrPros/Cons Most common implant Metal is usually made from cobalt chrome molybdenum alloy Pieces from wear and tear can cause inflammation/bone loss

6. Ceramic Ball with Polyethylene Liner Wear Rate: 0.05 mm/yrPros/Cons Harder than metal Don’t scratch very much Less wear means less inflammation/bone loss More expensive In the past ceramics were brittle and cracked ▫Not usual anymore

7. Metal ball with Metal Liner Wear Rate: 0.01 mm/yrPros/Cons cobalt chromium alloy Allows for a larger ball ▫More like natural joint ▫Increased range of motion Fairly low wear rate Particles from wearing may cause adverse health effects May perform better over long term More sizing options

8. Ceramic Ball with Ceramic Liner Wear Rate: 0.0001 mm/yrPros/Cons Incredibly low wear rate Very hard and strong No particles from wear are dispersed through the body ▫No inflammation ▫No bone loss A wide range of sizing to meet patient specific needs

10. Picture References http://www.mayoclinic.com/health/medical/IM 00342 http://www.bonesmart.org/hip_replacement.ph p?gclid=CNHJ-K_9jqECFd1n5QodrVJ_Mw http://www.mayoclinic.com/health/medical/IM 00341 http://www.yalemedicalgroup.org/stw/images/1 25680.jpg