DP-1 Logbook
- Rosalie Wang
- Nov 9, 2020
- 4 min read
Additional Materials Research
Acetabular Cup
Zirconia toughened alumina (ZTA) Ceramic The zirconia particles change their crystal structure from a tetragonal to a monoclinic structure, causing a volume expansion that compresses the surrounding crack in the alumina matrix Covalent bonding high strength, fracture toughness, elasticity, hardness, and wear resistance
The acetabular cup is the top part of our hip implant component. We decided to use Zirconia toughened alumina as it possesses important properties that an acetabular cup must have such as, high wear resistance as it is in direct contact with the liner which may cause some wear to occur, fracture toughness to decrease the possibility of the socket cracking and, high strength and elasticity as the cup is under high stress so the stronger and more elastic it is the smaller the chance for damage to occur.
The component makes sense for our patient as it has low wear resistance. This is very important as many times when you chose a metal acetabular cup rather than a ceramic, it causes the metal to wear which lead to metal ions being released into the bloodstream and urine. These free-floating ions now can have an adverse effect on Diane as they are very problematic for people who have kidney problems. Diane recently has passed 3 kidney stones which signifies she may have had some issues with her kidneys. Therefore, we must choose a material such as ZTA which has a very high wear resistance, but also is strong and tough enough to handle the stress posed on an acetabular head.
Polyethylene Liner
Proposed Material: UHMWPE (Thermoplastic polyethylene)
Explain why you selected this material based on the structure, properties and processing:
High corrosion resistance
High chemical resistance
Abrasion, wear, and impact resistant
Low friction, moisture absorption and coefficient of friction
Can survive exposure to body fluids
Very biocompatible
Nontoxic
Resistant to acids, alkalis as well as organic solvents
Doesn’t need any specific coating to increase any properties
Comment on why the material selected makes the most sense for your patient
Patient has osteoporosis, but liner does not come in contact with the bone, so materials that benefit bone growth or osteointegration may be focused on in other components (acetabular cup & femoral stem)
Patient has rheumatoid arthritis; thus, the liner must not have much wear debris and should be highly biocompatible to not trigger or further complicate her immune responses
Least expensive bearing, suitable for a patient who has other financial demands, such as her 3 children.
UHMWPE has a long life, and the patient is only 63, so it would prevent her from needing revisions or more implants further her life due to complications with this component.
Femoral Head The femoral head is essentially the ball part to the “ball in socket” hip implant. For our hip implant we chose to use Oxidized Zirconium or Oxinium as it poses high strength, hardness, wear resistance and low corrosion. Oxinium is a very new material used for femoral heads in hip prosthetics. When heated in an air environment, the surface of the metal zirconium converts to a black zirconium oxide which is not a coating, but a surface transformation by oxygen diffusion hardening process, which is expected to provide improved resistance under load bearing which is very essential for a femoral head. It is a relatively new material used as an alternative to alumina or zirconia ceramics, demonstrating increased hardness and decreased surface roughness like zirconia, but still possessing inherently high fracture toughness and fatigue strength because of the metal substrate. Oxinium combines both materials favorable attributes, which is why we selected it as our femoral head. Furthermore, Oxinium femoral heads produced 45% less wear than did smooth Co-Cr heads, and, when the heads were roughened, the difference was much greater, with oxinium producing 61% less wear.
The material selected makes sense for our patient because firstly, it has very low corrosion rates compared to other femoral heads, such as cobalt chromium. This is a large factor as femoral heads go through mechanically assisted crevice corrosion (MACC). This happens when materials such as cobalt corrode, they can cause many symptoms, such as stiffness and pain, and adverse local tissue reaction (ALTR) including necrosis of tissues. Our patient Diana is already taking prednisone to combat pain she experiences due to her osteoporosis, so the use of a high corrosion resistance material like Oxinium, would result in her feeling little to no pain. Beyond corrosion Oxinium heads are more durable than other common femoral heads, which is more cost effective in the long term. Although ceramic heads may be more expensive, these can be more cost-effective due to an associated lower revision rate meaning it will last you longer, therefore saving you money in the future.
Femoral Stem (must also look for drug delivery options) AK
Titanium-
Research specific type of titanium used.
Bioactive Porous Coating AK
**remember to relate it back to need statement and patient.
**check abrasion and see what is going into the body from the materials
**materials that promote bone growth
Make sure we answer each question here for each part chosen
Explain why you selected this material based on the structure, properties and processing
Comment on why the material selected makes the most sense for your patient
Comments