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Replacement Parts

Replacement Parts

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Replacement Parts

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  1. Replacement Parts Hip replacement parts UHMWPE Superalloy Polyethylene Cemented & Uncemented

  2. Ultra High Molecular Weight PolyethyleneUHMWPE - Properties • Is a long chain of repeating -CH2- units. • Very strong and resistant to abrasion. • Doesn’t deform easily and has strength against fatigue i.e. durable. • Lower density than high-density polyethylene. • Biocompatible and forms a low friction surface on parts.

  3. UHMWPE - Uses • Coat metallic surface to give the joint a smooth surface. • If the joints are not coated, friction can occur which can be painful. • Also rubbing of the joint parts can cause metal to flake off and debris accumulates in the joint tissue. • This debris can cause infection and loosening of the joint.

  4. Superalloys • A mixture of metals that combine to form a metal with greater strength than one metal alone. • Titanium alloys are most often used. • Open to page 179, activity and table 6.3. Elbow and wrist replacement parts

  5. Making the superalloy hip joint • A wax model of the hip joint is coated in ceramic liquid to form a mould.

  6. Making the superalloy hip joint • The ceramic mold is hardened in a kiln.

  7. Making the superalloy hip joint • The wax model is removed. • Liquid superalloy is poured into the mold and cooled.

  8. Making the superalloy hip joint • When the alloy is cooled, the ceramic mold is destroyed and the body part is revealed.

  9. Hip Replacement - Animation

  10. Knee Replacement - Animation

  11. Cemented joints • The superalloy structure in hip and knee replacements can be ‘glued’ in place. • The metallic femoral stem is cemented into the drilled space in the femur. • Cement can be mixed with an antibiotic to reduce risk of infection. • The cement when exposed with a catalyst reacts and forms a solid bond.

  12. Uncemented Joints • In uncemented joints the prosthesis has microscopic pores that allow the bone of the femur to grow into and around the artificial stem. • Uncemented joints are believed to have longer duration than cemented ones, especially in younger patients.

  13. Replacement Parts X-ray of a hip replacement

  14. Replacement Parts Artificial knees

  15. Replacement Parts Different types of artificial hips

  16. Replacement Parts Artificial shoulder joint Silicone finger replacement

  17. What shape is the human backbone and what does it enable us to do? Name three parts of the skeleton whose function is protection and name the organ(s) they protect. How are bones and blood related? Name one place in the body you might find the following types of joints: sliding, pivot, ball and socket and hinge. What is the function of cartilage and synovial fluid in the operation of a joint. What are superalloys? What characteristics must they possess to be used in prosthetics? Why would the joining ends of a superalloy joint need to be coated in UHMWPE? Sketch a diagram of how the end of an artificial stem would look if it were going to be implanted without the use of a cement. Why does it have this structure? Questions