metal replacement pieces are used for what
Answers
Answer:
Joints in the body may be replaced by metal alloys, ceramics and polymers.
Metals have the mechanical strength and stiffness necessary for load bearing. Ceramics are wear‐resistant and can exhibit osteoconductivity. Polymer‐on‐metal prostheses exhibit attractively low frictional effects.
The first alloy used was vanadium steel for plates and screws. Stainless steel is stronger and more resistant to corrosion than vanadium. The three alloy metals currently used are stainless steel, cobalt‐chromium and titanium alloys. The main characteristics and mechanical properties of these alloys are explored in this chapter. Tantalum trabecular metal is also discussed owing to its attractive qualities of corrosion resistance and biocompatibility. Magnesium alloy is also receiving increasing attention, despite its low strength and tendency to corrode, one attraction is low density.
Ceramics, notably aluminium oxide, are widely used in joint replacements. Aluminium oxide is found in total hip replacements owing to its hardness and low friction characteristics. Typical mechanical properties of this and other ceramics, including Hydroxyapatite (HA), are discussed.
The main applications of ceramics in joint replacements are explored. For example, alumina is used for the femoral heads of hip replacements; HA is employed to coat metallic implants in order to bond them to bone.
After an introduction to the structure of polymers, ultra‐high molecular weight polyethylene (UHMWPE) as a joint replacement bearing material is discussed. Polymers, such as poly(methyl methacrylate) (PMMA) are used as bone cement, fixing prostheses securely to adjoining bone. The preparation of bone cement is discussed; its reliability is well‐established. More than 30 types of cement have been approved by the regulatory bodies.
Examples are given of the effects of wear and friction, fatigue and creep, and corrosion on the materials used in joint replacement. Cases are quoted where wear from metal‐on‐metal hip bearings has led to risks of inflammatory tissue response and cytotoxicity.
Corrosion of implants can arise from fatigue, pitting, stress and crevice cracks. Although polymers and ceramics would not be expected to be affected by corrosion, they may be susceptible to other forms of chemical deterioration, some examples of which are discussed.
Metal replacement pieces are used in in orthopaedics.
Explanation:
- For example in case of a fracture of a bone which is a compound fracture the formation of a newborn cannot be accepted by a simple fracture and demobilization of the part.
- In that case and metal piece needs to be welded on the two ends of the broken bone so as to help in the formation of the the new born. This is known as metallic arthroplasty
to know more about Metallic arthroplasty,
Write the name of the biodegradable polymer used in orthopaedic ..
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