Artificial hip joint

Hydroxyapatite (HA) coating on the surface of the hip stem and the acetabular cup is the most recent advancement in artificial hip joint implant technology. This substance is a form of calcium phosphate, which is sprayed onto the hip implant. It is a material found in combination with calcium carbonate in bone tissue, and bones can easily adapt to it. When bone tissue does grow into HA, the tissue then fixes the hip joint implant permanently in position. These HA coatings are only used in press-fit, noncemented implants. 

Semlitsch, M., and Willert, H. G., Properties of Implant alloys for Artificial Hip Joints , Medical and Biological Engineering and Computing, 18, 511-520 (1980)... 

In a typical hip replacement operation, the top of the thigh bone is removed and a cavity is drilled along the direction of the long axis of the remaining bone. A metal prosthesis is placed in this cavity and secured in place with PMMA cement. In the pelvic girdle a plastic cup is fitted to act as the seat of the new, smaller hip joint. This cup is made of ultra-high molar mass poly (ethylene) and is also secured in place with PMMA cement. The components of an artificial hip joint are shown in Figure 10.1. 

These include attempts by surgeon M.N. Smith-Petersen in 1925, Robert and Jean Judet in 1938, and Dr. Edward J. Haboush in 1953. However, the first successful hip prosthesis was not developed until 1961 when Dr. Chamley made a hip prosthesis out of a high molecular weight polyethylene cup. Today, artificial hip joints are implanted in over 200,000 people each year in the USA (Ratner, 2004). 

This photo shows the components of an artificial hip joint. 

Enhancing the wear resistance of polymers (e.g., ultra-high-molecular-weight polyethylene-UHMWPE-used for in vivo implants, such as artificial hip joints). ... 

In the 1960s the first heart valve was replaced. At approximately the same time the Englishman Sir John Charnley developed a bone cement on the basis of PMMA. Nowadays an improved version of this cement is still used, e g. to secure an artificial hip joint to the upper leg. 

Because the shafts of artificial hips joints fractured quite often, much research was aimed at improving the solidity of the materials in the 1970s. Nowadays much better materials are available, notably titanium alloys. 

Many kinds of artificial hip joints are available commercially, but they all consist of the same parts, i.e. a metal stem or shaft, usually made of a titanium alloy and a ceramic head of aluminium or zirconium oxide. The production of the ceramic head starts with a powder and ends with the sintering process. The heat treatment will cause the head to shrink. After production, the head is thoroughly tested, e.g. on its spherical shape and surface roughness. 

The October 1996 issue of the Dutch magazine Natuur Techniek makes mention of a research of the University of Bristol, Great Britain into the effects of implanting artificial hip joints and knees into the body. This research showed that metal particles and pieces of plastic, cement and polymers are gradually released from the artificial joints. Such particles were found in the neighbourhood of joints and lymph nodes. However, they were also present in the bone marrow, the spleen and the liver. The more artificial limbs are exposed to loads, the more particles will be released. So far there are no indications of health hazards, but it is not possible to predict long term effects. 

Moro T, Takatori Y, Ishihara K, Nakamura K, Kawaguchi H. Frank Stinchfield Award grafting of biocompatible polymer for longevity of artificial hip joints. Clinical Orthopaedics and Related Research 2006, 453, 58-63. 

Derbyshire B, Fisher J, Dowson D, Hardaker C, Brummitt K (1994) Comparative study of the wear of UHMWPE with zirconia ceramic and stainless steel femoral heads in artificial hip joints. Med Eng Phys 16 229... 

The metallic elements are used for a lot more than building bridges and making jewelry. Platinum is used in a car s catalytic converter to help decrease air pollution. Titanium is mixed with other metals to construct orthopedic appliances, such as artificial hip joints. Zinc is used to make dry cell batteries. Some of the characteristics of metallic elements that give them such wide applications can be explained by an expaniiedversion of the model of solids presented in Section 2.1. (One of the characteristics of a useful model is that it can be expanded to describe, explain, and predict a greater variety of phenomena.)... 

Titanium metal is used to make metal alloys for aircraft, missiles, and artificial hip joints. It is formed in the reaction of titanium(IV) chloride with magnesium metal. The other product is magnesium chloride. Write a balanced equation, without including states, for this redox reaction. 

Titanium is also used to make artificial hip joints. 

It is said that the yttria-stabilized zirconia (Y-TZP) generally used will degrade if it remains for a long period of time under low-temperature and moist conditions, such as in the human body. Indeed, Piconi et al. have reported on a case of fracture of an artificial hip joint made of Y-TZP. 

Wallbridge, N. and Dowson, D., The Walking Activity of Patients Fitted with Artificial Hip Joints, Engineering in Medicine, U, 2, 95-96 (1982). 

Barb, W, Park, J.B., von Recum, A.F. et al., 1982. Intramedullary fixation of artificial hip joints with bone cement precoated implants I. Interfacial strengths. /. Biomed. Mater. Res. 16 447. 

FIGURE 19.3 Polymeric prostheses for othopedic applications, (a) Major components of an artificial hip joint, (b) Two examples of artificial cervical disks with polymeric components, (i) ProDisc-C disk with an insert fabricated from UHMWPE. (ii) Bryan disk with a nucleus fabricated from polyurethane. Panel (a) Adapted from Mattel et al. [166] with pmnission from Elsevia-, copyright (2011). Panel (b) Adapted from Link et al. [104] with permission from Elsevier, copyright (2004). 

L. Mattel, F. Di Pucdo, B. Picdgallo, E. Ciulli, Lubrication and wear modelling of artificial hip joints a review, Tribol. Int. 44... 

Chamley s design of an artificial hip joint was the product of an evolutionary process between 1958 and 1960 (Charnley 1979). Five design iterations occurred. Chamley s initial "double cup" design in 1958 mimick the natural joint. The acetabulum was replaced with a thin shell of PTFE and femoral head surface was replaced with a PTFE ball, as shown in Figure 4.1, taken of the collection at the Charnley Museum at Wrightington. 

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