Due to its high strength, low weight and non-corrosive properties, titanium and its alloys are used in a wide range of medical applications. Titanium is a major material used in the skeletal system for joint replacement such as hip ball and sockets and in internal fixators such as plates and screws. A titanium implant has high fracture toughness and enhanced fatigue properties over competing metals. These load bearing implants can stay in place for 15-20 years thereby, improving the quality of human life. Figure 1.1 shows the acetabular shell (socket portion) and the femoral stem. The socket is made of metal shell with a medical grade plastic liner which acts like a bearing. The femoral stem is made of metal such as titanium alloy.

Figure 1.2 shows one of the femoral stems being cemented to the bone using an epoxy. In the other design the femoral stem has fine mesh of holes on the surface that promotes tissue growth and subsequent attachment of the prosthesis to the bone.

Titanium is also used for bone-fracture fixation in spinal fusion devices, pins, bone-plates and screws. Due to its non-magnetic properties it does not pose any threat to patients with implants during magnetic resonance imaging and exposure to electronic equipment. Titanium is also used for wide range of surgical instruments. It does not corrode or lose surface properties with repeated sterilization and its light weight reduces surgeon fatigue during repetitive operations. Titanium is used in craniofacial and maxillofacial treatments to replace facial features of patients.

Fig. 1.1 Acetabular shell (socket-left) and femoral stem (right) implants (Courtesy: Depuy Orthopedics, Inc. [19])

Fig. 1.1 Acetabular shell (socket-left) and femoral stem (right) implants (Courtesy: Depuy Orthopedics, Inc. [19])

Fig. 1.2 Cemented (left) and uncemented (right) designs of femoral stem implants (Courtesy: DePuy Orthopaedics, Inc. [19])

Another prominent application of titanium alloy is in dental implants for tooth fixation. After the osseointegration of the implant with the bone an abutment is inserted into the implant. The abutment provides a seat for the crown which replaces the natural tooth. Tooth replacement using titanium implants is more effective than the use of traditional root canal and bridge constructs.

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