Bionic body parts

Poorly performing parts can be replaced by these medical miracles. The ball of the prosthetic hip joint fits into the socket in the pelvis. The spiked end is fitted into a hole drilled in the femur (upper leg bone).

Artificial limbs The first known prosthesis (artificial body part) was a wooden toe found on a B i on ic body parts L ending us a HAND—among other th ing s 2,700-year-old Egyptian mummy. Since that time, artificial hands, feet, arms, and legs have all been made. Early ones were forged from metal or carved from wood. Some wooden hands (above) had hinged finger joints and could be locked in a gripping position to hold objects. Hip joints can be replaced to relieve arthritis .

Hearing aid

Early hearing aids were big funnels called ear trumPets that channelled sound waves from the air into the ear. Some were made from silver and decorated ornately, while others were hidden in walking sticks so users could be more discreet. Modern hearing aids use a microphone to pick up sounds and an electronic amplifier to make them louder, before they are replayed close to or inside the ear.

Contact lenses

Early contact lenses were made of hard glass and were often very uncomfortable to wear. Czech chemist Otto Wichterle experimented at home with hydrogels (types of polymer material that hold water). In 1961, he built a machine on his kitchen table out of parts from a child’s construction kit and a record player motor. It spun out tiny disks of the material, which formed the first comfortable soft contact lenses.

Dentures

Many kinds of false teeth, also known as dentures, have been in use over centuries. The Etruscans in northern Italy made dentures from human and animal teeth starting in 700 bce. George Washington, the first president of the United States, wore dentures carved out of hippopotamus ivory and held in place by springs made of gold wire.

Modern dentures are made from plastics, and are colored and shaped to look like the real thing.

Pacemaker

Some people’s hearts don’t beat at a healthy rate or rhythm. Pacemakers help by sending out small electrical pulses to stimulate the heart muscles. One of the first, built by Canadian John hopps in 1950, was the size of a toaster and needed to be plugged into a wall socket. Nine years later came a successful implantable pacemaker placed completely inside the body. Some patients lived for 30 years with this model, developed by Americans Wilson greatbatch and William chardack. Glass eyeballs don’t help people see but loo k rea l ist i c .