With a generous three years' leave of absence from MRI, Charnley began work on developing a total hip replacement.
A biomechanics laboratory was completed in 1961 and The Hip Centre, with consulting rooms, conference and research facilities, followed a year later.
Charnley's first prosthesis comprised two Teflon cups. This evolved to a femoral implant of stainless steel with a large 'ball', to one with a smaller 'ball' that fitted into a Teflon cup. Both parts of the new artificial joint were held in place by pink, acrylic, dental cement.
In the laboratory, Teflon looked like the ideal material for implants – it was slippery, hard wearing and inert. But early replacement operations failed in large numbers and Charnley came very close to giving up on plastics.
However, following a timely visit from a plastics salesman, Charnley’s technician, Harry Craven, tested High Density Polyethylene (HDPE) against Charnley’s wishes.
Craven managed to convince Charnley of the merits of this new plastic material when he found that HDPE wore only 1/2000 of an inch after two days - far less than Teflon.
The resulting implant, with few modifications, is among the most successful replacement hips used today.
Read on: Quest For Perfection