John Paul obituary

Bioengineer whose meticulous experimental work improved the reliability and strength of hip replacement jointsThe biomedical engineer John Paul, who has died aged 86, played a crucial role in the development of reliable total hip replacement implants, which have improved the lives of great numbers of people. John produced the first realistic estimate of the forces that act on the hip joint during function; this information was essential for the design of safe implants and of machines to test them in the laboratory.In the early 1960s John Charnley, an orthopaedic surgeon, introduced a metal and plastic artificial hip joint with an unnaturally small femoral head to reduce the effect of friction, ideas incorporated into the successful joints in current use. The first joints had a metal femoral component and a polytetrafluoroethylene (PTFE) socket fixed to the pelvis. Unfortunately the PTFE was unsatisfactory and wore out rapidly. Using ultra-high molecular weight polyethylene produced much less wear, but many of the joints broke, because they had been designed using unrealistic estimates of the forces that would act on them during function.John set out to provide more reliable estimates of these forces and was able to do so because of his deep insight into the engineering principles needed to solve the problem and his meticulous experimental work.The forces transmitted across the hip joint are produced by the weight of the body, the accelerations of the body and the power in the...
Source: Guardian Unlimited Science - Category: Science Authors: Tags: theguardian.com Obituaries Biology Engineering Medical research Human biology Scotland University of Strathclyde Medicine Science Source Type: news