fashioned his own implants. He also had a workshop in his own house,
including a lathe where he turned his own hip socket implants from blocks
of Teflon. Craven assisted him in these endeavors, and the task of making
the widgets themselves was key to solving the problem of hip arthritis.
Flush with the excitement of a Hip Centre and hundreds of hip
replacement operations under his belt, Charnley was hopeful that an
acrylic-cemented hip implant with a small head and Teflon cup was the
long-term solution to hip arthritis. He had gone from one hundred
operations a year in 1959 to over four hundred hip replacements in 1962.
Of course, as a scientist, Charnley was interested in following his patients
and confirming their ongoing success. It was late in 1962 that Charnley
realized that something horrible was happening. Despite the robustness of
patients’ satisfaction and improved functional abilities, the three-year
follow-up X-rays showed a disastrous change occurring in the Teflon cups.
Charnley later explained:
It may seem strange that it took us some three hundred
operations and between three and four years to arrive at this
conclusion [that Teflon was unsuitable], but there were a
number of different reasons. First, the results up to three years
were so spectacular, and the patients so pitifully grateful, that
we could not bring ourselves to face the suspicion that, in such
highly successful results, the X-rays were showing incipient
harmful evidence. Second, by its chemical nature PTFE
[Teflon] was so extremely inert we felt that even if wear
debris was present it would be harmless. Third, though we
could see wear of the order of 1mm after about a year in the
X-rays, I thought that this was not unexpected and could be
explained by the “bedding-in” of the head in a socket that was
deliberately machined to have an internal diameter larger than
the head. It was only when the first year’s wear was more than
doubled in the second year and more than tripled in three
years that the seriousness of the problem became evident.^7On the precipice of a world-changing revolution, Charnley had to
wonder if all was lost. All the X-rays showed a similar pattern of superior