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 The benefits of hip resurfacing are
currently restricted to younger, more active individuals.
Individuals who have, or may develop, poor bone quality are
not suitable for resurfacing. Other potential drawbacks may
include early femoral neck fracture (a break in the bone
just beneath the ball of the hip joint), collapse of the
bone inside the metal cap and gradual thinning of the bone
around the stem. In countries where hip resurfacing is most
established, surgeons are still only using the operation in
a relatively small percentage of their hip replacement
patients and so there is still a need for a conservative
implant which can be used in a wider patient group."
The work carried out by Mr. Field and Professor Rushton in
London and Cambridge has resulted in the development of the
MITCH PER Mini-Hip implant. The PER is one element of a bone
conserving system of implants including a resurfacing
component and a large diameter total hip component. The
Mini-Hip is designed to preserve patient bone and overcome
the limitations of both hip resurfacing and standard hip
implants. The implant replaces the top half of the natural
femoral head and has a mini stem which strengthens the
femoral neck.
Much of the head and all of the neck of the femur (thigh
bone) are preserved, allowing for a conventional total hip
to be carried out later if needed.
Mr. Field goes on to say "Extensive computer simulation
studies were undertaken in Italy, Australia and America all
of which helped to optimise our design of the Mini-Hip
implant. Mechanical loading tests at the world famous
Rizzoli Institute in Bologna have provided strong evidence
that our design will protect the bone from the early
problems seen in conventional hip resurfacing and thus make
it suitable for the majority of patients. I started
implanting the new hip just over a year ago and thus far,
all the laboratory predictions have been confirmed."
Mr. Richard Field is a Consultant Orthopaedic Surgeon &
Director of Research at the South West London Elective
Orthopaedic Centre SWLEOC). He also practises at St
Anthony's Hospital in Cheam.
www.hipandkneesurgeon.co.uk
Professor Neil Rushton is Director of the Orthopaedic
Research Unit at the University of Cambridge and a
Consultant Orthopaedic Surgeon at Addenbrooke's Hospital,
Cambridge.
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