The ankle joint or
tibio-talar joint is made up of the tibia bone in the lower
leg and the talus bone in the back of the foot above the
heel. The ankle joint allows the foot to move up and down in
relation to the lower leg, whilst sideways movement is
provided by the joints within the foot and supported by the
fibula.
As in other
joints in the human body, the surfaces of the bones making
up the joint are normally covered in smooth cartilage which
allows the bones to glide over each other. Amazingly the
ankle supports a force about five times body weight during
normal walking. The cartilage in the ankle joint is
therefore vital in cushioning the bones so that the joint
operates smoothly and painlessly.
Arthritis can
affect the cartilage to the point where there is not enough
left to allow the joint to glide smoothly and bone-to-bone
contact occurs which can be very painful.
Until quite
recently, there were few treatment options for patients with
painful arthritis in the ankle joint. The most common
treatment was ankle fusion, where the tibia and talus bones
(and sometimes the fibula) are fused together. The patient
is put in a plaster for up to twelve weeks to allow the
bones to fuse together. Providing that the bones unite and
that the alignment of the bones is correct, fusion can
alleviate the pain of an arthritic ankle and the patient may
be able to walk without a limp. In addition the patient will
be allowed to partake in high impact physical activities,
making it suitable for the younger, active patient.
An alternative to ankle fusion is an ankle
replacement. Just like a conventional hip or knee
replacement device, an ankle replacement replaces the
bearing surfaces of the bones making up the joint with two
metal components – one on the end of the tibia and one on
the top of the talus. A “plastic” insert is placed in
between the two metal components, mimicking the
cartilage and allowing the new joint
to glide smoothly. Ankle replacements provide the patient
with up and down motion in their ankle joint, which is not
possible with ankle fusion
and as a result a more normal gait is achieved. While this
procedure will never be as popular as hip or knee
replacements, there is increasing evidence that these
devices are proving very successful.
Although early
results of ankle replacements were disappointing, a better
understanding of the joint itself combined with the
advancement of technology has allowed the development of
ankle implant and instrument designs to evolve over the last
three decades.
Not all patients
with arthritis of the ankle are suitable for joint
replacement. Generally those that have a severe deformity or
are very young and active will not be recommended to have an
ankle replacement, however this would need to be thoroughly
discussed with your doctor.
The pioneers of
ankle replacement Frederick Buechel and Michael Pappas have
recently published the results of those patients that they
have operated on over the past 12 years. The study shows that the
survivorship of the implants at 12 years is 92%1. This means
that the number of patients whose implant is functioning and
have not required any intervention since the joint
replacement procedure is 92%. In general the survivorship of
a successful ankle replacement can range between 87-95% at
10 years of clinical follow-up.
Clinical follow-up of all the patients that
have Zenith implants is being carried out by
an experienced team at the Avon Orthopaedic Centre in
Bristol and therefore we hope to publish results in the near
future.
In addition to this, Corin will soon
be adding patient case studies to this site. These studies
will allow you to review the procedure and the after-effects
from a patient perspective and hence provide you with
further information when choosing your treatment option, in
consultation with your orthopaedic surgeon.
It must be noted that all patient
details are kept in confidence by the hospital and not
released to Corin unless a patient has agreed for this to
happen.
References
F Buechel Sr, F Buechel Jr and M
Pappas "Twenty-year evaluation of cementless mobile bearing
total ankle replacement " CORR 2004)