Designer bone saves limb
Nicole Chidrawi, UCT
 A partnership between UCT's Dr George Vicatos and surgeon Dr Keith Hosking
has given hope to a young man with a bone-wasting disease, Nicole Chidrawi
reports.
The X-ray showed a vast area of dark nothingness where the bone of the young
man's left, upper arm should have been.
A rare bone disappearing disease had savagely rendered the young man's limb
ineffectual and confined it to a sling for the past 18 months.
Enter Drs Keith Hosking, Vincent Pallotti Hospital surgeon (and part time at
Groote Schuur Hospital) and George Vicatos, UCT mechanical engineering senior
lecturer, whose unique partnership has ensured the young man will have the
chance to lead a normal life with a fully operational arm.
They achieved this through the design and production of a titanium,
Hydroxy-Appatite (H/A) coated prosthesis, including a fully functioning elbow
and shoulder joint.
The prosthesis also includes a stem (protruding from the elbow), which links
the elbow to the bones in the lower arm. Thankfully, these bones were not
affected by the disease.
During a four-hour operation at Groote Schuur Hospital on August 7, Hosking
removed what remained of the patient's elbow and shoulder joints and inserted
the prosthesis, designed by Vicatos, which will allow the youngster to regain
full use of his arm. According to the doctors, the inimitable characteristics of
this case were not only the rarity of the disease but also their collaboration
with United Kingdom orthopaedic prostheses manufacturer BIOMET, the development
of a fully functioning elbow joint and the unique H/A coating (completed by
BIOMET).
The H/A coating, a coral-like substance, will allow the body to recognise its
own material and encourage bone growth onto the prosthesis, thereby creating a
more functional arm. Hosking said: "BIOMET is one of the biggest suppliers
of orthopaedic prostheses in the world. Our designs have now been recognised by
a major international company and that's a coup for us.
"The company has been of great assistance in making this project
possible. Jodi Myers of Macromed SA (regional representative of BIOMET) assisted
with transporting the prosthesis to and from South Africa," he added.
With only about 200 cases ever reported in medical history, Gorham's Disease
(also known as Bone Disappearing Disease) is characterised by bone loss often
associated with swelling or abnormal vessel growth.
Normally, bones replenish themselves through a cycle of bone dissolution and
re-growth. But in people with the disease, bone loss occurs and progresses in
certain areas of the body but no new growth takes place. This may occur in just
one bone or may spread to adjacent areas of the affected bone.
Hosking added that it's a disease that commonly affects long bones in the
bodies of young adults, usually in their 20s and 30s.
"In this particular case, although benign, the disease was particularly
aggressive and involved the entire humerus or upper arm," he said.
"With poor results from bone grafting - the disease simply jumps into the
new bone - the prosthesis offered a viable alternative."
Vicatos' task was to design and produce the custom-made prosthesis. This
process began about a year ago while he was in Europe. He made sketches from
initial X-rays sent from Hosking, whereafter a computer aided design package
allowed Vicatos to ascertain the exact dimensions.
The outcome was a modular design, which would assist Hosking, using simple
tools such as a spanner (sterilised of course), to assemble the correct length
of the prosthesis inside the operating theatre, outside the patient. "They
are designed to be simple and make the surgeon's job easier," Vicatos
added.
The manufacturing process was delayed due to Vicatos' stock of medical grade
titanium being depleted. But once a new shipment arrived from the UK it took Len
Watkins, Principal Technical Officer in the mechanical engineering department,
only three weeks to machine the components.
The machines used by the team produced the pieces with sharp edges. It
therefore took a further two days to smooth these by hand.
The elbow, shoulder and stem components were then sent to BIOMET for the
coating process and arrived back in South Africa, fully sterilised and packaged,
one day before the operation was scheduled to take place.
In total, the prosthesis cost R40 000. Had the custom-made implants been
imported from overseas, the cost would have soared to a staggering R250 000.
"Because they are locally designed and manufactured, these components
are far more affordable than the imported overseas equivalents, which makes them
more accessible to South African patients," said Vicatos.
In addition to their latest success story, Hosking, Vicatos and Watkins have
already collaborated on 27 implants of this nature.
Their range of prostheses include a distal radius, a proximal tibia, a
proximal femur, a proximal humerus, as well as a complete modular system for the
replacement of part of or even the complete femur.
Their designs are repeatedly revised, Vicatos explained. "Some parts are
exceptionally difficult to manufacture and others can be standardised and
produced in various sizes and options in advance so patients need not wait. With
our new machinery, however, we are expecting to manufacture some of the
components in half a day and with greater precision," he said.
Research and development in this exciting project is ongoing and UCT have
allocated space on upper campus for Vicatos and his team, which includes one MSc
and two undergraduate students, to set up a research and manufacturing unit.
ISIQU, the Xhosa word for "complete body" is the name they have
chosen for their unit, which falls under the umbrella of the Faculty of
Engineering.
World-class tumour implants have now become a possibility due to the
expertise at UCT and the dedication of the ISIQU team, but additional funding is
urgently needed to facilitate research, development and the purchase of the
expensive equipment needed to continue providing this valuable service.
At the time of going to press the young patient was making a good recovery
and was expected to be released from hospital later this week.
More information
(For more information please call Dr Hosking on 083 440-0969 or 021 532-3203
or Dr Vicatos on 083 424 3404 or 021 650-2492.)
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