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Leg rod helps strengthen kids' fragile bones
Canadian team's telescopic rod surgery is
less invasive, less painful
By Andrew Skelly
NEW ORLEANS – A telescopic rod invented by a pair of Canadian
orthopedic
surgeons shows promise in strengthening the femurs of
children with osteogenesis imperfecta, potentially with fewer
complications
and reoperations than the traditional technique.
The device is attracting attention from as far away as Kuwait, Peru
and
Sweden. It was developed by Drs. François Fassier and Pierre
Duval, along with Pega Medical, a Montreal firm specializing
in
orthopedic devices.
In an interview at the meeting here, Dr. Fassier, a pediatric
orthopedic surgeon and chief
of staff at Shriners Hospital for
Children in Montreal, said he even travelled to Slovenia last year to
perform the
operation on a girl whose family had heard about the
operation through word of mouth.
"Everything went very well
and I had a Christmas card from the family
saying that she's running now," said Dr. Fassier, who is also an
associate
professor of surgery at McGill University.
The Shriners Hospital is a world centre for the treatment of
osteogenesis
imperfecta (OI), caring for more than 250 patients with
the rare genetic disorder. The multidisciplinary team includes
a
pediatrician, geneticist, orthopedic surgeon, physical and
occupational therapists, a nurse and social worker.
The
clinic is also known for Dr. Francis Glorieux's pioneering use
(starting in 1992) of bisphosphonates to increase bone density
in
children with OI.
The goal of rodding is to correct deformed or fractured bone and
protect against future
fractures. Children typically undergo the
surgery at 18 months to two years, when they first try to stand.
Telescopic
rods that elongate during growth offer longer lasting
protection and have been used for decades.
But the traditional
system requires incisions at both ends of the
femur to insert the parts of the rod, Dr. Fassier said. "What is the
point
of opening a knee joint in a patient who may develop knee joint
problems in future?
"With the new rod, it's like
any femoral rod—everything is done from
the top. And osteotomies (to straighten deformed bone) whenever
possible
are done through the skin, through 2 mm incisions." The less
invasive approach also reduces blood loss and post-operative
pain, he
said.
He and Dr. Duval, an orthopedic surgeon at Brôme-Missisquoi-Perkins
Hospital in Cowansville, Que.,
started developing the new rod in the
mid-1990s and began implanting it in March 2000.
The steel rod consists of
a solid "male" component with a screw at
the distal end and a hollow "female" component with a screw at the
proximal
end. After reaming of the intramedullary canal and alignment
of the bone, the male rod is driven distally and screwed into
the
distal epiphysis. The female rod is then slid over the male rod and
locked proximally into the greater trochanter.
The
child is put in a posterior splint for three weeks instead of the
usual six weeks of immobilization. After the cast is
removed and
replaced by a knee-ankle-foot orthosis, intensive physiotherapy can
start.
At the meeting, Dr. Fassier
presented results at an average followup
of 14.7 months in 21 patients who received 31 rods.
At followup, 17 of
the children were classified as household (nine),
community (four) or therapeutic ambulators (four). There were no
fractures,
but this may also have been due to bisphosphonate therapy.
The complication rate was 32% (10 of 31 rods) and the reoperation
rate
was 16% (five rods). Complications included protrusion of the
male rod into the knee joint and migrating, nontelescoping
or broken
rods.
Dr. Fassier said these figures compare favourably with those reported
in the literature for telescopic
rods—a 39% to 72% complication rate
and a 10% to 40% reoperation rate—and at least some of the
complications
were related to the learning curve. Precise placement
of the male rod in the distal epiphysis is crucial.
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