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Ambareen,
I'll tell you what I know, but remember, I'm no doctor! Here goes.
Bone doesn't
just "grow" from anywhere along the bone, rather, it
grows length-wise from the ends of the bones toward the center. These
growth
areas at the ends of the bones are called the growth plates
(FYI - they don't grow equally, for instance, 80% of the growth
in a
tibia comes from the knee end, and 20% from the ankle end). OI tends
to hinder this bone growth in itself (malformed
bone cells preventing
proper growth as well as microfractures in the growth plates). Rods
may also slow growth (but
not always). When a rod is inserted, it
must be placed through the growth plate, and beyond it, almost to the
end of
the bones, so that screw threads do not hinder the growth of
the bone at the growth plate. Smooth metal doesn't seem to
slow the
growth of the bone moving past it, but screws threads do. That's
also why some rods have been made with no
threads in them at all. But
with the telescoping rods that must be attached on both ends, they go
beyond the growth
plate and into the soft area of bone just beyond it
called the epiphesis. That usually works okay, but sometimes the
rods
"migrate" one way or the other because the epiphesis is such
soft bone (you can't even see it on x-ray sometimes).
Back
to rods. A rod's primary function is NOT to prevent the bone
from breaking, but is to give the bone a straight "scaffold"
on which
to continue to build. It helps the bone resist bowing. Rods are used
most advantageously in surgeries where
bowed bones are broken by the
surgeon (osteotomies) and realigned to be straight. It is the
straightness of the BONE
that gives the most strength - not the rods
within them (although they do provide some support). That is probably
what
the surgeon is thinking about. However, in kids with OI, the
rods provide a kind of "inner cast" that keeps fractures from
being
so severe when they do occur (reduces the number of displaced
fractures), and is a source of "traction" once there
is a fracture,
thus reducing pain during fractures and facilitating faster healing
times.
In children with no
OI that get rods after an accident, they are
removed after the legs are healed (my brother had them in both femurs
and
his tibia after a terrible car wreck as a teen, then had them
removed). That is because the rods could cause growth issues,
and are
no longer needed because the break is healed. But with children with
OI, who may easily break again, that is
not the primary concern. For
kids with OI, bone strength, ambulation, down-time due to fracturing
(and loss of bone
and muscle strength due to this) as well as
fracture pain are primary issues that usually supercede whatever
losses
in growth that might occur due to keeping rods in the bone.
Normal-boned people can expect the rodding to be a one-time
event and
an additional surgery to remove the rods is reasonable; with OI kids,
there may be multiple surgeries during
their lifetimes, and an
additional surgery to remove rods (and possibly have to put them in
again after bowing or a
fracture occurs), is usually not advised.
Many adults with OI still have rods in their legs even though they
may not
have fractured in years.
If I were you, I would wait and talk with your regular orthopedic
about these issues. The
other surgeon's statements seem to be in line
with traditional orthopedic practices that apply to normal-boned
children,
but not to kids with OI.
Hey group, if I've said anything that's not quite right, I invite you
to jump in here and
correct any misstatements that I have made! But
this is my understanding. Hope this helps.
Lon
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