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One of my patients from India who has
had a resurfacing, briefed me on the current discussion in the
surfacehippy forum regarding Dr. Klappers opinion of losing
acetabular bone in an attempt to preserve femoral head bone in
resurfacing. He wanted to know my opinion and I thought it would be
appropriate for me to post my answer in this forum. Dr. Klapper's
opinion is way off the mark. The acetabular size is the most
important factor which determines the choice of femoral head size in
resurfacing and one never removes more acetabular bone in hip
resurfacings. In other words if I would be performing a conventional
hip replacement on a given patient instead of resurfacing, I would
be using precisely the same size acetabular component in both the
surgeries.
I would go as far as saying that if we are taking out more
acetabular bone in resurfacing than in conventional hip replacement
, then in my opinion there is no role for resurfacing and it must be
discontinued immediately. Acetabular conservation is as important if
not more than femoral bone conservation and all resurfacing surgeons
recognize and acknowledge this fact. The ability to put large heads
in resurfacing stems from the fact that thin shelled acetabular
components are possible with the modern metal on metal bearings.
However when one uses polyethylene it has to have a large thickness
,which in turn reduces the femoral head diameter, (assuming the acetabular outer shell diameter remains the same). The same argument
holds true for ceramic on ceramic bearing to a lesser extent and
therefore slightly large femoral head sizes than metal on poly is
possible. However an anatomical size is currently possible only with
metal on metal bearings.
I strongly object to the terminology of "large or jumbo head metal
on metal hip replacement" that some surgeons use to describe the
current versions of the total hip replacements which employ the same
metal on metal bearing used in resurfacings. I point out in all my
lectures that this variety of total hip replacement is the
anatomical head replacement giving the same natural size (of the
femoral head and the acetabulum) that the patient has in other
normal hip and the conventional THR are indeed small head hip
replacements. One must never lose this perspective. I hope this
helps to clear the sudden doubt that was cast on the hip resurfacing
principle recently.
Dr. Vijay C. Bose
Consultant orthopedic surgeon Chennai, India
www.hipresurfacingindia.com
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