Resurfacing Metal on Metal
Early resurfacing failed totally because the material used for the
cup was inappropriate. Polyethylene was used and this led to early
failure. The advent of modern metal on metal low friction design and
superior metallurgy has allowed the revival of this important concept.
The concept of resurfacing is that of exchanging the diseased joint
cartilage surfaces only without resecting bone. In the standard total
hip replacement the head and neck of the thigh bone are resected.
In resurfacing these are preserved: only the surface of the ball of
the head is refashioned and then a metal chrome cobalt cap is cemented
on. The cup on the acetabular side is affixed to the pelvic bone without
cement in a way similar to other cementless methods.
The advantages of this method are the preservation of bone and the
anatomical joint which results from preserving a head size almost
identical to the natural head size and thereby facilitating natural
muscle action in a biomechanically preserved environment, with a better
range of movement and excellent stability which result from the large
head size.
The disadvantage is that the known follow up is only about 7 years
and that there are several contraindications which do not allow its
application universally: particularly severe deformity of the femur
head, poor bone quality, and varus at the femoral neck. Also leg length
cannot be altered or corrected.
Resurfacing is today an option for active patients who have good quality
bone providing they understand that this method is very recent and
has a short follow up only.
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