Background: A dark metallic-appearing smear, resembling a lead
pencil mark, may be seen on a ceramic femoral head component at revision total
hip arthroplasty. The purpose of this study was to investigate the hypothesis
that such a mark on a retrieved ceramic femoral head is associated with
increased surface roughness of the head and increased polyethylene liner wear
in total hip replacement.
Methods: Fifteen ceramic prosthetic femoral heads retrieved from
fifteen patients at revision arthroplasty were examined in this study.
Thirteen heads had been in vivo for an average of 10.8 years (range, 7.8 to
14.2 years). The remaining two heads had been in vivo for less than one month.
The surface roughness characteristics of the explanted ceramic heads, the
linear wear of the polyethylene liner, and the patient activity levels after
the primary replacement and before the revision were determined.
Results: Four of the thirteen ceramic heads that had been in vivo
for =7.8 years had severe smears (>6% of the surface area), and the
remaining nine heads had slight smears (<6% of the surface area). The two
heads that had been in vivo less than one month had severe smears. The mean Ra
and Rpm, the values for surface roughness, were 44.95 nm and 571.15 nm,
respectively, in the hips with slightly smeared regions and 180.77 nm and
1245.88 nm, respectively, in the hips with severely smeared regions (p =
0.002). The mean linear liner wear rate was 0.10 mm/yr in the hips with
slightly smeared heads and 0.19 mm/yr in the hips with severely smeared heads
(p = 0.002). The activity score for all patients was 5 or 6 points on a
Conclusions: The results of this study confirm the hypothesis that a
visual dark metallic-appearing smear on a ceramic femoral head correlates with
increased surface roughness of the head and increased polyethylene wear. These
findings imply that contact of a ceramic femoral head with a metallic
material, such as may occur with femoral head reduction or dislocation of a
total hip replacement, is best avoided to prevent this metallic smear