Host response - Orthopaedic Biomaterials in Research and Practice - page 352

Table 14.3 metal content of human blood, serum, and urine

Metal Blood (ng/ml) Serum (or plasma) (ng/ml) Urine (ng/mg creatinine)

Al ? <10 ?

Co <0.3 <0.3 <2.5

Cr <1 <0.3 <0.6

Fe 445 (mg/ml) 1090 65

Mn ? <0.7 ?

Mo <1 <1 ?

Ni <1 <1 <5

Ti ? <2 ?

V ? <1 ?

Sources: Lyengar, G.V. et al., The Elemental Composition of Human Tissues and
Body Fluids , Verlag-Chemie, New York, 1978. Versieck, J., Cornelis, R.,
Acta Analyt Chim 116:217-254, 1980; Cornelis, R., Trace element stud-
ies in the biosphere with neutron activation analysis, Proc. Conf. on
Frontiers in Nuclear Methods of Analysis , College Station, TX, 1984.
Michel, R., CRC Crit Rev Biocompatibility 3:235-317, 1987; plus
author's data.
Note: ?: no reliable normal (control) data. ng/ml, p/pb.

With any method, interpretation of metal ion levels must be done cau-
tiously. There is a wide variability according to method, laboratory,
and patient.
The established release rates are sufficient, in animals and patients
with either stainless steel and cobalt-base components, to produce eleva-
tions of metallic content in tissue (at both local and remote sites) and of
metal-bearing ion concentrations in serum and urine. In TJR patients,
large elevations of chromium and cobalt concentration levels in serum
occur in the early postoperative period, significant elevations may persist
for more than a decade, and accumulations of 10 to 100 times normal of
chromium and nickel in tissues remote from the implanted hip are possi-
ble. It has been reported that elevated ion levels will decrease over time.
Typically, measured elevated levels are still within limits imposed on
employees in industrial settings exposed to pertinent chemicals. Levels
measured clinically are also reported to be lower than those that are
shown to cause toxicity in vitro . After revision of large-diameter MOM
implants, metal ions have been reported to decrease to near-normal lev-
els within 1 year. Long-term animal studies with titanium base alloy
implants suggest significant release of both titanium and aluminum and
concentration in remote tissues, including the lung. Of particular interest
is the apparent failure of these animals (baboons) to excrete more serum
aluminum, secondary to a presumed protein-binding process. Vanadium
release from the Ti6A14V alloy is a concern because of its potential high
in vitro cytotoxicity, but longitudinal concentration patterns have not yet
been studied.