DOS Kongressen 2014 ·
65
No association between pseudotumors, high serum
metal-ion levels and metal hypersensitivity in large-
head metal-on-metal total hip arthroplasty at 5-7-
year follow-up
Mette Holm Hjorth, Maiken Stilling, Kjeld Søballe, Lars Hans Bolvig,
Inger Mechlenburg, Stig Storgaard Jakobsen
Department of Orthopaedics, Aarhus University Hospital; Department of
Radiology , Aarhus University Hospital
Background:
The relationship between metal wear debris, pseudotumor for-
mation and metal hypersensitivity is complex and not completely understood.
Purpose / Aim of Study:
The purpose of this study was to assess the prev-
alence of pseudotumor formation in a consecutive series of metal-on-metal
(MoM) total hip arthroplasty (THA) and to investigate its relationship to serum
metal-ion levels and hypersensitivity to metal.
Materials and Methods:
Forty-one patients (31 males), mean age 52 (28-
68) years, with a total of 49 large-head MoM THA participated in a 5-7-year
follow-up study. Patients underwent ultrasonography (US), serum metal-ion
concentrations were measured, metal allergy (patch test) and atopic dermatitis
were evaluated, and the patients completed the questionnaires of the Oxford
Hip Score (OHS), Harris Hip Score (HHS) and the Short-Form Health Survey
(SF- 36).
Findings / Results:
Pseudotumors were found in eight patients, but they were
asymptomatic and their serum metal-ion levels were similar to those observed
in patients with no pseudotumors (p>0.36). The capsule- stem distance of
mean 8.6 mm (SD 3.82, 95% CI: 5.40-11.79) was wider (p=0.02) in patients
with pseudotumours than in patients without pseudotumors of mean 5.6 mm
(SD 2.89, 95% CI: 4.68-6.58). Positive patch test reactions were seen in three
patients (two to nickel and one to iron). Higher serum metal-ion levels of chro-
mium and cobalt were significantly correlated with steeper cup inclination and
smaller femoral head sizes, and were associated with female gender (p<0.04).
Conclusions:
We found no association between pseudotumor formation, serum
metal-ion levels, metal patch test reactivity, and atopic dermatitis. However,
clinicians should be aware of asymptomatic pseudotumors, and we advise fur-
ther exploration into the mechanisms involved in the pathogenesis of pseudo-
tumors.
12.
