Background: The results of total hip arthroplasty in patients with
osteonecrosis of the femoral head are not always optimal. The use of
alumina-on-alumina interfaces in young and active patients may decrease wear
and lower the rate of aseptic loosening of the implant and appears to be an
attractive alternative to the use of conventional
cobalt-chromium-on-polyethylene bearings. The purpose of this study was to
evaluate the safety and efficacy of the alumina-on-alumina bearing in patients
with osteonecrosis and to compare this group of patients to a group of
similarly treated patients with osteoarthritis and a group of patients who
received conventional cobalt-chromium-on-polyethylene bearings.
Methods: Patients were selected from a United States Investigational
Device Exemption multicenter prospective randomized clinical study that was
initiated in 1996. Seventy patients with osteonecrosis of the femoral head
(seventy-nine hips) received a cementless alumina-on-alumina bearing system
and were directly matched to seventy-six patients with osteoarthritis of the
hip (seventy-nine hips) who were managed with the same implant. Both groups
were compared with twenty-five patients (twenty-six hips) with osteonecrosis
and twenty-five patients (twenty-six hips) with osteoarthritis who were
managed with a cementless cobalt-chromium-on-polyethylene bearing system. All
patients received a cementless hydroxyapatite-coated femoral stem and were
followed both clinically and radiographically.
Results: The clinical outcomes for alumina-on-alumina bearings were
similar for both osteonecrotic and osteoarthritic hips. The seven-year
survival probability was 95.5% for the osteonecrotic hips and 89.4% for the
osteoarthritic hips in the alumina-on-alumina bearing group and 92.3% for the
osteonecrotic hips and 92.9% for the osteoarthritic hips in the
cobalt-chromium-on-polyethylene bearing group. At the time of the most recent
follow-up, the mean Harris hip score was 96 points for both the osteonecrotic
and the osteoarthritic hips in the alumina-on-alumina group and 96 points for
the osteonecrotic hips and 97 points for the osteoarthritic hips in the
cobalt-chromium-on-polyethylene bearing group.
Conclusions: The results of the use of alumina-on-alumina and
cobalt-chromium-on-polyethylene bearings in cementless standard total hip
implants in patients with osteonecrosis and osteoarthritis were comparable.
The low revision rate for the alumina-on-alumina bearing is encouraging and
offers a promising option for younger, more active patients who have this
Level of Evidence: Therapeutic Level III. See
Instructions to Authors on
jbjs.org for a
complete description of levels of evidence.