Presented May 24, 2012

Dr. De Smet and his team presented the 10 to 13 year
follow-up results of the BHR Birmingham Hip Resurfacing procedure during
the EFORT Congress in Berlin, Germany.

Authors: Catherine Van Der Streeten, Damien Van Quickenborne, Bart De Roset and Koen De Smet

• The overall survival was 95.1% at 13 years
• Survivorship in men was 98.6% at
  13 years
• Survivorship in women was 87.9% at 13 years

Introduction

Hip resurfacing (HRA) designer centres have reported
survivorships between 88.5 – 96% at 12 years. Arthroplasty
Registries (AR) reported less favourable results especially
in females gender and small sizes. The aim of this study was
to evaluate the minimum 10-year survival and outcome of the
Birmingham Hip Resurfacing (BHr) FROM AN INDEPENDENT
SPECIALIST CENTRE.
Methods

Since 1998, 1967 BHRs have been implanted in our
Centre by a single hip resurfacing specialist. The first 249
BHR, implanted between 1999 and 2001 in 232 patients (17
bilateral) were included in this study. The majority of the
patients were male (163; 69%) and hip dysplasis (11; 4.4%).
Mean follow up was 10.2 years (range: 0.1 (revision) to
13.1.) Implant survival was established with revision as the
end point. Harris Hip Scores (HHS), radiographs and metal
ion levels were assessed in all patients. Sub-analysis were
performed by gender, diagnosis and femoral component size
(Small: <50mm; Large: >50mm).

Results

Of the 232 patients, 15 were deceases 94bilater BHR), 16
lost to follow-up and 0 revised. 205 BHR were evaluated at
minimum 10 years postoperatively. Failure modes included 2
component malpositiong, 2 loose femoral heads, 1 fracture, 1
metal sensitivity, 2 impingement and 1 with high metal ions.
The overall survival was 95.1% (95% CL: 93.6-96.6) at 12.8
years. The mean HHS was 97.8 (ranage 65-100). Survivorship
in men was 98.6% (95% (95%CL: 97.4-99.8%) at 13 years.
Survivorship in women was inferior to men (log rank= 0.003);
87.9% (95%CL: 84.3-91.5%) at 12 years. There was no
difference in HHS between genders in the non-revised cases
(p=0.46). There was no difference in survivorship with
different pre-operative diagnosis (log rank = 0.83) but a
significant difference in 12 year survivorship between Small
(90.1%) and Large components (97.2%) (log rank= 0.01). After
adjusting for head size, the difference in survival between
males and females was no longer significant (log
rank=0.125). The median ion levels were Cr.2ug/l; Co:1.0ug/l
in 24 patients the ion levels were undetectable. Four
patients (1.9%) had ions above the upper acceptable limits
of Cr:4.6ug/l;Co:4.0ug/l for unilateral or
Cr:7.4ug/l;Co:5.0ug/l) for bilateral HR, in 67 patients with
consecutive ion measurements, levels decreased significantly
with time with a mean decrease of 0.97ug/l for CR and
0.60ug/l for Co.

Discussion

This study reports the more than 10-year survival of BHR and
reflects an experienced specialist’s practice, including his
learning curve of the procedure. The overall 12.8 year
survival was superior to registry reported figures of THA
amongst young patients and corresponded well with reports
from designer centres.

Survivorship and clinical outcome were excellent in men. In
women survivorship was significantly inferior and related to
smaller component sizes, but the >20-year clinical outcome
in non-revised cases was excellent. In well-functioning BHR,
the metal ions decrease significantly with time. The results
of this study support the use of HRA with good design.