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Birmingham Hip Resurfacing -
Literature Review
Safety: Revisions
There were 27 procedures that required revision. Two of the 27 revisions
occurred beyond the 5-year follow-up time point in the X-Ray cohort
(Table 12).
|
Table 12: Revisions Stratified by Cohort |
| |
X-Ray Cohort N = 124 |
| |
Pre-op |
1
Year |
2
Years |
3
Years |
4
Years |
5+
Years |
| Number of
Procedures* |
124 |
124 |
123 |
123 |
122 |
122 |
| Revisions |
- |
1 |
0 |
1 |
0 |
2 |
| |
Oswestry Cohort N = 1502 |
| Number of
Procedures* |
1502 |
1502 |
1430 |
1376 |
1116 |
794 |
| Revisions |
- |
9 |
5 |
4 |
1 |
1 |
| |
McMinn Cohort N = 759 |
| Number of
Procedures* |
759 |
759 |
466 |
87 |
3 |
3 |
| Revisions |
- |
3 |
0 |
0 |
0 |
0 |
| |
X-Ray + Oswestry Cohort N = 1626 |
| Number of
Procedures* |
1626 |
1626 |
1553 |
1499 |
1238 |
916 |
| Revisions |
- |
10 |
5 |
5 |
1 |
3 |
| |
Overall McMinn Cohort N = 2385 |
| Number of
Procedures* |
2385 |
2385 |
2019 |
1586 |
1241 |
919 |
| Revisions |
- |
13 |
5 |
5 |
1 |
3 |
* The number of procedures
is the number of hips that were surviving at the end of the previous
year based on the survival analysis. Note that for the Survivorship data
the “year 1” data is starting from day 1 and the “year 2” data is
starting from day 366, etc.
There were 10 revisions due
to a femoral neck fracture, 6 for femoral head collapse, 1 for
dislocation, 2 for AVN (1 led to femoral head collapse and 1 led to a
femoral neck fracture), and 8 for infections (2 led to head collapse, 1
led to a femoral neck fracture). Altogether, there were 12 femoral neck
fractures that required revisions. Factors that may have contributed to
the femoral neck fractures include age-related osteopenia (2 patients),
poor preoperative bone quality as evidenced by cysts in the femoral head
and acetabulum (1 case), SLE (1 case), severe RA (1 case), infection
that led to bone death (1 case), femoral head cysts (1 case), and malpositioned component (1 case). The 9 cases with femoral head collapse
(6 primary femoral head collapses, 2 collapses due to infection and
1 due to AVN). Factors that may have contributed to the femoral head
collapse include infection (2 cases), AVN (2
cases), femoral head cysts and soft bone (3 cases), osteopenia (1 case),
and 1 unknown.
Safety: Revisions Comparison with Literature References
A comparison of the revision rates between the BHR study cohorts and the
two literature reference groups was provided. The revision rate for the
primary efficacy cohort was 1.47% at 5 years compared to 1.2%, 5.2%, and
1.2%, respectively, for the D’Antonio ceramic-ceramic, D’Antonio
metal-poly, and Garino literature reference groups (Table 13).
|
Table 13: Revision Rate Comparisons |
| |
Cohort |
Literature Reference Data |
| |
X-Ray |
Oswestry |
X-Ray/Oswestry
Combined |
McMinn |
Overall
McMinn |
D’Antonio C/C* |
D’Antonio
M/P* |
Garino |
| N |
124 |
1502 |
1626 |
759 |
2385 |
338 |
151 |
333 |
| Revised |
4 |
20 |
24 |
3 |
27 |
4 |
8 |
4 |
| Rate % |
3.2% |
1.3% |
1.47% |
0.3% |
1.13% |
1.2% |
5.2% |
1.2% |
| f/u years |
5 |
4 |
4-5 |
1 |
3 |
3 |
3 |
1-3 |
* Revision rates are based
on a minimum of 2-year follow-up
Safety: Adverse Events
A time course distribution of adverse events was provided (Table 14).
The Overall McMinn Cohort contains the X-Ray, Oswestry, and McMinn
cohorts, and can be considered the safety cohort for this study.
|
Table 14: Adverse Events* - Overall McMinn Cohort |
|
Adverse Events* |
Overall McMinn
Cohort N = 2385 |
| |
Postop |
1
Year |
2
Years |
3
Years |
4
Years |
5
Years |
| Number of procedures |
2385 |
2157 |
1667 |
1378 |
1018 |
620 |
| Procedures with AE
(%) |
1126
46.2% |
847
39.3% |
155
9.3% |
64
4.6% |
34
3.3% |
53
8.5% |
| |
|
|
|
|
|
|
| AVN femoral
head/neck |
31
1.3% |
2
<0.1% |
1
<0.1% |
0 |
0 |
1
0.2% |
| Femoral head
collapse |
7
0.3% |
3
0.1% |
3
0.2% |
1
<0.1% |
0 |
1
0.2% |
| Component
migration/loosening |
1
0.1% |
7
0.3% |
8
0.5% |
2
0.1% |
0 |
1
0.2% |
| Femoral neck
fracture |
0 |
10
0.5% |
0 |
2
0.1% |
0 |
1
0.2% |
| Impingement |
2
<0.1% |
1
<0.1% |
0 |
0 |
0 |
0 |
| Infection (device
related) |
0 |
7
0.3% |
3
0.2% |
1
<0.1% |
1
<0.1% |
2
0.3% |
| Dislocation |
0 |
5
0.2% |
0 |
2
0.1% |
0 |
2
0.3% |
| |
|
|
|
|
|
|
| Cardiac event |
15
0.6% |
1
<0.1% |
0 |
1
<0.1% |
0 |
0 |
| Hg drop |
179
7.5% |
2
<0.1% |
0 |
0 |
0 |
0 |
| Heterotopic
Ossification |
0 |
33
1.5% |
19
1.1% |
3
0.2% |
1
<0.1% |
3
0.5% |
| Hypotension |
33
1.4% |
4
0.2% |
0 |
0 |
0 |
0 |
| Limp |
0 |
203
9.4% |
4
0.2% |
2
0.1& |
0 |
1
0.2% |
Event at implant
site
(clicking, etc.) |
0 |
51
2.4% |
14
0.8% |
9
0.7% |
1
<0.1% |
3
0.5% |
| Reaction at incision
site |
8
0.3% |
62
2.9% |
1
<0.1% |
1
<0.1% |
0 |
2
0.3% |
| Other (See
description below) |
171
7.2% |
121
5.6% |
19
1.1% |
7
0.5% |
7
0.7% |
5
0.8% |
| Thromboembolic event |
3
0.1% |
3
0.1% |
0 |
0 |
0 |
0 |
| Pain |
26
1.1% |
223
10.3% |
76
4.6% |
22
1.6% |
20
2.0% |
29
4.7% |
| Deep Vein Thrombosis |
5
0.2% |
1
<0.1% |
2
0.1% |
0 |
0 |
0 |
| Infection (hip
procedure related) |
28
1.2% |
13
0.6% |
0 |
0 |
0 |
0 |
| Pneumonia |
2
<0.1% |
0 |
0 |
0 |
0 |
0 |
| Fever |
171
7.2% |
1
<0.1% |
1
<0.1% |
0 |
0 |
0 |
| X-Ray report comment |
0 |
23
1.1% |
12
0.7% |
7
0.5% |
3
0.3% |
7
1.1% |
Stiffness, weakness,
flexion
deformity, restricted ROM |
0 |
184
8.5% |
11
0.7% |
9
0.7% |
3
0.3% |
3
0.5% |
| Urinary |
234
9.8% |
1
<0.1% |
0 |
0 |
0 |
0 |
| Wound Exudate |
588
24.7% |
1
0.1% |
0 |
0 |
0 |
0 |
* Time course of events
shows the number and % of subjects with at least 1 complication of the
specified type in the specified time period. Subjects may appear in more
than one time period. Events without time information were not included
in the table.
Safety: Adverse Events - Discussion of Infections
The infections identified in the clinical data series were categorized,
based on data collection procedures, as hip / procedure-related or
device-related based on the time of occurrence. There were 41 infections
associated with the index hip resurfacing procedure within 30 days of
surgery and were thus categorized as hip/procedure-related.
All of these events were
wound exudates or wound infections that resolved with antibiotics. There
were 15 infections that occurred more than 30 days after surgery and
were thus categorized as device-related. Of these 15 infections, 6
required revisions and 9 “resolved with antibiotics.” There were two
patients who were revised for other indications (component migration and
femoral neck fracture) who were found to be infected.
Safety: Adverse Events - Deaths
There were 20 patient deaths (26 procedures) in the Overall McMinn
Cohort. It was determined in no case was a death related to the BHR
procedure. The causes were reported to be: 2 stroke, 4 cancer, 1 motor
neuron disease, 1 esophageal cancer and pneumonia, 1 myocardial
infarction, 1 suicide, 1 ruptured aorta, 1 carcinoma prostate with
metastases, 1 unconfirmed – either diving accident or myocardial
infarction, 7 unreported.
Safety: Metal Ion Literature Analysis
Literature references were provided to address concerns for metal ion
release. An unpublished report by Daniel J, Ziaee H, and McMinn D,
entitled, “Metal ion studies in patients treated with the BIRMINGHAM HIP
Resurfacing, a comparable FDA-approved device and historic metal-metal
total hip replacements” was provided. The authors conducted 4 metal ion
studies in patients who received BHR, Metasul metal-metal total hip
replacements, and other marketed (historic) metal-metal total hip
replacements. In addition, a summary of literature references pertaining
to the medium and long-term safety of cobalt and chromium ion exposure
was provided.
The unpublished and
published literature demonstrate that serum and urinary metal ion
concentrations in patients with total hip replacement in general, and
metal-metal implants in particular, increase in the postoperative
period. However, there does not appear to be any conclusive evidence
that elevated cobalt and chromium levels have any significant
detrimental effects in total hip arthroplasty patients.
Return to BHR Literature Review
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2/4/2007
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