Blood Flow To The Femoral Head and its
Implications on Resurfacing Hip Replacement
H.W. Amarasekera M.L. Costa J. Achten D.R. Griffin
Hiran.W.Amarasekera@warwick.ac.uk
Background
Proposed Studies
Study 4 - Femoral Head Retrieval Study
Blood flow to the Hip has been a point of
debate among many researchers over
the past. Even though there are many
vessels supplying the femoral head, the
exact contributions from each vessel
towards the blood flow is not well
established. Previously when Total Hip
Replacements were done the femoral
head and neck was removed and was
replaced by a metal stem. However with
modern resurfacing hip replacements
most of the femoral head and neck is
preserved. This makes the blood flow to
this area a key factor in determining the
success of this procedure.
We proposed a series of studies to address the above Research Questions. Each study was
designed to understand the blood flow and it’s effect on hip resurfacing during two main
surgical approaches: The Posterior and The Trochanteric Flip(Ganz) .
Analysis of Retrieved Femoral
Heads from failed Resurfacing
Arthroplasty Patients.
Study 1 Study of Intra-operative blood flow using LASER Doppler Flow Meter.
Study 2 Study of Post-operative Blood flow using SPECT CT Scan.
Femoral heads were retrieved from patients who
underwent a revision hip replacement for failed
hip resurfacing .(n=12)(Results yet to be
analyzed)
Study 3 Validating SPECT Scan results using Phantom Study Models.
They were analyzed for following features,
a.Gross sections,
Study 4 Analysis of Retrieval Femoral Heads from failed Hip Resurfacings.
c. Microradiographs,
b. Cut Sections
d.Histology
Study 1- The Intra-operative Study
Comparison of Intra-operative Blood flow using LASER Doppler Flow meter.
a.
We compared the two approaches during five stages of operation Total of 24 hips, 12 in each
group were studied.The Results showed 40% Decrease with Posterior and 11% decrease
with Ganz Approach (fig 2 & Ref 1)
% Blood Flow
Blood flow to the Femoral
Head
100
90
80
70
60
50
40
30
20
10
0
b.
1. Pre
Exporsure Pre
Dislocation
2. Post
Exporsure Pre
Dislocation
Posterior
3. Dislocation
and
Relocation
4.Post
Arthroplasty
Pre closure
c.
5. Closure up
to Fascia Lata
Ganz
Study 2- Post-operative Study
Fig 1. Blood
supply of the Hip
The Research Questions
Assessment of Post-operative femoral head vascularity using SPECT CT Scan
At the end of one year following surgery we assessed the two groups for the Femoral head
vascularity.Eight from posterior group and six from trochanteric flip group (n=14) were
studied.
We did not find any significant difference between the two groups at the end of one year.(fig
3)
Conclusions
Tc-99 MDP
Isotope uptake
count
1. Does the blood flow to the hip drop
during different surgical
approaches used in Hip
Resurfacing?
2.If the blood flow drops during
surgery, is it transient or
permanent?
3.If Transient how long does it take the
blood flow to return to the
Hip?
4. Does this blood flow compromise
cause permanent damage to
the femoral head causing
complications and failure of
the Resurfacing Hip
Replacement?
d.
Posterior
Trochanteric flip
300.0
250.0
200.0
150.0
100.0
50.0
0.0
Head-neck
Inter trochanteric
Upper shaft
Mid shaft
Regions of interest
Fig 3. Graph showing there is no significant difference between the two groups
Tc99 Isotope Uptake.(p>0.5)
Study 3 -Phantom Study
In order to validate the accuracy of the SPECT CT Scan Results in presence of metal
implants and to obtain an attenuation correction on the SPECT CT scans a Phantom Study
was carried out.
The Results indicate that the Metal implants does not have a significant effect on the final
SPECT CT Data.
The blood flow to the femoral head falls during
surgery. The Percentage drop is more in some
surgical approaches (e.g Posterior) compared to
others.(e.g. Trochanteric flip/Ganz)
However this drop seem to be transient and
appear to return during the post-operative
period.
At the end of one year vascularity of the femoral
head is equal in both groups.
The effect of these vascular changes on the
long term survival of the resurfacing implant is
not yet fully established. We hope to find more
answers once our studies are completed.
References
1. Amarasekera HW, Costa ML, Foguet P,
Krikler SJ, Prakash U, Griffin DR. The blood
flow to the femoral head/neck junction during
resurfacing arthroplasty: a comparison of two
approaches using Laser Doppler flowmetry. J Bone
Joint Surg Br 2008;90-4:442-5.
2. Beaule PE, Ganz R, Leunig M. [Blood flow to
the femoral head and hip resurfacing arthroplasty].
Orthopade 2008;37-7:659-66