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Thomas Schmalzried, MD
800 Hip Resurfacings to date
Joint Replacement Institute at St. Vincent Medical Center
2200 West Third Street, Suite 400
Los Angeles, CA 90057
213 – 484-7600 phone
213-484-7670 fax
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Dr.
Schmalzried’s Profile
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Dr. Schmalzried Interview by Patricia
Walter Sept. 5, 2009 in Baltimore MD at the 3rd Hip
Resurfacing Course
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Dr. Schmalzried Chat Room Questions & Answers on Nov. 19, 2008 |
Which Hip Resurfacing Devices do you use?
I use the Cormet 2000 but have also used the C+ and the BHR.
Do you know of any problems with the conserve
plus?
The C+has worked very well in my hands. I have 8 year follow-up with this
device.
Do all the current devices use approximately the same
clearance?
There is difference in the clearances –
and it makes a difference in lab studies of wear – and some clinical studies –
low clearance has less wear and lower ion levels.
As far as clearances are concerned, which implants do
you think are best? Is implant selection something patients should be concerned
about, or do you feel it’s more about the physician’s
preference?
The ASR has the smallest clearance. I
think that the surgeon should choose.
What is the best
maintenance exercises for a bilat 61 yr old with good bone?
I like bicycling for exercise. Yoga is good too. Swimming never hurts. I don’t have any restrictions – so impact activities are OK if you can handle
it!
Are there any particular physical therapy
exercises that you like at about 5 weeks post op?
I would stretch for abduction, external rotation and flexion. I like the stat.
bike and swimming at this stage.
Would you consider using computer assisted surgery?
Navigation can be helpful but there is no data as yet to
show that the outcomes are better – in the hands of an experienced surgeon. The best benefit may be for the new surgeon.
Do cysts prevent hip
resurfacing?
The cyst, by itself, is usually not a problem. If your
bone density is good – and the shape of your head and neck are good –
resurfacing is probably a good option.
Can leg length problems be
corrected with hip resurfacing?
Limb length can be an issue with resurfacing – but probably less than
with THR. Our data indicates that on average we gain 4mm of
length.
Is it common practice for a representative of the
company manufacturing thehip resurfacing device to attend
the surgery?
It is common to have the rep in the room at
surgery.
What is your response to
the recent research showing “red flags” for doing the
hip resurfacing procedure on women?
The Aussie registry, and the experience in several
single-surgeon series show higher failure in women. More recent data indicate
that it is more related to SMALL SIZE. Probably the fundamental variable is
cross sectional bone mass – the short term failures are usually neck
fracture. Resurfacing can be
done on women with great success. It is not a gender issue per se. It is a bone
mass issue. Anyone with decreased bone mass has a higher risk of FNF Femoral
Neck Fracture.
What do you think of bone density
drugs like fosamax?
I like a
combination of nutrition, exercise and – in appropriate patients, chemical
treatment of osteoporosis.
When can a
paatient exercise on a recumbent
stationary bike after surgery?
Recumbent bike – wait one week.
Do you allow your patients to engage in
downhill snow skiing?
I do
not discourage any activities. There is no data on “appropriate” post-op.
activity – and I have researched and published more on this topic than
anyone.
How do you determine if a small woman
is a good candidate for hip resurfacing and has good bone mass?
For the petite woman – I can usually
tell by looking at their hip x-rays.
When
do most of the Femoral Neck Fractures occur?
Most Femoral Neck
Fractures occur within the first 6 months.
What generally would
contribute to femoral neck fracture within 1st six months?
Femoral Neck Fracture
is basically a mis-match between the strength of the neck after surgery and the
loads imposed on it by the patient activities. The factors include the density
and size of the femoral neck, the quality of the surgery and the activity of the
patient.
How many female Femoral neck
fractures have you experienced?
I have not had any patient have a Femoral
Neck Fracture – yet!
Is there any data on rehab?
Little data on rehab. The patient is
the biggest source of variability.
What is metallosis and who is at risk? Symptoms?
Metallosis is high wear if the bearing with the generation of lots of metal wear
particles. It is usually a result of sub-optimal component
positioning.
If components are
positioned incorrectly, how long before metallosis can occur?
If the components are well-made and
well-positioned – metallosis will not happen.
How can you find out if you
have elevated metal ion levels and or metallosis?
Ion levels can be
determined by a blood test. The issue is what level is too high?
If a hip resurfacing fails, does it complicate a
subsequent revision to a THR?
There are now 2 studies – Amstutz series and Mont series –
indicating that the conversion of a hip resurfacing to a THR gives a good
result.
Do you ever go into the surgery with the intention of doing resurfacing, but
once inside, decide that a hip replacement is what is needed?
I make the decision before surgery – I
am pretty selective on resurfacing. We published selection criteria in 2005 and
I stick pretty close to them – so I don’t have to make decisions in
surgery.
How can you determine
“good bone density” prior to surgery?
Bone density
can be assessed on the x-rays and by a DEXA scan.
Do you recommend
that patients be tested for metal sensitivity before receiving MOM
implants?
There are no good tests for metal
sensitivity to deep implants.
Do the protheses
come in smaller sizes? Does the rod change size
proportionately with the size of the device?
Some systems have smaller sizes and
some have proportionate pins. For example, the ASR and C+ have small sizes and
proportionate pins.
What is your
opinion about uncemented femoral implants with porous bone ingrowth
surfaces?
Uncemented femurs were used at UCLA in the 1980’s and they can work.
There is little data on cementless femurs with the current generation
implants.
Do you usually have patients do a CT scan
pre-op?
NO pre-op. CT.
How long is
the hospital stay typically for resurfacing surgery
Our
usual hospital stay is 2 days.
Is
there any way currently to measure bone density in femoral neck after
resurfacing?
Bone density can be measured by a DEXA
scan and there are at least 3 published studies on this.
If a person has a metal sensitivity, what is recourse?
If a patient has a metal sensitivity –
they may need a conversion to a non-metal-metal bearing THR.
Do you suggest rehab
following surgery?
I don’t favor rehab
units for my patients.
Can a person with hip dysplasia have a hip resurfacing?
With dysplasia – it depends on the amount of socket bone and the anterversion of
the femur. A look at x-rays can tell.
Can a person with AVN be a
candidate for resurfacing?
Patients with AVN
can be candidates for resurfacing. Many hips with AVN have been successfully
resurfaced.
Are a
large number of your patients resurfaced due to AVN?
I think that it is only about
10%.
How
quickly must you have surgery if AVN is detected ?
You should only have surgery if the pain
and disability out-weigh the risks of the proposed surgery.
Do you see a
lot of cam FAI in young men?
Yes. Cam impingement is common. I have
it in my own left hip – but have lived with it – played college basketball,
tennis – and I am still managing without any surgery.
Can a person destroy their hip resurfacing by being too active
early in their post op recovery?
There is the possibility to over-stress the resurfacing before adequate
healing.
What is adequate healing
time?
Adequate healing time is dependent on
patient and surgical factors – it is not a definite line.
You prefer the posterior
approach while some others prefer anterior (Dr. Mont). Which surgical approach
is the best?
Dr. Mont uses the antero-lateral approach. There are
trade-offs – but the overall quality of the surgery is more important than the
path into the hip joint.
Is surgery the only way to determine metal sensitivty?
Metal sensitivity can be determined by an examination of tissue from around the
hip – so a biopsy can give that information.
