01/06/2014    Todd Lamster, DPM

Hyperbaric Oxygen for Possible AVN of 1st Met Head?

First, I am very sorry to see your patient with
this complication. I have to disagree with the
radiographic assessment of "no positional
changes." From the 4 week x-ray, the capital
fragment has shifted medially and the hallux has
deviated laterally. There is loss of
correction, and the head has slightly impacted on
the shaft. Also, the 1st IM angle has increased
and there may even be some demineralization at the
base of the proximal phalanx. Last, there
appears to be far greater edema around the 1st
MTPJ at 4 weeks than 2 weeks.

Without knowing more about your patient,
differentials would include AVN,
osteomyelitis/septic joint, Charcot arthropathy,
and reactive inflammatory arthropathy from allergy
to hardware.

If your hardware is titanium, I would obtain an
MRI with metal suppression. That may give you some
information as to the vascularity of the capital
fragment and/or infection status. Next, I would go
back into the surgical area and obtain multiple
bone biopsies for histopathology and culture. If
you reach the diagnosis of AVN, you can use a bone
stimulator (I prefer the Exogen US unit) and cast
her nonweightbearing until the osteolysis stops
and the area stabilizes.

Then it is likely that you will have to remove the
capital fragment and perform a salvage arthrodesis
with bone graft (from tibia or calcaneus
preferably, or if the defect is too large
allograft with some type of osteoinductive
material). The same could be said for a
diagnosis of Charcot.

If your bone returns with a diagnosis of
osteomyelitis, then you will have to debride away
all dead and infected bone, and use an ex-fix
temporarily to maintain length of the 1st ray
while she's on 6 weeks of antibiotics. Time of
antibiotic use may be decreased if bone
margins are clear of infected bone. Then, a
salvage arthrodesis will likely be needed, again
with bone graft.

Although this is a reach, if the other diagnoses
do not fit, you may have to send her for allergy
testing against the metal used in the screws. Even
if this is the case, you would have to remove the
screws, debride away dead bone, and keep the
length of the 1st ray with an ex-fix. Allow the
area to become quiescent, and again finish
with salvage arthrodesis.

To answer your initial question, if your patient
has good perfusion and palpable pulses, which I
assume is the case, I believe that hyperbaric
oxygen would likely have little effect
on the outcome. Do the MRI or go straight for the
biopsy first and obtain a definitive
diagnosis; then you can treat the underlying
cause.

Todd Lamster, DPM, Scottsdale, AZ,
tlamster@gmail.com

Other messages in this thread:

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01/06/2014    Todd Lamster, DPM

Hyperbaric Oxygen for Possible AVN of 1st Met Head?

First, I am very sorry to see your patient with
this complication. I have to disagree with the
radiographic assessment of "no positional
changes." From the 4 week x-ray, the capital
fragment has shifted medially and the hallux has
deviated laterally. There is loss of
correction, and the head has slightly impacted on
the shaft. Also, the 1st IM angle has increased
and there may even be some demineralization at the
base of the proximal phalanx. Last, there
appears to be far greater edema around the 1st
MTPJ at 4 weeks than 2 weeks.

Without knowing more about your patient,
differentials would include AVN,
osteomyelitis/septic joint, Charcot arthropathy,
and reactive inflammatory arthropathy from allergy
to hardware.

If your hardware is titanium, I would obtain an
MRI with metal
suppression. That may give you some information
as to the vascularity
of the capital fragment and/or infection status.
Next, I would go
back into the surgical area and obtain multiple
bone biopsies for
histopathology and culture. If you reach the
diagnosis of AVN, you
can use a bone stimulator (I prefer the Exogen US
unit) and cast her
nonweightbearing until the osteolysis stops and
the area stabilizes.
Then it is likely that you will have to remove the
capital fragment
and perform a salvage arthrodesis with bone graft
(from tibia or
calcaneus preferably, or if the defect is too
large allograft with
some type of osteoinductive material). The same
could be said for a
diagnosis of Charcot.

If your bone returns with a diagnosis of
osteomyelitis, then you will
have to debride away all dead and infected bone,
and use an ex-fix
temporarily to maintain length of the 1st ray
while she's on 6 weeks
of antibiotics. Time of antibiotic use may be
decreased if bone
margins are clear of infected bone. Then, a
salvage arthrodesis will
likely be needed, again with bone graft.

Although this is a reach, if the other diagnoses
do not fit, you may
have to send her for allergy testing against the
metal used in the
screws. Even if this is the case, you would have
to remove the
screws, debride away dead bone, and keep the
length of the 1st ray
with an ex-fix. Allow the area to become
quiescent, and again finish
with salvage arthrodesis.

To answer your initial question, if your patient
has good perfusion
and palpable pulses, which I assume is the case, I
believe that
hyperbaric oxygen would likely have little effect
on the outcome. Do
the MRI or go straight for the biopsy first and
obtain a definitive
diagnosis; then you can treat the underlying
cause.

Todd Lamster, DPM, Scottsdale, AZ,
tlamster@gmail.com