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I may be wrong, but I seem to recall that "Dr. Bill Hamilton" suggested this
theory in an "Aquacorps" article a couple of years ago.  I have not seen
much related to this since.  Anyone else recall this?


Patrick Duffy
zooea@hi*.co*


At 10:15 AM 2/14/96 -0000, you wrote:
>>Has anyone seen any updates on the theory that Osteonecrosis is caused
>>by elevated PO2s?
>
>Are you sure that's elevated PO2? I've not heard that theory, but as a 
>bone pathologist new to diving, needless to say I've a personal interest 
>in the topic.
>
>I'm at the Armed Forces Institute of Pathology and we've done some work 
>in this area. Our theory goes that the osteonecrosis (bone death) that 
>occures in dysbaric conditions 
>(doc-speak for the bends) is the result of more then just N2 bubbles 
>embolizing in the small blood vessels. Animal studies seem to show that 
>there is a 5-fold greater solubility of nitrogen in fat cells with a 
>swelling of the fatty tissue at the cellular level. (more reason to stay 
>in shape and not get overweight!)
>
>In soft tissue that's not such a problem, but the marrow fat in all our 
>bones (especially in such areas as the hips, knees and shoulders...where 
>coincidently you get most cases of osteonecrosis) is encased in a shell 
>of unyielding bone. As the fat cells swell, the pressure in the marrow 
>compartment goes up and decreases the already low blood flow to these 
>areas. We figure that the nitrogen transport out of the fatty tissue in 
>these areas is only about half of that in other tissues. Throw in low 
>oxygen partial pressures on top of sluggish blood flow and you 
>essentially strangle the bone. 
>
>So it may be that there is a two-fold hit on "rapid" decoms. There is the 
>formation of bubbles (the classic theory) that is supported by the 
>observation of microscopic damage to the lining of small blood vessels as 
>well as doppler sound-wave detection of bubbles as well as the swelling 
>of fat cells in bone marrow, raising the internal pressures and reducing 
>the blood flow and supply to bone.
>
>What I need to do is start to "bone up" (sorry) on the various "tissue 
>profiles" that are used in the commercial dive computers so I get a 
>better feel for what I'm dealing with on just personal grounds. I'm just 
>now getting my basic and advanced certs and am starting to surf the dive 
>catalogs.
>
>
>CDR Robert B. Wolov, MC, (FS), USNR
>Department of Orthopedic Pathology
>Armed Forces Institute of Pathology
>Washington, DC 20306-6000
>
>wolov@hi*.co* (preferred)
>wolov@em*.af*.os*.mi*
>
>
>--
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>Send subscription/archive requests to `techdiver-request@terra.net'.
>
PJD [\]

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