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Re: Перипротезный перелом
Sandro Reverberi 28 Декабрь 2008, 12:07
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dear Alexander,
your is a fine and elegant solution.
You transformed a cemented hip prosthesis to a cementless revision hip prosthesis with a little approach.
But I have some questions:
* your nail has a point of minus resistance at the tip of femural stem and at the fulcrum of the fracture; by the time could it break?
* by the time stem and nail could reciprocally move?
* distal fixation of the nail is based near only on two screws : are they sufficient to secure a good stability before fracture consolidation?
* materials of the stem and nail (I think Iron steel in both); if they should be different (and many hip prosthesis are made by an alloy that is not the same of the nails) we could see electrolytic phenomena
So I think that your is a good idea, it can be actually good in this case, but is not sure in all cases.
   
I generally should prefer a long stem revision prosthesis, as that allegated.
Sandro Reverberi
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Re: Перипротезный перелом
Alexander Chelnokov 31 Декабрь 2008, 16:33
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Dear Sandro.
rs> ° your nail has a point of minus resistance at the tip of
rs> femural stem and at the fulcrum of the fracture; by the time could it break?
I don't expect early breakage because of lack of bending forces. Though precise estimation of fatigue strength should be performed in lab tests sooner or later.
rs> ° by the time stem and nail could reciprocally move?
The nail tip is jammed. Since it is conical, it can only be jammed more with axial load.
rs> ° distal fixation of the nail is based near only on two
rs> screws : are they sufficient to secure a good stability before fracture consolidation?
I'd say yes because we use same 6 mm screws for femoral nailing and allow immediate weight-bearing regardless of fracture pattern.
rs> ° materials of the stem and nail (I think Iron steel in
rs> both);
The nail is Ti-based alloy.
rs> if they should be different (and many hip prosthesis are
rs> made by an alloy that is not the same of the nails) we could see electrolytic phenomena
Maybe, but i don't know exactly its clinical significance.
rs> So I think that your is a good idea, it can be actually good in
rs> this case, but is not sure in all cases.
rs> I generally should prefer a long stem revision prosthesis, as that allegated.
Bill Burman provided us with good references which show us that the topic is very hot, and the new option is being developed and evaluated. So it is too early to make final conclusion about its place and role.
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