Thanks Thanks:  0
Likes Likes:  0
Needs Pictures Needs Pictures:  0
Picture(s) thanks Picture(s) thanks:  0
Page 1 of 2 12 LastLast
Results 1 to 15 of 23
  1. #1
    Join Date
    Mar 2009
    Location
    Brisbane
    Posts
    85

    Default Miniature Titanium Orthopedic Bone Screws For Surgery

    Miniature Titanium Orthopedic Bone Screws For Surgery.


    These are “cortical” bone screws that were used, along with a tiny plate, to hold one of my family’s finger together after an accidental fall. They were removed after about four months when the bone knitted and self repaired.
    Most screws like this are apparently 3 mm diameter or larger.

    These tiny screws are self drilling CSK head M 1.3 x 0.5 and in various lengths of 5, 8 and 10 mm.
    The heads are cross point.
    The flat bottomed straight sided slots are machined, and have a small circular hole in the centre of the cross. Under my 50x microscope, the threads have spiral striations and appear to be machined or ground and not rolled. Under the head, the "rounded" finish of the single thread ends in what seems to be the end of a grind operation, and not a "V" cutting tool operation.

    The thread form is asymmetrical and similar to a mix of buttress one side of the thread and normal type on the other.
    The material tests as being non-magnetic (even to a very strong rare earth magnet). It probably is titanium.

    No off-colour or non-funny posts please.

    Mr Moderator, I was in doubt as to where best to put this post.
    Please move it if you think best.

    Cheerio

  2. #2
    Join Date
    Nov 2008
    Location
    Perth WA
    Age
    71
    Posts
    6,458

    Default

    Interesting Mike,

    We often hear of plates being screw fixed to align broken bones but never think about the screws. They look like scaled down Type 17 self drilling screws. It would be fascinating to find out the reason for the differing threadforms. The buttress would minimise pull out, I imagine.

    I wonder what the surgeon uses to drive them into place.

    Bob.

  3. #3
    Join Date
    Nov 2008
    Location
    Perth WA
    Age
    71
    Posts
    6,458

    Default Screwdriver

    I had a quick look. Surprisingly (to me), the manufacturers were mostly Indian.

    Orthopedic Screwdriver Set (Kit), Torque Screwdriver Manufacturers in India

  4. #4
    Dave J Guest

    Default

    I always wondered why my leg never sets off the metal detectors.
    They said mine will only come out if I have problems.

    I broke my tibia and fibula in my left leg 7 years ago and I can tell you it was the most painful thing I have ever had happen to my. It was a spiral break and they put in 2 plates in with 18 screws. I have one screw on the inside of ankle bone and I can feel the edge of the counter sunk where it was not put in deep enough. They gave me the xrays and I can see the screw put in at a 45 deg angle along with all the others that are all over the place at different angles (must have been a learner,lol).
    From what I have seen on the TV shows they use an air drill to put them in.


    Dave

  5. #5
    Join Date
    Aug 2003
    Location
    Wodonga
    Age
    59
    Posts
    96

    Default

    My left knee: What they call a half replacement.

    Some spare screws that were in place from an earlier reconstruction, used as anchor points for the new ligament.

    A few of the 70 odd staples are shown as well.

    Screws are in the range of 30-50mm long, depending where they are

    It doesn't set on metal detectors either.

    Pic 1 is from the inside looking outwards

    Pic 2 is from front on

  6. #6
    Join Date
    Apr 2009
    Location
    Ballina N.S.W.
    Posts
    644

    Default

    Hi Dave,
    Now you know why the orthopeadic surgeons are refered to as "carpenters". I had some "K" wires inserted into a broken ankle joint, they were only suposed to go into the bone but the xray showed they went right through the entire joint a good 25mm further than they should have. When I showed the xray to the surgeon he had no idea that they he had driven them in so far.
    Bob

  7. #7
    Join Date
    May 2010
    Location
    tasmania
    Posts
    96

    Default orthopaedic screws

    I have experience with these screws from the other end of the screwdriver!

    Most of them (there are a few manufacturers) are Titanium but some are 316 stainless.

    The stainless ones are easier to use (especially to get out) as the heads can break off the Ti ones with overtorque. The bone grows up to the Ti on a microscopic scale and can make them better fixed with time and impossible to get out in one piece.

    The cross-shaped head is used on the smaller sizes (with a hex or torx (star-drive) on those larger than 2.0mm in most instances). The screwdriver has a flat cross with a central point. this allows the driver to be put back into the screw more easily.

    The threads are of a semi-buttress design in the larger sizes. The profile was worked out in the 1950s by the swiss. Previously wood screws were used.

    The kits include a core diam drill and a gliding dia drill (for lagging fragments). The drills are usually electric now (the old air stuff largely phased out).

    Very large dias (cores 2.5 and 3.5) can be safely screwed in with a power screwdriver.

    The angle is a compromise between 90deg to the fracture plane (best compression of the fracture) and 90 deg to the load and so the screws are always angled. Not just on learner jobs!!

    The kits do include a countersink if a plate isnt used.

  8. #8
    Join Date
    Apr 2008
    Location
    Canberra
    Posts
    805

    Default

    Cool insights furzer. I have a bunch in my knee too and always thought it looked a bit hap hazard the way they were driven in...now I know why!

  9. #9
    Join Date
    May 2010
    Location
    tasmania
    Posts
    96

    Default bone screw

    I have found that the Swiss text discussing the design is accessible on google books (so much for keeping a library!)
    Manual of internal fixation: techniques recommended by the AO-ASIF Group

    By Maurice Edmond Müller, Martin Allgöwer, Stephan M. Perren, Arbeitsgemeinschaft für Osteosynthesefragen

    The info on the screw design is page 179-191

    There are now newer screw designs that have a threaded head to fit into a threaded hole in the plate which has some advantages in terms of pull-out strength.

  10. #10
    Join Date
    Nov 2008
    Location
    Perth WA
    Age
    71
    Posts
    6,458

    Default

    " The bone grows up to the Ti on a microscopic scale and can
    make them better fixed with time and impossible to get out in one piece."

    My daughter had a bilateral mandibular osteotomy last year. I asked her yesterday about the screws and she told me that they are a permanent fixture so based on your comments there is a good chance that they are titanium. The procedure was performed in Melbourne, making it difficult for me to ask the oral surgeon
    any questions. A search on the net provided some graphic images of the surgery involved but they don't really focus on the hardware used.

    Thanks to Mike and you, I now have some idea of what was used to hold her jaw together.

    Bob.

  11. #11
    Join Date
    Jul 2006
    Location
    Athelstone, SA 5076
    Posts
    4,255

    Default

    I had one in my shoulder...
    it was around 2 inches in length if i recall correctly, maybe a tad longer...kept it for ages so I could brag about it....but you know who tossed it as junk

    mine actually looked more like wood screw...not threaded all the way

  12. #12
    Join Date
    Dec 2005
    Location
    Burleigh Waters
    Age
    67
    Posts
    53

    Default

    Titanium alloys will "osseointegrate" as rfurzer says above. This is just the ticket for dental implants placed to accept crowns, bridge abutments and dentures. They are extremely difficult to remove.
    In oral surgery stainless steel is probably better if the fixation is to be removed later. I don't know for sure, but I assume stainless steel is still used a lot (I'll check with one of my surgical colleagues) in surgical treatments for fractured jaws and the treatment of skeletal discrepancies (osteotomies - literally cuts in the bone).
    Bob, hope your daughter is healing well. The things the oral & maxillofacial surgeons do is marvellous and amazing, although it's nice to avoid if you can As an orthodontist I help plan these treatments and I have to admire any patient who undergoes one of these treatments.

  13. #13
    Join Date
    Nov 2008
    Location
    Perth WA
    Age
    71
    Posts
    6,458

    Default

    Thank you Rpepper,

    I took the liberty of forwarding your response to my wife and daughter.

    Whilst my daughter is still wearing braces she, and we, have been assured by both her orthodontist and surgeon, that her teeth are now aligned as they should be.

    Regards
    Bob.

  14. #14
    Join Date
    Dec 2005
    Location
    Burleigh Waters
    Age
    67
    Posts
    53

    Default

    Bob, it sounds like the worst is behind her. It's a bit counter intuitive, but most people have more post op discomfort after their lower wisdom teeth are removed than from the lower jaw osteotomies. Hope there's not too much swelling and that your daughter can soon get her teeth into a decent steak! (Unless of course she is a vegetarian, and I unreservedly apologise for such a disgusting suggestion...)
    Best wishes,
    Richard

  15. #15
    Join Date
    Nov 2007
    Location
    melbourne australia
    Posts
    3,228

    Default

    It's all good stuff, but it comes at a price. I have a titanium screw in my jaw which has a porcelain tooth glued to it. The oral surgeon told me the screw cost $400 when he put it in about 10 years ago.

Page 1 of 2 12 LastLast

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •