Dear List,
On May 10th the following question was asked and few responses were received. I regret for the delay in the response.
Original question:
>Can I be fovored to get the archive references or direct info on
>current highly recommended A.K. socket designs, their indications,
>merits and demerits. I have to prepare a presenttation before
>orthopedic surgeons on ‘why and when we use a particular socket ( Quadrilateral, Isch.
>Containment,
>Plug, or others) in TF prosthetics. I am of the view that when no
>vacuum valve/ suction socket is used then it is quadrilateral and when
>silicon gel liner is used there are different contours.I also want to
>know the H-Socket.
>I shall post the responses.
…………………………………………………………………………………
RESPONSES
If you are going to make a presentation to orthopedic surgeons on this topic I would ask that you make a concerted effort to become much more familiar with the subject than your email suggests. Your statements included in your email are incorrrect. I would highly suggest that you may want to contact John Michael CPO for the information that you seek. He can be found at oandp.com and is listed in the resources. You might also try him on his cell at 612-281-4290, Good luck with your presentation.
……………………………………………………
I use the ischial containment designs all the time except when I have someone who has worn another socket design for a long time, needs a new prosthesis and is happy with their old one. I am reluctant to change someone to a new design, unless they come to me and ask about new designs.
The quadrilateral and plug designs are antiquated and should only be used in unusual cases. Orthopedic surgeons are not still using Harrington rods for spinal fusions (that I am aware of) since newer and more effective methods have been developed.
—————————————-
The socket is different from the suspension. For the socket, the description really tells how it limits rotation. The ischial containment limits rotation by locking into the ischial seat, great trochanter, and adductor longus tendon. The quadrilateral socket uses a square shape and tries to equalize the pressure. A plug-fit tries to mirror the shape of the limb and have even pressures around a round area. The gel liner with pin has some issues with rotation, but practitioners have used a plug fit style, equal pressure, and defined muscle groups (such as isolating the adductor longus muscle). The issue with the gel liner is that the lip created is often lower than the ischial seat, so some practitioners cannot get a good lock on the pelvis due to the irritation caused by the lip edge.
As for suspension, this is how the socket is held on in swing phase. The gel liner and pin are good because it is easy, a firm lock, and does not require much hand stregnth. The suction socket works well for firm tissues and people who are strong. however, with fleshier limbs and poor hand stregnth and balance, it is hard for people to pull hard enough to cause enough pressure inside their residual limb to effectively transfer the weight and hold the prosthesis on. The firmer the soft tissue, the easier it is to transfer the weight of walking into the skeletal system. However, there is also a self suspension socket for knee disartics that lock onto the condyles. Knee disartics are nice for end bearing capabilities, leverage, and the balance between ad- and ab- ductor muscles (adductor mangus is not cut), but poses a real issue when making the socket and the fitting of the leg from the practitioners side and sitting issues from the patients side because the knee center is lowered. You can also have a waist-belt and sock fit…which is really good for new amputees who will be shrinking dramatically.
As to the papers on the subject, I would suggest you talk with Mr. Tim Staats who teaches at CSU dominguez hills/Ossur. He likely will know the references and may have copies of them.
Hope this helps.
…………………………………………………………………….
Quadrilateral design held paradigm status for approximately 30 years from 1950’s to the 1980’s. There were a number of consistent problems with this design. Today, there are a number of new design approaches that have shown clinical superiority – greater comfort, stability, and function.
Common to all of these newer designs is anatomic shape, more intimate musculo-tendinous-skeletal stabilization, containment of the ischial tuberosity within the socket margin, a narrow M-L dimension, a wider A-P dimension, and greater conformity of the socket to the lateral surface of the residual-limb’s femur. Long was the first to describe such a socket design calling it NSNA [Natural Shape Natural Alignment]. Other clinicians have used acronyms to describe their particular approach.
For a more complete discussion on this topic, see pages 309-314 in, LOWER EXTREMITY AMPUTATION, by Wes Moore, Jim Malone – Saunders.
Yours in Prosthetics
…………………………………………………………………….
I am a prosthetic technician, working on a biomechanical engeneering degree with an emphasis in prothetics. And I would be honored to have a copie of your thesis related to this topic. You have my utmost word that I would not place forgery over your thaughts and words, and would mention your name if source, and would gladly send you a copie of any work of mine siting your work.
I am trying to design a prosthesis for an AK amputee,and any information I can receive related to this topic will be helpful.
P.S. I am greatly impressed with the Sabolich socket. John and Kevin are amazing creatures. And I’ve seen it do marvelous things.
Thank you
_________________________________________________________________
Post Classifieds on MSN classifieds. http://go.msnserver.com/IN/44045.asp
Buy and Sell on MSN Classifieds.
