strong joint for BK - summary of replies

strong joint for BK - summary of replies

Ted A. Trower

10/5/1997

At 04:07 PM 9/29/97 -0400, I wrote:


I have a young woman client who has proven to be especially challenging to
fit successfully. She is of average build and height with an extremely
short tibia and no fibula on her right BK (trans-tibial) limb. For many
years she refused to wear joints and a lacer because she would not wear a
waist belt suspension. This caused her to ambulate with up to 30 degrees of
varus instability at the socket but was functional. Some time ago I
successfully converted her to using joints and a lacer with a sleeve
suspension. Then more recently to joints and laminated thigh section with
an ICEROSS suspension.

In both of these latter fittings she has ambulated with a much more stable
and plumb gait. Unfortunately she has never gone more than three months
with out breaking one or both of her joint uprights. I have used Bock BK
joints, Bock KD joints and most recently joints from a Townsend knee orthosis.

What joint would you recommend I try next? She dropped into my office this
morning to express her willingness to give up on using the thigh support and
to return to the uncosmetic and inefficient gait of her previous fitting as
the frequent structural failures have become inconvenient. I know that I
have only one try left, I want and need it to work. I want to stay with the
laminated thigh section as well.


Thanks for your thoughts




Ted A. Trower C.P.

<Email Address Redacted>


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>I feel looking at the reason why the joints are breaking might be
>helpful. I say this as in my experience, alignment relative of the foot
>position, type of foot, joint upright shape relative to minimum bends,
>can make all the difference. With all due respect, the joints should be
>strong enough. If the patient were very heavy, and extremely active, and
>lived in an extreme environment, then I would feel the joints were not
>strong enough.
>Even with hip joint placement and alignment, also bending
>considerations, I found I could be successful with repeated joint
>breaking, by minimizing stress to the join in this way.
> You might try nylon knee joints with moderate uprite bending if they
>would offer enough M.L. stability for your patient.
>Kevin S. Garrison C.P.
>
>

--------------------------------------------------------------
>Hello Ted
>
>For cases like this we have used Foster knee joints available from Pel. Take
>a look on page 110,111 in thier cataloge for various selections. Good luck!
>
>Brian Gustin
>
>
--------------------------------------------------------------
>
>I use those big bad stainless steel Otto Bock
>polycentric joints when I have a patient
>who breaks my second favorite, the big bad
>stainless Otto Bock single axis joints. I'm
>not sure why I've had better clinical success
>with these, since they have more moving parts
>than the SA design, but thats what I've observed.
>Maybe it's because I think of polycentrics when
>I make ischial bearing BK designs and these are
>the legs where I worry about the structural
>strength, and I'd like every possible advantage
>for sitting and walking comfort.
>
>IMHO you've already covered the most important point
>for joint breakers: a laminated thigh section
>saves the joints from torque, which I feel
>(without scientific basis) is often the cause for
>joint failures. I laminate the joints INTO
>socket and thigh laminations, not rivit them
>on. And I favor a solid (full circumference)
>thigh shell if the leg shape will allow it, for
>an even stiffer and solid foundation for the joints.
>The job ends looking a lot like a laminated KAFO
>such as OOS and others make these days.
>
>And some folks just break 'em all!
>
>Best of luck, Ted,
>
>Daniel Watkins CPO
>
>
>
>
--------------------------------------------------------------


>
>You don't mention her weight, but you may want to try Becker SS orthotic
joints.
>Look up the non protrusive 2000 series.
>
>Good Luck.
>
>Bob
>
--------------------------------------------------------------
>Dear Ted,
>You may want to contact Vessa Ltd in the UK. I believe they still manuacture
>heavy duty joints which are used primarily in the manufacture of conventional
>prostheses but they may have something you could use or adapt. Good Luck!
>
>Regards
>
>Arthur Graham CPO(UK)
>
>
>
>
--------------------------------------------------------------
>
>
>Try to get in touch with Generation II in the USA and see if they can
>use one of their Medial Unloader Adjustable joints (for Osteoarthritis)
>in the lamination. The biggest advantage of the joint is that it is
>mounted, unilaterally, on the medial side. The valgus angulation of the
>joint can be increased/decreased to provide more/less pressure from the
>lateral wrap-around, diagonal force strap. This will allow you to
>pull the knee out of a varus position.
>
>Try them at:
>
> <URL Redacted>
>
>Hope this works for you. Let us know.
>
>Mark Harasimiuk, Orthotist
>Caribou Orthopedic Services
>Prince George, BC, Canada
>
>
>
--------------------------------------------------------------
>I would suggest you try a leather thigh corset with the 7U1 O.B. joints.
>I have found that flexable is better than rigid on the thigh corset.
>
>Errol Lishman
> <URL Redacted>
--------------------------------------------------------------
>
>You've done well to convert her to using the joints and lacer. Have
>you tried a rotator unit? What kind of a foot are you using? Is it
>too stiff? Do you have an ankle joint? This would absorb some of
>the torque and rotation and take it off the joints. Do you think
>the laminated thigh section might be too rigid, perhaps using a
>polyethelene thigh section which would be less rigid and allow more
>movement?
>
>David Barnhart, C.P.
>
>
>
--------------------------------------------------------------
>
>Here's a forwhaxxxxworth idea (obviously untried). How about using PTS or PT
>SC/SP trimlines on the socket in addition to the joints? Yes it would not be
>terribly cosmetic and the posterior socket--distal posterior thigh section
>trim lines would be a nightmare, but you would be able to absorb some of the
>ML forces within the socket before they impact on the joints. In addition,
>perhaps more flexible joints rather than more rigid joints might prevent
>breakage (Bock polypropylene swimming joints or even (God forbid) something
>like Daw Cabon orthotic joints might have enough additional resiliance to
>avoid fracture). As I say, these are brainstorms, not things tried in the
>real world. But then I always did like to get other people in trouble
> (let's you and him fight!). I hope this helps.
>
>Harry Phillips, C.P.O.
--------------------------------------------------------------
>Hi Ted
> I had an AK who used to break hips joints with a familar frustrating
>regularity. I finally brought the heaviest joint I could find to a local
>tool maker and he welded on a double thickness to the joint. The extra
>weight was worth it in that case. Maybe there is some such talented fellow
>near you who might be clever enough to do the same. Some of those guys are
>really brilliant.
>Good luck
>Keith Cornell CP
>
>
>
--------------------------------------------------------------
> About your patient that breaks knee joints; some questions come up in my
>mind.
> Are the uprights and / or joints always breaking at the same or similar
>areas?
> Is it at the rivit points, or always the medial upright that breaks
>first? If the uprights continually break at a significant bend, perhaps
>making that bend longer and more gradual will reduce metal fatigue. Some O
>and P companies like Becker make orthotic joint and upright combinations in
>many sizes and some with a joint and upright junction designed to curve
>around so that the upright is bent less severe. Another possibility is to
>weld small gussets in an area that has fatigued often in the past. I hope
>this helps,
> Good Luck, Steve Baum, C.O., Menlo Park, CA.
>
>
>
--------------------------------------------------------------
>
>Have you considered the Generation II hardened Genucentric joints?
>Randy www.sunnyhills.com
>
>
>
--------------------------------------------------------------
>
>I've used the heavy duty OB polycentric joints over the years, and seem to
>stand up quite well.
>
>BTW, I'm not sure why you commented on the waistbelt suspension. Are you
>still using this now? There are several variations on the whole
>thigh-section and elastic extension assist, if you need it. I'm not sure if
>I can picture what all you need to make her walk plumb.
>
>I tell you what, why don't I come to your lab and we work on this case
>together?!
>
>Tony van der Waarde CP(c)
>
>
--------------------------------------------------------------
>
>Ted,
>USMfg makes a steel BK joint with brass rings inside. If your patient doesn't
>mind the weight, this may be suitable for her. It's heavy, but it's strong.
>Sorry I don't have the product number for you.
>Joseph F. Carideo Jr., CP
>
>
>
--------------------------------------------------------------
>
>Hi Ted
>This John Russell, I talked to you at 1996 Para games in the cycling shed,
>about the movable back wall of a B/K socket.
>My first thought, with the infomation given is have a Cirrus foot, will take
>the m/l forces from the socket.
>Second, is compression of the distal tibia M/L with pullin shuttle lock, and
>liner 3/S
>I have a couple patient that have had the same problem.
> <Email Address Redacted>
>510-943-1119
>
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>
>Dear Ted:
>
>Assuming that it is the lateral joint that is bothering you and your
>patient, where exactly does it brake? Couldn't it be because of excess of
>weight placed on the thigh and less on the stump?
>Have you tried to fit her stump with the TEC system and a total contact socket?
>I've had several cases of very short stumps , using Otto Bock joints and
>never had a failure like you describe.
>Tell me your comments.
>Good luck!
>Carlos/Padrao Ortopedico
>
>
>
>
--------------------------------------------------------------
>Ted - You've probably thought of this, but mightn't a PTS level trimline,
>combined with joints & lacer, dissipate some of the forces to the joints?
>Just an idea.
>
>Mark Smith CP
>
>
>
--------------------------------------------------------------
>A wild idea from an orthotist; consider a plastic fracture type joint, It
>will not give you as good of control but would be better than no joints.
>
>Good Luck
>Gary A. Lamb CO
>
>
--------------------------------------------------------------
>Ted, her constant failures indicate that the problem is one of alignment,
>more than componentry. However, you might want to try the USMC titanium
>orthotic sidebars. I don't know that the titanium strength is in the
>coronal plane, but is should be. It might be that you cannot get the
>necessary alignment to prevent failure, but I would sure look at this issue
>again. I recently had a BK who had a terrible ML knee instability. I used a
>FlexTech knee orthosis over the BK. It seems to work fine, but this guy
>doesn't necessarily return when there are problems, so there might be
>problems that I am unaware of. Anyway, it is an interesting concept, but
>probably too bulky for your young female patient.
>
>For a varus knee with breakage, you would normally outset the foot as much as
>possible (or as much as the patient will allow); right?
>
>Please let me know the outcome with this patient. I am interested.
>
>Wil
>
--------------------------------------------------------------
>
>Have a look at the Acme below knee joint(Knite-Rite #12 page 259).
>David Home CP
>
>
>

--------------------------------------------------------------
>
>Have a look at the Acme below knee joint(Knite-Rite #12 page 259).
>David Home CP
>
>
>
------------------------------------------------------------------
>Ted,
>Consider the joints normally dedicated to Orthotic use. There are a huge
>range of KAFO knee joint sets on the market and these are usually much more
>robust than those commonly used for prosthetics. In particular, consider
>the steel USMC single axis types: they generally have a greater cross
>section (you will obviously have a concomitant weight gain but durability
>is enormously improved) Richard Ziegeler P&O
>
>E.C.A.T
> <Email Address Redacted>
>
>
--------------------------------------------------------------------

Thank you all for your input. The breakage has occured within the joint as
well as in the uprights. The problem does not lie with bending technique.
The clients limb is only about 1cm longer than it is wide, either a-p or
m-l. In addition the distal tissues are highly mobile. she can, if she
tries, flex her tibia right out of the socket. Prior to the use of the
lacer she preferred an alignment that was predictably unstable in a single
direction. Proper alignment was never an option as it was too
unpredictable for her. After nearly twenty years of leaning sideways into
the prosthesis she has acquired some undesirable gait habits that add to the
stress on the joints. These, combined with the instability of the socket,
lead to the breakage of the joints. I have tried many of these suggestions
in the past, especially the high trim lines and radical socket contours
distally for greater m-l stability. I was in fact able to obtain about a
50% decrease in undesired m-l motion. Unfortunately it came at the cost of
increased a-p instability.

The idea of altering the foot is one that I have not tried and sounds worth
exploring. Same for going full circumference on the laminated thigh
section. To be honest I had not considered the impact of torque forces in
this situation, I believe that was a significant error.

Thanks again,


Ted A. Trower C.P.
<Email Address Redacted>

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