Sunday, December 4, 2022

Replies to: Pediatric Exo vs. Endo

M Hall

Thanks to those who replied to my posted question.
I posted this question both to the OANDP List-serv and the Pediatric Lower Limb Prosthetics Group of the Academy’s Lower Limb Prosthetics Society.. We had a nice dialogue going on the LLP Pediatric Group page.  It’s well worth checking out.  I’ve included the dialogue below for those of you who have not joined that Society. 
General Consensus: Go endo if you have room for it.
Michelle Hall, CPO, FAAOP
Original post:
With the advancement of endoskeletal lower limb prosthetic components for children, when do you choose endoskeletal over exoskeletal design?
Context:   We have a 3 1/2yo child with fibula hemimelia coming to clinic and has outgrown his existing exoskeletal prosthesis.  He is growing rapidly and we often have to take away the prosthesis to make growth height changes.  We are debating whether or not an endoskeletal prosthesis would be a better option.
LLP Society’s Pediatric Group Dialogue:
–   My stance on endo verse exo for such young kids is that I try to use endo whenever possible for the versatility in adjustment for growth.. If the patient is outgrowing the length of the exo quicker that he/she is outgrowing the socket, it is my opinion that endo should be used. I prefer the length adjustability and over all adjustability ease by use of endo over exo for most age groups, but kids are on the top of the list! (Sarah Thomas, CPO,  Academy LLPS Pediatric Prosthetics Group Leader)
-   Thanks for the insight. We had a similar thought, but were unsure about issues with the screws in the endo components rusting because of exposure to puddles, sand boxes, etc. that kids often find their way into. Any problems or experience with this?  (Michelle Hall, CPO, FAAOP)
-  The set screws certainly are the first endo components to corrode. Every time I see my children patients, I remove their set screws and look for corrosion, if I find any, I dispose of the set screws and replace them with new and clean out the component that they belong to with compressed air and silicone spray prior to putting in the new screws, This tends to prevent severe corrosion/rust issues. I also find that feet with foot shells and knee units tend to collect sand, wood chips, dirt, grass, basically anything a kid can get themselves into. Every appointment with kids I clean out the feet and knees with compressed air to help prevent any problems. With these steps, I have found that most kids out grow their prostheses before corrosion becomes an issue. I have also used electrical tape on components to provide a barrier to teh elements that a child might expose their prosthesis. The tape best wards off dirt, sand, dust etc. It doesn’t keep out
water. But this additional step can prolong the set screws from needing to be replaced. (Sarah Thomas, CPO)
-   I would have to agree. We fit all of our kids with endo skeletal prostheses. It allows for ease of adjustment and componentry changes. We typically only get to see our kids annually. Many of them live in harsh eviroments and we have not seen corrosion to be a problem. On occasion, we do have to swap out a tube clamp or some screws, but not that often. We mostly end up changing out feet and sockets due to growth. Using endoskeletal components definately gives us more options as the child grows and/or changes activities.  (Another LLP Society Member)
List-Serv Replies:
Go Endo….
-  Just my opinion, but if I have clearance for endo components I use them.  As you mentioned, today’s compenents are very durable (perhaps as durable as exo designs) and the adjustability is great. 
-  Some rust occurs on the tube clamp screws.  I have had no problems related to that.  It is easier to replace tube clamps than to legthen and exo in my opinion.  You can not cover a endo prosthesis for kids obviously (the cover also tends to dramatically increase the rust factor).  I usually have had a conversation with the parents about the benefits of the endo system and the cosmetic drawback to the system.  Most parents have like the thought of adjustability and have like the endo system.  If cosmesis is extremely important than I stick with the exo.  Good luck
-  If you have the room go endo. Offers both height and alignment adjustability.
-  If there is enough clearance for endoskeletal components, it certainly makes our jobs of adjusting for growth a lot easier.  I talk with the parents and discuss the pros and cons of having cover vs. no cover on the endo.  Usually they are excited about laminating fun designs or colors into the socket, which eliminates the cover option.-  As soon as you can fit Components into the space between the socket and the foot. 
– We’ve done a thin “exo” shell over a bk with endo construction so we could make adjustments. This was a 9 y/o boy, so we had a bit more room to work, but I thought it was a nice balance between the durability of a laminated “exo” vs. the adjustability factor of an endo. Kids tear up foam or skin covers waaaay too fast! Hope that’s an option for you.
– We rarely, rarely do exo construction on a child. The ability to adjust length without retaining the prosthesis is essential.
-  I would consider endo systems like Trulife, they have spacers for growth inbetween pylon changes.
- One option would be to use a College Park Truper foot w/exo ankle block. They have kits for lengthening with 1/4″ spacers you can stack
– I would see no problem as long as you do a light 4ply removable laminated protective shell over the components. Also the shell has to have a water tight seal.  Kids are active, and soft foam covers will smell and never clean up. Components from endo’s also could hurt other children even when covered by foam
-In my opinion you should transition from an exo prosthesis to an endo prosthesis as soon a you have enough room for the components. The first reason is obvious, ease of lengthening prosthesis. Second, regardless of the hemimelia being partial or complete there is a good chance that the residual limb will at some point start to migrate into a valgus position. It is easier to apply corrective forces with an endo prosthesis and therefore delay the need for medial femoral condyle stapling to correct this valgus migration. Hope this helps
Go Exo…
-  If a toddler is not potty trained, an exoskeletal design is easily
cleaned verses a foam covering, which can soak up urine.  Also, the
external lamination holds up better when climbing on trees and playground equiptment.  The soft covers/skins tend to shred up quickly. 
– I will go exo with a seattle childs play foot, that way I just add a lift between the post and the foot… works great.
– It is much easier with endo, but the covers get completely torn up too soon. I like exo at that age and can lenghten with pieces of wood at the ankle and longer foot bolts.
– We do a lot of children.  Most get exo due to lower cost for the Shrine Hospital, which most of them go through.  Durability is an issue with kids and exo holds up the best.  Lenghtening is not an issue, just add a block. 
– I would favour endoskeletal prostheses for short trans tibial and higher amputation levels for young children.  In the case of the child you mentioned, my inclination would be to stay with a robust and lightweight exoskeletal design.  They are likely to need it, with rough play and activities, and at their age will not really need high performance feet or other components.


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