Wednesday, October 9, 2024

Replies: Heavy Duty Pin Lock

Kristin Faircloth

*Question:*

I have a BK patient who weighs about 400 pounds. I will be using the Ossur
AK locking liner, size 45 for suspension. My go to lock is plastic and I
do not trust it with the weight of this patient. Does anybody know of a
lock that is rated to 450 pounds?

Two people recommended Bulldog. I spoke will Bulldog and their lock won’t
work because there is no room in this prosthesis for increased build height.
I used the plastic Bulldog lock with the check socket and was only able to
fit a 1.5” Statts adapter between the socket and 500# SACH foot from
Kingsley. Here are the other ideas…..

*Responses:*

I had the same problem so I decided to use the shuttle from Otto Bock and It
is a two part lamination. You laminate the shuttle with the first lay- up
then I used the Kit from Freedom innovation that you laminate the pyramid in
for the second lay-up. This is a special order and takes about two weeks to
get delivered.

Call Prosthetic Design. They have one with titanium at the center hole.

Check with PDI

Use Fillauer lock with titanium four hole housing. Indestructible. We had
bilateral 375 pounder that climbed trees to shoot turkeys off tree stand,
and he could not break them. He busted anything else. Also, pins are much
stouter than other ones.

If your ‘go to lock’ is the puck shape (Bulldog, PDI), I think OWW still
sells a ‘G-Lock’ which has the same dimensions but the base is machined
aluminum instead of plastic. Make sure the screws are rated high, too.

Really the only stress on the lock is when the patient picks up the
prosthesis during swing. The prosthesis may be a little heavier to support
his weight but probably not significant. The real stress is on the foot
and socket lamination during stance.

Do not use an integrated lock with the distal attachment. Take the Coyote
airlock for example: it has a weight rating, but it is totally worthless.
The patient is not weight bearing on the lock. The four hole attachment
device or three pronged adaptor is the weight bearing structural component.
I would be way more concerned with the amount of weight the lock can
suspend (prosthetic device plus foot wear plus x factor) over the course of
a million cycles.

I don’t think that you have to worry about weight limits since the lock
only holds the weight of the prosthesis. What you need are the right
connectors, pylon and foot that are rated for that weight. I think the
only foot the can accommodate that weight without being custom is from
Fillauer. The other components you can get from Ossur.

A pin lock is not the best idea. A lanyard suspension is much safer for his
weight.

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