Q
The knee abruptly locks:
A - The alignment may be set up too
posteriorly. The pylon should be ver tical
and the knee center 9mm posterior to
weight line.
- The forefoot may be too soft.
- The dorsiflexion bumper may be too soft.
Q
The knee does not unlock or it is difficult to
sit or get into a car:
A - The weight line must move on the toe of
the foot for the knee to unlock. This can be
accomplished by having the user slide the
prosthetic foot slightly behind the sound
limb and initiate knee flexion by loading the
toe. By shifting weight anteriorly, the knee
will release, allowing the user to sit.
Q
How do we instruct the user to go down
stairs:
A - The heel should be back on the step and
the user will have to transfer weight over
the alignment reference line, causing the
knee to release in a natural motion. If the
user is leaning back it will be difficult for
the knee to release. The user must have
the weight over the knee and onto the toe
of their forefoot with the heel back on the
step.
Q
Is the extension assist adjustable:
A - There are only three adjustments possible.
The light duty spring (Yellow), the heavy
duty spring (Blue) and the extra heavy duty
spring (red).
Q
The friction is fully reduced but when I flex
the knee by hand it feels stiff:
A - The knee needs to have the user's weight
applied to the system to release the
braking mechanism fully and then knee will
swing freely. Incorporate the knee into the
prosthesis and then test the smoothness
of the knee while walking.
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