Otto Bock C-Leg User manual

A: Charging the C-Leg
1. Basic Charging Every Night
Plug the charger into the wall. Connect the charger to
the C-Leg. The C-Leg will vibrate. When charging has
completed, the yellow light will turn off. Unplug the
C-Leg and it will beep. The C-Leg is ready for daily use.
B: Training for the Gait Functions of the C-Leg
1. Disengagement of Stance Flexion Resistance
It may be necessary to manually lower the maximum toe
load threshold. When manually adjusting the Maximum
Toe Load feature, have the user flex the knee when
they have full weight on the forefoot and the knee is
in full extension. This will show the user the condition
that must be met for stance to disengage in the C-Leg.
Next, have the user stand with their feet side by side
(and then repeat with the prosthetic foot out in front),
have the user try to flex the knee easily. Since it won’t
flex easily, the user will start to realize the criteria for
stancedisengagement.
2. Stumble Recovery
While manually adjusting the Stance Flexion Damping
feature, in the parallel bars, have the user put the
prosthetic foot in front and test the resistance of the
knee by flexing the knee. The knee should have a slow
enough yield so that the users will have enough time
to catch themselves in case of a stumble. Testing this
feature in this manner can build confidence in the
reliability of the Stance Flexion Damping feature.
3. Stance Flexion
Stance Flexion is the flexing of the knee at Loading
Response that occurs during normal gait. This motion
helps to absorb shock and keeps the body’s center of
gravity on a more natural sinusoidal pathway. The
Microprocessor Stance Control of the C-Leg allows
Stance Flexion to occur. For many experienced
amputees, Stance Flexion may not be a comfortable
feeling. This stems from the fact that with most
prosthetic knees, if the knee bends at Loading Response,
a fall is almost always imminent. Therefore, trust in
the reliability of the Stance Flexion Damping feature of
the C-Leg must be built-up over time. For many users
this only comes with use of the C-Leg in many different
situations. In many instances, Stance Flexion should
only be introduced to the user after they have been using
the C-Leg for some time.
Alignment is critical to achieving proper Stance
Flexion. If the alignment is too stable, Stance Flexion
will not occur. Shifting the knee axis further anterior
or dorsiflexing the foot may help to create a less stable
alignment. A less stable alignment has the added benefit
of making it easier to initiate Swing Phase.
Foot selection is another important component of Stance
Flexion. The softer the heel of a prosthetic foot (shorter
heel lever), the less the tendency is towards Stance
Flexion. A firmer heel of the prosthetic foot (longer heel
lever arm) will encourage Stance Flexion. For example,
the 1C40 foot has a very long heel lever to encourage
Stance Flexion. A longer heel lever is also useful to
preserve momentum early in the gait cycle, as the user
does not “sit back” on the heel of the foot.
4. Swing Phase Initiation
Because of the flexion resistance to either initiating or
proceeding through Pre Swing that is inherent in many
other prosthetic knee designs, many users may show
poor gait habits through this part of the gait cycle.
a. Un-weighting the Prosthesis
This deviation is especially seen in users who have
Quick Guide #3
C-Leg® User Training Overview
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Use this guide as a checklist to ensure that all aspects of using the C-Leg have been reviewed with the user before
delivery of the C-Leg. Please remember to give the “User Information Sheet” to the patient.

become used to a weight activated brake. If this habit
persists, Stance Phase disengagement with the C-Leg
will be inconsistent since 70% of Maximum Toe Load
may not be achieved with every step. Train the user in
the parallel bars by cueing the pelvis to rotate as the hip
joint flexes to initiate knee flexion rather than lifting
the leg to initiate knee flexion. It may be necessary to
manually lower the toe load threshold for the user to
be successful initially. Remember to raise the toe load
threshold as the user becomes more comfortable using
the C-Leg and can achieve a higher toe load value.
b. Excessive Force Used by the Hip Flexors During
Pre Swing
Users who are accustomed to a high flexion resistance
will be in the habit of forcefully flexing the hip during
Pre Swing. Because the C-Leg can have minimal
resistance during Pre Swing, such forceful action is
unnecessary and consumes more energy. Train the user
in the parallel bars by having them practice flexing the
knee. Change the Initial Swing Flexion Damping from
low (20) to high (50) settings so that the user will feel
the difference. Remind the user that the lower setting is
preferred, as it will consume the least amount of energy.
Have the user try to reduce the force of hip flexion as
they practice proper hip rotation and easy hip flexion.
5. Swing Phase Limb Activity
Many users will use forceful hip flexion during swing
to ensure that the knee comes into full extension at
Terminal Swing. This habit is a consequence of having
the knee buckle when loading has been initiated on a
flexed knee. The user should be reminded that the C-Leg
re-engages Stance Flexion Damping the instant the knee
stops flexing at the end of Initial Swing. This means that
Stance Flexion Damping will be available even if the foot
catches during swing phase and the knee does not come
into full extension at Initial Contact.
6. Stance Phase Activities
There are two main training tools for Stance Phase
Control: Stair Descent and Declines
a. Stair Descent Step Over Step
Stair descent is an excellent exercise to return the user
to a “normal” function and to build confidence in the
reliability of the Stance Phase resistance of the C-Leg.
Posture and foot placement are important points to
emphasize with the C-Leg. The user should maintain
good upright posture so that the “nose is not out over the
toes.” This will allow the user to “ride” the C-Leg down
to the next stair. Foot placement is the other important
factor for stair descent training. The forefoot must be off
the front of the stair to prevent disengagement of Stance
Flexion Damping. Consistent foot placement takes
practice until it is achieved. Remind the user to use a
handrail when descendingstairs.
There will be users who have not descended stairs foot
over foot with a prosthesis. Often times these users will
request a higher level of Stance Flexion Damping to feel
secure at first. Once they become accustomed to stair
descent, they will usually request a lower setting.
Other users will be using their prosthesis to “jack-knife”
down the stairs. These users will often request a lower
Stance Flexion Damping with the C-Leg because it is
much slower than the ‘free-fall” they experience with
their current prosthesis. Remind the user that “jack-
knifing” down the stairs creates a lot of force on the
joints of the lower limb and these forces could have a
detrimental long-term cumulative effect. Encourage the
user instead to “ride” the stance of the C-Leg to a low
impact landing on the stair.
b. Declines
Declines such as ramps and hills are difficult for the
transfemoral user because of the large flexion moment
at Loading Response that they entail. With the C-Leg, the
transfemoral user is able to descend the hill by “riding”
the flexed knee down to the next Stance Phase. The user
must learn to let the knee flex early in Stance and then
step across with the sound limb. Pulling back on the
prosthesis will create a “snowballing” effect, as the users
have to descend quickly to catch themselves. Start with
a ramp that has a handrail so that the user can learn to
put weight on the flexed knee as they descend down
the decline. Remind the user to use a handrail (when
available) when descendingramps.
7. Walking Backwards
It is important to instruct the user how to properly walk
backwards. If the user puts the prosthesis behind them
and weights the toe, they could release Stance Flexion
Damping. It is recommended instead to have the user
step back with the sound limb to avoid loading the toe of
the prosthesis.
8. Using the Remote
Each C-Leg comes with a remote that the C-Leg user can
utilize to unlock further functions of the knee. These
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C-Leg® User Training Overview Continued, page 2

functions are:
• Switching between 1st
and 2nd Mode
• Enable and disable
Standing Mode
• Change swing phase
dynamics
Communication
between the C-Leg and
the remote must be
established before any
of the functions can be
activated. Communication
is established by holding
down the ‘3’ key until
the C-Leg vibrates.
Communication between the C-Leg and remote will
end after a short period of time in order to save
batterypower.
Switching between 1st and 2nd Mode
After communication has been established, hold down
the ‘2’ button until the C-Leg beeps twice to signal that
the knee is in 2nd Mode. To change back to 1st Mode,
communication must be established by holding down
the ‘3’ button and then the ‘1’ button is held down
until the knee beeps once to signify that the knee is
in 1stMode. NOTE: It isn’t possible to switch into 3rd
Mode with the remote control. Third Mode must be
activated manually by bouncing on the heel.
Enable and disable Standing Mode
Standing Mode allows the C-Leg user to lock the knee
against flexion at an angle between 7 and 70 degrees of
knee flexion.
Standing Mode must be enabled using the remote
before the user can utilize this feature. Once Standing
Mode has been enabled in the C-Leg it will stay enabled
until it is disabled via the remote. After establishing
communication with the C-Leg by holding down the
‘3’ button, Standing Mode is enabled by holding down
the ‘1’ and ‘2’ buttons until the C-Leg beeps three times
and is disabled by holding down the ‘1’ and ‘2’ buttons
until the C-Leg beeps one time. In addition, the knee
must be in full flexion in order to enable or disable
StandingMode.
Once Standing Mode has been enabled through the
remote, the C-Leg user will activate this function in the
following manner:
Flex and hold the knee for 1 second. The knee must be
flexed between 7 and 70 degrees and it is best to flex the
knee just past the desired ‘locked’ angle. After holding
the knee for 1 second, slightly extend the knee to the
desired angle of knee flexion and hold the knee for 0.8
seconds. The C-Leg will vibrate and the flexion valve will
close to block flexion of the knee.
To deactivate Standing Mode, the C-Leg user can either
extend the knee quickly or extend the knee within 7
degrees of full extension.
Change swing phase dynamics
The final remote function is the ability to change the
swing phase dynamics. The remote allows the C-Leg user
to make changes to the swing flexion resistances set by
the prosthetist. There are three possible settings that the
remote can toggle through:
• Standard - This is the swing flexion setting
programmed by the prosthetist.
• Comfort - This lowers the dynamic factor by one
and increases the knee angle threshold by 5 from the
Standard setting.
• Dynamic - This increases the dynamic factor by one
and lowers the knee angle threshold by 5 from the
standard setting.
The C-Leg user can toggle between these three settings
using the remote. After activating communication with
the C-Leg, holding down a combination of the ‘1’ and
‘3’ buttons will go to a lower swing phase adjustment
and holding down a combination of the ‘2’ and ‘3’
buttons will go to a higher swing phase adjustment.
The following beeps will sound when the changes have
beenmade:
• Comfort (lowest) - 1 beep
• Standard (medium) - 2 beeps
• Dynamic (high) - 3 beeps
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C-Leg® User Training Overview Continued, page 3

C: Alerts to the User, Safety Mode
It is important to instruct the user regarding the various
alerts that the C-Leg system uses to inform the user
about the current state of the C-Leg.
1. Safety Mode
If a critical error occurs in the system, the C-Leg will
immediately switch to the Safety Mode. In that mode,
the prosthesis will not easily flex as it goes to “high
flexion damping,” (high safety/reduced comfort). This
allows the user to walk even though the system is not
active. The switch to the Safety Mode will be announced
immediately prior to the switch with sound and
vibration signals.
2. Battery Empty Mode
The C-Leg automatically switches to Battery Empty
Mode when the battery is almost empty. In this mode,
the prosthesis either sets “high flexion damping” (high
safety/reduced comfort) or “low damping” (less safety/
higher activity). This allows the user to walk even though
the system is not active. The standard factory setting for
the knee joint is “high flexion damping.” The prosthetist
is responsible for deciding whether the user can safely use
the “low damping” setting when the Battery Empty Mode
is active and manually sets high or low in C-Soft.
3. Vibrations
a. Battery Discharge
A series of vibrations are used by the C-Leg to inform
the user of the current charge state of the battery in the
C-Leg. The first warning is three short vibrations that
occur approximately one hour from the battery going
dead. The next warning is about one half hour later and
is five longer vibrations. The final warning occurs as the
C-Leg goes into Empty Battery Mode and consists of 10
long vibrations.
b. Hydraulic Cylinder Temperature
When the hydraulic cylinder of the C-Leg reaches 80
degrees Celsius (176 degrees Fahrenheit), the C-Leg will
give a pulse vibration and will continue to do so until
the hydraulic unit cools 10 degrees Celsius.
4. Beeps and Vibrations
There are three instances when there will be both beeps
and vibrations in the C-Leg:
a. Malfunctions
The C-Leg will beep and vibrate when there is a
malfunction in the system and will attempt to go into
Safe Mode. The C-Leg should be sent into Ottobock for
service if the warning beeps and vibrations occur. It is
important to remind the user that if they are walking and
the C-Leg begins to beep and vibrate, they must stop and
test to make sure that Safe Mode has engaged.
b. Programming
Beeps and vibrations will occur in the C-Leg when initially
logging into the C-Soft program via the PC and also when
program changes are being made to the C-Leg.
c. Engaging and Disengaging 2nd Mode and 3rd Mode
When entering and leaving 2nd Mode and 3rd Mode
there will be a sequence of beeps and vibrations
thatoccur.
Remind the user that plugging the C-Leg into the charger
will automatically reset the C-Leg to 1st Mode.
D: Basic Care of the C-Leg
There is no maintenance necessary by the user when
it comes to the C-Leg. However, there are certain
guidelines that the user should follow to ensure proper
functioning of the C-Leg.
1. Storing the C-Leg
The C-Leg should be stored with the hydraulic unit in a
vertical position when charging or the prosthesis is not
in use.
2. Avoid Exposure to Water and Other Fluids
Use of the silicone cap (or the red plugs) will certainly
help to prevent water damage to the C-Leg. To help with
this, it is important to remind your user that either the
silicon cap (or the red plugs) must always be in place in
the C-Leg. It is also vital to remind the user that exposure
to water always carries the risk of damaging the C-Leg and
creating a malfunction. If the C-Leg is exposed to water
or other fluid, have the user dry the leg immediately and
bring the prosthesis in so that it can be sent to Ottobock
for service. Exposure to water voids the warranty.
3. Avoid Strong Magnetic and Electrical
InterferenceSources
Since the C-Leg utilizes a magnetic sensor in the knee
to read knee angle, large magnetic interference sources
can cause false readings to occur. Strong magnetic or
electrical interference sources could also possibly cause
damage to the C-Leg and should be avoided. However,
we have had no reports of damage to the C-Leg due to
airport metal detectors.
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C-Leg® User Training Overview Continued, page 4
C-Leg® is a registered trademark of Otto Bock Health Care GmbH. LuXon, Axtion, C-Walk and Lo Rider are registered trademarks and trademarks of Otto Bock HealthCare LP. ©2012 Otto Bock HealthCare LP. • 12062361.3 • 6/12