Otto Bock C-Leg - User Manual

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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

Ottobock · P 800 328 4058 · F 800 962 2549 · www.ottobockus.com

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.

Need help?

Do you have a question about the Otto Bock C-Leg and is the answer not in the manual?

Summary

Charging the C-Leg

Basic Charging Every Night

Guide for daily C-Leg charging procedure. Ensure yellow light off for completion.

Training for Gait Functions

Disengagement of Stance Flexion Resistance

Manually adjust toe load threshold to help user understand stance disengagement criteria.

Stumble Recovery

Test knee's slow yield in parallel bars to build user confidence in stumble recovery.

Stance Flexion

Explains C-Leg's Stance Flexion, shock absorption, and building user trust over time.

Swing Phase Initiation

Addresses user gait habits during swing phase and how C-Leg improves this.

Un-weighting the Prosthesis

User habit of forceful hip flexion during pre-swing, and how to retrain.

Excessive Force Used by Hip Flexors

Addresses forceful hip flexion in pre-swing and training to reduce energy consumption.

Swing Phase Limb Activity

Training users to avoid forceful hip flexion for full terminal swing extension.

Stance Phase Activities

Key training for stance control, covering stair descent and declines.

Stair Descent Step Over Step

Exercise for normal function and confidence in C-Leg's stance resistance.

Declines

Training users to descend ramps/hills by 'riding' the flexed knee.

Walking Backwards

Proper technique for walking backwards to avoid releasing stance flexion damping.

Using the Remote

Introduction to the C-Leg remote for unlocking advanced functions.

Switching between 1 st and 2 nd Mode

Instructions for switching between the C-Leg's 1st and 2nd modes via remote.

Enable and Disable Standing Mode

How to use the remote to enable/disable Standing Mode for knee flexion locking.

Change Swing Phase Dynamics

Using the remote to adjust swing phase dynamics: Standard, Comfort, Dynamic.

Alerts to the User and Safety Mode

Safety Mode

System switches to high safety/reduced comfort mode upon critical error.

Battery Empty Mode

C-Leg enters Battery Empty Mode when battery is nearly depleted.

Vibrations

C-Leg uses vibrations to alert user about battery status and temperature.

Battery Discharge Vibrations

Sequence of vibrations indicating battery charge level and impending depletion.

Hydraulic Cylinder Temperature

Pulse vibration alerts when hydraulic cylinder reaches 80 degrees Celsius.

Beeps and Vibrations

Alerts for malfunctions, programming, and mode changes in the C-Leg.

Malfunctions Alerts

Beeps and vibrations signal malfunctions; require immediate stop and check.

Basic Care of the C-Leg

Storing the C-Leg

Store C-Leg with hydraulic unit vertical when charging or not in use.

Avoid Exposure to Water and Other Fluids

Use silicone cap to prevent water damage; exposure voids warranty.

Avoid Strong Magnetic and Electrical Interference

Avoid strong magnetic/electrical sources that can cause false readings or damage.

Overview

Function Description
Key Gait Functions
Usage Features
Important Technical Specifications & Alerts
Maintenance Features

The Ottobock C-Leg is a microprocessor-controlled prosthetic knee designed to provide enhanced stability, natural gait, and user confidence for transfemoral amputees. It integrates advanced sensor technology and real-time control to adapt to various walking conditions and user movements.

Function Description:

The C-Leg's primary function is to mimic the natural movement of a human knee during walking. It achieves this through a sophisticated system that continuously monitors the knee angle, forces, and moments, adjusting hydraulic damping in real-time. This allows for controlled stance flexion, smooth swing phase, and robust stumble recovery.

Key Gait Functions:

Stance Flexion: The C-Leg allows for natural knee flexion during the loading response of gait, absorbing shock and maintaining a more natural sinusoidal pathway for the body's center of gravity. This feature, while initially unfamiliar to users accustomed to traditional prosthetic knees, builds confidence over time in the C-Leg's reliability. Proper alignment and foot selection are crucial for optimal stance flexion. A less stable alignment (knee axis further anterior or dorsiflexing foot) can facilitate stance flexion and swing phase initiation. A firmer heel on the prosthetic foot (longer heel lever arm) encourages stance flexion and helps preserve momentum early in the gait cycle.
Disengagement of Stance Flexion Resistance: The C-Leg's stance resistance disengages when the user shifts weight off the forefoot, allowing for easy knee flexion. Users can be trained to understand the conditions for disengagement by practicing knee flexion with full weight on the forefoot (knee in full extension) and then attempting to flex the knee easily with feet side-by-side or with the prosthetic foot in front. The maximum toe load threshold can be manually adjusted to optimize this function.
Stumble Recovery: The C-Leg is equipped with a stumble recovery feature that provides controlled yield during unexpected knee flexion, giving the user time to regain balance. This feature's reliability can be tested by having the user place the prosthetic foot in front and flex the knee, ensuring a slow enough yield.
Swing Phase Initiation: Unlike many prosthetic knees with high flexion resistance during pre-swing, the C-Leg offers minimal resistance, promoting a more natural swing phase. Users accustomed to "un-weighting" the prosthesis or forcefully flexing the hip during pre-swing may need training to adapt to the C-Leg's smoother initiation. Training involves cueing pelvic rotation rather than leg lifting to initiate knee flexion, and practicing knee flexion in parallel bars. Adjusting the Initial Swing Flexion Damping (e.g., from low to high and back) can help users feel the difference and understand that lower settings conserve energy.
Swing Phase Limb Activity: The C-Leg re-engages stance flexion damping as soon as the knee stops flexing at the end of initial swing, ensuring stability even if the foot catches during swing phase or if the knee doesn't fully extend at initial contact. This helps users overcome the habit of forceful hip flexion during swing to ensure full knee extension, a habit often developed to prevent knee buckling with traditional prostheses.

Usage Features:

The C-Leg offers several user-controlled features via a remote control:

Switching between 1st and 2nd Mode: The C-Leg has multiple modes for different activities. Users can switch between 1st and 2nd Mode by holding down specific buttons on the remote after establishing communication. The 3rd Mode requires manual activation by bouncing on the heel.
Enable and Disable Standing Mode: This feature allows the user to lock the knee against flexion at an angle between 7 and 70 degrees. Standing Mode must first be enabled via the remote and then activated by flexing and holding the knee at the desired angle for specific durations. It can be deactivated by quickly extending the knee or extending it within 7 degrees of full extension.
Change Swing Phase Dynamics: The remote allows users to adjust the swing flexion resistances set by the prosthetist. There are three settings:
- Standard: The default setting programmed by the prosthetist.
- Comfort (lowest): Lowers the dynamic factor and increases the knee angle threshold, indicated by 1 beep.
- Dynamic (high): Increases the dynamic factor and lowers the knee angle threshold, indicated by 3 beeps.
- Switching between these settings is done by holding down combinations of buttons on the remote.
Stair Descent Step Over Step: The C-Leg facilitates a more natural stair descent. Users are trained to maintain upright posture and ensure the forefoot is off the front of the stair to prevent disengagement of stance flexion damping. Consistent foot placement and handrail use are emphasized. The C-Leg allows users to "ride" the flexed knee down to the next stair, reducing impact compared to "jack-knifing" with traditional prostheses.
Declines (Ramps and Hills): The C-Leg enables transfemoral users to descend declines by "riding" the flexed knee. Users learn to allow the knee to flex early in stance and then step across with the sound limb. Handrail use is recommended during training.
Walking Backwards: Users are instructed to walk backwards by stepping back with the sound limb to avoid loading the toe of the prosthesis, which could release stance flexion damping.

Important Technical Specifications & Alerts:

Battery: The C-Leg is charged nightly. A full charge is indicated by the yellow light turning off and a beep when unplugged. The C-Leg provides vibration warnings for battery discharge: three short vibrations (approx. 1 hour before dead), five longer vibrations (approx. 30 minutes before dead), and ten long vibrations (entering Empty Battery Mode).
Safety Mode: In case of a critical error, the C-Leg automatically switches to Safety Mode, setting to "high flexion damping" (high safety/reduced comfort). This allows the user to walk even if the system is not active. This transition is announced with sound and vibration signals.
Battery Empty Mode: When the battery is almost empty, the C-Leg switches to Battery Empty Mode, setting to either "high flexion damping" or "low damping" (less safety/higher activity), allowing continued walking. The standard factory setting is "high flexion damping."
Hydraulic Cylinder Temperature: If the hydraulic cylinder reaches 80°C (176°F), the C-Leg will give a pulse vibration until it cools to 70°C.
Malfunctions: The C-Leg will beep and vibrate during a malfunction and attempt to enter Safe Mode. If this occurs, the C-Leg should be sent for service. Users must stop and test for Safe Mode engagement.
Programming: Beeps and vibrations occur during initial C-Soft program login and when program changes are made.
2nd and 3rd Mode Engagement/Disengagement: Beeps and vibrations occur when entering and leaving these modes. Plugging the C-Leg into the charger automatically resets it to 1st Mode.
Magnetic Sensor: The C-Leg uses a magnetic sensor for knee angle measurement. Strong magnetic or electrical interference sources can cause false readings or damage, and should be avoided. Airport metal detectors have not been reported to cause damage.

Maintenance Features:

User Maintenance: No specific user maintenance is required for the C-Leg.
Storage: The C-Leg should be stored with the hydraulic unit in a vertical position, especially when charging or not in use.
Water and Fluid Exposure: The silicone cap or red plugs must always be in place to prevent water damage. Exposure to water or other fluids carries a risk of damage and voids the warranty. If exposed, the leg should be dried immediately and sent to Ottobock for service.