Amputee Gait Training
Otto Bock C-Leg: Training Strategies
The C-Leg is a microprocessor controlled knee joint introduced in 1997, and updated in 2011. Its main distinguishing feature is an ability to flex under load, allowing knee yield in early stance phase, and the ability to descend stairs step-over-step. The gait pattern required to make full functional usage of this knee joint is somewhat different to that typically used in mechanical, pneumatic, or other less advanced hydraulic knees. This page contains links to several training videos on YouTube, and training ideas brainstormed at previous AustPAR events. For a description of the functionality of the C-Leg, see our C-Leg page in the Prosthetics Portal.
Training Videos
Actual links are shown, for those services where access to YouTube is blocked.
C-Leg Training, Part 1 of 3 youtu.be/LHjunPj3MPA
C-Leg Training, Part 2 of 3 youtu.be/jcZxoLp5Iys
C-Leg Training, Part 3 of 3 youtu.be/aVrxat7Q0iY
C-Leg Training on Stairs youtu.be/Z6bvgDaOkcI
Training Strategies
The ideas listed below were provided from Physiotherapists and Prosthetists, with much thanks. Your choice of exercise should be made depending on the amputee's skill and confidence level, and their goals. Safety should be the highest priority when selecting which exercise to practice.
Several studies have shown the while the knee flexion moment in early stance may be increased with the C-Leg, the knee itself still tends to remain in extension, with little apparent dynamic flexion during stance. They suggest that this may be due to short periods of acclimation in the studies, and go on to suggest that the knee flexion / yield must be specifically trained, and may take a period of time to learn, particularly in users who have previously learnt to provide excessive hip extension force to lock the knee.
| Strategy | Description |
|---|---|
| Strategies for training knee flexion in stance... | |
| Teach stance flexion resistance disengagement | Have the amputee flex the knee when they have full weight on the forefoot and the knee is in full extension. This will show the amputee the condition that must be met for stance to disengage in the C-Leg. Next, have the amputee stand with their feet side by side (and then repeat with the prosthetic foot out in front), have the patient try to flex the knee easily. Since it won’t flex easily, the patient will start to realize the only conditions for stance disengagement are toe / forefoot loading. |
| Stand to Sit Practice | Practice moving from standing to sitting, with weight on the prosthesis. This is to allow a feel for how the hydraulics allow knee bending under load, and build trust in the knee while it is flexing. |
| Step Forward with the Prosthesis | Step the prosthesis forward, almost like lunging. This is to allow the amputee to learn how to accept weight in such a way that the hydraulic provides flexion resistance, and to build trust in the knee while it is flexing under load. They must get a feel for loading the prosthesis as soon as the heel contacts. This should be done in parallel bars for safety, until skill level increases. |
| Step Down onto a Wedge with the Prosthetic Limb | A wedge is placed at the bottom of a step. The amputee steps onto the wedge with the prosthetic foot. The slope of the wedge causes the toes to move down as weight is accepted, which forces the knee to flex. The amputee should be encouraged to shift weight onto the foot with the correct timing, to engage the hydraulic and resist the tendancy for knee flexion. This should be practiced initially with rails, until skill level & confidence improves. |
| Step Off a Step with the Intact Limb | With only the rear of the prosthetic foot on the edge of a step, the amputee steps off with the intact limb, allowing the prosthetic knee to flex during the Controlled Lowering phase. This teaches the amputee how to engage the hydraulic (if weight is borne correctly), and learn trust in the hydraulics. It should be practiced in rails for safety until skill and confidence improves. Manual guidance by the Therapist can prove useful here too. |
| Walking Down Ramps | The amputee walks down a ramp or slope, using a handrail for safety. The angle of the slope tends to flex the knee as the foot moves to foot-flat. They then 'ride' the knee flexion resistance down, ensuring a reasonable step length with the contralateral foot. This is to teach the amputee to accept weight with the correct timing and alignment to engage the hydraulic to resist knee flexion, and learn to trust the knee while it is flexing. It is important to train the amputee not to excessively extend their hip, which would force the knee back into extension. |
| Walking Down Stairs | The amputee walks down stairs step-over-step, using a handrail as appropriate. The prosthetic foot should be placed such that the rear foot is on the step, and forefoot over the edge, allowing the foot to rotate over the edge of the step (which prevents the lack of prosthetic ankle dorsiflexion range limiting the forward movement of the shank). The amputee then 'rides' the hydraulic flexion resistance down. This is to teach the amputee to accept weight onto the prosthesis with the correct timing and alignment to engage the hydraulic to resist knee flexion, learn correct prosthetic foot placement on each step, and learn to trust the knee while it is flexing. An upright posture is important to ensure correct alignment & timing |
| Strategies for terminal stance hip extension / toe loading... | |
| Prone-lying hip extension | The amputee lies prone, and is instructed to press the ASIS of their amputated side into the bed, while simultaneously extending their stump. This is to give them the idea of pushing the pelvis forwards while extending the hip. |
| Walk "Down the Aisle" | Walk with a step-to pattern, leading with the intact limb. The amputee should be trying to push off the prosthetic toe to generate the forward momentum for the intact leg step & forward weight shift. Hip extension / trunk upright is crucial. |
| Walk "Down the Beach" | Walk in a step-to pattern, leading with the intact limb. The amputee should be imagining the toes of their prosthetic limb digging into the sand, trying to push off the prosthetic limb. Hip extension / trunk upright is crucial. |
| Discouraging Unweighting the Prosthesis | Patients who have previously used knees that lock under load to prevent knee flexion may have compensatory strategies such as hip hithcing, vaulting, or circumduction to unlock the knee and intiate swing phase. However, loading the toe with the knee extended is required to disengage the stance phase resistance with the C-Leg. Train correct initiation of swing by getting the amputee to rotate their pelvis as the hip joint flexes to initiate knee flexion rather than lifting the leg to initiate flexion. Excessive use of the hip flexors should be discouraged. |
| Step Up onto a Small Step, Leading with the Prosthetic Limb | The amputee steps up onto a small size step or block, leading with the prosthesis. Circumduction during the swing phase should be discouraged. They then step up with the intact foot, landing with feet level, or progressing to stepping through with the intact foot. The idea is to teach weight acceptance with a small amount of knee flexion, but train the hip extensors to control that flexion, and then extend the stump to allow for the intact foot step. Rails may be needed until skill improves. |
| General Strategies... | |
| Train correct technique for backwards walking | As loading the prosthetic toe with the knee extended may disengage stance flexion resistance, the amputee should be taught to place the prosthetic foot flat when stepping backwards, rather than extending / lifting the prosthetic limb back and contacting the ground with their toes. |
| Improve core stability | |
| Teach normal pelvic rotation and arm swing | |