1. OTTO BOCK 3R80 Hydraulic Knee
Tony Fitzsimons – April 2008

2. OTTO BOCK 3R80 Hydraulic Knee
Variable cadence
Speed adjusts to that of the amputee
Stance phase flexion damping
Resistance to flexion in stance phase
Stumble recovery

3. OTTO BOCK 3R80 Hydraulic Knee
Suitable for K3 & K4 amputees:
K3: The patient has the ability or potential for ambulation with variable cadence. Typical of the community ambulator who has the ability to traverse most environmental barriers and may have vocational, therapeutic or exercise activity that demands prosthetic utilisation beyond simple locomotion.
K4: The patient has the ability or potential for prosthetic ambulation that exceeds basic ambulation skills, exhibiting high impact, stress or energy levels. Typical of the prosthetic demands of the child, active adult, or athlete.

4. OTTO BOCK 3R80 Hydraulic Knee
How does it work?
Single rotary axis
Single hydraulic chamber
Independently adjustable hydraulic control over flexion & extension
Independently adjustable hydraulic control over flexion in stance & swing.

5. OTTO BOCK 3R80 Hydraulic Knee

6. OTTO BOCK 3R80 Hydraulic Knee
Stance flexion:
During weight acceptance there is mechanical flexion of up to 4 degrees around the trigger axis.
This causes compression of the posterior elastic bumper, which dampens the flow of hydraulic oil, increasing resistance to movement.
For swing, after the limb is unloaded, compression is removed from the bumper, decreasing resistance to flexion.

7. OTTO BOCK 3R80 Hydraulic Knee
Increasing extension resistance
Altering flexion resistance for swing & stance
Alterations best done under functional conditions (stairs)

8. OTTO BOCK 3R80 Hydraulic Knee
Taking advantage of the stance phase yield requires attention to:
Prosthetic alignment:
GRF falls 40mm anterior to the main rotary axis during bench alignment
Patient alignment:
Trunk position
Hip extension during weight acceptance

9. OTTO BOCK 3R80 Hydraulic Knee

10. OTTO BOCK 3R80 Hydraulic Knee
Advantages:
Reduced peak hip extensor heelstrike c/w others knees that require hyperextension for stability.
Less sinusoidal motion of CoM due to stance yield.
Greater peak hip extension in late stance c/w knees that require hyperextension to “unlock”.
Reduced hip flexor activity to initiate swing phase.
Extension damping late swing.
Reduced work of other limb quads / plantarflexors.

11. OTTO BOCK 3R80 Hydraulic Knee
Advantages:
Ability to descend stairs & slopes step over step.
Stumble recovery due to flexion resistance in stance phase.
Ability to cope with uneven terrain.
Ride the knee down during stand  sit.
Can load toe without risk of disengaging hydraulic stance control

12. OTTO BOCK 3R80 Hydraulic Knee
Training:
Standing balance / LHPS.
Hip extension throughout stance (not as much as with safety knee)
Must maintain trunk alignment through early stance
Increase forward rotation of pelvis through late swing / early stance.
Train confidence to load knee immediately, and get a feel for engaging the hydraulic flexion resistance.

13. OTTO BOCK 3R80 Hydraulic Knee
Training (cont’d):
Step down / loading response
Ramps
Down step