Transcript OTTO BOCK 3R80 Hydraulic Knee

OTTO BOCK 3R80
Hydraulic Knee
Tony Fitzsimons – April 2008
OTTO BOCK 3R80
Hydraulic Knee

Variable cadence
–

Stance phase flexion damping
–

Speed adjusts to that of the amputee
Resistance to flexion in stance phase
Stumble recovery
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.
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.



OTTO BOCK 3R80
Hydraulic Knee
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.
OTTO BOCK 3R80
Hydraulic Knee
•Increasing extension resistance
•Altering flexion resistance for
swing & stance
•Alterations best done under
functional conditions (stairs)
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
OTTO BOCK 3R80
Hydraulic Knee
OTTO BOCK 3R80
Hydraulic Knee

Advantages:
–
–
–
–
–
–
Reduced peak hip extensor activity @ 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.
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
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.
OTTO BOCK 3R80
Hydraulic Knee

Training (cont’d):
–
–
–
Step down / loading response
Ramps
Down step