otto bock 3r80 hydraulic knee tony fitzsimons – april 2008

OTTO BOCK 3R80Hydraulic Knee

Tony Fitzsimons – April 2008


Variable cadence– Speed adjusts to that of the amputee

Stance phase flexion damping– Resistance to flexion in stance phase

Stumble recovery


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.


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.


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.


•Increasing extension resistance

•Altering flexion resistance for swing & stance

•Alterations best done under functional conditions (stairs)


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


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.


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


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.


Training (cont’d):– Step down / loading response– Ramps– Down step

otto bock 3r80 hydraulic knee tony fitzsimons – april 2008

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