OTTO BOCK 3R80 Hydraulic Knee Tony Fitzsimons – April 2008

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

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