Orthomobility VGK-Go! User manual

Very Good Knee - Go!
Instructions Manual
Distributeur

The knee joint
for transfemoral
amputees and knee
disarticulation

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Very Good Knee - Go! GebruiksaanwijzingVersion 2.4.2 3
VGK-Go! van Orthomobility Ltd., distributeur Loth Fabenim B.V.
Contents
1. Introduction ......................................................................................................... 5
1.1. Intended Purpose ................................................................................................. 5
1.2. Technology .......................................................................................................... 5
1.3. Recommended User Prole ........................................................................................... 5
1.4. Installation and Adjustments ......................................................................... 6
1.5. Compatibility ........................................................................................... 6
1.6. Lifetime of the Device .............................................................................................. 6
1.7. Identication of the Device ........................................................................................ 7
1.8. Normal use (note stairs) ............................................................................................ 7
1.9. Contact with Water ...................................................................................... 8
1.10. Expectation Management ................................................................................................ 8
1.11. Irregular and Extreme Use ........................................................................................ 8
1.11.1. Extreme Temperature .............................................................................................. 9
1.11.2. Extreme Device Settings ................................................................................ 9
1.12. Body Weight and Additional Load ................................................................................. 9
1.13. Prevention of Overheating ......................................................................................... 9
1.14. Wear and Tear ............................................................................................... 9
1.15. Storage ........................................................................................... 9
2. Alignment ............................................................................................................ 10
2.1. General Alignment ............................................................................................................. 10
2.2. Leg Length ......................................................................................................................... 12
2.3. Socket Flexion .................................................................. 12
2.4. Foot Alignment ......................................................................................................... 12
2.5. Kneeling ............................................................................... 13
3. Controls .......................................................................................................... 14
3.1. Swing release ................................................................................... 15
3.1.1. Setting Swing Release Threshold .......................................................... 15
3.1.2. Conditions for Swing Release ....................................................................... 15
3.2. Stance Flexion Handle ........................................................................................ 16
4. Adjustments .......................................................................................................... 17
4.1. Adjusting the Stairs Mode ............................................................................................. 17
4.2. Ultra High Resistance Mode ........................................................................................... 17
4.3. Adjusting the Cycle Mode ............................................................................................. 17
4.3.1. Bench Testing Cycle Mode ................................................................................... 18
4.3.2. Clinical Set up of Cycle Mode ................................................................... 18
4.4. Swing Phase Adjustments ............................................................................ 19
4.4.1. Maximum Knee Flexion Limitation in Swing ......................................................... 19
4.4.2. Nominal Swing Phase Resistance ..................................................... 19
4.4.3. Terminal Impact Damping ........................................................................................ 20

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5. Finishing Check Points ....................................................................................................... 21
5.1. Essential Movement in Mechanism ........................................................................ 21
5.2. Cosmetic Cover ........................................................................................... 21
5.3. Final Checklist ............................................................................................ 21
6. Care and Maintenance ............................................................................................ 22
7. Product Disposal .............................................................. 23
8. Warranty ................................................................................ 24
9. Liability .................................................................................................................. 25
10. Reporting of a Serious Incident ..................................................................................... 26
11 Declaration of Conformity ............................................................................................... 27
Contents
!
Use the Final Checklist on page 20 to
check the essential installation points

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1.1. Intended Purpose
The VGK-Go! is intended to be solely used in lower extremity prosthetic limbs as a
prosthetic knee joint to assist ambulation and activities of daily living. The product
can be used for uni- or bilateral amputation. The VGK-Go! is compatible with
osseointegration, however, permission MUST be obtained from the manufacturer
prior to use with osseointegration. Permission for use with osseointegration is
considered on a case-by-case basis.
The VGK-Go! is best used for medium and long femur length in the residual limb. For
short transfemoral the VGK-S is recommended, and the VGK-X is a good alternative
for people with body weight under 80 kg. Please see our website www.orthomobility.
com
1.2. Technology
The VGK-Go! is a Fluidic Processor Knee (FPK), which uses uidic sensors to respond
to changes in gait in real-time, by adjusting motion resistance within a single step.
1.3. Recommended User Prole
The VGK-Go! is recommended for independent prosthetic users typically of mobility
classes 1-4**. The user’s body weight can be up to 125 kg.
** Users with signicant comorbidity must be carefully monitored in the rehabilitation
period to ascertain the suitability of the device for their needs.
1Introduction

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1.5. Compatibility
The VGK-Go! is compatible with the full complement of prosthetic components,
energy-storing feet, hydraulic ankles, hip components, shock absorbers, etc.
1.6. Lifetime of the Device
In compliance with the EU Medical Device Regulations, Orthomobility has dened a
maximum usage period of 5 Years + 3 months for VGK-Go!. The rate at which the
device is used will vary between patients, but this limit puts a practical, manageable,
and measurable limit on its use. The additional “3 months” have been added to
allow time for shipping and replacement limb tting.
VGK-Go! must not be used after the maximum usage period. The usage period
starts on the date of shipment by the distributor and this date appears on the
product label. If the shipping date is not known, the date of invoice will be used.
Please contact the distributor if the start date is not available.
1.4. Installation and Adjustments
1Introduction
The VGK-Go! must be installed by a Certied Prosthetic/Orthotist (CP or CPO) to
make sure the alignment and control settings are adjusted safely.
The user may adjust the controls under the guidance of their CPO. The CPO must
assess whether the user is able to adjust the knee joint safely. There are special
instructions with regards to use in a wet environment that must be passed to the
user by the CPO.

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1.7. Identication of the Device
A VGK-Go! unit may be identied with the serial number that is engraved on the
product, as shown in Fig 1.1.
1Introduction
Fig 1: Location of serial number
1.8. Normal Use (note stairs)
The VGK-Go! has been developed for ambulation and ordinary mobility use: walking,
sitting, kneeling, cycling, and occasional wetting by rain or tap water. The use of
handrails or bannisters is recommended when descending downstairs. Note: to set
up the knee for cycling requires a special procedure to be followed.

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1Introduction
1.10. Expectation Management
Please advise the user that this device is designed to oer functionality that is
compatible with a high level of safety. The high level of safety is likely to elevate their
expectations of their ability, and consequently your patient may nd limits in the
performance of the device. When such an event happens, they are asked to record
the circumstances and report the event back to their CPO.
1.11. Irregular and Extreme Use
Irregular and extreme use may occasionally be required and this should be agreed
with the manufacturer beforehand. Such use may involve water and dirt, mechanical
shock and forceful use. Whereas these may be considered as part of intended use,
it will be required that written permission is sought from the manufacturer so that
such irregular use can be risk assessed, supported, or denied on grounds of risk.
A considered permission/denial/support programme will be discussed on request.
Use of the product in a sauna is excluded. Avoid sand entering the knee.
1.9. Contact with Water
The VGK-Go! is suitable for occasional use in water up to a depth of 1.5 m. However,
the knee joint has no buoyancy in water. There is also a risk of snagging on plants
or objects.
If the knee joint is to be used in wet environments more frequently than once a
month, this requires the manufacturer’s prior agreement such that a care and
maintenance program can be discussed. The manufacturer may limit the use of the
knee joint in wet environments if a care and maintenance program is not followed.
Also note the instructions in Section 6.
1.11.1 Extreme Temperature
The VGK-Go! has been designed for a stable performance over a range of
temperatures. The use in very low temperatures (sub-zero) may cause some
stiffening in the swing and yield action of the joint, which in hands-free slope and
stairs descent could cause an imbalance. In this instance, it is advised to first try
using it close to a handrail. In elevated temperatures (40 degrees plus), the VGK-Go!
maintains its performance fairly well.

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1Introduction
1.11.2 Extreme Device Settings
The VGK-Go! permits a high level of resistance in yield. The device has been designed
to contain hydraulic pressures that arise during normal use, including leg-over-leg
stair descent. However, when significant weight is placed on the leg, the device is
not intended to be loaded in flexion in a ‘locked’ mode.
1.12. Body Weight and Additional Load
The VGK-Go! has been designed to allow for a patient body weight of 125 kg and
these persons, at this maximum body weight, to carry not more than 15 kg of
additional load on a daily basis.
1.13. Prevention of Overheating
Do not use VGK-Go! in the sauna because the heat may damage the metal surfaces.
When used intensively, allow heat to escape via the frame by avoiding use of
cosmetic foam covers.
1.14. Wear and Tear
As with any device with mechanical elements, mechanical wear and tear will
eventually occur, and the user and CPO are required to see that regular inspections
and maintenance are carried out. Fair wear and tear includes the possible formation
of corrosion due to regular wet use, especially in salt and chlorinated water, and
urine. Cleaning with fresh water may reduce the impact of salt and chlorinated
water. Fair wear and tear falls outside the standard scope of warranty.
1.15. Storage
The VGK-Go! must be stored in an extended position.

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2.1. General Alignment
The alignment of the knee joint must follow the straight hip-knee-ankle line. The
‘Ankle’ refers to where the natural ankle would be, that is between 1/4 and 1/3 of
the foot length. Ideally the knee axis should be 10 mm behind the hip-ankle line (see
Fig 2.1).
2Alignment
Fig 2.1: Alignment of VGK-Go!.

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Fig 2.2: A vertical hip-knee-ankle line is the preferred alignment. A posteriorly placed
hip/greater trochanter is liable to make swing release more dicult.
2Alignment

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2.2. Leg Length
To help the user easily initiate the swing release, the prosthesis length must be
assessed as a LEVEL pelvis, or no more than 10 mm shorter. DO CHECK THE LEG
LENGTH.
2.3. Socket Flexion
A vertical hip-knee-ankle line must be maintained as well as possible, even if initial
hip exion is required in the socket. This may be achieved by moving the socket and
foot forward relative to the knee joint, and letting the user exercise a small amount
of hip extension to maintain extension of the knee (see Fig 2.2).
2.4. Foot Alignment
The VGK-Go! requires a toe load in late stance to release into swing. Too much
dorsiexion of the foot may make it dicult to release the knee into swing if there is
insucient forefoot loading. Equally, an unusually high heel on the shoe will reduce
the eective length of the foot and therefore may cause diculty for swing release.
2Alignment
Fig 2.3: Kneeling onto the cylinder is permissible when the contact point is in the green
regions

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2.5. Kneeling
Extreme or maximum knee exion will cause the socket to touch the hydraulic unit.
This unit can take the forces of kneeling and squatting provided the contact is made
in the region as indicated in Fig 2.3. It is important to measure the indicated contact
point to be 100 +/- 5 mm from the knee axle. If required, the socket may need a local
build up, so that the internal structure of the hydraulic takes the load at the correct
point. DO adhere to this rule. Alternatively, the socket may rest on the frame of the
knee.
2Alignment

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Controls
3
Fig 3.1: Locations of controls for clinical adjustments
Fig 3.2: Positions of the Stance Flexion Handle

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3.1. Swing Release
3.1.1 Setting Swing Release Threshold
The VGK-Go! relies on the presence of knee extension and toe-load for swing-phase
release. This condition is natural in terminal stance. For most users this switching
behaviour is set to be as light as possible. For bilateral amputees, the transition
may need to be more deliberate to secure standing balance. If the threshold for
switching to swing-phase must be increased, the Swing Release Threshold, Rin Fig
3.1, is turned clockwise using a 8 mm Hex key.
The VGK-Go! senses toe load by a slight swivelling action of the distal knee section.
There is a spring system (a green spring) in the distal knee, which for safety allows
the distal knee to be biased to the stance-phase position. When weight is placed on
the forefoot, the distal knee can overcome the spring tension and swivel into the
swing-initiation position. Therefore the more the spring is preloaded (by clockwise
turning Rin Fig 3.1), the higher the toeload must be to cross the threshold for swing
initiation. There is only a limited range of adding preload! A stiffer (red) spring can
be ordered in case the tension needs to be higher. When used outside the parallel
bars, no slack rocking action may be present between the frame and the distal knee.
3Controls
3.1.2 Conditions for Swing Release
The knee joint will release into the swing phase when there is a hyperextension
moment, immediately followed by a high knee flexion moment. Using the knee joint
in a forceful way can, in exceptional circumstances, lead to an unintended release
into the swing phase. An example of such nonrecommended use is attempting
to land hard on the mid-foot onto a curb or step (see Fig 3.3). This userinduced
failmode is unlikely to happen in ordinary walking. User confidence in the VGK-Go!
should not be lost, provided the usual behaviour continues after such an incident or
event of exceptional use.

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Controls
3
Fig 3.3: Avoiding unintentional swing release
3.2. Stance Flexion Handle
The use of yield resistance (stance resistance) is set using the stance exion handle,
Hin Fig 3.1. See Fig 3.2 for possible positions of handle H.
Position Description
WStairs mode. Stance resistance compatible with ordinary walking,
including stairs and slopes (adjustable)
UUltra high stance resistance
CCycle mode, which is a free mode with safety catch for when the
piston exceeds a threshold speed (threshold is adjustable)

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4Adjustments
4.1. Adjusting the Stairs Mode
See Fig 3.1 and Fig 3.2. The stairs mode is selected by positioning the stance exion
handle (H) in position W. The rate of knee exion in stance can be adjusted with the
Yield Resistance Valve, Y. Use a 2 mm Hex key to turn the valve anticlockwise for
faster knee exion, or clockwise for slower knee exion.
To get the right setting for the user, allow them to descend from the last step of a
stairs and adjust the valve until it is comfortable. Then adjust the valve further as
required to accommodate more steps being taken in sequence.
DO take note that the resistance in stumble recovery = the resistance in stance
mode. Therefore it is recommended to keep the stance mode resistance as high as
is comfortable.
4.2. Ultra High Resistance Mode
See Fig 3.1 and Fig 3.2. The ultra high resistance mode is selected by positioning the
stance exion handle (H) in position U. This mode eectively blocks the yielding, but
allows free swing (as long as the walking speed is not too high). For this reason, this
mode is NOT A FULL LOCK. The user can still release the knee into the swing phase.
4.3. Adjusting the Cycle Mode
See Fig 3.1 and Fig 3.2. The cycle mode is selected by positioning the stance exion
handle (H) in position C. In this mode, there is a safety catch that kicks in when the
knee exion speed crosses a threshold.
The factory setting of the cycling function is ultrasafe! In this factory setting, the
cycling function may not work for the user. Use the Cycling Safety Valve(CS in Fig 3.1)
to lower the safety threshold, therefore permitting higher cycling speeds.

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Adjustments
4
4.3.1 Bench Testing Cycle Mode
Bench test the prosthesis to become familiar with the cycling settings. Turn the
stance flexion handle to cycling mode and observe that in the factory setting,
the knee does not bend easily. This is because the safety valve activates almost
immediately. To turn the safety valve off, dial in the Cycling Safety Valve (CS in Fig
3.1) fully. Now the safety valve is effectively off and the knee should bend very easily
irrespective of the flexion speed. By incrementally winding the Cycling Safety Valve
screw anticlockwise again, a setting can be found where slow flexion movement
is easy but fast movement incurs resistance. This is the basis for the VGK-Go! to
differentiate between the slow cycling movement that is to be permitted, and
fast movement that may occur if the patient tries to walk on the knee and it has
accidentally been left in the “cycling mode”.
4.3.2 Clinical Set up of Cycle Mode
For clinical set-up, first select the cycling mode and turn off the safety valve (by
dialling in the Cycling Safety Valve, CS in Fig 3.1, fully). Now, let the user cycle and
incrementally dial out the safety valve until the safety feature applies itself during
cycling. Agree with the user how much to reduce the sensitivity of the safety feature,
where if they simulated a collapse, they would still feel confident afterwards walking
on it. Naturally, if faster cycling is required, there is less safety available in walking!
4.4. Swing Phase Adjustments
Fig 4.1: Adjustment of the maximum knee exion

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4Adjustments
4.4.1 Maximum Knee Flexion Limitation in Swing
Reducing the maximum permissible knee flexion creates more forward drive of the
knee. This is the MAIN control for swing phase adjustments.
The Knee Flexion Limiter (MF in Fig 3.1) is operated with a 1.5 mm Hex key. The valve
is factory set with maximum knee flexion. To reduce the maximum permitted knee
flexion, slot in the Hex key and slide the Knee Flexion Limiter over to the left (do not
turn the key, only swivel across as in Fig 4.1).
4.4.2 Nominal Swing Phase Resistance
If there is insufficient forward drive of the shin, even after adjusting the maximum
knee flexion, the swing resistance can be increased. The Swing Resistance Valve (S
in Fig 3.1) is operable using a 2 mm Hex key.
4.4.3 Terminal Impact Damping
The terminal impact dampening is auto-corrective and dynamically adjusts itself to
the walking speed, and is not otherwise adjustable.
NOTE: there is no external adjustment to alter the extension resistance.

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5Finishing Check Points
5.1. Essential Movement in Mechanism
An essential part of the VGK-Go! mechanism is the slight swivelling motion in the
distal knee section. The small gap between the distal knee section and the main
frame must remain free of cosmeses, glue, dust particles, wedges, or anything else
that could inhibit the movement. Warn the user against ingress of objects between
moving parts and recommend a quarterly visual inspection. In case of doubt, a
planned inspection by the clinician is recommended.
5.2. Cosmetic Cover
When using a cover, regularly inspect the knee in case anything has fallen into the
knee, to prevent damage between moving parts. Also ensure that the cover does
not inhibit the essential movement described in Section 5.1.
5.3. Final Checklist
Use this checklist to nalise the set-up of the VGKGo!:
• Socket contact in safe position? (see Fig 2.3)
• Knee aligned 10 mm behind Hip-Knee-Ankle?
• Is the pelvic level with contralateral side, or less than 10 mm shorter?