Nabtesco Symphony NK-6 User manual

For Prosthetists
Instruction Manual
6-Bar Hydraulic Knee Joint
NK-6 Symphony
6-Bar Hydraulic Knee NK-6
Introduction
Thank you for using the NK-6 Symphony.
This product is a prosthetic knee joint
which ensures high stability of stance
and excellent ability to response to the
walking speed through unique 6-bar
linkage system and hydraulic cylinder.
Before using the product, read this
Instruction Manual, and understand the
correct procedures for using. Keep it
handy for future reference. Hand the
separate User’s Guide to the user, and
explain the instructions for use.

P.1
Important Information
■Intended purpose of NK-6 Symphony
NK-6 Symphony was designed and is manufactured
for use as an artificial knee joint by above-knee,
knee disarticulation, hip disarticulation. Do not use
NK-6 Symphony for any other purposes.
For hip prostheses, it is recommended to use a
torsion adapter to prevent application of large
torsion to NK-6 Symphony.
This device is intended for single patient multiple
use.
For the specifications for NK-6 Symphony, see 8.
Outline of the Produ ct.
Do not use NK-6 Symphony outside of
the specification range. Do not modify
the main body or parts.
Doing so can cause injury or damage
NK-6 Symphony.
■Cautions for handling NK-6 Symphony safely
Nabtesco Corporation (hereinafter, referred to as
Nabtesco) cannot foresee all of potential residual
risks of NK-6 Symphony and risks resulting from
human errors and usage environment.
Although there are a lot of instructions and
prohibitions for handling NK-6 Symphony
(assembling, adjusting and maintaining the
prosthesis), all these matters cannot be described in
this document or on the warning labels on the body
of NK-6 Symphony.
Therefore, when handling NK-6 Symphony, it is
necessary not only to observe the precautions
stated in this document, but also to take safety
measures necessary for prosthesis knee joint.
Particularly important matters concerning the safe
handling of NK-6 Symphony are described below.
These matters apply to the persons who assemble
and adjust NK-6 Symphony.
If you have a serious incident related to NK-6
Symphony, please report it to the manufacturer
(contact information on the back cover) and the
competent authority in your country.
■Read this document thoroughly
Before handling NK-6 Symphony, thoroughly read
this document, and sufficiently understand the
contents. Strictly observe the safety precautions
stated in the document.
WARNING

P.2
About This Document
■Target of this document
This document is intended for the prosthetists
to fit the product for prosthetic users.
It covers the following references: NK-6, NK-
6SH, NK-6+L and KN-6SH+L.
■Copy right
Nabtesco owns the copyright for this
document. It is not permitted to duplicate any
part of drawings and technical documents
including this document by any means
(copying or recording on electronic media)
without our prior authorization.
When you have questions about the copyright
of this document for copy or reference, contact
Nabtesco.
■When this document is lost or damaged
If this document or any related document is lost
or damaged, immediately ask the Local sales
representative or Distributor (hereinafter,
referred to as the Distributor) to reissue it.
Handling NK-6 Symphony without this
document can cause accidents.
■Information
The information on this manual is subject to
change without prior notice for product
improvement.

P.3
Contents
1. Safety Precautions........................................................ P.4
1-1 Contraindications .................................................... P.4
1-2 Definition of Symbols .............................................. P.4
1-3 Mandatory Precautions............................................ P.5
1-4 Compatible medical devices (prosthesis components)
............................................................................... P.5
2. Basic Construction and Operational Principle................ P.9
2-1 Basic Construction .................................................. P.9
2-2 Operational Principle ............................................... P.9
2-3 Stance Phase Control............................................ P.10
2-4 Swing Phase Control............................................. P.11
3. Before Use.................................................................. P.12
3-1 Scope of Delivery .................................................. P.12
3-2 Assembly Procedure ............................................. P.12
3-2-1 Static alignment .............................................. P.12
3-2-2 Contact of socket at the maximum
flexion angle.................................................... P.13
4. Adjustment.................................................................. P.14
4-1 Adjusting the Stance Phase Control ...................... P.14
4-1-1 Adjusting the stance-flexion rubber ................. P.14
4-1-2 Adjusting the extension assist spring .............. P.15
4-2 Adjusting the Swing Phase Control........................ P.16
4-2-1 Adjusting the flexion resistance
of hydraulic cylinder ........................................ P.16
4-2-2 Adjusting the extension resistance
of hydraulic cylinder ........................................ P.16
5. Operation Procedures and Precautions....................... P.18
5-1 How to Activate the “Stance-Flexion” Function ...... P.18
5-2 Procedures for Operating the Selective Lock......... P.19
5-3 Precautions for Operating the Selective Lock ........ P.20
5-4 Precautions When Sitting in and Standing up
from a Chair .......................................................... P.21
6. Troubleshooting .......................................................... P.22
7. Maintenance ............................................................... P.23
7-1 Replacing the Extension Stopper Rubber .............. P.23
7-2 Replacing the Stance-Flexion Rubber ................... P.24
7-3 Removing the Base Bracket Cover........................ P.25
7-4 Wiping Off Dirt on the Surface ............................... P.25
8. Outline of the Product ................................................. P.26
9. Disposal...................................................................... P.27
10. Symbols Used on Labels........................................... P.28
10-1 UDI Label (Packing Box) ..................................... P.28
10-2 Body Mass Limit Label (Knee Joint Body)............ P.28
10-3 Product Type Label (Knee Joint Body) ................ P.28

P.4
1. Safety Precautions
1-1 Contraindications
Person who cannot understand how to use
the knee and caution for use
Person who has problem and pain on the
residual limb
Person who weighs over 125kg (if high-active
user: over 100kg)
Use for any sports which give high impact on
the knee
1-2 Definition of Symbols
WARNING
Indicates a potentially
hazardous situation which,
if not avoided, could result
in death or serious injury.
CAUTION
Indicates a potentially
hazardous situation which,
if not avoided, may result in
minor or moderate injury or
property damage.
Indicates a general caution
to be observed.
PROHIBITION
Indicates prohibition of a
specific action.
MANDATORY
ACTION
Indicates obligation of a
specific action.

P.5
1-3 Mandatory Precautions
WARNING
Hand the separate
User’s Guide to the user
and explain the
instructions for use.
Improper use can cause a fall or
injury.
Upon
detecting
any
abnormal noise, play, or
drop in hydraulic
resistance, discontinue
use and contact your
local sales
representative/dealer.
Continued use despite a detected
abnormality may cause damage
of parts, leading to a fall.
This product shall be
used as a prosthetic
knee joint. Never use it
for
other
purposes.
We do not warrant the product
against damage caused by use
for any unintended purpose.
MAN ATORY
ACTION
MAN ATORY
ACTION
MAN ATORY
ACTION

P.6
DO NOT use for a
person who weighs over
125 kg.
PROHIBITION
NK-6 Symphony was tested for 3
million walking cycles with load of
125kg which corresponds to the
average working distance within
about 3 years. We will not assume
liability for ageing or damage of the
product. If used to a person who
weighs over 125 kg, damage
of parts
may occur, leading to a fail. This,
however, does not preclude loading
and unloading of baggage, etc.
occurring in daily life.
ISO 10328
-
P6
-
125kg *
)
*)Body mass limit not be exceeded!
For specific conditions and limitations of use see
manufacture’s written instructions on intended use!
Specific condition: For persons on a
high activity level and persons wearing
a hip prosthesis, the weight limit shall
be 100 kg.
PROHIBITION
DO NOT place the hand
behind the knee when
flexing the knee.
DO NOT touch the knee
when extending it.
Your hand can be caught, thereby
causing injury.
Never attempt to
disassemble or
modify the knee joint.
PROHIBITION
Parts may be damaged, thereby
causing a fall.
Never attempt to
heat or put in a fire
PROHIBITION
Risk of fire or explosion.

P.7
DO NOT contact liquids
such as water, salt water,
chlorinated water, soapy
water, gel soap, body fluids
an exudates.
DO NOT use any detergent
or solvent (thinner) for
cleaning it.
Make adjustments in
accordance with the
adjustment procedures
stated in the Instruction
Manual.
Improper adjustments may result
in poor performance.
CAUTION
DO NOT drop parts such
as a screw in the frame.
Continued use after any part is
dropped may cause damage of a
pneumatic cylinder, impending
normal walking.
Could result in rusting,
discoloration, desiccation of the
grease, could result in a
malfunction and abnormal noises.
When making a socket,
ensure that the socket
or the buttock is in
contact with the foot
part at the maximum
flexion angle.
If the socket or the buttock is not
in contact with the foot part,
excessive load may be applied to
the knee joint, thereby causing
damage of parts.
PROHIBITION
PROHIBITION
MAN ATORY
ACTION
MAN ATORY
ACTION

P.8
1-4 Compatible medical devices
(prosthesis components)
Symphony
reference
NK-6
NK
-
6+L
NK-6SH
KN
-
6SH+L
Proximal
connectors
Female
pyramidal
connectors
M36 screw
connectors
Distal
connectors
Female
pyramidal
connectors
Female
pyramidal
connectors
Do not store the product
where the temperature
may exceed the range of
-20 to 50°C.
Parts may be deteriorated or
deformed, thereby causing
failure.
PROHIBITION

P.9
Hydraulic cylinder
Selective lock
(optional)
Stance-flexion rubber
6-bar linkage
(p-MRS system)
Stance-flexion stiffness
adjusting screw
Extension assist
spring adjusting
screw
Fig. 1 Main Components
Fig. 2 Walking on a Level Floor
2. Basic Construction and Operational Principle
2-1 Basic Construction
The NK-6 Symphony consists of a 6-bar
linkage which controls the stance phase and
a hydraulic cylinder which controls the swing
phase. The selective lock with which the
user can lock the knee by himself/herself
can be chosen at the user’s option. (Model:
NK-6+L, NK-6SH+L)
2-2 Operational Principle
The geometric self-locking system reliably
functions while the prosthesis is in contact
with the floor, thus preventing abrupt
buckling. When the prosthesis leaves the
floor, the hydraulic cylinder functions,
providing cadence responsive swing control.
Stance
-
Flexion
Hydraulic
cylinder

P.10
Fig. 3 p-MRS System
Fig. 4 Stance-Flexion
2-3 Stance Phase Control
●p-MRS system (Polycentric-Mechanism of
Stance-Flexion Stiffness Sensing)
The 6-bar linkage detects the floor reaction
force position and controls the stance
phase. The center of rotation of this linkage
system, the sensing point is located around
the toe break. If the floor reaction force is
applied on the heel side from the sensing
point, the knee joint geometrically locks the
knee flexion, and if it is applied on the toe
side from the sensing point, the lock is
released. Since the stance phase is
controlled according to the position of the
floor reaction force, the stance phase
control works reliably at a low heel
contact load and is released smoothly at
the push-off stage. This leads to the user’s
relief and smooth shifting to the swing
phase.
●Stance-Flexion
The knee joint provides a stance flexion
during from the heel-contact to the mid-
stance. This feature results in absorbing
shocks at the heel-strike and reducing
bobbing of center-of-mass.
The amount of the stance flexion can be
easily adjusted to maximum 10°.

P.11
2-4 Swing Phase Control
A hydraulic cylinder is used for swing
phase control. The swing phase is
controlled based on the hydraulic
resistance generated when the knee is
flexed and extended. The resistance at the
initial swing phase is kept at a low level so
that the user can initiate the swing phase
easily, and the resistance is increased
when the flexion angle is 40° or more. This
provides the user a comfortable walking
and less fatigue as if wearing a pneumatic
knee joint, and also powerfully response to
various walking speeds.
High
pressure
in flexion
High
pressure
in extension
Fig. 5 Swing Phase
Fig. 6 Hydraulic Resistance
Knee
Angle
NK-6
Conventional Hydraulic Swing
Flexion
Extension
Hydraulic
Resistance
40 deg

P.12
3. Before Use
3-1 Scope of Delivery
Please confirm that the following items are
included.
・NK-6 Symphony ...................................... 1
・User’s Guide............................................ 1
(After explaining the instructions for use,
hand it to the user.)
・Instruction Manual (this document)......... 1
3-2 Assembly Procedure
3-2-1 Static alignment
Perform static alignment according to the
following procedure.
●Alignment of frontal plane
Complete alignment so that the load line
passes through the center of the knee
joint and falls in the heel center of the
foot section.
●Alignment of sagittal plane
As shown in Fig. 7, complete alignment
so that the weight load line passes
through the center of the knee axis of the
knee joint within a deviation of ±5 mm
(0 mm recommended).
Improper alignment may result in poor
self-lock performance. Excess load
applied to the parts may accelerate wear.
For users who wear hip prostheses and
play any sports such as golf, use of a
torsion adapter is recommended. If the
adapter is not used, large torsion force
will be applied to the prosthesis, and
wear of parts may be accelerated.
±5 mm
(0 mm
recommended)
Center of the
frontal upper axis
Fig. 7 Statistic Alignment
CAUTION

P.13
3-2-2 Contact of socket at the maximum
flexion angle
Make the socket in such a way that the
socket or the buttock is in contact with the
foot part when the knee joint is flexed at
the maximum flexion angle.
If the socket or the buttock is not in
contact with the foot part, excessive load
may be applied to the knee joint, thereby
causing damage of parts.
While making a prosthesis, do not touch
the knee joint when the knee is flexed
and extended. Your hand can be caught,
thereby causing injury.
The socket must not
be in contact with the
knee joint.
The socket must
be in contact with
the foot part and
the pipe adapter.
Fig. 8 Contact of socket at the maximum flexion angle
CAUTION

P.14
4. Adjustment
4-1 Adjusting the Stance Phase Control
4-1-1 Adjusting the stance-flexion rubber
For adjustment of the stance phase
control, adjust the stiffness of the
stance-flexion rubber.
▪Adjust the adjusting screw shown in Fig.
9 with a 3 mm hexagonal wrench.
▪Turning the screw clockwise increases
the stiffness and decreases the degree of
bouncing. Turning it counterclockwise
decreases the stiffness and increases the
degree of bouncing.
CAUTION
If the stiffness of the stance-flexion
rubber is too high, the self-lock may not
work properly. Adjust the stiffness
appropriately to the body weight and/or
the impact at the heel strike.
CAUTION
Do not loosen the adjusting screw until
its head is lower than the bottom of the
pyramid (sealing surface). Doing so may
drop the screw.
* When the head of the adjusting screw
is set on the same level as the pyramid
bottom, the stiffness of the stance-flexion
rubber is lowest.
Stance-flexion rubber
Increase stiffness
Adjusting screw
Decrease stiffness
Fig. 9 How to Adjust Stance-Flexion Stiffness
IMPORTANT
The adjusting screw has been set to a
position which is common to most people
in the factory default setting. When you
are unable to find a suitable position, turn
the screw to reset the position to the
standard setting shown below.
Standard setting: A position obtained by
turning the screw fully clockwise to
tighten and loosening it 3.5 turns.

P.15
4-1-2 Adjusting the extension assist
spring
The extension assist spring keeps the knee
joint in the full extension when the
prosthesis is lifted from the floor.
▪Adjust the adjusting bolt shown in Fig. 10
with a 2.5 mm hexagonal wrench.
▪To increase the extension assist force,
turn the bolt clockwise. To reduce the
force, turn it counterclockwise.
CAUTION
If the extension assist force is too low for
the prosthesis, there is a possibility of
landing with the knee flexed, and the
user may fall down due to knee buckling.
Adjust the spring so that the foot can
contact to the ground with the knee fully
extended.
The adjusting screw has stoppers between
the maximum and minimum positions. It
can be adjusted in the range of about four
turns.
CAUTION
If the adjusting bolt is turned to an
excessively high torque, it may be
damaged.
Extension assist spring
Adjusting bolt
Decrease stiffness
Increase stiffness
Fig. 10 How to Adjust the Extension Assist Spring
IMPORTANT
The adjusting screw has been set to a
position which is common to most people
in the factory default setting. When you
are unable to find a suitable position, turn
the screw to reset the position to the
standard setting shown below.
Standard setting: A position obtained by
3 turning counterclockwise from fully
tightened position.

P.16
4-2 Adjusting the Swing Phase Control
To adjust the swing phase control, select
appropriate flexion and extension
resistances using the two adjusting valves
of the hydraulic cylinder.
4-2-1 Adjusting the flexion resistance
of hydraulic cylinder
At first, adjust the flexion resistance.
As shown in Fig. 11, the flexion adjusting
valve (F) is located on the right when
viewed from the user. As shown in Fig. 12,
the scale is graduated from “1” to “8”.
“1” corresponds to the highest hydraulic
resistance, and “8” corresponds to the
lowest.
(Reference) Factory default: “8”
To adjust the valve, use a 2 mm hexagonal
wrench. Insert the wrench from the lowest
hole in the front link side face.
CAUTION
This hydraulic cylinder is intended for
swing phase control. Do not use it for any
other
purpose. If the prosthesis is used
under overload, for example, by applying
the body weight at a high flexion
resistance, it may be damaged.
4-2-2 Adjusting the extension
resistance of hydraulic cylinder
If terminal impact occurs at the end of the
swing phase, adjust the extension
resistance. As shown in Fig. 13, the
extension adjusting valve (E) is located on
the left when viewed from the user. As
shown in Fig. 14, the scale is graduated
from “1” to “8”. “1” corresponds to the
highest hydraulic resistance, and “8”
corresponds to the lowest.
(Reference) Factory default: “8”
To adjust the valve, use a 2 mm hexagonal
wrench. Insert the wrench from the center
hole in the front link side face.
CAUTION
If the extension resistance is set too
high, the knee
does not extend fully,
thereby causing falling.

P.17
Front link
Hydraulic cylinder
Flexion adjusting
valve (F)
Fig. 11 Location of the Flexion Adjusting Valve
Reference mark
Max. resistance Min. resistance
F
Nabt ESCO
Fig. 12 Graduated Scale of the Flexion Adjusting Valve
Extension adjusting valve (E)
Fig. 13 Location of the Extension Adjusting Valve
Reference mark
Max. resistance Min. resistance
HC10x14RC E
NO.
Fig. 14 Graduated Scale of the Extension Adjusting Valve

P.18
5. Operation Procedures and Precautions
5-1 How to Activate the
“Stance-Flexion” Function
Fig. 15 shows how to apply the body weight
to the prosthesis. When the weight is
placed on the heel as shown in the left
figure while the knee is fully extended, the
knee is automatically locked (self-locked)
and slightly flexed (stance-flexion). The
maximum flexion angle is 10° depending on
the load and the setting of the adjustment.
If the weight is placed on the toe as shown
in the right figure, the lock is released.
~10°
Fig. 15 Differences in the Self-Lock function depending
on floor reaction force
CAUTION
Until the user gets used the knee joint,
confirm that he/she understands the
self-locking function while holding on the
parallel bars and placing weight on the
prosthesis. He/She should be thoroughly
familiarized with the function prior to use.
CAUTION
In a standing posture, put the prosthesis
slightly forward, and weight on the heel
side while fully extending the knee. If the
weight is placed when the knee is not
fully extended or the toe side is in contact
with the floor, knee buckling may occur,
and the user may fall down. Particularly
users who have a habit of standing with
their prostheses slightly backward shall
keep this in mind.
Instruct the user to put the prosthesis
slightly forward in a standing posture and
place weight on the heel side while fully
extending the knee. If the weight is
placed when the knee is not fully
extended or the toe side is in contact with
the floor, knee buckling may occur, and
the user may fall down. Give a sufficient
explanation particularly to users who
have a habit of standing with their
prostheses slightly backward.