Joint Assembly NEURO FLEX MAX

Joint Assembly

NEURO FLEX MAX system knee joint

This online tutorial describes the joint assembly for locked system knee joints using the example of the NEURO FLEX MAX in its basic function. The basic function includes a lock lever and a locating pin that are used to activate the permanent unlock function. Due to the constructional differences, the NEURO FLEX MAX system knee joint is assembled a little differently than the NEURO LOCK and the NEURO LOCK MAX.

For example, the NEURO LOCK has, in contrast to the NEURO LOCK MAX and the NEURO FLEX MAX, no permanent unlock function. Furthermore, a flexion stop disc is already integrated into the joint's lower part of the NEURO LOCK MAX system knee joint, whereas, in the case of the NEURO FLEX MAX, it still needs to be mounted.

Consult the manual (chapter 11 “Assembly Instructions”) of the corresponding system joint to learn about the differences regarding

  • mounting the extension stop,
  • mounting the spring unit and the locking pawl,
  • mounting the cover plate and
  • checking the lock function.

Besides, this online tutorial shows in detail the four alternative functions of the NEURO FLEX MAX system knee joint.

Note: You will find information regarding torque (Nm) and locking pawls for all system widths in the manual of the corresponding system joint.

 Basic Function

Step 1/23

Clean the system joint. In order to clean the threads in the cover plate, use the Super Clean LOCTITE® 7063 to remove any insulating wax residues.
Note: Mind the safety data sheet when using the Super Clean LOCTITE® 7063.

Step 2/23

If you are using a supporting joint, shorten the extension stop damper with a sharp knife. Now, the system joints reach the extension stop at the same time and the locking pawl should lock without difficulty.

Step 3/23

Apply spray adhesive to one side of the first sliding washer and adhere it to the cover plate. Grease the other side of the sliding washer slightly with the delivered orthosis joint grease.

Step 4/23

Place the flexion stop disc on the joint's lower part and press both by using a vice.
Note: Use a vice with plain or soft jaws in order not to affect the joint function.

Step 5/23

Mount the extension stop to the joint's upper part.

Step 6/23

If you have to demount the extension stop, screw it out of the joint's upper part by using the pan head screw delivered with the system joint. If it is mounted correctly, you do not have to demount the extension stop.

Step 7/23

Insert the pressure spring by pushing it from below into the spring duct of the joint's upper part.

Step 8/23

Grease the axle bore of the locking pawl and the friction surfaces of the bearing nut with the delivered orthosis joint grease.

Step 9/23

Put the bearing nut into the intended opening of the joint's upper part and make sure that it is in the correct position. Fix the bearing nut with one finger. Mount the locking pawl.

Step 10/23

Place the ball and push the locking pawl to the top. Insert the pressure spring and the locating pin for adjusting the permanent unlock function in the locking pawl.

Step 11/23

Push the locating pin against the spring force into the system joint until it locks in the joint's upper part. The locking pawl is now secured, which facilitates the following assembly of the system joint.

Step 12/23

Grease the axle bore of the joint axis and the friction surfaces of the bearing nut with the delivered orthosis joint grease.

Step 13/23

Put the joint axis’ bearing nut into the intended opening of the joint's upper part and make sure that it is in the correct position. Fix the bearing nut with one finger.

Step 14/23

Grease the second sliding washer slightly with the delivered orthosis joint grease.

Step 15/23

While still fixing the bearing nut, place the second sliding washer onto the joint's upper part and mount the joint's lower part.

Step 16/23

Mount the cover plate. Turn in the first countersunk flat head screw (axle screw). Continue with the second countersunk flat head screw while still fixing the bearing nut.

Step 17/23

If the sliding washer has been damaged during the assembly of the cover plate (audible cracking), remove the particles and place a new sliding washer.

Step 18/23

Check if the bearing nuts are placed completely in the intended openings.
Note: The delivered screws are always matching the system joint. Even if the screws are not as long as the thread of the bearing nuts, that does not affect the system joint’s load capacity.

Step 19/23

Check if the system joint moves freely. Bring the system joint in extension. In order to check the flexion, hold the orthosis in a horizontal position and then let go of the femoral shell. The femoral shell should smoothly fall downward until it has reached the maximum possible flexion grade. If the system joint does not move freely, mount the next thinner sliding washers, repeat all steps from step 12 onwards and check again.
Note: With a bilateral orthosis, only check one system joint at a time.

Step 20/23

Check if the system joint moves without lateral play. Hold the tibial shell and try to move the femoral shell in varus-valgus direction. If the system joint runs with lateral play, mount the next thicker sliding washers, repeat all steps from step 12 onwards and check again.
Note: At a bilateral orthosis, only check one system joint at a time.

Step 21/23

Bring the system joint as far as possible in extension. Then, disable the permanent unlock function by pressing the locking pawl against the joint's upper part. Check if the locking pawl is locked. Fix the tibial shell and try to move the femoral shell against it. There should be no movement in the system joint.
Note: Mind the information on the locking pawls in the manual.

Step 22/23

Check the position of the locking pawl. You can see the correct position on the left picture. If the locking pawl does not fit well, exchange it.

Step 23/23

Secure both screws with LOCTITE® 243 medium strength and the torque corresponding to the system width. Let the adhesive harden (final strength after approx. 24 hours).
Note: Mind the safety data sheet  when using LOCTITE® 243 medium strength.

 Alternative Function 1

Step 1/28

The locked system joint can be used for locking in different flexed positions (alternative function 1) by exchanging the locking parts. To do so, exchange the extension stop according to the intended extension position by choosing a degree.
Note: You will find the article numbers of the extension stops in our product catalogue System Joints and Articulated System Side Bars.

Step 2/28

Secure the locking pawl (permanent unlock function). Disassemble the system joint.

Step 3/28

Demount the flexion stop disc. To do so, clamp the flexion stop disc in a vice and carefully lever it of the joint's upper part.
Note: Use a vice with plain or soft jaws in order not to affect the joint function.

Step 4/28

Demount the extension stop. To do so, screw it out of the joint's upper part by using the pan head screw delivered with the system joint.

Step 5/28

Demount all further system components. Clean the system joint. In order to clean the threads in the cover plate, use the Super Clean LOCTITE® 7063 to remove any insulating wax residues. Check all system components and exchange them if there are signs of wear.
Note: Follow the maintenance instructions in the manual of the system joint.
Note: Mind the safety data sheet when using the Super Clean
LOCTITE® 7063.

Step 6/28

The flexion stop disc is marked with lines that serve as a guide when filing the desired flexion and thus enable an accurate locking of the pawl at the lock area (R1). The marked lines are not straight but slightly bent! Do not use a flat file and ensure a smooth transition from lock area to lock disc (R2).
Note: Mount the system joint in order to check the proper locking function and to be able to readjust the flexion degree, if required.

Step 7/28

File the flexion stop disc according to the flexion grade corresponding to the extension stop. The line should remain visible! Make sure that the stop face remains even and is not inclined to the sides.

Step 8/28

Place the flexion stop disc on the joint's lower part and press both by using a vice.
Note: Use a vice with plain or soft jaws in order not to affect the joint function.

Step 9/28

Apply spray adhesive to one side of the first sliding washer and adhere it to the cover plate. Grease the other side of the sliding washer slightly with the delivered orthosis joint grease.

Step 10/28

Mount the extension stop to the joint's upper part.

Step 11/28

Insert the pressure spring by pushing it from below into the spring duct of the joint's upper part.

Step 12/28

If you exchange the delivered locking pawl with another, choose the smallest possible locking pawl that still fits. As locking pawls are wear parts and wear out, you can then mount the next bigger locking pawl, if necessary.
Note: Mind the information on the locking pawls in the manual.

Step 13/28

Grease the axle bore of the locking pawl and the friction surfaces of the bearing nut with the delivered orthosis joint grease.

Step 14/28

Put the bearing nut into the intended opening of the joint's upper part and make sure that it is in the correct position. Fix the bearing nut with one finger. Mount the locking pawl.

Step 15/28

Place the ball and push the locking pawl to the top. Insert the pressure spring and the locating pin for adjusting the permanent unlock function in the locking pawl.

Step 16/28

Push the locating pin against the spring force into the system joint until it snaps in the joint's upper part. The locking pawl is now secured, which facilitates the further assembly of the system joint.

Step 17/28

Grease the axle bore of the joint axis and the friction surfaces of the bearing nut with the delivered orthosis joint grease.

Step 18/28

Put the joint axis’ bearing nut into the intended opening of the joint's upper part and make sure that it is in the correct position. Fix the bearing nut with one finger.

Step 19/28

Grease the second sliding washer slightly with the delivered orthosis joint grease.

Step 20/28

While still fixing the bearing nut, place the second sliding washer onto the joint's upper part and mount the joint's lower part.

Step 21/28

Mount the cover plate. Turn in the first countersunk flat head screw (axle screw). Continue with the second countersunk flat head screw while still fixing the bearing nut.

Step 22/28

If the sliding washer has been damaged during the assembly of the cover plate (audible cracking), remove the particles and place a new sliding washer.

Step 23/28

Check if the bearing nuts are placed completely in the intended openings.
Note: The delivered screws are always matching the system joint. Even if the screws are not as long as the thread of the bearing nuts, that does not affect the joint’s load capacity.

Step 24/28

Check if the system joint moves freely. Bring the system joint in extension. In order to check the flexion, hold the orthosis in a horizontal position and then let go of the femoral shell. The femoral shell should smoothly fall downward up to the maximum possible flexion grade. If the system joint does not move freely, mount the next thinner sliding washers, repeat all steps from step 18 onwards and check again.
Note: With a bilateral orthosis, only check one system joint at a time.

Step 25/28

Check if the system joint moves without lateral play. Hold the tibial shell and try to move the femoral shell in varus-valgus direction. If the system joint runs with lateral play, you need to mount the next thicker sliding washers and repeat all steps starting at step 18. Check again.
Note: At a bilateral orthosis, only check one system joint at a time.

Step 26/28

Bring the system joint as far as possible in extension. Then, disable the permanent unlock function by pressing the locking pawl against the joint's upper part. Check if the locking pawl is locked. Fix the tibial shell and try to move the femoral shell against it. There should be no movement in the system joint.
Note: Mind the information on the locking pawls in the manual.

Step 27/28

Check the position of the locking pawl. You can see the correct position on the left picture. If the locking pawl does not fit well, exchange it.

Step 28/28

Secure both screws with LOCTITE® 243 medium strength and the torque corresponding to the system width. Let the adhesive harden (final strength after approx. 24 hours).
Note: Mind the safety data sheet when using LOCTITE® 243 medium strength.

 Alternative Function 2

Step 1/16

The locked system joint can be used as a free moving, monocentric joint with integrated posterior offset (alternative function 2) by removing the locking parts. Note the next work steps for the removal of the locking parts.
Note: You will find further information on alternative function 2 in the manual

Step 2/16

Secure the locking pawl (permanent unlock function). Disassemble the system joint.

Step 3/16

If you have to demount the extension stop, screw it out of the joint's upper part by using the pan head screw delivered with the system joint. If the extension stop is mounted correctly, you do not have to demount it.

Step 4/16

Demount all system components. Clean the system joint. In order to clean the threads in the cover plate, use the Super Clean LOCTITE® 7063 to remove any insulating wax residues. Check all system components and exchange them if there are signs of wear.
Note: Follow the maintenance instructions in the manual of the system joint.
Note: Mind the safety data sheet  when using the Super Clean
LOCTITE® 7063.

Step 5/16

If you have demounted the extension stop before, place it correctly on the joint's upper part now.

Step 6/16

Apply spray adhesive to one side of the first sliding washer and adhere it to the cover plate. Grease the other side of the sliding washer slightly with the delivered orthosis joint grease.

Step 7/16

Grease the friction surfaces of both bearing nuts with the delivered orthosis joint grease.

Step 8/16

Put the bearing nuts into the intended openings of the joint's upper part and make sure that they are in the correct position. Fix the bearing nut of the locking pawl with one finger. The locking pawl is not mounted again.

Step 9/16

Grease the second sliding washer slightly with the delivered orthosis joint grease.

Step 10/16

While still fixing the bearing nut, place the second sliding washer onto the joint's upper part and mount the joint's lower part.

Step 11/16

Mount the cover plate. Turn in the first countersunk flat head screw (axle screw). Continue with the second countersunk flat head screw while still fixing the bearing nut.

Step 12/16

If the sliding washer has been damaged during the assembly of the cover plate (audible cracking), remove the particles and place a new sliding washer.

Step 13/16

Check if the bearing nuts are placed completely in the intended openings.
Note: The delivered screws are always matching the system joint. Even if the screws are not as long as the thread of the bearing nuts, that does not affect the system joint’s load capacity.

Step 14/16

Check if the system joint moves freely. Bring the system joint in extension. In order to check the flexion, hold the orthosis in a horizontal position and then let go of the femoral shell. The femoral shell should smoothly fall downward until it reaches the maximum possible flexion grade. If the system joint does not move freely, mount the next thinner sliding washers, repeat all steps from step 8 onwards and check again.
Note: With a bilateral orthosis, only check one system joint at a time.

Step 15/16

Check if the system joint moves without lateral play. Hold the tibial shell and try to move the femoral shell in varus-valgus direction. If the system joint runs with lateral play, mount the next thicker sliding washers, repeat all steps from step 8 onwards and check again.
Note: With a bilateral orthosis, only check one system joint at a time.

Step 16/16

Secure both screws with LOCTITE® 243 medium strength and the torque corresponding to the system width. Let the adhesive harden (final strength after approx. 24 hours).
Note: Mind the safety data sheet when using LOCTITE® 243 medium strength.

 Alternative Function 3

Step 1/26

The locked system joint NEURO FLEX MAX can be used with a step lock function with locked flexion. For this purpose, you can use the NEURO FLEX MAX with premounted alternative function 3 or, in case you are already using the NFM with a different function and want to convert it, exchange the mounted flexion stop disc and the locking pawl with a step lock stop disc and a step lock pawl. This enables a gradual locking of the system joint from a flexed position of 55° or 60° via 10° steps to the required flexed position (premounted is it at 5°).
Note: You will find the article numbers of the step lock stop disc and the step lock pawl in our product catalogue System Joints and Articulated System Side Bars.

Step 2/26

Secure the locking pawl (permanent unlock function). Disassemble the system joint.

Step 3/26

If you want to use the NFM with a different flexed position than the premounted 5°, exchange the mounted extension stop with a 10°, 20° or 30° extension stop and choose a corresponding step lock stop disc AF3 with 0°, 10°, 20° or 30°. The system joint locks the first time in a flexed position of 60° and after that in 10° steps. You do not need an extension stop for a 0° knee flexion angle.

Step 4/26

If you have to demount the flexion stop disc, clamp the flexion stop disc in a vice and carefully lever it of the joint's upper part.
Note: Use a vice with plain or soft jaws in order not to affect the joint function.

Step 5/26

Then, place the step lock stop disc AF3 on the joint's lower part and press both by using a vice.
Note: Use a vice with plain or soft jaws in order not to affect the joint function.

Step 6/26

If you have to demount the extension stop, screw it out of the joint's upper part by using the pan head screw delivered with the system joint. If it is mounted correctly, you do not have to demount the extension stop.

Step 7/26

Demount all system components. Clean the system joint. In order to clean the threads in the cover plate, use the Super Clean LOCTITE® 7063 to remove any insulating wax residues. Check all system components and exchange them if there are signs of wear.
Note: Follow the maintenance instructions in the manual of the system joint.
Note: Mind the safety data sheet when using the Super Clean
LOCTITE® 7063.

Step 8/26

If you have demounted the extension stop before, place it correctly on the joint's upper part now.

Step 9/26

Apply spray adhesive to one side of the first sliding washer and adhere it to the cover plate. Grease the other side of the sliding washer slightly with the delivered orthosis joint grease.

Step 10/26

Insert the pressure spring by pushing it from below into the spring duct of the joint's upper part.

Step 11/26

If you exchange the delivered locking pawl with a step lock pawl, choose the smallest possible fitting step lock pawl. As locking pawls are wear parts and wear out, you can then mount the next bigger locking pawl, if necessary.
Note: Mind the information on the locking pawls in the manual.

Step 12/26

Grease the axle bore of the locking pawl and the friction surfaces of the bearing nut with the delivered orthosis joint grease.

Step 13/26

Put the bearing nut into the intended opening of the joint's upper part and make sure that it is in the correct position. Fix the bearing nut with one finger. Mount the locking pawl.

Step 14/26

Place the ball and push the locking pawl to the top. Insert the pressure spring and the locating pin for adjusting the permanent unlock function in the locking pawl.

Step 15/26

Push the locating pin against the spring force into the system joint until it snaps in the joint's upper part. The step lock pawl is now secured, which facilitates the further assembly of the system joint.

Step 16/26

Grease the axle bore of the joint axis and the friction surfaces of the bearing nut with the delivered orthosis joint grease.

Step 17/26

Put the joint axis’ bearing nut into the intended opening of the joint's upper part and make sure that it is in the correct position. Fix the bearing nut with one finger.

Step 18/26

Grease the second sliding washer slightly with the delivered orthosis joint grease.

Step 19/26

While still fixing the bearing nut, place the second sliding washer onto the joint's upper part and mount the joint's lower part.

Step 20/26

Mount the cover plate. Turn in the first countersunk flat head screw (axle screw). Continue with the second countersunk flat head screw while still fixing the bearing nut.

Step 21/26

If the sliding washer has been damaged during the assembly of the cover plate (audible cracking), remove the particles and place a new sliding washer.

Step 22/26

Check if the bearing nuts are placed completely in the intended openings.
Note: The delivered screws are always matching the system joint. Even if the screws are not as long as the thread of the bearing nuts, that does not affect the joint’s load capacity.

Step 23/26

Check if the system joint moves freely. Bring the system joint in extension. In order to check the flexion, hold the orthosis in a horizontal position and then let go of the femoral shell. The femoral shell should smoothly fall downward until it reaches the maximum possible flexion grade. If the system joint does not move freely, mount the next thinner sliding washers, repeat all steps from step 14 onwards and check again.
Note: At a bilateral orthosis, only check one system joint at a time.

Step 24/26

Check if the system joint moves without lateral play. Fix the tibial shell and try to move the femoral shell in varus-valgus. If the system joint runs with lateral play, you need to mount the next thicker sliding washers and repeat all steps starting at step 14. Check again.
Note: At a bilateral orthosis, only check one system joint at a time.

Step 25/26

Bring the system joint as far as possible in extension. Then, disable the permanent unlock function by pressing the step lock pawl against the joint's upper part. Check if the step lock function works properly. The step lock pawl should lock with each toothing up to the maximum set extension limitation. Then, fix the tibial shell and try to move the femoral shell against it. There should be no movement in the system joint.
Note: Mind the information on the locking pawls in the manual.

Step 26/26

Secure both screws with LOCTITE® 243 medium strength and the torque corresponding to the system width. Let the adhesive harden (final strength after approx. 24 hours).
Note: Mind the safety data sheet when using LOCTITE® 243 medium strength.

 Alternative Function 4

Step 1/29

Alternative function 4 is an expansion of alternative function 1. At AF 1, the locked system joint can be used for locking in different flexed positions by exchanging the locking parts. To do so, exchange the extension stop according to the intended extension position by choosing a degree. When the system joint is unlocked at AF4, it can be used as a locked system joint with adjustable limitation of the maximum knee flexion grade by filing. To do so, exchange the flexion stop disc AF4 and cover plate AF4.
Note: You will find the article numbers of the flexion stop disc AF4 and cover plate AF4 in our product catalogue System Joints and Articulated System Side Bars.

Step 2/29

Secure the locking pawl (permanent unlock function). Disassemble the system joint.

Step 3/29

Demount the flexion stop disc. To do so, clamp the flexion stop disc in a vice and carefully lever it of the joint's upper part.
Note: Use a vice with plain or soft jaws in order not to affect the joint function.

Step 4/29

If you have to demount the extension stop, screw it out of the joint's upper part by using the pan head screw delivered with the system joint. If it is mounted correctly, you do not have to demount the extension stop.

Step 5/29

Demount all other system components. Clean the system joint. In order to clean the threads in the cover plate, use the Super Clean LOCTITE® 7063 to remove any insulating wax residues. Check all system components and exchange them if there are signs of wear.
Note: Follow the maintenance instructions in the manual of the system joint.
Note: Mind the safety data sheet when using the Super Clean
LOCTITE® 7063.

Step 6/29

The flexion stop disc is marked with lines that serve as a guide when filing the desired flexion and thus enable an accurate locking of the pawl at the lock area (R1). The marked lines are not straight but slightly bent! Do not use a flat file and ensure a smooth transition from lock area to lock disc (R2).
Note: Mount the system joint in order to check the proper locking function and to be able to readjust the flexion degree, if required.

Step 7/29

If applicable, file the flexion stop disc AF4 according to the flexion grade corresponding to the extension stop as well as the maximum possible flexion position when the system joint is unlocked. The lines should remain visible! Make sure that the stop faces remain even and are not inclined to the sides.

Step 8/29

Place the flexion stop disc AF4 on the joint's lower part and press both by using a vice.
Note: Use a vice with plain or soft jaws in order not to affect the joint function.

Step 9/29

If you demounted the extension stop before, place it correctly on the joint's upper part now.

Step 10/29

Apply spray adhesive to one side of the first sliding washer and adhere it to the cover plate. Grease the other side of the sliding washer slightly with the delivered orthosis joint grease.

Step 11/29

If you exchange the delivered locking pawl with another, choose the smallest possible locking pawl that still fits. As locking pawls are wear parts and wear out, you can then mount the next bigger locking pawl, if necessary.
Note: Mind the information on the locking pawls in the manual.

Step 12/29

Insert the pressure spring by pushing it from below into the spring duct of the joint's upper part.

Step 13/29

Grease the axle bore of the locking pawl and the friction surfaces of the bearing nut with the delivered orthosis joint grease.

Step 14/29

Put the bearing nut into the intended opening of the joint's upper part and make sure that it is in the correct position. Fix the bearing nut with one finger. Mount the locking pawl.

Step 15/29

Place the ball and push the locking pawl to the top. Insert the pressure spring and the locating pin for adjusting the permanent unlock function in the locking pawl.

Step 16/29

Push the locating pin against the spring force into the system joint until it snaps in the joint's upper part. The locking pawl is now secured, which facilitates the further assembly of the system joint.

Step 17/29

Grease the axle bore of the joint axis and the friction surfaces of the bearing nut with the delivered orthosis joint grease.

Step 18/29

Put the joint axis’ bearing nut into the intended opening of the joint's upper part and make sure that it is in the correct position. Fix the bearing nut with one finger.

Step 19/29

Grease the second sliding washer slightly with the delivered orthosis joint grease.

Step 20/29

While still fixing the bearing nut, place the second sliding washer onto the joint's upper part and mount the joint's lower part.

Step 21/29

Mount the cover plate AF4. Turn in the first countersunk flat head screw (axle screw). Continue with the second countersunk flat head screw while still fixing the bearing nut.

Step 22/29

If the sliding washer has been damaged during the assembly of the cover plate (audible cracking), remove the particles and place a new sliding washer.

Step 23/29

Check if the bearing nuts are placed completely in the intended openings.
Note: The delivered screws are always matching the system joint. Even if the screws are not as long as the thread of the bearing nuts, that does not affect the joint’s load capacity.

Step 24/29

Check if the system joint moves freely. Bring the system joint in extension. In order to check the flexion, hold the orthosis in a horizontal position and then let go of the femoral shell. The femoral shell should smoothly fall downward up to the maximum possible flexion grade. If the system joint does not move freely, mount the next thinner sliding washers, repeat all steps from step 18 onwards and check again.
Note: At a bilateral orthosis, only check one system joint at a time.

Step 25/29

Check if the system joint moves without lateral play. Fix the tibial shell and try to move the femoral shell in varus-valgus. If the system joint runs with lateral play, mount the next thicker sliding washers, repeat all steps from step 18 onwards and check again.
Note: At a bilateral orthosis, only check one system joint at a time.

Step 26/29

Bring the system joint as far as possible in extension. Then, disable the permanent unlock function by pressing the locking pawl against the joint's upper part. Check if the locking pawl is locked. Fix the tibial shell and try to move the femoral shell against it. There should be no movement in the system joint.
Note: Mind the information on the locking pawls in the manual.

Step 27/29

Check the position of the locking pawl. You can see the correct position on the left picture (here AF1). If the locking pawl does not fit well, exchange it.

Step 28/29

Check the maximum possible flexion grade.

Step 29/29

Secure both screws with LOCTITE® 243 medium strength and the torque corresponding to the system width. Let the adhesive harden (final strength after approx. 24 hours).
Note: Mind the safety data sheet when using LOCTITE® 243 medium strength.