Joint Assembly Locked System Knee Joints

You will find an overview of all component parts for the locked system knee joint in the instructions for use or in the product catalogue System Joints and Articulated System Side Bars.

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 (degree).
Note: You will find the article numbers of the extension stops in our product catalogue System Joints and Articulated System Side Bars.

Disassemble the system joint. By doing so, secure the locking pawl (permanent unlock function). 

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 and you do not want to use a different extension stop, you do not have to demount it.

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

If you want to exchange the extension stop in order to use a different flexion grade, the flexion stop disc must be filed as well. To do so, demount the flexion stop disc of the NEURO FLEX MAX by clamping it in a vice and carefully lever it of the joint’s lower part.
Note: Use a vice with plain or soft jaws in order not to affect the joint function.

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.

If you have demounted the flexion stop disc before, place the disc on the joint's lower part and press both by using a vice.

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 orthosis joint grease.

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

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

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

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.

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.

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

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. Secure the bearing nut with one finger.

Grease the second sliding washer slightly with orthosis joint grease.

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

Mount the cover plate. Screw in the first countersunk flat head screw (axle screw). Continue with the second countersunk flat head screw while still securing the bearing nut.
Note: You can find the appropriate torque (Nm) on the cover plate of the system joint or in the instructions for use. 

Make sure not to damage the sliding washer during the assembly. Jammed sliding washer particles can cause lateral play in the system joint.

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.

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 angle. If the joint does not move freely, mount the next thinner sliding washers, repeat all steps from step 10 onwards and check again.
Note: At a bilateral orthosis, only check one system joint at a time.

Check if the system joint moves without lateral play. Hold the tibial shell and try to move the femoral shell in varus-valgus. If the joint runs with lateral play, mount the next thicker sliding washers, repeat all steps from step 10 onwards and check again.

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.

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. Hold 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 instructions for use.

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.

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.

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.