2 Description and Function

2.1 Application

The monocentric Modular Knee Joints CHG-03S(stainless steel) and CHG-04T (titanium) with adjustable manual lock are to be exclusively used for the prosthetic fitting of amputations of the lower limb. The knee joints are recommended for transfemoral amputees with lower functional levels (high stance phase stability, minimal swing phase control) and with a body weight up to 100 kg/220 lbs (CHG-04S) or 125 kg/275 lbs (CHG-03T). Not recommended for patients with moderate and higher functional levels. Due to the small space requirements above the axis it is suitable for long above knee amputation levels. Further, the CHG-04S and CHG-04T Knee Joints can be interchanged with our CHG-04S, , CHG-05S and CHG-05T Knee Joints.

2.2 Construction

The Upper Joint Section (9) is connected to the Lower Joint Section (21) by the Axis (5).Mediolateral movement is prevented by Ball Thrust Bearings (15). The axis is a hardened, precision ground bolt and is mounted in special bushings. The Nut for Axis (17) is serrated and secured with a Lock Set Screw (16).

2.3 Extension Assist

The Extension Assist consists of two Spring Guide Pins (7), two Spring Guide Housings (2) and two Compression Springs (20). The primary function of this unit is to aid the knee in reaching full extension to help insure that the lock engages.

2.4 Lock Mechanism

When the knee is in full extension, the Compression Spring (27) forces the Lock Cam (25) into position against the distal segment of the Upper Joint Section (9). This blocks flexion of the knee. The adjustable Extension Stop (11) controls hyperextension of the knee. When the Lock Handle (8) is pulled upward, the Lock Lever (3) rotates the Lock Cam (25) downward, unlocking the knee and permitting it to flex. On reaching full extension once again, the Compression Spring (27) forces the Lock Cam (25) back into position locking the knee automatically. If the patient wishes to walk with a free knee, the Lock Handle (8) is designed so that it will hold the lock mechanism disengaged and override the automatic lock feature. In place of the Lock Handle (8) the Lock Control Unit may be used, which is adjustable left or right and for push or pull.

3 Alignment

When it is known that the patient will desire to walk with a free knee, we recommend aligning the CHG-04S and CHG-04T resp. as you would a normal single axis knee joint. The graph illustrates our alignment recommendations for the CHG-04S and CHG-04T Modular Knee Joints, when used with different ankle/foot components. The posteriorly located axis in addition provides relief for the lock mechanism during upright standing.

4 Adjusting the Extension Stop

The Extension Stop (11) can be adjusted with the Set Screw (14) to control the amount of hyperextension movement in the knee when the lock is engaged. Flex the Knee Joint until the Set Screw (14) becomes accessible.

Turning clockwise = reduces hyperextension movement Turning counter-clockwise = increases hyperextension movement Important:

Reducing the hyperextension movement makes it more difficult for the lock to engage.

5 Exchanging the Compressing Spring (20)

5.1 Removal

Press the Spring Guide Pin (7) downward using the flat blade of a screw driver, until it disengages from the Axis Pin (10).

5.2 Installation

Place the notch of the Spring Guide Pin (7) onto the Axis Pin (10). Push the head of the Spring Guide Housing (2) up and into the receptacle in the Lower Joint Section (21).

6 Compensating for Mediolateral Movement

If mediolateral side play develops, it may be reduced by tightening the Axis Nut (17). Remove the Lock Set Screw (16) and tighten the Axis Nut (17). Overtightening the nut may restrict normal movement of the Knee Joint. Be sure to install the Lock Set Screw (16) after the adjustment has been made. The Foam Cover is used with the CHG-03S/CHG-03T Knee Joints.

!!! Attention To eliminate noise in the cosmetic foam cover, use Silicone Spray. Do not use talcum powder! Talcum powder reduces the lubrication of the mechanical parts, which may lead to a malfunction and thus increase the risk of falling. Apply Silicone Spray directly on the friction surfaces of the cosmetic foam cover!

7 Technical Data

Structural Height (knee center to top of proximal adjustment core) 37 mm

Warranty applies only when product is used as intended, without modification, following all Manufacturer’s recommendations. My company will offer an extended product warranty of 2 years, if exclusively Modular Components have been installed according the requirement.