Ottobock 3R20 Gebrauchsanweisung Seite 13

4 Handling
4.1 Alignment
The three-dimensional arrangement of the prosthetic socket and the modular components affects
the static and dynamic functions of the prosthesis. Function of the joint is influenced by the position
of the axes. In extension, the instantaneous centre of rotation is located above the pyramid adapter
and behind the alignment reference line, thus providing knee stability in the stance phase (Fig. 11).
The advantages of the 3R20 and 3R60 Knee Joints can only be made optimal use of in case of
a correct alignment.
The optimal residual limb position must be anticipated when positioning the socket connector.
Plumb lines in the frontal and sagittal planes (drawn from the hip joint's centre of rotation and
marked during plaster cast taking and trial fitting of the test socket) will facilitate correct positioning
of the lamination anchor or socket adapter.
To align the prosthesis please proceed in two steps:
1. First make the bench alignment using an alignment tool such as 743L200 L.A.S.A.R.
Assembly.
2. Then use 743L100 L.A.S.A.R. Posture for static alignment optimisation.
4.1.1 Bench Alignment with Alignment Tool (the following steps refer to Fig. 11)
Position the middle of the foot 30 mm anterior to the alignment reference line.
Add 5 mm to the required heel height of the foot. Set correct outward rotation of the foot.
Clamp the knee joint using the appropriate adapter inserts. For bench alignment, the alignment
reference line should run through the upper anterior axis (alignment reference point).
At that point the pyramid base should be horizontal. Pay attention to the knee-ground distance
and outward rotation of the knee (adapter inserts provide for a rotation of approx. 5°). Recom-
mended positioning of the alignment reference point: 20 mm above the medial tibial plateau.
Connect the foot to the modular knee joint using a tube adapter.
Mark the centre of the socket proximally and distally on the lateral side. Draw a line through
both marks from socket brim to the distal end of the socket.
Now position the socket such that the alignment reference line passes through the proximal
centre mark of the socket. Set the socket flexion to somewhere between 3° and 5°; however,
the individual situation (e.g. hip joint contractures) must be taken into account and, if necessary,
more flexion should be provided. Also pay attention to the ischial tuberosity to ground distance.
Connect the socket and modular knee joint using a corresponding adapter (e.g. 4R111, 4R41,
4R55, 4R51 Socket Adapter).
4.1.2 Static alignment optimisation using L.A.S.A.R. Posture 743L100
(the following steps refer to Fig. 12)
The bench alignment can be substantially improved using L.A.S.A.R. Posture. In order to ensure
appropriate stability combined with easy swing phase initiation, please proceed as follows:
To make the load line visible, the transfemoral amputee stands on the L.A.S.A.R. Posture with
the prosthetic side on the force plate and with the other leg on the height compensation panel.
The prosthesis side should be sufficiently loaded (> 35 % of the body weight).
Now adapt the alignment by only adjusting the plantar flexion of the foot. The load line (laser
line) should be approx. 35 mm anterior to the upper knee axis (see Fig. 12).
After step 2, dynamic optimisation can take place between parallel bars.
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