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the patella. With the knee in full extension, a
bone hook is inserted at the distal pole of the
patella. While pulling proximally on the bone
hook, in the direction of the femoral shaft, the
tape is temporary tied in the drill holes on the
patella (fig. 5). The stability of the patella is
compared with that of the opposite knee and
the length changes in the tape are observed as
the knee is flexed and extended. If the femoral
fixation point is correct the patella will be
stable in full extension. The tape should be
maximally tight at full extension and become
progressively more lax with flexion. If this
tension pattern is not seen the position of the
guide pin on the femur needs to be adjusted.
Moving the guide pin more proximally will
decrease the tension in extension and increase
the tension in flexion (fig. 1). Conversely,
moving the guide pin more distally will increase
the tension in extension and decrease tension in
flexion (fig. 2). The ideal position is where the
tape is at its tightest in extension and becomes
lax with flexion while stability of the patella is
maintained. Care should be taken to ensure that
there is more tension in the patellar tendon than
in the reconstructed MPFL. This is best
Fig. 5 : Pull proximally with a bone
hook on the patella and the knee
in full extension. Tension in the
patellar tendon should be more
than in the reconstructed MPFL.
Fig. 4 : Dissecting with scissors
between the second and third
layer from the patella to the
epicondyle.
Fig. 3 : Skin incisions over the
gracilis, the medial patella and the
medial epicondyle.