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WHY DO I PREFER OUTSIDE-IN IN ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION?
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Femoral tunnel length
The tunnel length is another factor that has to be
considered. In case of a too anterior tunnel
placement, a tunnel length shorter than 30mm
could be drilled. It is reported that it predisposes
to tunnel enlargement, graft loosening, loss of
flexion and intercondylar roof impingement [2].
A short femoral tunnel socket is one of the
disadvantages of the IO procedure. In order to
reduce this problem, the knee should be over
flexed because the femoral tunnel length
increases at higher knee flexion angles. A short
femoral tunnel can reduce the amount of the
graft in the tunnel compromising the healing
process. Therefore, the OI technique would be
more advantageous in graft healing than the IO
technique mainly when a suspensory fixation
device is used [2].
Disadvantages
OI technique it is a more demanding procedure
[2, 8]. In a recent 3D CT scan study, Park
& al.
[14] observe a more acute femoral graft
bending angle in OI technique. It is supposed
that this can increase the stresses on the ACL
graft, damaging it and enlarging the tunnel. We
suggest to smooth the tunnel entry with the
shaver in order to reduce the femoral graft
bending. Comparing IO and OI, Otsubo
& al.
register an average difference in the femoral
graft bending angle of 6.6° [16].
The graft passage, especially using BPTB, and
the second incision are other disadvantages
described for OI technique. However, the risk
of lateral structure damage is limited.
Fig. 5:
OI technique is a safer procedure compared to IO. IO technique allows the anatomic ACL
reconstruction. However, drilling through AM portal could damage the remnant and the medial condyle.