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F. WEIN
90
However, the length of the femoral tunnel was
significantly (
p
<0.05) longer in the Flexible
population (Rigid: 34mm [25-45]; Flexible:
41mm [35-50]), as was the anteversion (Rigid:
20° [5-25]; Flexible: 40° [35-45]).
Discussion/Conclusion
The use of the antero-medial portal and rigid
instrumentation to correctly position the
femoral tunnel may cause problems during
surgery (e.g. the need to flex the knee by more
than 110°). The results of this study show that
it is possible to avoid these problems during
surgery by using flexible instrumentation, as it
allows the femoral tunnel to be placed in an
ideal position with the knee flexed at 90°.
INTRODUCTION
The results of anterior cruciate ligament
reconstruction primarily depend on the anatomic
intra-articular positioning of the transplant. As
we now have a better understanding of the
anatomy of theACL, the ideal positioning of the
transplant is well established.
When drilling the femoral tunnel, the surgeon
must therefore endeavour to place the femoral
tunnel aperture as close as possible to the
insertion site of the native ACL. For this, two
aimer methods are available: an out-in method
and an in-out method. For in-out aimers, two
portals are possible: a transtibial portal, where
the femoral aimer is inserted into the tibial tunnel;
and an antero-medial portal, where the aimer is
inserted
via
an antero-medial instrument portal.
Several publications have reported a high rate
of incorrect positioning of the femoral tunnel in
the notch when using the transtibial portal,
which, in most cases, resulted in an excessively
medial and anterior positioning. However,
there is a risk with the antero-medial portal,
which is more tangential to the axis of the
femur, of causing common peroneal nerve
damage [1-3] when placing the guide pin, or of
perforating the posterior cortex when drilling
the tunnel [1, 2, 4] or of drilling a femoral
tunnel that is too short [1, 4], which may
compromise the fixation and osseointegration
of the transplant. To antevert the femoral tunnel
and therefore limit such risks, flexing the knee
beyond 110° [2, 5] is recommended when
placing the guide pin and drilling.
However, the following problems may be
encountered when flexing the knee beyond 110°
during the surgery [1, 4, 5]: difficulties
performing on obese patients, gradual closure of
the antero-medial portal when increasing the
flexion of the knee, problems visualising the
joint and femoral footprint, risk of ovalisation of
the femoral tunnel and internal condyle lesions.
The benefit of using flexible instrumentation
(flexible pin and flexible reamer) is precisely to
avoid such surgical problems, as it allows
satisfactory anteversion of the femoral tunnel
without hyperflexion of the knee [6-8]. In fact,
with this instrumentation, the orientation of the
femoral tunnel is guided by the direction of the
guide pin, which is flexible and inserted
via
an
aimer with an extremity angled at 42°;
consequently, with the knee flexed at 90°, the
guide pin and the femoral tunnel should be
anteverted at 42°.
Flexible instrument technology is supposed to
require less knee flexion than the antero-medial
portal to position the anatomic femoral tunnel
with greater length and with less potential for
injury compared with rigid instrumentation. The
goal of our study was to evaluate this ability.
We compared the anteversion and length of the
femoral tunnel drilled using two different
techniques; one technique used rigid instru
mentation with the knee flexed at 120° while
the other used flexible instrumentation with the
knee flexed at 90°.
PATIENTS AND METHODS
Patients: This was a prospective, comparative,
randomised and monocentric study involving
a continuous series of 80 single-bundle ACL
reconstructions, at the middle-third patellar
tendon, carried out by a single surgeon from
May 2012 to December 2013. Using the