- Discussion:
- the two incision ("backdoor") approach has remained the gold standard for ACL reconstruction,
because it is the only technique which can reliably position the femoral tunnel at the
10 o'clock (or 2 o'clock) position (which is necessary for anatomic reconstruction);
- the one incision (transtibial) technique often cannot reliably reproduce this insertion;
- in the report by Arciero MD et al 1996, the two incision technique was comparted to the one incision technique.
- the functional results between the two groups was similar but there was a trend toward a residual
pivot glide in the endoscopic technique vs the two incision technique and there was more screw
divergence in the endoscopic group;
- Initial Arthroscopic Debridement and Notchplasty: (see
notchplasty)
Bone Patella Bone Harvest
- Lateral Incision:
***
- lateral condyle is exposed for the second incision.
- this is done thru a 3-4 cm longitudinal incision laterally beginning at the mid-patellar level (or
just proximal to the lateral condylar flare) and extending proximally;
- it is probably better to error w/ incision slightly posterior rather than anterior;
- incision is taken down thru skin & subQ tissues, exposing iliotibial band which is sharply incised.
- note that the posterior one third of the IT band attaches to the femoral epicondyle, and that this
attachment provides resistance to
varus stress;
- disruption of this attachment may lead to late lateral instability;
- retract the vastus lateralis anteriorly with a bent Homan retractor;
- the starting point for the two incision technique is just proximal to the femoral condyle and
just posterior to the midline;
- note that there are case reports of AVN of the medial femoral condyle when the PCL femoral tunnel
has been placed too close to the femoral condyles;
- the tunnel should not be placed so far posteriorly that the back wall will blow out during the
reaming, but should be placed as posteriorly as possible;
- Femoral Guide Placement:
- after an adequate
notchplasty has been performed, use an angled curret to create a starting
hole at the 10 o'clock (or 1 o'clock) position which is about 5 mm from the over the top position;
- the femoral tunneling guide is set at 105 deg, and the guide wire position in the jig should be checked
prior to drilling of the femur;
- this is then checked arthroscopically & placed over top position at 10 o'clock to 10:30 position;
- use a grabber to hold the femoral guide tip and later to block forward passage of the guide pin;
- guide pin is placed over which a 10 mm tunnel is then drilled using guide;
- careful not to shear off the guide pin;
- plug up the hole with a stopper;
-
chamfer the tunnel:
- a curet & a shaver may be used to facilitate passage of graft at the articular entrance,
and inaddition this chamfering helps prevent tendon graft fraying on the articular surface;
- this step cannot be overemphasized;
- care must be taken, however, not to enlarge the drill hole;
***
- Tibial Tunnel Placement:
- Graft Fixation:
- normal ACL has approximately 3 mm of excursion from 30 deg of flexion to 0 deg extension; (Garrett and Cavallo, unpublished data);
- in a typical ACL reconstruction there will be 2-3 mm of excursion from 30 to 0 deg of extension;
- hence graft should be fixed w/ the knee in 20-30 of flexion, so that the physiologic tension can be maintained;
Single vs two incision arthroscopic anterior cruciate ligament reconstruction.
LTC RA Arciero MD et al.
Vol 12. No 4. Aug. 1996. p 462.
Thanks to James Davidson MD.
