- Discussion:
-
graft entry point:
-
determination of graft length:
-
optimal graft angle:
- Technique:
- starting point has already been described;
- before drilling the tibia, check where the guide pin ends up on the tibial guide, and ensure that
all moving parts on the drill guide have been screwed down tightly;
- tibial tunnel guide is inserted and appropriate landmarks for graft placement are established;
- appropriately sized drill is then driven over the guide wire (dont shear the guide wire);
- leave the drill 1 cm protruding into the joint and slowly extend the knee;
- this will give an indication of whether residual notch impingement is present;
- if impingement is still present, then additional notchplasty can be performed and the tibial interference screw
can be placed anterior to the tibial bone plug (which moves the graft slightly posteriorly);
- 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;
- care must be taken, however, not to enlarge the drill hole;
- note: attempt to save all bone fragments obtained from reaming so the patellar (and tibial) graft harvest sites can be grafted;
- following drilling of the tibial tunnel, remove surrounding tissue which may complicate graft passage;
-
final notchplasty check:
- shut off the inflow cannula, and insert the scope thru the tibial tunnel;
- directly observe the femoral condyle and the notch as the knee is taken thru a full range of motion and ensure that there is no bony impingement;
- some authors will advance the reaming drill 1 cm into the notch inorder to determine whether there is residual impingement w/ flexion and extension;
- references:
-
Failure of reconstruction of the ACL due to impingment by the intercondylar roof. SM Howell JBJS 75-A. Jul 1993. p 1044-1055.
- Graft Fixation:
-
graft fixation:
-
tying over a post:
- tying over a post is often used as a salvage technique (when bone plug interference fixation has failed);
- main disadvantage is that this type of fixation is less stiff, since a longer graft length will undergo more strain;
- Post Operative Radiographs:
- on a hyper-extension lateral, the tibial tunnel should remain posterior to Blumenstat's line;
- often Blumenstat's line lies just anterior to a point that bisects the tibia;
- other authors strive to place the tunnel in the anterior half of the middle third of the tibial plateua;
- Complications:
- Tibial Tunnel Syndrome:
- tibial tunnel may enlarge following ACL reconstructive surgery;
- over a one year period the tibial tunnel may increase in diameter by 2 mm (average) over one year;
Definitive landmarks for reproducible tibial tunnel placement in anterior cruciate ligament reconstruction.
Tibial tunnel placement in anterior cruciate ligament reconstruction and graft impingement.
SM Howel and JA Clark.
CORR. Vol 283. p 187. 1992.
Roofplasty requirements in vitro for different tibial hole placements in ACL reconstruction.
GS Berns and SM Howell.
Am J. Sports Med. Vol 21. 292. 1993.
Parsons' knob (tuberculum intercondylare tertium). A guide to tibial anterior cruciate ligament insertion.
Tibial tunnel placement in ACL reconstruction.
DW Jackson and SI Gasser.
Arthroscopy. Vol 10. p 128. 1994.
Anterior cruciate ligament reconstruction: the effect of tibial tunnel placement on range of motion.
VM Romano et al.
Am J. Sports Med. Vol 21. p 415. 1993.
The effects of tibial tunnel placement and roofplasty on reconstructed anterior cruciate ligament knees.
T. Muneta et al.
Arthroscopy. Vol 11. 1995. p 57-62.
Posterior tibial tunnel placement to avoid anterior cruciate ligament graft impingement by the intercondylar roof. An in vitro and in vivo study
Definitive landmarks for reproducible tibial tunnel placement in anterior cruciate ligament reconstruction.
