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PEARLS & PITFALLS – SURGICAL TECHNIQUE
Tips in ACL Revision Surgery
Two stages revision surgery may be also needed when ROM deficit more than 5o in extension or 20o in flexion, as well as in case of active infection. Two-stage revision usually requires a 4 to 6-months gap between procedures. Surgeon and patient have to be aware that his prolonged period of instability can produce secondary chondral and/or meniscal injuries but also that every single additional surgery carries the risk for potential inherent complications (e.g., anesthesia- related, infection, deep venous thrombosis).
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3. EXECUTE YOUR PLAN
Intraoperative Tips to Correct Tunnel Malpositioning
When ACL reconstruction has failed due to non-anatomical tunnel placement, one of the most important aspects of the revision surgery is to ensure adequate visualization of the previous tunnels and the integrity of the postero- medial wall of the lateral femoral condyle. Occasionally, trochleoplasty can be needed, specially when narrowing or osteophytes in the intercondylar notch. Once these previous steps have been conducted, drilling of the new tunnels may be performed as close as possible to their anatomical location. The femoral insertion site of the ACL encompasses approximately the lower 30% to 35% of the intercondylar notch wall, and revision tunnels should thus be placed accordingly; If possible, both tunnels should be placed far enough and divergent enough from previous tunnels to prevent tunnel overlapping.
In order to avoid previous non-anatomical femoral tunnel, in a single bundle reconstruction an anteromedial (AM) parapatellar portal can be created just in front of the medial femoral condyle and as low as possible; special care has to be taken to avoid damaging the medial femoral condyle and the anterior horn of the medial meniscus respectively. The drilling of the femoral tunnel should be performed at least with 110o of knee flexion in order to get adecuate tunnel length and decrease the risk of damaging the lateral neurovascular structures.
Depending on surgeon’s preference several surgical options can also be performed to create a new anatomic femoral socket or If the medial-posterior wall of the lateral femoral condyle is insufficient:
a) extra-cortical fixation with suspensory devices;
b) over-the-top fixation through a lateral post;
c) changing the orientation of the femoral tunnel through the use of accessory AM portal;
d) using the classical open outside-in drilling technique;
e) using flexible reamers through the AM portal allowing a more modest knee flexion
f) new options as arthroscopic retro-drilling outside-in technique.
Hardware removal is another factor to consider and should be planned in advance as it may involve intraoperative difficulties, longer surgery and may entail a bone stock loss, thus hardware should only be removed when it is in the way of the new tunnels. Sometimes previous hardware can be useful in avoiding old tunnels when the new ones are drilled. New screws should be placed with caution, taking care that they do not enter into the old tunnels. If both communicate, the graft should be positioned in contact with the “healthy” wall instead of the old tunnel; this can be checked intraoperative just visualizing with the scope through the tunnel. When previous interference screws removal is necessary, it is imperative to have the adequate screwdriver and reproduce portal and knee flexion degree used during insertion. If previous screws are not removable, it is possible to drill over them if reabsorbable. If staples were used, it is strongly recommended to have the appropriate extractors and consider the potential bone loss after removal, which could affect tibial fixation.
Tibial tunnel can be also challenging as even with previous transtibial technique was performed; we have to be specially careful in trying to diverge from the previous tunnel in the coronal and sagital planes and exit as far as possible in the joint from the previous tunnel; in many occasions partial or complete convergence of the tunnels occur creating a double barrel effect; in order to avoid that the new graft “falls” into the old tunnel, we can with fill in the old tunnel with impacted bone graft or even with a press-fit cannulated interference screw to create some support; again, the graft should be positioned against the “healthy” wall instead of the old tunnel.
Fixation Mode
Kurosaka et al. established that the weakest point of a fixation is the weakest link during the immediate postoperative period. For this reason, a solid fixation is essential to prevent changes in the position of the graft inside the tunnel, keeping in mind that autologous and bone-bone integration happens faster than soft tissue-bone or allografts integration.
For the BTB fixation, the interference screws have proven to be more effective than staples, posts or other devices. Yet, screws can pose problems at the time of fixation, such as being driven into the tunnel, divergence caused by the screw, rupture of the bone plug or screw, damage of tendinous fibers, among others.
16 ISAKOS NEWSLETTER 2015: Volume I