So, think of me, if you will, as your stagecoach. Here are my disclosures. ACL graft failure may not be the end of the world for you, but it certainly is for your patients. Here's where we're going to talk in just a short time. Explain the common causes of ACL failure, emphasize osteolysis, talk about one versus two stage in some depth, look at our CT studies, biopsies, and probably not have time for a bonus case. So the bottom line is that in order to avoid a revision, you need to do it right the first time. And I encourage those of you, especially, that haven't done a lot of ACLs to take an intra-operative fluoroscopy. This is what I consider ideal tunnel position prior to drilling. On the femoral side, about three-quarters of the way across Blumenstadt's line and below that line. And on the tibial side, about 35 to 40 percent across Staubli's line. These are the causes of graft failure from the MARS group, and Rick Wright has done a phenomenal job with that group. As you can see, the combination of errors is very common. And also, I would submit to you that technical errors are based upon who's determining that. If it's your own patient, you're very unlikely to call it a technical error. This is an infographic or what I call a composite figure that's in the review book that talks about the various causes of ACL failure. It's really worth taking some time to study this diagram because it really shows clearly some of the problems involved with ACL reconstruction, especially those that have failed. And you can see that tunnel osteolysis shown here is perhaps one of the biggest concerns in revision ACL reconstruction. There's also problems with tunnel placement. The most common error is incorrect femoral tunnel position. This is quite an anterior placement. You probably shouldn't have your button right below the patella. And malpositioning of either tunnel can give excessive graft failure. Vertical grafts result in an unstable rotational phenomenon. Interference screws need to interfere. They need to be completely in that tunnel and trap your graft. Both buttons need to engage the cortex. That's the way they're designed. If you have a deficient cortex, then use a bigger button. So we can have an error screw as shown here. We can have an error button as shown here. And of course, we all can have the error Jordan. So you need to also look at concurrent pathology. Look for meniscal ramps and repair them. In order to see a meniscal ramp, you have to look in the back of the knee. Repair all meniscal root tears. If you need to, consider adding an extra articular augmentation. The lemur is shown here. And then this is something you have to really force yourself to look at it because it's relatively new. But when you're considering a revision, look at the tibial slope. Any slope more than 12 degrees, you should consider changing that slope as part of your revision or perhaps in lieu of your revision. So one of the biggest problems though is tunnel widening. And so tunnel widening may not be the cause of ACL failure in itself, but it's certainly something we have to address at the time of revision ACL reconstruction. It may be caused by a windshield wiper effect or a bungee cord effect. It's really not clear. Or in deference to Eddie George, the Ohio State University researchers suggest that there may be some low-grade infection involved here. And they felt they determined that only with polymerase chain reaction. If you culture these debris, as I have often done, you won't get any infection show up in your lab. The histology is fibrous tissue, foreign body reaction, surgical debris of the schmoo that you take out of the tunnels. And it's unclear then why it causes such widening. We're still investigating that. So how do you work a patient up for a revision ACL? Get plain radiographs. Get stress radiographs if indicated. Get full-length standing alignment films. Get a full-length tibia to look at your slope. Get an MRI and an MRI orthogram if necessary for the meniscus. And then get a CT scan. A CT scan is the most reliable imaging modality for evaluation of bone tunnels and osteolysis. Then you've got to figure out how and with what you're going to fill your widened tunnels. There's a variety of options available regardless of your choice. The sequence is to remove the debris and then fill the defect. If your tunnel is more than 14 millimeters and or directly where you plan the new tunnel with over 50% overlap, you may need a stage. Our preference for fill is allograft bone dowels. In fact, there's an article in Arthroscopy from 2016 that demonstrates that this technique is the only technique that gives comparable biomechanics to primary ACL reconstruction. Bone dowels are available commercially. They're fully cannulated and bullet tipped. And the way they're inserted is by serial drilling. You drill by two millimeter intervals until you see nothing but bone on tunneloscopy. Look up your tunnel as you drill and see if there's debris. Then center the guide pin. A dilator can be helpful to do that. And then use a cannulated tamp to tap the bone dowel into place gently. These are somewhat brittle and can fracture if you're too aggressive. This is one time in orthopedics that the mallet is not necessarily your friend. So you can do this with single stage. If the tunnel enlargement is not too large, you see debris in the graft, you center the guide pin, you drill the tunnel, and then you impact the dowel. And then you can do it in a single stage sometimes. Here's a case to breed the graft, center the guide pin, and then prepare to place the graft in place as shown here. Two years after the graft is in place, plan your new tunnel. And then drill your new tunnel without adversely affecting the dowel that you placed. If you didn't place a dowel here, as some of you would suggest, then you're going to have an oval or figure eight shaped tunnel. And the graft's going to migrate. Then as you fix the graft, the interference screw can secure both the graft and the dowel. The dowel in and of itself is usually stable without the adjacent tunnel, but the screw helps secure the whole gambit. You can do a one stage and a PD ACL where this tunnel was placed too far anteriorly in a single stage. We placed the dowel in the previous anterior tunnel and then placed our tunnel in the anatomic location behind it in a single stage. We did a single stage study represented in the JAALS, and we showed good results, although in revision ACLs, good results aren't as good as primary ACLs. A two stage approach is when you have massive osteolysis, more than 14 millimeters of widening, convergent tunnels, and a poor biologic milieu. The problem is patients don't like this option and therefore we don't either. So you have to do this sometimes and you have to be a good salesman. Here's a case of a two stage revision with dowels. We had 15 millimeters of osteolysis in both tunnels. We again do the same technique by center the guide pin, serially drill, and then place the dowel. Here we are placing that dowel with a cannulated tamp. Here's the dowel in place. Here's the dowel in place with the plug, and the plug is very happy in this new environment. So alternatives for the femoral side is if you want to get access to the femoral side through a trans-tibial previously done procedure, you can first drill the tibial tunnel and prepare that and then place the dowel through the tibial tunnel trans-tibially. You got to make sure you don't fill the tibial tunnel before you do this because you got to think ahead. Then you can fill the tibial tunnel after you've placed the femoral tunnel. You can also avoid the accessory medial portal or the medial portal by placing the dowel from outside in, retrograde. Here's an example of that, we're retrograding that dowel into place from the outside in. The tibial side, serially drill, fill it. Sometimes you have to use two dowels because it's long. Here we are placing the tibial dowels in place, and then after you place them, you can gently burr and smooth out that location so you have a good bed to go back to when your revision comes around. Here's after we're done. And then here we CT scans about three or four months post-op and look for integration. We have a poster number 173 that shows you how that technique works. I encourage you to stop by that poster number 173. Here's an example where we had a dowel that was too short and so I used some DBM and chips to supplement that dowel. I would encourage you not to use DBM and chips because you can see that they don't integrate anywhere as near as much as the dowel, so use two dowels in those cases. We go back, you can see where the dowel was, the new tunnel. You can see on the tibial tunnel, you don't even know where the dowel was, and you place your revision, in this case, quadriceps tendon. Our bone dowel incorporation is equal or almost equal to iliac crest bone graft from another study. Again, I encourage you to go to poster 173, and we've done this 3D studies we hope to publish soon, demonstrating good integration of these dowels. The histology at time zero, the reason I like allografts, I'm not a big allograft fan, but this allograft has no cells, so there's no immune reaction, and so this is a very good conduit for new cells to come into. We see that in biopsy at four months with new cells integrating, new cement lines. And at one year, we see repopulation of that dowel with host cells, creeping substitution. And so this is better than calcium phosphate, in my opinion. We'll see what Kevin Bonner says tomorrow in our instructional course lecture, I encourage you to go to instructional course here, section 301 if you're interested in this, we'll have a debate about this. And we plan future studies with calcium phosphate versus bone dowels in our two institutions. So I was asked to give an editorial on this topic to the Arthroscopy Journal, I encourage you to, it's a few issues ago, I encourage you to take a look at that. Here's the top 10 advice I have for staging. Number one, one stage is preferred, but a successful two stage is better than a failed one stage. Number two, CT scans, focus on both sagittal and coronal reconstructions. Preoperatively I place this, the femoral tunnel on the top with a sagittal and coronal best image and the tibia on the bottom with the best sagittal and coronal image for intraoperative viewing. If your tunnels are more than 14 millimeters, you need a two stage approach. You can partially fill oval tunnels to create round tunnels. You need to diverge your new tunnel from the old tunnel if you're doing a one stage. Consider retrograde femoral tunnel drilling and filling as I just showed you. Use secure fixation and revision ACL reconstruction. I strongly encourage you to consider backup fixation. Never compromise anatomic tunnel location. Always have a plan B and C because this is a case where you sometimes need them. And address all concurrent conditions and risk factors including the tibial slope. So thank you very much for your attention and I look forward to working with you in the future. Thank you.

ACL graft failure

tunnel placement

tunnel widening

revision ACL reconstruction

allograft bone dowels