I'm kind of happy talking about this one because I've done all the other complications myself already. So I'm glad to see everybody in the room. These are my disclosures. You know, I think one of the things is I want to briefly go over why placement of these tunnels is important, how accurate are we, how to place it correctly, and what to do if misplaced. Tunnel malposition is really important because otherwise you can end up with medial patella overload, you might have medial instability, you might end up with medial arthrosis or loss of range of motion. It can increase your compressive forces across the patella femoral joint significantly. One of the things is it's also one of the risk factors for patella fracture after NPFL reconstruction. Risk factors for this is patella tunnel, but placement of the femoral tunnel is obviously one of the significant risk factors. So tip number one, put the graft in the right place. And it's, I think if you try to do this without all the assistance you can have, it's very easy to miss. So whenever I do an NPFL reconstruction, there's three parts to it. I always use a large C-arm, get a true lateral, look for a shuttle's point, and then I make my incision, make the exposure, palpate the saddle region between the epicondyle and adductor tubercle, and then the other thing is I want to make sure that my graft or suture after it's attached to the patella loses inflection. So errors in placement are very common. This is from the Leone group. They used palpation alone. This is AJSM in 2011. One-third had greater than seven millimeters of error. Now one of the interesting things, though, is at two years of follow-up, they actually didn't have a lot of difference in clinical outcome. So I think one of the critical things is even if it's misplaced a little bit, it's better if you're, if there's enough slack in the system, it'll probably be not terrible in the early, but we don't know what happens at later time points. So this was actually kind of a fun thing. We presented this at one of the sports medicine meetings a few years ago, and this was a pin the tail on the NPFL. There were 38 doctors at the patella femoral study group. Bill Post is here. He helped us lead this study. Thank you, Bill. And so basically these are people who really are patella femoral and have a strong interest in that. We had people do it just by palpation. We took fluoroscans of where they put a pin and then compared it to the actual insertion, and then we measured where the position was. Almost 20% had greater than five millimeters of error when using just plain palpation, and some of them were like totally off. So palpation alone is probably not good enough for, at least for this group of patella femoral experts. So what do you do if it's in the wrong place? If you identify it and see it interoperatively, obviously you reposition that and put it into the right place. And I think that's a pretty straightforward thing. But occasionally, I've been seeing, you'll get a situation where it's clearly in the wrong place and the patient has continued symptoms. So I was sent this patient. You can see the femoral tunnel is clearly not at the native insertion. And so you can imagine what happens. There was over-constraint. The patient had pain, some arthrosis, and actually had instability because it wasn't really capturing. You can see where the interference screw is. But one of the things that I did notice is that there was actually intact graft adjacent to the screw. What we know is with interference screw fixation of a graft, the graft actually remains intact next to the screw for a period of time. So I was able to use that. So if you have a situation where the graft is in the wrong place, you want to obviously put it in the right place. If the graft is intact, then you don't have to necessarily use a brand new graft. Identify the correct location. And then sometimes you can actually mobilize the graft within the tunnel. I used a Freer elevator in this situation, took out the interference screw, used the Freer elevator to loosen up where the graft had scarred to the walls of the tunnel and was able to pull it out, and then repositioned the graft using a suture anchor, which was probably sufficient fixation for an MPFL graft. So in conclusion, if primary situation, use fluoro and palpation is much better than just palpating alone, even for experts. The graft should loosen inflection. I usually also allow one quadrant lateral glide and extension like your normal patella would. If you're revising it, you may be able to free up the graft in a tunnel to get more length. But if you can't, you might consider like a Z lengthening or maybe even using a strip of the adductor tendon or other graft to help lengthen your graft. So thanks a lot.

NPFL reconstruction

tunnel placement

complications

graft tension

fluoroscopy