Ankle-Brachial Index, CT Angiography, and Proximal Tibial Traction for GSW Femoral Fracture
What we're looking at here is a plain film of a patient's left femur following a single gun shot wound to the left lower extremity. As you can see, with these ballistic injuries, you have high force, and can get pretty large, displaced femur fractures. What we are going to be doing today is going through how to obtain an ABI, which stands for an ankle-brachial index, which is commonly used in these incidents when you have these high force injuries that can cause, not only the mechanical trauma that you see here with the broken bone, but also cause arterial damage and result in arterial insufficiency. So, the ankle-brachial index is a tool that you use to compare the blood pressure in the upper extremity to the lower extremity, and what you should see in a normal human is a ratio of 1.1 or greater, and the ratio that would start to get us worried is when the lower extremity has a systolic blood pressure that is 0.9 or less in its ratio to the blood pressure from the upper extremity.
Because this patient has diminutive dorsalis pedis pulses, we will be using his posterior tibial pulse instead. The way that you do this is you have the blood pressure cuff set up and you want this to be distal to your injury that you're trying to evaluate. So, this is, as you can see by the sort of gauze, distal to where this patient's gunshot wound has been, and we will be evaluating the blood flow distal to the wound. At this point, you're going to go ahead and get your doppler all set up. You're going to get your jelly. Turn the volume up. Then you want to find the strongest pulse that you can because that's going to give you the best ratio when you're comparing. And once you have your doppler in place, making sure not to push too hard so as to occlude the artery, you are going to ask your assistant to go ahead and pump up the sphygmomanometer. And what you're looking for is for that triphasic flow to diminish, and then once it's gone, you slowly release the pressure. And that moment when you first hear the return of the doppler flow, which for this patient was at approximately 108 mmHg, is the systolic blood pressure that we're going to use for this. When we are moving quickly, we can at times use the systolic blood pressure that we have on the screen, which is being measured from the patient's left upper extremity with an automatic cuff; however, a true ankle-brachial index is used, again, with the doppler using the cuff from the left upper extremity and measuring it again in this same manual fashion. The second part of it is going to be your brachial portion of the index. For this, we usually use the radial pulse, and you, once again, find a nice strong pulse in the radial artery, and making sure not to compress it too hard. You again have your partner go ahead and inflate the sphygmomanometer. And you wait for the return of the triphasic flow like you heard just now at approximately 114 mmHg. For this, what you do is once you've done this procedure, you take your ankle portion of the ankle-brachial index, which is going to be, for this case, a systolic blood pressure of 108 and you put it over your brachial, which is a systolic blood pressure of 114. It is at 0.94 by my superiors who are much better at mathematics than I am. However, it is still above our worrisome line, which is gonna be at 0.9, at which point a CTA is traditionally indicated.
So, we're up here now, getting our CTA for our patient, and the reason why we are getting this CTA is that, off camera, we ended up performing an API. The only difference is that instead of it being from ankle-to-brachial, you can do from the same level of limb. For instance, in this, we did ankle-to-ankle, and that index was less than 0.9, and because of this, there is concern for potential vascular injury. And we are evaluating this along with the trajectory as an indication for evaluation with CTA. This is a radiograph of the femur. We see a lot of the ballistic material down here. It looks like there's like an obliquely-oriented, displaced fracture of the midshaft of the femur. Then also down here, more in the distal femur, it looks like a comminuted fracture with multiple, small displaced fracture fragments. And that's pretty much it that I can see in the radiograph. He's got this, you know, old screw affixing his femoral head from who knows what. We also had some X-rays of his tibia and fibula. There's really nothing else that's exciting from that. Those are really the only injuries in the lower leg. Okay. As you guys said, there's a reported history of a possible gunshot wound to his head, but I already looked through this and I didn't - it looks completely normal. I didn't see any injury at all, even the soft tissues. Yeah. Seemed normal, I didn't see any injury. Perfect. No hemorrhage or fractures. Right now I'm bringing up, this is the non-contrast and the arterial phase that we have. We always get those, according to the trauma protocol. But there is no evidence of any injury to his abdomen or pelvis? On physical exam? I'm asking you. There wasn't. No. Like a - no? Okay. As far as we can tell, it was just what's going on with the left lower leg. Yeah, okay. Just, on first glance, it looks very clean. No free fluid or any like injury to the soft tissues that would suggest any injury. So now coming down to the leg. You can see, here's the initial - that larger displaced fracture. Yeah. It looks like there's a few small little fracture fragments there. Kind of the main vessel that's coming down into this area now is the SFA that we'd be worried about. I'm following it right here. And so far it looks intact. You can see right here, it's getting very close to those bone fragments. Down at this level it's probably the popliteal artery at this point, coming down into the knee. There's a lot of soft tissue gas around there. Mm hmm. There's a little stranding around the vessel itself, but I mean it seems like it's intact. I don't see any, like, definite contrast extravasating out of it. So there's, I'd say, very, very little suspicion for injury, but just because there's a little stranding around it… Can't say for certain? Yeah. Maybe keep an eye on it. The rest of the runoff looks pretty good. So let's look at this in… I don't know if the joint is involved. That may be the next question. Here's the delayed though before we get to that. These are the delayed phase. I mean, at this point I don't see any significant joint effusion or any hematoma. There may be a tiny bit of fluid in there, but even that I'm not so sure. I think there is some gas in there though. Okay. In the joint capsule itself? I think so. Yeah? Let me try to look at it in different views. And these are the coronal views, they're just MIPs, so they're kind of - They're not great for seeing air. I don't know, it's close. Those little pockets, those little foci of gas, it's like right at the top of the - joint. Mm hmm. Actually I'm not so sure. I think it might be outside the joint. Okay. Just because this is me coming down, and then - this is the only area that's kind of giving me pause, right here. Mm hmm. I don't know, I kind of think that there is. All right. Yeah. I'll pass it on to orthopedics. Yeah. Yeah, see what they say. Mm hmm. So that's pretty much it. Okay. I didn't see anything else. Perfect, thank you so much. Okay, sure.
I'm one of the orthopedic residents taking care of this patient. In this particular patient, he has sustained a ballistic wound to his distal femur as well as a spiral fracture, likely from a secondary fall to the shaft of the femur itself. As a means for pain control, as well as helping reduce shortening, we often put skeletal traction in place. In this particular case, we are unable to do distal femoral traction due to the concomitant fracture distally, so we're going to proceed with a proximal tibial traction. Landmarks for this include palpation of the tibial tubercle and then 1.5 cm distal, another 1.5 cm lateral. Just general rule of thumb whenever you're doing a percutaneous fixation, you always want to go from an area of known to unknown. If we are doing distal femoral, you would go from medial to lateral because the femoral bundle is on the medial side. In this particular case, we're going to go from lateral to medial because of the common peroneal nerve.
First thing we're going to do is numb up the area with a local anesthetic. You numb up both sides. Might feel a little poke and burn. Whenever you inject - withdraw, make sure you're not within a blood vessel. Make a wheal at the skin. In this case, the bone is relatively close to the subcutaneous region. Go down to bone, you feel periosteum. Numb the periosteum. And then you can numb up as you're pulling out. Then you move to - medial side, do the same thing. Another poke. Again, down to periosteum.
So we'll let that set. Then we prepare for the actual traction pin itself. For this, we'll be inserting a 4 mm Steinmann pin. All right.
So then we'll formally prep out the area before placing down some sterile drapes.
All right. Then you take your 11 blade. Check for sensation. Does it feel numb there? I can feel it a little bit. Pressure or pain? Pressure. All right. Double check your landmark. Small incision.
Then you take a hemostat down to bone.
Again, check your landmark. Tibial tubercle, 1.5 cm down, 1.5 cm. Aiming for your landmark on this side. He's young, so the bone can be strong, but you should hear - a pitch change as you're going through the first cortex, which is happening right there. And then you should hear a second pitch change as you're going for the second cortex. Right there. Almost done. Strong bone. There is is. Now it's through. As you can see, lined up with our anticipated mark on the far side, which is the medial.
Grab your 11 blade again. Palpate. Small incision on either side.
Completing proximal tibial traction. You can even out the sides. Cautions: while there is neurovascular bundles posteriorly, you don't want to cut it too far anterior because you could inadvertently go through a single cortex or clip the tibial tubercle off. But as you can see, we've got good, solid fixation from which we can hang weight to help alleviate pain as well as - prevent shortening of the femur fracture, which can aid with ultimate surgical management of this problem.
So, I will set up the tension bow here, dress the wounds, and then apply the weight. These pin sites can drain, so it's important to one - make as small of an incision as you can, and also, in terms of dressing, placing an occlusive dressing like Xeroform or Adaptic can help minimize that. Followed by some Curlex to bolster up the dressing itself. So aside from adding weight, setting up the traction apparatus, that is a proximal tibial traction pin. Do you feel that pulling? Hell yeah. Kind of like what I was pulling before. Yeah. All right, I'm going to go run upstairs and grab some weights. We'll probably put 20 - 30 pounds.