Okay? Thank you, Brian and Jason, for having me. So, up to this point, you know, the course has been about orthobiologics, and now we're going to shift gears and talk about, essentially, it's delivery. And we go through a lot of trouble to obtain whatever orthobiologic we're going to do, and we need to be able to deliver it accurately to our target structure. So, I was just to raise of hands, who has never touched an ultrasound probe? Everybody here has used ultrasound? This morning? How many of you have not done an ultrasound guide injection? Okay, a fair amount. So, I was told that there will be people here that have never even picked up a probe, so the first part of the lecture is just some ultrasound basics, so we're all on the same page. And then we'll actually go into the concepts of ultrasound guide injections and talk about some of the specific injections as it relates to orthobiologics. I have no disclosures. Okay, so the goals, again, are review some basic principles, and even if you don't plan on doing ultrasound in the office setting, ultrasound has been a game changer in orthopedics. If you talk to your hand colleagues, foot and ankle colleagues, I know in our institution, it's changed the paradigm. It's changing the paradigm, how we manage tendinopathies. So, even if you're not the one getting your hands on it, it's worth knowing about this because you're going to see it more and more. I know in our institution, we've replaced many of the logarithms for MR with ultrasound, and so, again, you're going to get these reports, and so a better understanding will be helpful. We'll also talk about recognizing the sonographic appearance of common MSK structures and then develop an approach to optimizing the image. We pick up the ultrasound machine. How do we get the image that we want to get? All right, so this is the 45 second physics 101 in ultrasound. So, basically, an ultrasound machine is a computer, and this computer transmits and receives signals from our ultrasound probe. It transmits electric current, which goes down into the probe, into the crystals at the bottom of the probe, but then emits an ultrasound wave, and that's what frequency is then, is frequency is our cycle per seconds and one cycle per second is one hertz, and what defines ultrasound is that these are megahertz. These are millions and millions of sound waves coming out of this probe, and so one to 20 megahertz is the usual range that we are at right now with MSK ultrasound, and just to contrast that, human sound is 20 to 2, you know, 20,000 hertz, and so, again, it's several magnitudes beyond what we hear. So, this megahertz doesn't penetrate air, which is why we need ultrasound gel against the skin and not have any air gaps, and so this ultrasound waves are being emitted from the transducer going down into our soft tissue, and then based on the properties of the soft tissue, they're reflected back to the probe that now becomes the receiver, takes that information, puts it back into the computer, and now we get an image. So, again, it interprets these signals, and these signals are based on the difference in tissue properties, and we call that acoustic impedance. Acoustic impedance is basically the resistance to sound waves of different tissue properties. So, in this case, we see the patellar tendon. We see the patella on the left-hand side here. Bone has a very high acoustic impedance, so no sound waves go through. This is all shadowing versus fluid has almost no acoustic impedance and appears dark on ultrasound. And so it's this computer-generated ultrasound waves at these high frequencies that give us these images that are becoming unbelievable because as computers advance in technology, so does ultrasound. So, here we see the supraspinatus tendon. We can actually see the individual collagen bundles of the tendon. We can see the subacromial bursa. You can see the individual striations within the muscle itself, and we contrast that with the MR. So, I think of ultrasound as actually seeing the leaves through the forest where we get a bigger picture with MR. We see the whole forest. And so it has advantages and disadvantages, both of these imaging studies. We talk about ultrasound imaging in terms of echogenicity, so something that's brighter. We call hyper-echoic or more reflection, and something that's darker is hypo-echoic. So, here we see the brightest is the cortex of the greater tuberosity. Tendon is hyper-echoic, where here the muscle, the deltoid is hypo-echoic compared to the tendon. Now, ultrasound machines are also equipped with what's called Doppler imaging that detects motion, and I'll talk about that in a couple minutes. And then finally, with ultrasound, we tend not to use the typical anatomic terms, and we use long and short axis of the image that we're imaging, again, because we are magnified on an image. And so we would say this is a coronal oblique of the shoulder, where we would say this is a long axis of the supraspinatus tendon. Many structures in the musculoskeletal system will change planes, for example, the tendons of the ankle, so we can stay on the short axis throughout its course, unlike MR, where you'll lose some of the resolution as you angle through.

ultrasound

orthopedics

orthobiologics

imaging modalities

echogenicity