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Super. Hi, Phil. Good. I'm glad you're here. I need to talk to you about a conference that we're going to be doing in Poland next year. You'll, uh, we may be able to work together on that one. We'll have fun. Great. Super. Yeah, I'm gonna wait until I have. Oh, almost everybody's here. That's pretty good. 12345. Ok. Well, I'm gonna wait, as I said, for just a couple of minutes probably till four minutes after the hour and then start the lecture. Give everybody a chance to arrive. It's good that you arrive on time because most of these lectures are 45 to 50 minutes and I don't want to go over time because everybody has stuff that they need to do. Uh, this lecture series is broken down into four sections. There will be this lecture today and then three others that will cover all of the major arthri so that at the end you'll have a pretty good grasp of what's going on. Ok. Now, if any, if at any time you stop hearing me, you need to stay open your mic or do something so that you can so I know because I won't be able, I won't be able to tell since my screens will be occupied. Ok, let's start in the next approximately 50 minutes. I will cover general considerations regarding the radiographic presentation of arthritis. I will spend a lot of time discussing the differences between noninflammatory arthritis. Using the example, osteoarthrosis and inflammatory arthritis using rheumatoid arthritis. As the example, we will learn an approach to systemically evaluate joints of the hands and feet and perhaps other joints for the presence of arthritis. We will use the target area approach to diagnosis to pinpoint the most likely types of arthritis. We are looking at, we will learn in detail, the presentation of osteoarthrosis and rheumatoid arthritis. Our learning objectives are to become familiar with the radiographic findings and the common arthritis learn in detail the index diseases, osteoarthrosis and rheumatoid arthritis. Better understand the target area approach to diagnosis of arthritis in the most common conditions that are clinically seen and become more confident in the radiographic diagnosis of arthritis. So let's begin in this lecture. We provide an overview of the different imaging findings of common joint diseases as a useful tool in daily musculoskeletal arth uh radiology, arthritis is a challenging topic. A long list of diagnosis must be considered when looking at x-rays of the hands and feet each with its own extensive set of findings. Sometimes the abnormalities are pathognomonic for a specific disease, but more often the findings are nonspecific because there is a lot of overlap between different joint diseases. When you start looking at arthritis cases, remember the following, if it is the first examination, then try to make a differential diagnosis based on imaging findings as well as patient information and lab findings. Mm In most cases, we don't have access to much patient information as you all know, as radiologists. Uh so you basically have to sort of if they say rule out arthritis, then you have to do go through this entire process, master yourself in diagnosing osteoarthritis and rheumatoid arthritis. And remember the distinctive features between these two entities, they will be the most common diseases that you will see. Osteoarthritis is the most common degenerative noninflammatory disease of people. If it is not a ty if it is not typical osteoarthritis or rheumatoid arthritis, then use the systemic approach in the first paragraph. If it is a follow-up case, then check disease progression and look for new erosions. Remember that secondary osteoarthritis can develop secondary osteoarthritis can also be a sign of low-grade pro pro progression of the original disease. The flow chart shows the approach to radiographic evaluation of arthritis in the presence of joint space narrowing. It is important to defer degenerative from inflammatory conditions. It looks complicated but don't let it scare you. In both rheumatoid and osteoarthrosis, we begin with joint space narrowing but in O A, the joint space narrowing is symmetric, there may be osteophytosis and there may may be sclerosis in R A, I'm sorry. It's, it's asymmetric, that's I made an error in O A. The joint space narrowing is asymmetric. There may be osteophytosis and sclerosis in rheumatoid. On the other hand, we see symmetric joint space narrowing, erosions and soft tissue swelling, degenerative joint disease is characterized by osteophytes and subchondral sclerosis with an asymmetric distribution. Both when you compare left and right, as well as within the joint itself. Usually thi this is typical with osteoarthritis when findings are atypical, including an unusual combination of age affected joint and severity. Think of posttraumatic arthritis, CPPD crystal deposition disease, arthritis, neuropathic or rare diseases like hemophilic arthritis. Inflammatory joint disease is characterized by bone erosions, osteopenia, soft tissue swelling and uniform symmetric joint space narrowing. Inflammation of a single joint should always raise concern for infection. Multiple symmetric joint inflammation is a in a proximal distribution in the hands or feet without bone proliferation suggests rheumatoid arthritis when the inflammation is more in the distal distribution in the hands or feet with bone proliferation. It suggests the constellation of diseases known as the seronegative spondyloarthropathies. Spondyloarthropathies is a group of chronic inflammatory diseases associated with the HLAB 27 annotation, axial spondyloarthropathy. Most commonly the disease, ankylosing spondylitis is located of course more in the axial skeletal axial skeleton, peripheral spondyloarthropathies like psoriasis, reactive and inflammatory bowel diseases associated arthritis is located more in the peripheral skeleton joint diseases have variable manifestations with an overlap of radiographic features. The ABC DS mnemonic is a helpful tool for a systemic and complete radiologic interpretation and reporting. We use this system which stands for a articular B, bone C cartilage D distribution, E extras and S soft tissue. There are also variants of this demonic as well that you can use. Here, we see a typical synovial joint on the left. We see two bones separated by a joint space and covered in articular cartilage which is demonstrated in blue. We see the joint capsule in red surrounding the joint. Notice the bare area indicated in the left diagram. This region is not covered with articular cartilage and therefore, hypertrophic synovia, synovium can cause erosions in this region. When we look at rheumatoid diagrammed in the middle image, we see these marginal erosions located at the bare areas of bone. Marginal erosions are typically seen in rheumatoid arthritis at the metacarpophalangeal joints and in psoriatic arthritis, but not at the metacarpophalangeal joints. Instead, psoriatic is seen at the distal interphalangeal joints. If we look at the right hand diagram, we see subchondral erosions in the cartilage which are a typical feature of osteoarthritis. In severe osteoarthritis, the mo bones may actually interdigitate and 1 may look like it's fitting into another. I will show you a radiograph of this. Later here we see more examples of articular erosions in erosive osteoarthrosis. We see osteophyte formation and a central erosion which can be termed the dull wing deformity in psoriatic arthritis, we see a combination of erosive changes and bone proliferation as seen in the middle diagram. These changes occur because psoriatic arthritis, although inflammatory has a much slower progression than rheumatoid arthritis thus can begin bone forming at the margins of the distal bone. As we see in this diagram in psoriatic arthritis. This picture is called the pencil and cup deformity. When we look at the right-handed diagram, we see a marginal erosion that is eccentric, just uh juxta-articular and has an overhanging edge. This is characteristic of the disease gout, typical marginal erosions in rheumatoid arthritis. In the metacarpophalangeal joints. We see that in image number one. In the middle image, we see osteo erosive osteoarthritis demonstrating subchondral erosions in the distal interphalangeal joints and proximal interphalangeal joints. This results in a gullwing deformity indicated by the arrow. There also may be interdigitation of the bones. The distal interphalangeal joint to the left is a classic gullwing deformity. In this one here, this is gullwing. This is the interdigitation in gout which we see in the third radiograph, eccentric erosion with an overhanging edges present the sclerotic margin. In this case indicates the chronicity and slow moving indolent disease. In this fourth image, we see infection, we see permeated, destructive changes with cartilage loss and erosions, sometimes soft tissue swelling. As we see here, infection in many cases affects a single joint. So any kind of destructive disease at a single joint, you must first rule out infection and indicate it that it's a possibility. In the middle image, we see bony erosions narrowing, the end of the proximal phalanx as in a pencil which rests in the cup formed by the expanded base of the distal phx as a result of bony proliferation. And in image number three, we have an unusual less common disease, scleroderma, scleroderma and other multisystem disorders can produce erosions at the distal Tufts causing what we see here termed acro osteolysis. You will see more examples and we will cover these disease processes as we move forward in parts two and three of these lectures. Let's now look at alignment with rheumatoid arthritis, ulnar deviation of the digits may occur as a late finding. Notice the joint space narrowing and erosions as well. In image number one to the left in erosive arthritis or erosive osteoarthritis malalignment may occur and as an end-stage finding, but the erosions and interdigitation give away the disease. Once again. In the middle image, we can see these lovely erosions, the interdigitation and the gall wing formation. In the third image, we see a nice example of subluxation, perhaps frank dislocation, soft tissue swelling and increased soft tissue density. As we see in the disease gout, bone formation is an important finding in osteoarthrosis C PV D crystal deposition disease and psoriatic arthritis as probably the only bone forming inflammatory arthritis, bone formation or proliferation is seen in many joint diseases and especially in osteoarthritis, diffuse idiopathic skeletal hyperostosis and spondyloarthritis, like ankylosing spondylitis and psoriatic arthritis. It is not present in the active phase of rheumatoid arthritis. So none of these pictures look like rheumatoid osteophytes are common in osteoarthritis, bony proliferations that develop at the margins of a synovial joint. As we see in the third image secondary to articular cartilage damage osteophytes. In a patient with C PB D, we notice that in the second image, notice the soft tissue calcifications within the circle, they're very, very hard to see. You have to look closely for them and we see bony proliferation in image number three. As we see in psoriatic arthritis, sometimes described as fluffy periostitis osteophytes in the spine and spondylosis degenerative disease are quite common. The typical orientation of osteophytes is horizontal or perpendicular to the spine. Syn sys. On the other hand, are paravertebral ossification in the ligaments of the spine, typical orientation is vertical parallel to the spine. This is the hallmark of ankylosing spondylitis. In diffuse idiopathic skeletal hyperostosis ossification occurs in the anterior longitudinal ligament. These ossification are bulkier compared to ossification in ankylosing spondylitis. They also in severe cases will cross the anterior aspects of the vertebral bottom bodies and connect like lumpy bumpy shield of bone anterior to the spine. Most commonly seen in the cervical and thoracic sections changes in bone density present as either osteopenia or as osteosclerosis. Periarticular osteopenia is typically seen in rheumatoid arthritis and not in osteoarthritis. Periarticular demineralization develops as a result of hypo hypo U uh um I'm sorry, de develops because of hyper eia of the inflamed synovium and soft tissues. The inflammation, the proliferation of synovium causes inflammatory response which causes increased blood circulation to the area that increased blood circulation, washes out the bone and causes the periarticular osteopenia, subchondral sclerosis. However, is typically seen in osteoarthritis. It can be also found in patients with neuropathic arthritis. Here are two examples of periarticular osteopenia. In patients with rheumatoid arthritis, the osteopenia can be very subtle. It may sometimes help to play with the window settings or to squint your eyes to see the osteopenia. I do this all the time when I'm looking at imaging in the first image on the left, the light blue box demonstrates the periarticular osteopenia in the metacarpophalangeal joints in the yellow box. In the middle image, you can see the characteristic periarticular osteopenia. This is also clearly seen in the orange box on the left in these diagrams which demonstrate degenerative changes on the left and inflammatory changes on the right. We can see that degenerative diseases can affect the cartilage in a non uniform manner because of the mechanical load, which is not evenly distributed throughout the joint in inflammatory diseases. The cartilage is affected uniformly since the synovitis and the synovial proliferation is present in the entire joint. Here is a nice example of typical osteoarthrosis with cartilage loss on the medial side, subchondral sclerosis and osteophytes. In image number one, this also demonstrates mild medial femorotibial shift which occurs because of laxity in the medial and lateral collateral ligaments. When these ligaments become lax, the joint then becomes unstable. And the more lax the joint is the more it requires joint replacement surgery. In image number two, on the contradistinction, we see uniform cartilage loss, no osteophytes. And in such a case, your first thought should be inflammatory joint disease. The distribution of joints involved in various disorders will be discussed throughout this talk. Understanding the distribution patterns is a very powerful tool. Since most common diseases such as osteoarthritis, rheumatoid arthritis, and psoriatic psoriatic arthritis have distinctive patterns. As we can see here as I move through this talk about the various joint diseases, I will start each section with an illustration of distribution. The classic distribution for osteoarthritis is seen in the left image osteoarthritis. Most commonly affects the tri scapha joint and the base of the thumb in the wrist and the distal interphalangeal joints of the hand occasionally as seen in yellow. The proximal interphalangeal joints may be affected. Rheumatoid arthritis has a totally different distribution. Rheumatoid affects the wrist. As we see here, the metacarpophalangeal joints and the proximal interphalangeal joints. This is an important pattern to memorize and understand if you look at these three patterns, you see that osteoarthritis is more distal rheumatoid is more proximal and psoriatic is a little mixed in psoriatic arthritis, changes are noted in the distal interphalangeal joints. The proximal interphalangeal joints with sparing of the metacarpophalangeal joints. But in the wrist, the tri scapha joint and the triquetra hamate joint are affected. Please also remember that serologic tests can be helpful if rheumatoid diseases are suspected a positive rheumatoid factor or anti CIN peptide. Also known as CCP antibody can support the diagnosis when rheumatoid arthritis is suspected a positive HLA B 27 antigen test can aid in establishing the diagnosis of ankylosing spondylitis, which we will look at later. Also nonspecific inflammatory markers including the erythrocyte sedimentation rate and c reactive protein are often elevated in any inflammatory disease. It is important to look at the soft tissue when evaluating the joints for arthritis, soft tissue swelling and calcifications are frequently seen in arthritis and can help to narrow narrow the differential diagnosis here are three different images that demonstrate the importance of soft tissue changes and calcification. In the first image of an A P wrist radiograph with calcium pyrophosphate dihydrate crystal deposition disease. We see several findings that suggest this disease. Chondrocalcinosis is a descriptive term when we find calcifications within the joint, although not specific CPPD is very likely when chondrocalcinosis is located around or in the triangular fibrocartilage complex, the radiocarpal joint or within the knee joints as well as the symphysis pubis. Another finding that we see on image number one is scapholunate dissociation which is an end stage of CPPD crystal deposition disease. We see that the scaphoid and the lunate have separated with a large space between them. In the middle image, we see chondrocalcinosis in the meniscus of the knee. If you remember back to my previous lecture, and I'm speaking about my CPPD lecture, which many of you have not heard chondrocalcinosis in the knee can be quite bizarre and quite extensive. Finally, in the third image with which represents gout, the arrow indicates a soft tissue swelling that is denser than the adjacent soft tissues. This soft tissue mass with increased density is almost pathognomonic for gout. Other typical locations are tendon insertions around the knee. For example, the popliteus tendon or flexor tendons around the ankle joint. In the left image, we see fusiform periarticular soft tissue swelling, which is a common finding in psoriatic arthritis and may involve the entire digit resulting in dactylitis or in what we could call a sausage disci digit. Did you notice the pencil and cup deformity of the distal interphalangeal joint in the middle di in the middle image, we see coarse calcifications in the subcutaneous tissue surrounding the distal ends of the thumb. This type of calcification seen in the fingers and toes is very likely secondary to scleroderma. We see a periarticular dense calcification in image number six, which is also most likely secondary to scleroderma. And here we have more soft tissue findings in the specimen photograph, we see an arrow pointing to a Heberden's nodule seen commonly in osteoarthritis. In the specimen picture on the left in the middle image, we see masses that we might think look like gout. However, the patient has a normal serum uric acid and a high rheumatoid factor. So these are more likely rheumatoid nodules. Additionally, they are too large for Heberden's nodules and no osteophytes or degenerative changes are noted at the adjacent joints. The third image is very important and we see an A P projection of the wrist. Multiple findings consistent with CPPD crystal deposition disease, arthropathy in its end stage are present including severe narrowing of the radiocarpal joint, particularly the radios joint in this region, widening of the scapha luna joint. We see here marked narrowing of the midcarpal joint, large subchondral and intraosseous cysts and finally, chondrocalcinosis in the triangular fibrocartilage complex. This pattern is referred to as a slack wrist which stands for scaffold lunate, advanced collapse. Remember if you see this pattern in the wrist without the present, without the presence of chondrocalcinosis, you can still confidently make the diagnosis of CPPD crystal deposition disease arthropathy because this pattern is typical for that disorder. Now we're going to move on to our first index disease osteoarthrosis. Many people refer to this in fashion rather than osteoarthritis because in osteoarthrosis, there is little or no inflammation in the diagram, you can see the most common areas affected by this disease, including the cervical spine, the acromioclavicular joint, the lumbosacral spine, the hip and the knee in the hand. Osteoarthrosis affects the tri scapha joint and the base of the thumb along with the distal interphalangeal joints and rarely the proximal interphalangeal joints in the foot. The most common location is the metatarsophalangeal joint of the great toe. Osteoarthrosis is the most common joint disease in the world. Its incidence increases with age. It is characterized by noninflammatory destruction of cartilage which is usually somewhat asymmetric. These are two form, there are two forms, primary idiopathic and secondary secondary osteoarthrosis occurs because of changes, post-traumatic or in obese patients. The radiographic findings include using our ABC de criterion articular. There are no erosions noted in this disease B bone, there is no osteopenia, productive changes like osteophyte formation and subchondral sclerosis are common. The cartilage demonstrates non uniform joint space, narrowing, subchondral cyst formation and sometimes marginal sclerosis. The distribution is as we see in the illustration. Extra findings include subluxations associated with hallux valgus or hallux rigid is finally soft tissues include hire's nodes in the distal interphalangeal joints, or Bouchard's nodes in the proximal interphalangeal joints. An important pearl of knowledge to remember is that in many arthropathies, secondary osteoarthritis can be seen in the later stages. If we think about osteoarthrosis in the knee, it can be classified by the Kel Gren and Laurence classification. Also, it can be characterized by the degree of joint space narrowing, which I find to be much easier when we say mild, moderate or severe joint space narrowing. The degenerative pattern in the knee is one of the medial compartment, knee, joint space narrowing with usually a normal lateral compartment. This is asymmetric joint space narrowing. This is because the vector of the body weight travels through the medial compartment of the knee. I will move on and discuss degenerative changes in the knee. Using the recently developed top five tips in the diagnosis of osteoarthritis, which recently have been published on the European Skeletal Society Radiology musculoskeletal website. I will discuss the five tips in the diagnosis of osteoarthrosis. Hip number one has to do with the imaging modalities that we use in osteoarthrosis. Radiography really is the imaging modality of choice for the diagnosis of this disorder. This method allows the diagnosis and enables the grading of its severity, which as we discussed is done using the Kel Gren Laurence system or using a consistent system which demonstrates the variable findings of mild, moderate and severe osteoarthrosis. Cross sectional imaging methods are used usually not needed. They are used for the assessment of focal cartilage lesions and for the preoperative setting. If a prosthesis is to be placed. MRI techniques are mainly used in research and currently have no routine clinical application in the basic diagnosis of this disorder. Standing weight-bearing images of the knee are important to quantify the degree of joint space narrowing. Here we see radiographs of the same patient, a non-weight bearing A P view of the left knee and a standing pa A V view of the right. This is both, these are both the right knee, but one's weight-bearing and one's not weight bearing. Notice the difference in joint space narrowing in the right radiograph. This really looks like moderate joint space narrowing. However, looking at the standing P A view, weight bearing of the knee, we realize that the joint space narrowing of the medial knee compartment is severe with bone on bone and marginal sclerosis. At our institution, we do pa bilateral weight-bearing knees and then the lateral view of the knee. In question, this allows us to compare both knees, which helps in deciding whether the joint space narrowing is mild, moderate or severe. Also on both radiographs, we see squaring of the lateral and medial aspects of the tibial plateau, which represents early osteophyte formation seen commonly in osteoarthrosis. Also, please note in the right radiograph that the arrowheads indicate subchondral bone sclerosis, which is also a common finding in osteoarthrosis. Subchondral cysts are also commonly seen in osteoarthrosis. The pathogenesis is not clearly known but there are two theories. The bony contusion theory states that high loads or trauma lead to trabecular microfractures, necrotic bone and focal bone resorption resulting in the development of these cysts. The synovial fluid intrusion theory states that the alt alterations of the calcified barrier between cartilage and subchondral bone allow the entrance of fluid into the subchondral bone causing a fluid-filled cystic lesion here we can see indicated by the arrowheads, a subchondral cyst in plain radiography which is very, very clear to see. And in magnetic resonance imaging, this image of magnetic resonance of the magnetic resonance cyst is a bit confusing without having the plain radiograph radiograph to refer to. Now it's time to look at multiple examples of joints with osteoarthrosis. Looking at the radiograph labeled a a joint space narrowing is seen at the fourth distal interphalangeal joint indicated by the white arrow with osteophyte formation and subchondral sclerosis. In the images designated B asymmetric joint space narrowing of the second through fifth distal interphalangeal joints with osteophyte formation, subchondral sclerosis and slight ulnar deviation of the third distal interphalangeal joint are noted indicated by the black arrow. The proximal interphalangeal joints are also affected but to a lesser degree. Here are images of the hip and the shoulder. When we look at the image of the hip, we see severe and non uniform narrowing of the hip joint with osteophyte formation, subchondral sclerosis and a large cyst formation in the shoulder. We see severe narrowing of the glenohumeral joint space with osteophyte formation and subchondral sclerosis. This would be designated a Krenn Laurence classification grade four. Here we have two terrific examples of osteoarthrosis. These are really classic in the image of the hip. We see severe non uniform narrowing of the hip joint with osteophyte formation, subchondral sclerosis and a large subchondral and intraosseous cyst. In these later stages, joint deformity with broadening and flattening of the femoral head can occur. As we see in this example, looking at the knee joint, we see classic evidence of moderate to severe asymmetric narrowing of the medial compartment of the femorotibial joint with osteophyte formation and subchondral sclerosis. This would be a Krenn Laurence classification grade 3 to 4. In my practice, I would report the knee image by saying severe near bone on bone and joint space narrowing is noted at the medial knee joint compartment with subchondral sclerosis, subchondral cyst formation and small medial osteophyte formation, squaring and sharpening of the lateral tibial margin is also noted. This would be consistent with moderate to severe osteoarthrosis. Patients Exts the two of the class of the class of o of the w risk on the left. We see base of the thumb, carpometacarpal osteoarthrosis with non uniform joint space narrowing, osteophyte formation and subchondral sclerosis. There is a large subchondral cyst in the base of the first metacarpal indicated by the white arrow tri scapha osteoarthrosis is present in the right hand image. This image shows non uniform joint space, narrowing of the tri scapha joint with osteophyte formation and subchondral sclerosis. This is very classic. This is a very classic uh example of osteoarthrosis. These two areas are the target areas for osteoarthrosis of the wrist and finally, a somewhat more complex case that leads us into the next section. The dominant finding is non uniform joint space narrowing in the carpometacarpal joints and the distal interphalangeal joints. We can say that this patient has osteoarthrosis. The severity of the findings may however suggest erosive osteoarthrosis. However, there is also joint space narrowing in the metacarpophalangeal joints and a possible erosion in the in the blank. I'm sorry, I just blanked out in the lunate bone without abnormalities in the proximal interphalangeal joints. It is very likely that these abnormalities are all due to osteoarthrosis. Most likely the patient had both rheumatoid and osteoarthrosis which can occur together. Now, we will turn our attention to the second index disease that should, that you should know well, rheumatoid arthritis, the distribution of rheumatoid arthritis. As you can see in the diagram is different than that seen with osteoarthrosis. Rheumatoid arthritis involves the wrist and midfoot as well as the metacarpal phalangeal joints and the proximal interphalangeal joints of both the hand and the foot. Additionally, rheumatoid arthritis has a high proclivity for the cervical spine without the affecting the rest of the spine. It likes the shoulder, the elbow, the hip and the knee. However, this disorder is diagnosed by changes most commonly found in the hand and foot in rheumatoid arthritis, synovial hyperplasia causes cartilage damage with marginal erosions at the bare areas of bone, which we mentioned earlier in this talk, predominantly in the metacarpophalangeal joints, the wrist and the proximal interphalangeal joints. The distal interphalangeal joints are not affected. No bony proliferation is noted clinically, rheumatoid arthritis usually starts to develop between the ages of 40 50 rheumatoid factor and anti CCP are most often positive because this is a systemic disease. It has a symmetric pattern and usually begins in the appendicular skeleton. Now, if we pay attention to our, our mnemonic and we go through the different findings, articular changes consist of erosions typically at the bare areas of the joint which is not covered with articular cartilage. In later stages, we may see bony deformity. The bones demonstrate periarticular osteopenia. This is because synovial inflammation causes hyperemia at the affected joints. And this hyperemia washes out the bone adjacent to the joint. There is no prudent production or proliferation in rheumatoid arthritis. During the active phase. The cartilage of the joint demonstrates uniform cartilage destruction. The distribution is bilaterally symmetric and peripheral as in the diagram above. The extra findings are that of systemic autoimmune inflammatory disease that affects many organs such as the lungs, the skin, the eyes or the heart, soft tissue swelling also will be seen demonstrated by fusiform soft tissue swelling about the joints, rheumatoid nodules and joint deformity. We will see these changes as we move forward in this lecture. I will now show you multiple examples of the findings noted in rheumatoid arthritis. In this radiograph, we see typical marginal erosions and joint space, narrowing of the metacarpophalangeal joints. Three through five indicated by the black arrowheads also note the uniform joint space narrowing of the metacarpophalangeal joints, the proximal interphalangeal joints only show minimal joint space narrowing. These are images of the hands in end-stage rheumatoid arthritis. We can see severe erosive changes and ligamentous laxity with destruction causing dislocation of the metacarpophalangeal joints. Scapholunate dissociation indicated by the white arrow is a common finding due to diffuse carpal inflammation that inflammation causes destruction of the six small ligaments between the scaphoid and the lunate. And the destruction of those ligaments causes separation of the bone rheumatoid is one of the two diseases that causes changes in the radiocarpal joint. In rheumatoid, we see joint space narrowing without sclerosis or osteophytosis. In CPPD crystal deposition disease. As I have said before, the radiocarpal joint shows degenerative changes with joint space narrowing, sclerosis, subchondral cyst formation and osteophyte formation. This is not seen in rheumatoid arthritis, erosions of the distal ulnar styloid can also be seen in rheumatoid arthritis. This is indicated by the light blue arrow. These erosions are important and they may be one of the first signs we see in early rheumatoid arthritis. When I look at a case of r uh hands with early rheumatoid arthritis, I first look at the ulnar styloid, then I look everywhere else. If there's erosions in the ulnar styloid, then it's most likely rheumatoid. Here is a nice example of rheumatoid arthritis in the feet, erosions in rheumatoid may occur in the feet at the fifth metacarpophalangeal joint as we see here. So if you have hands and feet. Look to the ulnar styloid and look to the head of the fifth metacarpal and that should give you your diagnosis. Remember that when you look at the hands and feet, you should check these areas. Soft tissue changes in rheumatoid arthritis are often seen at various joints. Rheumatoid nodules are firm masses that appear subcutaneously in up to 20% of patients with rheumatoid. These nodules usually occur adjacent to overexposed joints that are subject to trauma or pressure such as the finger joints and the elbows. Here we see radiographs in elbow. In a patient with rheumatoid arthritis, notice the masses at the olecranon and immediately indicated by the arrows. Observe that they are the same density as muscle as opposed to gouty to five, which demonstrate a denser an interior structure. Atlanto axial subluxation is an important finding in the in rheumatoid arthritis which is seen in the cervical spine. The cervical spine is a frequently affected area and can present as Atlanto axial subluxation or basal or evagination with cranial settling. CST A set occurs when the dens extends into the for and magnum. Atlantoaxial subluxation is an important and potentially life-threatening complication. It is defined when the space between the dens of C two and the arch of the atlas exceeds more than three millimeters in width. It is caused by inflammatory ligamentous laxity instability in this joint may result in numerous neurologic symptoms because of the compression of the spinal cord patient is ac two lateral images of the cervical spine. The left image is in extension and the right image is in flection. Notice that in extension, the anterior arch dense distance is difficult to measure. It almost looks like they're laying against one another. However, in flection, the distance increases to 14 millimeters. The norm in adults is about three millimeters. Here is the lateral view taken from a computed tomography image of the cervical spine, basilar invagination also called cranial settling or basilar impression occurs in 5 to 10% of patients with cervical rheumatoid arthritis in basilar invagination, the odontoid process projects into the foreman magnum limiting this space for the spinal cord. Clinical presentations range from chronic headaches, limited neck motion to acute neurologic deterioration because of spinal cord and brain stem compression which can lead to paralysis or even death if the neck is moved in certain positions. The next lecture will be a continuation of the target approach to arthritis. We will discuss many entities and you will see lots of images. I hope you've enjoyed this presentation and have taken away some good pearls about these two important entities. I hope that this has helped you learn these entities so you can at least differentiate these two which will put you on the path of being able to differentiate other arthritides. Thanks for your time. Any questions, are they allowed to ask questions? Are they able to ask questions? Can you still hear me. I hope anyway, this is the end of the lecture and thank you all for joining. Please tell your colleagues about this lecture series so they can take advantage of it as well. I would have liked to have had more people attending so that I don't have to do them so frequently. But that's perfectly fine with me. I don't mind talking. All right, have a lovely Sunday afternoon and please all take care. There we go. Am I still alive or am I out? See Phil or I'm in? Am I out? Oh, ok. Well, you guys can go on. I'll just shut down the system. Hi, Phil. Hey, Dennis. How are you doing? Can we, can you, what do I need to do to just be with you? Uh, at the bottom of your screen you see three little dots. Yes, you click the three little dots and then stop broadcast.