 Hello everyone. So this is going to be a presentation which I'm going to do right now on the recent advances in prosthesis and I hope that I will be able to take you through some of the slides as swiftly as possible and give you a brief idea about what to see and what to expect when you're looking at prosthesis while doing radiological imaging. By the way to introduce myself I'm Dr. Shion from Tata Medical Center Kolkata. I'm doing fellowship here. Before we start what is a prosthesis? A prosthesis is basically just defined as an artificial substitute or a replacement of a part of the body such as a tooth, eye, a facial bone, a hip, knee or another joint. It is basically an artificial extension that replaces a missing body part. So what are the indications for a prosthesis? Now a prosthesis can be used for three major indications. These are basically a bone tumor which can result in amputation resulting in the loss of the normal limb function of the patient, degenerative joint diseases which need a replacement by a prosthesis and peripheral vascular diseases which again result in loss of limb function necessitating the use of a prosthesis. So first of all what is the imaging that we do for malignant bone tumors while utilizing prosthesis? So staging malignant bone tumor primary bone tumors requires both intra and extramarillary involvement evaluation. So intramarillary extension includes an assessment of the longitudinal extent, epifacial involvement as well as the skip metastasis. Extramarillary extension basically provides an assessment of the muscle compartments and the joint feasibility which helps in the movement of the joint. When a bone tumor is encountered in a skeletally immature child, we have to evaluate the growth plate and epifaceous as well. Indeed, fasciospary may be significant to the very young in whom growth is essential. Joint involvement requires extra-articular resection therefore it is essential to assess the presence of intra-articular masses or focal replacement of intracinomial fat. Finally, a pathological fracture is taken to confirm the joint contamination as it is equivalent to extra-compartmental extension. So these are the things that we should keep in mind or we should evaluate while we are looking at a bone tumor initially. So just to give a startup, this is an aving sarcoma in a 10-year-old boy where the fast spinico inversion recovery sequence shows the medullary extent of the lesion and as we can see in the coronal image going to the contrast between the growth plate and the tumor, we can see that there is some fascial involvement. So fascial involvement should always be accurately assessed since it influences the surgical strategy. Another example of skewed lesion is a medullary hyperplasia. This is a tumor-invited image where we can see there is a black arrow which is recognizable distal to the tumor and as a result of the signal alteration which is caused by medullary hyperplasia. The low signal is pronounced and it has got a blurred margin. So now coming to the main part that is what are the components of a prosthesis. Prosthesis has some basic components. These basically include a socket which is basically a plastic receptacle where the residual limb discontain, an appendage which may be a hand or a foot depending on whether it is the upper limb or the lower limb, a joint which is basically the connection between the appendage and the main proximal part of the limb. It can be the wrist joint, the elbow joint, the shoulder joint or the ankle joint or the knee or the hip for that matter and a connecting module that connects the appendage and the joint to the socket. So what is a shank? A shank is basically a substitute for the human leg. It helps in restoring the length and shape and is located above the foot ankle assembly. It can be below the socket in case of trans tbl prosthesis and there are two types of shanks. One is the exoskeleton shank, other is the endoskeleton shank. Now coming to the types of prosthesis. First of all we can have an endoprostesis. So as we can see in this image there are two prostheses which we can see one is for the humerus that is the upper limb and there is one the femur that is the lower limb. Both are endoskeleton prosthesis where we can see the receptacle is placed within the residual part of the bone where the rest of it has been amputated and there is an articulation which is present with the joint where we can see the fixators placed within the joint cavity. Self-expanding prostheses. Self-expanding prostheses basically works in the principle of expansion on its own and it is one of the most common types of prostheses that is used which helps in proper functioning of the limb even after the amputation or the removal of the original limb has taken place. So what are the uses of the socket? A socket helps in maximum distribution of the load. It helps in venous blood circulation and it also provides a tactile feedback. Now tactile feedback is important since that will help in the individual to properly assess the position of the artificial limb and change himself or modulate his actions accordingly and it has also got some reliefs and build-ups. Patellar tendon bearing socket has a prominent indentation over the patellar tendon. So these are some images that I've collected to give an idea about how these components look. As we can see there is a hard socket. There is a hard socket with a pellite liner. Now patellar tendon bearing socket as we can see it is impending on the patellar tendon as mentioned earlier. It is used for the lower limb basically for the knee joint and patellar tendon bearing socket can be supra condylar as well as supra patellar in nature. Now this is for the elbow as we can see above elbow prosthesis then we have the above knee prosthesis as well as the below the knee prosthesis. These images may help in understanding how the hardware is basically where we can see flexible inner liner socket, a laminated frame and the bionic knee in the case of the above the knee prosthesis. There is a microprocessor as we can see in the image which helps in sensing the movement and gives the necessary tactile feedback to the individual. Also we can see there is a shock absorber which is used for below the knee prosthesis. So this is again just a depiction of the components of the prosthesis. This is basically a mammary-based prosthesis where we can see an acetabulum as well as the femoral stem. There is an acetabular liner which is placed within the acetabular cup. It helps in proper articulation between the main femoral stem and the acetabulum and helps in proper movement to take place at the joint that is the hip joint for this case. Now the acetabular liner can be made up of various components. It can be a cemented type or a cementless type and it can also involve the cementless type of the femoral prosthesis articulated in the cemented type of the acetabular cup and all these have got various nuances and complications attached to each of them. I'm not going to discuss them in lot of details because that may be too much to cover within this span of time but still this gives us a broad idea about what are the basic components which we will see if we can dissect the prosthesis and make out the individual hardware. This is the imaging depiction of the mammary-based prosthesis as we can see which has been placed in the right hip joint in this patient as we can see that there is an acetabular cup along with the part of the femoral stem and there is a lining which is placed in the inner side so one is cemented and the other is non-cemented. So these are the groin zones which we have to keep which we have to look at probably when we are evaluating a limb after the placement of the prosthesis. So we have to keep in mind that there are some complications that can occur after the placement of the prosthesis one of which is basically loosening. We can divide the joint into these three quadrants as we can see in the image on the left hand side of the screen where the anything in zone one is considered to be normal but in zones two and three if there is any kind of loosening or any kind of a lucency that is seen between the prosthesis and the main limb then it is considered to be pathological. Again there is another type of division where we can see that they are divided into seven zones based on the femoral shaft again something in the region one is normal and the other parts is not considered to be normal. This is a depiction of the elbow prosthesis where we can see there is a prosthesis which has passed through the annus shaft and into the lower end of the humerus where we can see the articulation taking place at the elbow joint and this mode of prosthesis is used for considering the fixation of the elbow and helps in proper movement as well as mobility of the elbow joint after the patient has undergone a procedure or a prosthetic replacement for some reason. This is a prosthetic cap which is used for the medial femoral tbl joint where we can see the articular surfaces have been covered of both the medial condyle of the femur as well as the tbl plateau which helps in preventing frictional contact between the articular surfaces with each other and as we can see on the image on the other image on the left hand side there is a reduction of joint space that has taken place in this individual probably due to some underlying joint disease or degenerative condition and this processes will help reduce the damage that will be caused to the articular surfaces and helps in better preservation of the joint functions. Again coming to the hardware components so this is the metal tbl component as we can see the patellar component the polyethylene which is placed inside the metal tbl component and acts as a liner metal condyle component which is placed in the femur and all these components together make up what is called the process. Now this much of hardware may be not necessary for a radiologist's point of view because we won't be looking at the hardware what we will do is mainly go into the imaging part and see that how this processes can be evaluated or how that can help in on interpretation of the images when a patient presents with a prosthesis and we have to image that patient. So as we can see in this image there is a shoulder prosthesis in this individual where there is a shaft going into the humerus and there is an articulation at the start of taking place with the glenoid cavity on the right side. Again below the ankle prosthesis where we can see the taller dome as well as the lower end of the tbl being covered with artillery caps. Same the ankle prosthesis which I just showed on the x-ray the components there is a tbl plate there is a taller component there are some mobile bearing which are present between the two components and these bearings help in the smooth functioning of the striker at the ankle prosthesis and helps in the movement of the ankle joint. Now coming to the one of the most important parts of this presentation so what are the complications that we need to be careful about when we are dealing with a patient who has undergone a prosthesis. So there are some certain complications the most common is metallosis, particle disease, infection, loosening, tendon injury and muscle injury. So this is an example of a metallosis where we can see that there is a lobulated T2 hypo intense lesion or a structure which is seen adjacent to the joint and we can see that there are some hypo intense components which are also seen lining the lobulated cavity. So this is typical example of metallosis which is basically seen in certain cases of prosthesis especially with cobalt chromium alloy usage in the prosthesis. It is basically hapten mediated hypersensitivity reaction which is adjacent to the joint and can be seen in the case of a prosthesis especially if the metal alloy is used at cobalt and chromium we need to be on the lookout for this and need to identify this. We need to differentiate it from the other possibilities like maybe infectious causes or other more sinister complications that can occur. So the typical feature is the T2 hypo intensity which we can see and it is like a globular in shape and this probably gives us a good idea that this can be considered metallosis which is an aseptic condition and need not be confused with infection. Particle disease. Particle disease is a synovial inflammatory reaction which basically occurs secondary to the prosthesis placement. Unlike the previous example which was basically a hapten mediated hypersensitivity reaction, particle disease is not like that. Particle disease is basically when after placement of the prosthesis there are certain destructive processes that come into play and that results in the formation of a fluid like T2 hyper intense lesion which we can see adjacent to the joint as we can see. So the main differentiation which we can probably do is based on the signal intensity as we saw in the last case a metallosis is T2 hypo intense whereas a particle disease will result in the formation of a T2 hyper intense lesion. Both these conditions are related to particular use of metal prosthesis and are peculiar to those peculiar to them. This has got no such correlation with cobalt chromium alla usage as we saw in the last case. So this is separate from that and this also needs to be kept in mind when we are dealing with the prosthesis. Lucene is basically a lucency or a demarcation that appears between the parent limb or the residual limb and the prosthesis. It can be seen as a hyper intense linear demarcation if you are using MRI for T2 weighted image or for that matter fat suppress sequences. If you are using an X-ray we will see it as a lucent lining which will cross two to three millimeters in width and that should always indicate that there is a possibility of lucenine taking place and we have to make sure that we inform the findings to the orthopedician in case the lucenine results in the dislodgement or the prosthesis is not properly lodged within the joint and it cannot serve as proper function. Infection is obviously what we know infection can happen so the key is not to confuse the other complications with infection. Infection will have subcutaneous edema as we can see on the stir sequences. It will have joint diffusion as we can make out and like I told earlier the signal intensity of the subcutaneous tissue and the joint diffusion along with the marrow edema or the edema in the surrounding bones will probably point towards the possibility of an infection rather than the other complications that have been discussed earlier. Infection obviously needs an urgent action we have to inform the clinician and suggest proper antibiotic usage to prevent it from going further and further complicating the scenario. So basically this is just a gross flow chart that can be used so history of pain discomfort then we can go for serology ESRC reactive protein total wild blood cell count and a radiograph. Normal criteria of infection low probability of infection so first we have to see if there is any raised major criteria of infection. If there is a major criteria of infection the further imaging should be done in the form of bone scan CT scan or if necessary a biopsy for that matter. If there is a low probability of infection we have to go for the component position. If it is satisfactory then we have to think of radiographic osteolysis. If there is no osteolysis seen on the normal X-rays then we have to go for CT MRI meta-iron measurement if necessary. Now if there is loosening of osteolysis the further imaging needs to be needed using Mars protocol MRI CT aspect CT and finally we have to diagnose the presence of osteolysis inform the clinician whether the implant is stable or unstable that is the key. If it is stable then we can follow it up if it is unstable probably needs some inter intermission on the part of the clinician. So quickly going through the drawbacks so there are some drawbacks which we come across when imaging metal processes one is the metallic artifact production some the metallic process magnetic process not suitable for MRI because the MRI can cause hitting of the implants which can cause tissue damage and also it can cause migration of the implants. This is an example of streak artifacts that have been that have resulted from the usage of bilateral hip processes in this patient as we can see the image is very poor and we cannot discern anything within the pelvis for that matter. Again artifacts resulting from the use of processes when MRI there is a lot of hypo intense metal artifact production as we can see in this image as a result the joint cannot be visualized properly and because of this artifact the evaluation will not be properly done. So this is just a gross protocol which we can use where we can use the fast pinnacle T182 image so the types of metal artifacts that we should be kept in mind in plane distortion and signal loss poor or absent fat suppression geometric distortion and two section distortion. Now what are the remedies quickly some few points to keep in mind high bandwidth can help in reducing the artifacts as well as stopping the frequency encoding and the phase encoding directions we can use pinnacle fast pinnacle instead of GRE because that also reduces the artifacts you stir instead of spectral fat suppression because spectral fat suppression will not be properly applicable if we are using metallic processes since that can result in lack of homogeneity and thin sections are also helping this matter. There are some special sequences like Mars Maverick CMAC probably I'll just go through them briefly this is a VAT view angle technique where we can see the readout direction is altered so that the view angle tilting helps in reducing the artifacts from the metallic processes. Mars protocol just a overall tabular representation of which are the sequences and what are the various timings. CMAC is slice encoding metal artifact reduction technique which is another technique we use by different vendors which helps in reducing artifacts and we can understand how the frequency encoding direction is changed and it helps in altering the readout gradient so that artifacts are reduced. Maverick another technique similar to that which also helps in reducing the artifacts in the frequency encoding direction by providing repeated excitations and then reading them out in a swift fashion so that the artifacts in the final image are reduced. The common metal suppression sequences according to the various vendors of Mars which is the most commonly used clinical man warp which is used by Siemens, CMAC again used by Siemens and Maverick which is used by GE. So these are the basic techniques they use I'm giving them in tabular format high bandwidth is used by warp CMAC uses back folding of the off resonance signal and Maverick uses particularly non-selective excitation. Now the complications lastly to round it off it can be metal suppression can have certain complications like specific absorption rate in increased imaging time specific absorption rate will probably increase the heat caution and increased imaging time will increase the duration of the study. So this is just a quick idea of how useful these sequences are as we can see there is the image in the middle is poorly discernible because of the artifacts of the metal used in the lower end of the femur however after using of the Mars technique it we can see that the margins of the femur are better visualized because the metal artifact reduction has taken place. Another example with metal artifact reduction technique where the right shoulder in the first image is not that clearly seen but in the second image is much better seen because we have used metal artifact reduction techniques. Similar application can be done in case of vertebral imaging also where the speed encoding and corresponding Maverick sequences so significant reduction of metal artifact reduction and also helps in interpretation whether there is any disc herniation or not in this particular patient. In a sacroiliac joint also similarly we can use whether the screw fixation has been done and following that we have imaged with the help of Maverick to see for better depiction of the adjacent end of the cord and also to visualize whether there is any complications taking place at that particular joint. So these are my basic references hope I was able to give you some kind of an idea about processes thank you so much for watching that's it for now.