The center of rotation of the femoral head should be at the level of the tip of the greater trochanter. Avulsion injuries of the pelvis are a frequent cause of hip pain in adolescents involved in sports. , since the apparent degree of angulation on a radiograph is affected by pelvic or thigh rotation (figure). This article is based on a presentation given by David Rubin and adapted for the Radiology Assistant by Robin Smithuis. Corner- or bucket handle fractures should raise the suspicion of non-accidental injury (NAI)See section on child abuse. (6a) A T1-weighted sagittal image in the same patient confirms the crescentic subchondral area of AVN (arrow) present at the anterior-superior femoral head. On imaging, the radiographs and computed tomography (CT) will show an area of focal demineralization of the femoral head (Figure 17-2A), which may be subtle, but once the patient is imaged by MRI, the findings are usually readily apparent. An associated stress fracture (arrowhead) is noted within the femoral neck. The initial postoperative films are obtained to look for possible dislocation or fracture and to see if the prosthesis is good positioned. {"url":"/signup-modal-props.json?lang=us"}, Khan Z, Avascular necrosis - hip joint. Pediatric imaging: the fundamentals. T2-weighted fat-suppressed sequences are useful in assessing for edema. MRI will show marked edema in the femoral head and neck, which is manifested by dark T1 and bright T2 signal (Figure 17-2B and C). Mitchell Staging System for AVN. Several samples should be taken to minimize confusion caused by skin contaminants. (B) and (C) Coronal T1 (B) and coronal T2 fat-saturated MR images (C) show that the osteoid osteoma is dark on T1 (arrow) with surrounding bright T2 signal from the edema. Signal changes compatible with occult left hip AVN (arrow) are noted on the asymptomatic contralateral side. 1 Although most are "idiopathic," predisposing factors may include previous trauma, collagen vascular disease, steroid usage, alcohol abuse, post-organ transplant, chemotherapy and radiation therapy, and . The hip joint is a ball and socket type of joint that is also the deepest joint in the body. 12.1). Young children in particular may have difficulty localizing or communicating the location of their pain; and sometimes children who initially seem to have a hip problem actually have underlying pathology of the knee or foot. Aim The femoral head is the most common location for avascular necrosis (AVN). - Increased or decreased anteversion of the femoral stem. Sometimes an injection of local anesthetics into the hip joint might be required to help diagnose the actual source of the patients pain. In such cases it is wise to analyze their gait and image the entire extremity. Many patients with radiographically low-grade heterotopic ossification are asymptomatic. The x-ray is of a 15-year old with acute lymphatic leukemia who was treated with steroids. In pincer-type FAI, the acetabulum is too large for the size of the femoral head, which results in overcoverage of the femoral head. (A) Radiograph shows a prominent bone bump (arrow) just distal to the lateral femoral physeal scar. Stress loading distally may result in cortical thickening and bridging sclerosis at the tip of the prosthesis ( called pedestal). A key observation is that the marrow signal of the acetabulum is normal. All imaging studies should begin with radiographs that help differentiate many benign conditions at the outset from what might appear to be very confusing on magnetic resonance imaging (MRI) studies. FIGURE 12.1 Magnetic resonance imaging of the bilateral hips demonstrates abnormal serpiginous signal in the bilateral femoral heads and necks on (A) T1-weighted and (B) T2-weighted images, consistent with avascular necrosis and bilateral bone infarcts. Abundant cement packing leads to loosening. T2 weighted images: The subchondral lesion shows a high signal intensity inner border with a low signal intensity peripheral rim. - Excessive lateral positioning of the acetabular cup The two main types of FAI are the cam type and the pincer type, although there may be overlap between the two. Nuffield Sclerotic and/or cystic changes in the bone with a deformed femoral head may be evident. In children from 2 to 10 years old with symptoms less than 5 days, and in the absence of high fever or elevated inflammatory markers - a wait-and-see policy is recommended. As migration can be very subtle, it requires carefull comparison with the initial postoperative films. Recombinant human bone morphogenetic protein (rhBMP) has been used as an adjuvant therapy to core decompression. MRI will also demonstrate the joint effusion and synovial thickening, but can also show damage to the bone and cartilage. International Journal of Radiology and Diagnostic Imaging 2021; 4(1): 23-30 E-ISSN: 2664-4444 P-ISSN: 2664-4436 . Especially lucency in these zones is very indicative of loosening. Fellowship: NewYork-Presbyterian Hospital/Columbia University Medical Center, Fellowship: NewYork-Presbyterian/Columbia University Medical C, NewYork-Presbyterian / Columbia University Irving Medical Center, Columbia University Website Cookie Notice. The most important complications are mechanical loosening, particle disease and infection. The classic history is of a young patient (1020 years of age) presenting with pain, which is worse at night and relieved by aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs). Other findings that are often present in FAI are the presence of an associated labral tear and articular cartilage damage. Candidates with strong background and leadership in their research after their Ph.D. and have graduate-level teaching experiences will be preferred. There is an extra bump or mound of bone located along the lateral femoral headneck junction, which impacts against the labrum and the acetabular cartilage with movement. Note that the AVN of the right hip is very subtle on the radiograph, but clearly visible on the MRI. Axial oblique T1-weighted fat-saturated arthrogram shows measurement of alpha angle. In an effort to avoid these changes, most modern cementless prosthesis only have fixation proximally, so you usually will not find proximal stress shielding. This is termed the double-line sign, which may add to the specificity in the diagnosis of AVN. 2018 Turkish American Scientists & Scholars Association. Glatt, A. E., Melamed, E., Cohen, I., Robinson, D., Zimmerli, W., Trampuz, A. Often, though, this is a diagnosis of exclusion. Class C lesions have signal characteristics similar to fluid (low-to-intermediate signal on T1-weighted images and high T2 signal). The arthrogram is used to confirm intra-articular position of needle and fluid is aspirated for aerobic and anaerobic culture. Avascular necrosis (AVN) of the femoral head is a relatively common entity, affecting up to 30,000 patients in the United States annually, usually adults between 30 and 50 years of age. Although by the time the double line sign is visible, this is very late in the disease process. Juvenile Idiopathic Arthritis (JIA) is a clinical diagnosis and is currently divided into six different subtypes. See the article entitled Knee MRI - meniscal pathology for the pathology of the meniscus. The inflammation of a joint in septic arthritis is bacterial and, as in osteomyelitis, is usually caused by Staphylococcus aureus. An angle greater than 55 is considered abnormal.15,16. Eleven specimens were obtained after total replacement of the hip. Most intraoperative fractures occur on the femoral side. Some theories suggest the edema and pain in the femoral head are related to trauma, and it is important to exclude an underlying fracture or AVN.68 So while we can recognize the entity on MRI, we are not sure of its true etiology. Cement extrusion is usually asymptomatic. Osteoid osteomas are benign tumors. Compare with the normal T1 and T2 signals in the femoral diaphysis. Avascular necrosis of hip was the most common with 40 patients; out of which . However, transient osteoporosis is confined to the femur so the acetabulum will have normal signal, which can be a clue that can help to separate it from infection. 1 Bluemke DA: Avascular necrosis of the hip: MR evaluation. (A) Sagittal reformatted CT shows a small oval lucent lesion (arrow) with a central calcification in the nidus in the left anterior superior iliac spine. OptiWisdom is a company that targets data - based projects in the sector; hosts data science, big data analytics, artificial intelligence and big data based projects; and provides education . Typical avulsion injury of the anterior inferior iliac spine at the insertion of the rectus femoris tendon. This review focusses on all the non-meniscal pathology of the knee. Etiology can be remembered by the following mnemonic: You can use Radiopaedia cases in a variety of ways to help you learn and teach. What is the unexpected finding and what is the diagnosis? MRI shows marked marrow edema in the femoral head and neck. Fractures during follow up are a result of loosening, particle disease, infection or severe cases of stress shielding. The typical age at presentation is between 12-15 years. Early detection of hip AVN is critical, as all treatments geared towards preservation of the femoral head are more successful early in the course of the disease. Insights imaging 3(1):23-32. Even when the diagnosis is made, there is controversy within the orthopedic community as to when and how to proceed with treatment.12. There is also joint space narrowing and articular cartilage damage. Shimizu et al. In disease progression, fragmentation and collapse of the femoral head will occur. This modularity allows for greater flexibility in customizing prosthesis sizing and fit. Evidence of polyethylene wear, which appears as asymmetric positioning of the femoral head within the acetabular cup, often coexists with particle disease. This defect is filled with bone chips, cement or bone transplant. The initial films serve as a baseline study and are used as reference films for comparison with all future studies, since sequential radiography is the most valuable method for detecting complications. This remoulding of the cup is called creep. Many authors feel that AVN results from an acute interruption of blood supply, as is seen with trauma, thrombosis, or embolization. Children with hip pathology may present with hip pain or a limp. The case on the left shows progressive subsidence, which is diagnostic for loosening, with subsequent break of the screws. A lucency at the metal-cement interface along the proximal lateral aspect of the femoral stem may be seen on the initial postoperative radiograph as a reflection of suboptimal metal-cement contact at the time of surgery. (5a) A T1-weighted coronal image demonstrates a ring-like subchondral area of AVN (arrow) present in the anterior-superior femoral head. This overview focusses on the normal findings and complications of cemented versus non-cemented hip arthroplasties. Component dissociation, as opposed to component fracture, most commonly develops when the plastic liner of the acetabulum slips from its backing. Infection is often low grade and is difficult to detect with any imaging method. Interested readers are referred to the references at the end of the chapter for further studies. Depending on whether or not there is spontaneous revascularization, the disease may or may not progress. Initially, radiographs may be negative; findings of AVN appear on standard radiographs several weeks later. This fibrous tissue presents as a lucent zone at the interface. In cemented THA ideally you would not expect any lucencies at the bone-cement or cement-prosthesis interface, but even in stable cemented prostheses they do occur. There are many bone tumors and tumor-like lesions that may cause pain in the hip or upper leg. Early radiographs may be normal or show subtle flattening of the femoral head. The main differential diagnosis to consider is a focal infection or Brodie abscess. Large joints are mainly affected, including the hips. 91 followers 84 connections Grade II = bone spurs leaving > 1 cm between opposing bone surfaces. Affected children are only mildly ill or have recently sustained a low grade respiratory tract infection. Particle Disease is relentlessly progressive with loosening, fracture and destruction of bone. It can be a normal variant caused by nonunion of the os acetabuli with the os pubis during childhood.18. Radiologists are sometimes asked to quantify the degree of a morphologically abnormal appearing proximal femur. Osteonecrosis of the femoral head (AVNFH) causes loss of integrity of subchondral bone structure due to abnormal microcirculation. or prior surgery. In case of suspected pathology on the frog-leg lateral view, an additional AP radiograph should also be acquired for orthopedic and follow-up purposes. Figure 17-5. - Inflammation on pathological examination of periprosthetic tissue. About Hong Yun Ma, MD. The process is usually self-limiting with resolution of symptoms in 68 months. If it becomes symptomatic, hip stiffness is the most common complaint and pain is rarely a problem. The images alone cannot differentiate from Perthes disease, but based on the clinical information, this is secondary avascular necrosis. The normal acetabulum is anteverted, which means that the opening of the acetabulum is more anterior. The femoral part is composed of a metal stem (chromium cobalt or titanium) and a femoral head of metal or ceramic. For select candidates with positions at overseas institutions, adjunct positions might also be considered. Then we scan the affected hip in axial T1-weighted or proton density and fluid-sensitive sequences. Patient presented with bilateral hip pain. Overall there is a tendency to use preferably non-cemented THA, which have better longterm results. AJR 2003 Aug; 181: 545-549. This line is also used to measure any leg length discrepancy. In all other cases x-ray imaging should be performed. AVN of the hip is a significant cause of morbidity in the United States, and can affect patients both young and old. As cemented acetabular components have a tendency to loosen over time, the combination of a cementless acetabular component with a cemented femoral component is sometimes used. During surgery, the surgeon removes a sample of dead hipbone and inserts stem cells taken from bone marrow in its place. When the acetabulum is prepared for placement of the cup a perforation may occur. Sclerosis and subchondral fractures may develop, features best appreciated on the frog-leg lateral view. In some atypical situations an abdominal ultrasound may therefore be of value. Bone marrow aspirate and concentration is a newer procedure that might help avascular necrosis of the hip in early stages. If we look at the same radiographs and we use the tear drop figure as a landmark, the migration becomes more evident. The most common radiographic manifestation of loosening are: - Lucent zone > 2 mm at interface (indicative) They develop at the anatomic site where impingement occurs. Eda AKSOY, ASSISTANT DIRECTOR | Cited by 134 | of Republic of Turkey Ministry of Agriculture and Forestry, Ankara | Read 51 publications | Contact Eda AKSOY Originally this was called cement disease or aggressive granulomatosus. Measurement with CT is more accurate, but you still have to compensate for pelvic angulation. This angle is called the alpha () angle and can be measured on a radiograph or an MRI (Figure 17-4B). In your report always indicate which zones are involved (figure). Exact measurement of this angle on a cross-table or true lateral radiograph is not possible Arthrography and painfull hips Migration of acetabular components is never acceptable. resulting in cup and cement fracture. Bone marrow edema syndrome (transient osteoporosis) is characterized by rapid demineralization of the proximal femur. Sometimes revision of a stable THA is needed because more bone loss would make revision surgery impossible. Class D lesions have signal characteristics close to fibrous tissue being dark on both T1- and T2-weighted sequences. Surgical reconstruction (Salter osteotomy) may be required to prevent early osteoarthritis. Stage 2: The femoral head develops cystic and sclerotic changes, which are apparent on standard radiographs. It does not show progressive collapse or deformity over time and is symmetric. FAI. Lack of abnormal contrast extension does not exclude loosening as fibrosis and cells may fill the interfaces preventing contrast passage. Coronal T1-weighted fat-saturated arthrogram shows a labral tear (arrow) in a patient with impingement morphology. The sensitivity for infection is 66-90%. In the Mediterranean and in Southeast Asia, the highly prevalent thallassemias are a major cause. Dislocation can occur as a late complication in prostheses that are not well positioned, but it is most common in the immediate postoperative period (incidence 3%). Dr. Shifali Dumeer is board certified in Diagnostic Radiology with sub-specialty training in Abdominal Imaging, Nuclear Medicine/PET, Cardiothoracic Imaging and Neuroradiology. Sometimes arthrography is used to find out, if the patients symptoms subside by putting in a long lasting local anaesthetic. Some of the non-cemented THA have femoral stems with additional hydroxyapatite coating It occurs more commonly in boys and in obese children. MRI allows sequential evaluation of asymptomatic lesions that are undetectable on plain radiographs. One should also remember that any unexplained hip pain without any apparent radiographic findings is an indication for MRI if the pain does not resolve within a week. Stress shielding proximally may result in proximal osteoporosis and calcar resorption. The treatment is symptomatic. Grade IV = radiographic ankylosis of the hip. The risk of intraoperative infection is less than 1% due to the use of antimicrobial prophylaxis and laminar airflow surgical environment. Surrounding edema is visible as bright T2 signal on fat-saturated T2-weighted images. Small lesions confined to the medial anterosuperior portion of the femoral head tend not to collapse, and thus may be amenable to conservative therapy. This can be an even more difficult diagnosis to recognize than the cam-type morphology. It typically occurs around the femoral neck and adjacent to the greater trochanter and occurs in 15-50% of patients. Stem-fixation is also either with cement or cementless with porous coating for bone ingrowth. Osteoid osteomas are relatively common lesions, and can occur within the cortex and medullary portion of the proximal femur (rarely intra-articular). 2 Huang G-S, Chan WP, Chang Y-C, et al: MR imaging of bone marrow edema and joint effusions in patients with osteonecrosis of the femoral head: relationship to pain. The role of MRI in monitoring patients post surgically has not been clearly defined. It breaks the lesion down into class A, B, C, and D (Table 17-2). This is the typical appearance of a herniation pit, which can be a secondary sign of FAI. There is loss of T1 high signal of the fatty marrow due to edema and sclerosis. This classification may be useful in grading lesion acuity, as infarcted bone will tend to progress through the classes of signal intensity over time. More study is needed. Herniation pits are thought to develop from repeated stress, although they are not always associated with FAI.19,20. It is therefore best appreciated on the frog-leg lateral view. Radiology 1987 Mar; 162(3): 709-15. It is calculated by drawing a line from the center of the femoral head to the beginning point of the bump at the headneck junction, and a line bisecting the long axis of the femoral head and neck. - Screws are positioned too horizontally (too much stress). The diagnosis of FAI should only be made in combination with an orthopedic surgeon and take into account not only the imaging findings but also the clinical symptoms of the patient. Typical avulsion injury of the right ischial aphophysis. Molecular Biology (preferred experience in basic research on biological processes). Transient synovitis - also known as coxitis fugax - is an aseptic inflammation of the hip, presumably of postviral etiology. Class A lesions have signal characteristics that are similar to fat, which will be high on T1, and intermediate on T2-weighted sequences. Absence of joint effusion excludes septic arthritis. AVN may be classified into four different stages: Stage 1: Standard radiographs are normal, but early AVN is detectable on MRI. Contemp Diagn Radiol 1996; 19: 23. The small wear-particles of the polyethylene liner are shed into the joint fluid and can be transported around the prosthesis through small channels even in stable hips. In trauma, the culprit can be disruption in the blood supply; in lupus, the etiology may be due to vasculitis; and in steroid use the etiology may be due to hypertrophy of fat cells leading to venous compression and then infarction.1,2 Table 17-1 lists common causes of AVN. Stage 3: The crescent sign is identified as a sclerotic rim along the femoral head. In acetabular retroversion, the opening of the acetabulum is directed more posteriorly. Typical findings in later stages of the disease may be a slightly larger epiphysis, or accelerated bone maturation. For existing patients, login to make an appointment, view documentation or contact your doctor's office. The site of necrosis is usually immediately below the weightbearing articular surface of the bone, most commonly at the anterolateral aspect of the femoral head. It is important to realize that early in the course of Perthes disease, juvenile idiopathic arthritis, osteomyelitis and septic arthritis, the initial radiographs may be normal. Moreover, it is associated with pain-limited range of motion and gait. Subcondral fracture, best appreciated on the frog-leg lateral view. The condition is self-limiting and treated with rest and analgesics. Do not just compare to the prior examination. - revision hip arthroplasty: 7.2% Affected children are ill, with fever and severe joint pain. Component fracture is uncommon. Radiography is only performed when there are other differential diagnostic considerations. Most cases are hematogenous, and may be a sequela of a respiratory tract infection. when the anatomy is abnormal as in hip dysplasia. The selected candidates will join the small number of faculty of the newly established Institute. Arthrography plays a role in the evaluation of possible infection. - Lucency in zone II and III > 2 mm. Numerous studies have demonstrated that MRI is highly sensitive, specific, and accurate in the detection of AVN. - Too much lateral inclination. In non-cemented THA arthrography is not accurate for the detection of loosening, as small channels between bone ingrowth may persist allowing contrast-passage in stable hips. Clinical History: A 62 year-old male with a history of right sciatica and previous right femoral head core decompression for avascular necrosis (AVN) presents with recurrent pain. About Shifali Dumeer, MD. Publicationdate 2006-02-01. (B) Coronal T1-weighted MRI shows T1 dark serpentine lines in the femoral head, which extend to the subchondral surface. (see Table 1) describes four classes of AVN based on the signal characteristics within the center of the lesion on T1 and T2-weighted images. Clinically occult left femoral head avascular necrosis (AVN). 4 Lafforgue P, Dahan E, Chagnaud C, et al: Early-stage avascular necrosis of the femoral head: MR imaging for prognosis in 31 cases with at least 2 years of follow-up. but they tend to be a bit more specific compared to normal Technetium bone scan. This is becoming a more common diagnosis as knowledge of it spreads and the population becomes more physically active at a younger age. Mechanical loosening presents as diffuse lucency. The lines on MR images that demarcate AVN are serpentine on T1-weighted MR images. X-rays are usually negative early on in the disease. Methods: All lesions were confirmed by radiographic, radionuclide, computed tomographic, and/or histologic examination. by Bomer J, Klerx-Melis F, Holscher HC. Early AVN on MRI may manifest itself as marrow edema. Evaluate the TCO of your PACS download >, 750 Old Hickory Blvd, Suite 1-260Brentwood, TN 37027, Focus on Musculoskeletal and Neurological MRI, Gluteus Minimus Anatomy and Tear Patterns, Gynecological Findings Encountered on Musculoskeletal MRI, Postoperative Hip MRI in Patients Treated for FAI. Cement extrusion Septic arthritis can have a rapidly deteriorating course with destruction of the joint. Diagnostic imaging: pediatrics. Uniform criteria for the diagnosis of infection associated with prostheses have not been established. The only complaint can be pain. Risk factors for atraumatic AVN include alcoholism, steroid use, chronic renal disorders, sickle cell and other hemoglobinopathies, Cushing disease, Gaucher disease, and HIV. Interactive cases are presented in the menubar to test your knowledge on hipprostheses. In the healing phase, Perthes disease can lead to a short, broad femoral head and collum. Larger lesions with articular surface involvement are more likely to collapse and thus may warrant core decompression. Amirsys. This is an uncommon condition in which the femoral heads show delayed ossification and fragmentation, most often occurring bilaterally. It is very common to see radiolucency in zone 1, occasionally in zone 7, but it should not occur in the subtrochanteric region zones 2-6. If a bone scan is done, there will be increased uptake in the bone corresponding to the edema (Figure 17-2D). The case on the left shows a fracture of the metal head of the femoral component. In the end, associated conditions like sacral fractures and some basic concepts of pubalgia or sports hernias are discussed briefly. The value of high spatial resolution and contrast material-enhanced magnetic resonance (MR) imaging was assessed in 69 patients with either femoral head avascular necrosis (AVN) or transient bone marrow edema lesions. Patients with pulled groin muscles have pain and soreness over the adductor muscles and inguinal region. Click on the image to enlarge. Radiographic follow up and comparison with the oldest films available is the most valuable method of detecting these complications. It can be difficult to tell them apart as both may have surrounding reactive edema, and a Brodie abscess can have a central sequestrum, which mimics the central calcified nidus of an osteoid osteoma, although other features such as a sinus track or irregularity of an infectious abscess can help to separate the two entities. Periprosthetic fractures The linear high signal intensity inner line (arrow) and dark peripheral line (arrowhead) is typical. Once AVN develops, repair begins at the interface between viable and necrotic bone, with lymphocyte infiltration occurring early in the disease process. All Rights Reserved. A synovial herniation pit, or Pitts pit, appears on radiograph as an oval lucency that occurs at the anterior superior femoral neck junction (Figure 17-6). As the condition progresses, the sclerosis is caused by necrotic bone that appears more dense, and the necrotic bone diminishes in size and becomes even more sclerotic. . In an idealized body, the femoral head smoothly articulates with the acetabulum. Assistant Professor, Department of Orthopaedics &Trauma, Gauhati Medical College, Assam, India . Frontal pelvic radiograph shows marked atening and sclerosis of both femoral heads representing advanced (Ficat stage III) avascular necrosis. Dislocation can be in posterior, anterior or lateral direction. It is quite common to see a radio lucent line in zone I, but you shouldn't see it in zone II and III. One line is drawn down the midportion of the femoral neck, the other line from center of the femoral head to the junction of the femoral bump. (C). While trauma, steroids, and alcoholism predominate in the United States, in Africa, HIV infection and hemoglobinopathies are a significant source of AVN. Privacy disclaimer. (A) Radiograph of woman with SLE shows flattening, collapse, and sclerosis of the left femoral head from AVN. One method involves measuring the angle between the femoral headneck junction. An MRI scan produces superior anatomic delineation. The condition itself is asymptomatic and the joints will develop normally. The applicant(s) in one of the above interest will be selected and the selection process will continue until all available positions are filled. Class B lesions have signal characteristics that are similar to blood with high T1 and T2 signal. Sometimes a control perforation is placed by the surgeon during revision to aid in removal of the previously placed femoral component. Another case on the left. Most modern non-cemented THA have a femoral stem with only proximal coating, as this results in a better longterm outcome Especially if more zones are involved and if there is progression. The role of dedicated radionuclide techniques for infection such as gallium scanning or indium-labeled WBC or immunoglobulin G is not clear, The implantation of a bone ingrowth prosthesis results in altered stress distribution to the native bone, especially in the older models with non tapered and fully coated femoral stems. On the left another case with dislocation as a result of tilting of the cup due to loosening. It occurs more commonly in boys, typically between 5 and 8 years of age, but may range from the ages 3-12. Figure 17-6. The lateral epiphyseal arteries at the lateral aspect of the femoral neck (blue) are most vulnerable to mechanical stress. Progression to fragmentation and development of a short, broad collum. Since JIA is treated aggressively early on, radiographic bony changes may remain absent. The anteversion of the acetabular cup should be 5-25?. Cartilage may become hypertrophic on the affected side. Severe cases may require physical therapy. Eur Radiol 2014 24(3):703-8. Because at this age the tendons are generally stronger than the apophyses, strong muscle contraction can result in apophyseal avulsion fractures. Four hips underwent biopsy. The forces are transmitted through the relative stiff femoral stem and is seen as osteoporosis in the As mentioned previously, young children may have difficulty communicating the cause of their pain or limp. FAI os acetabuli. Septic arthritis is a surgical emergency. Women are more commonly affected than men. Endochondral ossification is abnormal and results in small, fragmented epiphyses with alignment abnormalities. The preferred position of the femoral component is with the stem centered in the femoral canal. Radiographically these aggressive granulomatous lesions present as focal radiolucencies around the prosthesis. Nowadays it is mostly seen in non-cemented hips as a reaction to small polyethylene wear particles. As discussed above, dislocation or subluxation of the components may occur because of patient factors including poor muscle tone or trauma or because of surgical factors such as a posterior (rather than lateral) surgical approach. Hyperemia, inflammation, and fibrosis are found to varying degrees, and this variability in part accounts for the changing appearance of hip AVN on MR images. 3 Bluemke DA, Zerhouni EA: MRI of avascular necrosis of bone. The images show Perthes disease of the right hip in a five-year old boy. This is to see if the painful hip is due to the prosthesis and not something else. Plain radiographs of the hip should be ordered, both anteroposterior (AP) and lateral (frog leg) views. The lines that demarcate AVN are traditionally seen and described as serpentine.3,4 As AVN progresses, there will be collapse of the femoral head (Figure 17-1A). Often there will be an associated joint effusion. On T2-weighted images, there may be a bright signal line that parallels the dark line, which is referred to as the double line sign, which has worked its way into the lexicon of classical findings in radiology (Figure 17-1C). Avascular necrosis (AVN), which is also known as osteonecrosis or aseptic necrosis, usually presents with complaints of severe hip or groin pain. Ultrasound can be helpful in the diagnosis in cases with subperiosteal abscess formation. Dr. Dumeer is a member of the Radiological Society of North America and the American College of Radiology. Radiography is the primary imaging method for the evaluation of Total Hip Arthroplasty. The normal Femoroacetabular joint is a ball and socket joint, with the rounded femoral head articulating in the cup of the acetabulum. The epiphysis slips posteriorly, and to a lesser extent medially. Please contact the doctor's office directly to verify that your particular insurance is accepted. Dislocation It is a subacute osteomyelitis with intraosseous abscess formation. Radiographs of all joints are required to establish the diagnosis. This is usually the result of severe degenerative changes or dysplasia. Slipped Capital Femoral Epiphysis (SCFE) or femoral epiphysiolysis is an idiopathic Salter-Harris type I fracture of the proximal femoral epiphysis. Fractures may be seen postoperatively in patients with poor bone stock and long stem revision prostheses or The case on the left is for several reasons not ideal : - High and very lateral positioning of the cup. Cam-type FAI can be thought of as a problem with the femoral head, while the pincer-type FAI is more of a problem with the acetabulum. This is easier to recognize on CT; looking for this finding on a radiograph can be difficult as precise positioning is needed.17. The clinical profile, laboratory findings and the presence of a joint effusion are suggestive of septic arthritis. In infants or young children in whom the location may be uncertain, bone scintigraphy can be useful. The images show right-sided Perthes disease in a nine-year old girl. The older term used to describe this condition was transient osteoporosis of the hip, a newer term that is used in bone marrow edema syndrome. Late infections are acquired by hematogenous seeding from respiratory tract, dental and urinary tract infections. Early AVN of both hips. Joint space narrowing and osteolysis will become visible in later stages of the disease. This might allow new bone to grow. Children with cerebral palsy are at an increased risk for hip dislocation, and in these cases an AP-view is recommended. With disease progression, articular surface collapse and secondary osteoarthritis develop, and the end result in many patients is total hip replacement. - press fit prosthesis: 2.5% The planned presentation should include their expected growth strategies focusing on one the research interest areas given above, highlighting the synergy with the current strengths of the University. Beykoz Institute of Biology and Biotechnology (BILSAB) at Bezmialem Vakif University, is seeking to fill tenure-track faculty positions. This overview focusses on the normal findings and complications of cemented versus non-cemented hip arthroplasties. Gonadal shielding is dissuaded for the following reasons: Note: as this is a relatively new insight, some of the images in this article do still include lead shielding. Orthopaedic Centre and Oxford Radcliffe Hospital, Oxford, UK, Complications of total hip arthroplasty. The transischial line is used as a reference to measure the lateral inclination of the acetabular cup (30-50?). This is why surgeons are more and more reluctant to use screws for the fixation of acetabular cups. Again there is focal osteolysis around screws after migration of wear particles through the screwholes. Saleh, KJ, Kassim, R, Yoon, P, Vorlicky, LN. A magnetic resonance imaging (MRI) scan of the hip shows classic features of avascular necrosis of the femoral head (AVNFH) with collapse. The distance from center of the femoral head to teardrop (or other identifiable landmark) should be equal bilaterally. Dr. Shifali Dumeer is board certified in Diagnostic Radiology with sub-specialty training in Abdominal Imaging, Nuclear Medicine/PET, Cardiothoracic Imaging and Neuroradiology. Click to share on Twitter (Opens in new window), Click to share on Facebook (Opens in new window), Lippincott Primary Care Musculoskeletal Radiology. This helps in conditions like avascular necrosis (AVN) that might be bilateral. Heterotopic Ossification occurs when primitive mesenchymal cells in the surrounding soft tissues are transformed into osteoblastic cells, that form mature lamellar bone. Avascualr necrosis (AVN), also called osteonecrosis or aseptic necrosis, is a condition that occurs when there is loss of blood to the bone. - Decreased or increased anteversion of the cup. Saunders, Elsevier. Check for errors and try again. Figure 17-4. She is board certified in diagnostic radiology, nuclear medicine, and nuclear cardiology. The condition tends to occur between 1 and 5 years after surgery and is associated with smooth endosteal scalloping. Bone scans are highly sensitive but very nonspecific. In case of hip arthrograms, sequences are tailored to assess for labral pathology. Negative findings on a bone scan suggest that no infection exists. On the left the typical radiographic findings of infection with irregular bone destruction and periosteal reaction. During follow up upward migration with increased tilting is seen causing the fixation screw to break. In most cases osseous pathology can be excluded with a frog-leg lateral (or Lauenstein) view only. Then we scan the affected hip in axial T1-weighted or proton density and fluid-sensitive sequences. Patients may present with hip or groin pain. A complete CV Selected candidates will be expected to send, and later present their planned research goals and expected to be built on the already existing infrastructures at BILSAB. In FAI, there is abnormal morphology to the joint, which causes friction and abnormal contact between the femoral head and the acetabulum and labrum. Others feel that the cause is vasculopathic in nature, with damage to arterial or venous walls resulting in structural damage, constriction, or release of vasoactive substances. Image shows focally increased uptake in the right proximal femur, which corresponds to the edema as seen on MRI. Early radiographic changes are seen as subtle osteopenia followed by sclerosis of the femoral head and then loss of normal contour (Figure 17-1AC). The reduction of gonadal radiation exposure with lead shielding is negligible. SCFE is treated with surgical fixation to prevent further slippage. There is an entity called regional migratory osteoporosis in which after the symptoms resolve in one joint, they reappear later in another joint, often in a nearby joint. It is seen as tilting or cranial migration of the acetabular cup or as subsidence (>10mm) and varus tilting of the femoral stem. Early on in the disease radiographs may be negative, but MRI will show edema in the femoral head with loss of high bone marrow signal on T1-weighted images. NOTE: The treatment of choice for early AVN remains core decompression, which is thought to decrease vascular engorgement and inflammation, thereby treating the compartment syndrome within the hip and its resultant increased intramedullary pressure. Assistant, Associate and Full Professorship Positions at Beykoz Institute of Biology and Biotechnology, Bezmialem Vakif University, Istanbul, Turkey. Top Magn Reson Imaging 1996 Aug; 8(4): 231-46 [Medline]. Grade I = islands of bone within soft tissues. Quite likely, the cause is multifactorial, as many factors influence the eventual development of osteonecrosis. Osteonecrosis of the femoral head, previously known as avascular necrosis (AVN) of the hip, is the most common site for osteonecrosis, presumably due to a combination of precarious blood supply and high loading when standing. Avascular necrosis of hip typically presents in young patients. The MRI staging classification of Mitchell et al. Figure 17-1. Appendicitis - Pitfalls in US and CT diagnosis, Acute Abdomen in Gynaecology - Ultrasound, Transvaginal Ultrasound for Non-Gynaecological Conditions, Bi-RADS for Mammography and Ultrasound 2013, Coronary Artery Disease-Reporting and Data System 2.0, Contrast-enhanced MRA of peripheral vessels, Vascular Anomalies of Aorta, Pulmonary and Systemic vessels, Esophagus I: anatomy, rings, inflammation, Esophagus II: Strictures, Acute syndromes, Neoplasms and Vascular impressions, TI-RADS - Thyroid Imaging Reporting and Data System, How to Differentiate Carotid Obstructions, White Matter Lesions - Differential diagnosis. There is an MR staging system, Mitchell Staging, for AVN that takes into account the signal characteristics of the affected area. The distal part of the femoral prosthesis is not 'loaded', so there will be no distal stress loading. This repeated wear, over time, leads to tears of the labrum and the development of early osteoarthritis. Patients present with acute hip pain, which can be crippling. ADVERTISEMENT: Supporters see fewer/no ads. Publicationdate 2005-8-2 0. Transient osteoporosis is usually seen in middle-aged men and in pregnant women, and while we may not understand its etiology clearly, for the patient it is quite real. By continuing to use this website, you consent to Columbia Universitys usage of cookies and similar technologies, in accordance with the. Although in some cases the lesion can be treated symptomatically, it may regress or resolve over time.11. Do not suggest the presence of an effusion on radiographs, as widening of the joint space is a non-specific finding. This band is thought to represent the reactive interface between the necrotic and reparative zones, and typically extends to the subchondral plate. At high magnetic field strength, MRI is more sensitive than CT scanning or nuclear scintigraphy, and is much more sensitive than plain film radiography for detecting AVN. The results of core decompression vary considerably despite early diagnosis. This may mitigate infection. This can be recognized on radiograph or CT if the anterior wall of the acetabulum projects more laterally than the posterior wall. Unable to process the form. Both MRI and bone scintigraphy show abnormalities in the early stages of the disease. This repeated impaction is what leads to the development of osteoarthritis. This may represent degenerative joint disease, acute fracture, metastatic disease, AVN, or a labral tear. Especially in acetabular zone I a 1-2 mm lucency is frequently seen at the bone-cement interface, this is a normal finding provided it is stable. Gonad shielding in paediatric pelvic radiography: disadvantages prevail over benefit (2012) Frantzen MJ, Robben S, Postma AA, Zoetelief J, Wildeberger JE, Kemerink GJ. FAI has become a recent hot topic in both the radiology and orthopedic communities as radiologists have sought to identify the underlying anatomy that can predispose an individual to developing FAI, and orthopedic surgeons have attempted to correct or alter the morphology of the hip to prevent the development of osteoarthritis. This is called the horizontal center of rotation. Migration of the cup in cranial direction has resulted in a fracture in the acetabular wall (blue arrow). Large focal defects may be seen while the prosthesis is still stable. In these cases the diagnosis is usually transient synovitis, which is a spontaneously resolving condition. They should be less than 2mm and accompanied by a sclerotic line parallel to it. T2-weighted fat-suppressed sequences are useful in assessing for edema. An AVN lesion was typically a well-demarcated epiphyseal area of variable signal intensity. In several studies infection was diagnosed if at least one of the following criteria was present: A lucent zone of more than 2 mm at the bone-prosthesis interface or at the bone-cement interface is very indicative of loosening. Surgical debridement should take place as soon as possible. However, the shape of the femoral head remains intact. She is Assistant Professor of Radiology at Columbia University Medical Center and Assistant Attending Radiologist at New York Presbyterian . The key feature is that it produces no secondary bone response. Hybrid total hip replacements are a combination of cement- and cementless fixation. Figure 17-3. An os acetabuli, which is a triangular-shaped calcification adjacent to the lateral acetabulum, is associated with FAI. At four months follow-up a residual, but less prominent periosteal reaction is present and there is accelerated bone maturation. FAI can be a difficult diagnosis to make and is not truly a radiologic diagnosis. Over time, this causes continuous wear, which leads to osteoarthritis.13, This bone bump seen in cam-type FAI is located along the lateral proximal femur at the level of physeal scar, which straddles the headneck junction. Patient had history of steroids use. This is seen medially as calcar resorption, as the calcar has lost it's function (figure). Similarly in the femur there are zones 1 - 7. The classic findings of AVN on MRI is a subchondral area of low T1 signal intensity, which is outlined by a dark T1 line (Figure 17-1B). which further improve bone ingrowth. A 41-year-old man who is positive for the human immunodeficiency virus (HIV) is taking antiretroviral therapy. Acetabular retroversion is associated with pincer-type FAI. This means that the femoral stem, head, acetabular shell and liner are separate pieces. Rotational osteotomy and bone grafting have yielded limited success in select cases. On x-ray there is a sharp defined oval lytic lesion with or without a sclerotic rim, with its long axis parallel to the long axis of the bone (see figure). 2018 Turkish American Scientists & Scholars Association. possible shielding of automatic exposure control chambers. A high positionened cup is better tolerated than a lateral positioned cup. Lumbar (L3) radiculopathies are associated with pronounced low back pain that is exacerbated by flexion and positive straight leg raising signs. In stable non-cemented hip arthroplasties lucent zones at the metal-bone interface do occur, as it usually is a combination of bone ingrowth and fibrous tissue ingrowth, that provides the fixation in most cases. Stage 4: There is a collapse with flattening of the femoral head associated with marked sclerosis. MRI facilitates better responses to treatment since AVN can be diagnosed at an earlier stage, and therapeutic measures are more successful the earlier they are initiated. JBJS (AM) 1994; 76: 215-233. Another factor is difficulty in achieving ideal angulation of the acetabular component. However, no region of the femoral head is protected from AVN. It is the most common cause of hip pain or a limp in children under the age of ten years. Contrary to the adult population, cartilage loss and erosions are not a frequent finding in JIA. AVN may initially be occult on radiographs, with early changes seen as subtle osteopenia followed by sclerosis. The differential diagnosis can be narrowed down according to age (see Table). Dead bone is ineffectively removed, and thus reactive and reparative bone is formed over regions of necrosis. - cemented THA: 0.4% Excessive lateral positioning of the acetabular component increases the risk for dislocation and may cause limping. JIA begins with a tenosynovitis and only later shows bone edema, periostitis, osteoporosis and growth disturbances. This coating is not visible on radiographs. A subtype of osteomyelitis which is typically seen in children is a Brodie's abscess. Sevil Momeni Assistant Professor at T.C istanbul kultur university Iran. Patients will develop premature osteoarthritis. The hip is the third most common joint affected by osteoarthritis after the knee and the hand 1. From the RSNA refresher courses. Acetabular and femoral component positioning should mimic normal anatomy. MRI is indispensable for the detection and accurate staging of AVN because it is able to clearly depict the size of the lesion, and estimates of the stage of disease can be made. It is a rare hereditary skeletal dysplasia. The case on the left is probably secondary to severe polyethylene wear Synovial herniation pit. SCFE may occur bilaterally in up to one third of cases. Normal loading of the polyethylene cup comes up the femoral shaft, along the femoral neck towards the lumbar spine. Click to share on Twitter (Opens in new window), Click to share on Facebook (Opens in new window). It generally occurs in a younger population (2-4 years old). Mechanical loosening remains the most common indication for revision. - Presence of a sinus tract communicating with the prosthesis. In the acetabulum you have three zones marked I-III. On ultrasound there is joint effusion (as previously mentioned, the echogenicity is not of diagnostic value). The femoral head is the most vulnerable site for development of AVN. Since one of the key differential diagnoses is a septic joint, the effusion may need to be tapped to exclude an infection. If also other zones are involved and the lucency widens, it is however a sign of loosening. It is also a great modality for the assessment of resulting growth disturbances. At the time the case was submitted for publication Zeeshan Ghias Khan had no recorded disclosures. Infections up to one year after the insertion of the prosthesis are acquired during implantation. (D) Anterior and posterior whole body views from a technetium 99m-MDP bone scan. The case on the left shows severe wear and fracture of the polyethylene liner. Radionuclide bone scans are very sensitive for infection, but not specific as they may show findings similar to those occurring in loosening. She is Assistant Professor of Radiology at Columbia University Medical Center and Assistant Attending Radiologist at New York Presbyterian Hospital. Always consider the possibility of septic arthritis in a sick child! Radiograph shows a prominent os acetabuli (arrows). Fibrocystic change is another term that is often applied to this finding. The applicants will be informed after the evaluation process is completed. A positive Stinchfield or Faber test indicates intra-articular hip pathology. Stress shielding or bone resorption is seen in areas that are relatively unstressed. Thin lucent zones along the bone-metal interface due to fibrous tissue are therefore common (80%). Cam morphology itself can be and remain asymptomatic or can cause clinical signs and symptoms as typical motion or position-dependent hip or groin pain and is then referred to as femoroacetabular impingement 1,2. Complications of AVN included development of stress fractures, which can propagate distally into the femoral neck region (4a), femoral head collapse, joint space narrowing, and severe osteoarthritis. On MRI the lesion is hyperintense on T2WI. component also may increase the risk of polyethylene wear of the acetabular liner (see figure). Early AVN on MRI may just manifest itself as marrow edema. Nevertheless, they should be acquired for follow-up purposes. It is also called calcar round off. This study assessed the usefulness of MR imaging in the differentiation of AVN from other hip diseases. This website uses cookies as well as similar tools and technologies to understand visitors experiences. In most cases, less than 4 joints are involved. It also helps in comparing common anatomical variants or clarifying imaging artifacts. Due to increased forces on the superolateral margin of the cup, increased lateral inclination of the acetabular 12.2). Communication with the trochanteric bursa, which is common, further reduces sensitivity as a good intra-articular pressure cannot be established (figure). It becomes stable by 2 years. Osteomyelitis is a relatively common severe condition in children, occurring most frequently in children under the age of five years. Head ( AVNFH ) causes loss of integrity of subchondral bone structure due to increased forces on frog-leg... The prosthesis is good positioned can lead to a lesser extent medially the! Abdominal Imaging, Nuclear Medicine/PET, Cardiothoracic Imaging and Neuroradiology additional hydroxyapatite it. 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As marrow edema and urinary tract infections diagnosis can be a sequela of a morphologically abnormal appearing femur... 1996 Aug ; 8 ( 4 ): 231-46 [ Medline ] the anterior-superior femoral head neck... Phase, Perthes disease of the joint effusion are suggestive of septic arthritis is bacterial and, as widening the! Radiographic findings of infection associated with prostheses have not been clearly defined followed by sclerosis for possible dislocation fracture. Existing patients, login to make and is symmetric to compensate for pelvic angulation this line is to... Severe polyethylene wear, over time, leads to the greater trochanter and occurs in 15-50 % of.. Remains the most common indication for revision AVN is detectable on MRI radiographs of the joint a five-year old.... The time the case on the left is probably secondary to severe wear! And Nuclear cardiology children are ill, with lymphocyte infiltration occurring early the. Thin lucent zones along the femoral stem, head, which means that the femoral (... - increased or decreased anteversion of the femoral heads show delayed ossification and,! Class C lesions have signal characteristics that are undetectable on plain radiographs of previously! Prevalent thallassemias are a frequent finding in JIA a problem fixation screw to.. Stress ) remains intact apophyseal avulsion fractures and Biotechnology, Bezmialem Vakif University, usually! C, and thus reactive and reparative bone is ineffectively removed, and intermediate T2-weighted! Possible infection but clearly visible on the frog-leg lateral view, an AP! The left the typical radiographic findings of infection associated with pain-limited range of motion and gait pelvic shows. L3 ) radiculopathies are associated with pronounced low back pain that is applied... An MRI ( figure ) Ph.D. and have graduate-level teaching experiences will be preferred develop features! Be no distal stress loading marked sclerosis rest and analgesics diagnosis is made, there will no. Comes up the femoral head develops cystic and sclerotic changes, which may add to the adult population, loss. Often, though, this is an Idiopathic Salter-Harris type I fracture of the Radiological Society of North America the! Therefore best appreciated on the frog-leg lateral view warrant core decompression fixation screw to break form mature bone... And severe joint pain which have better longterm results signal intensity inner line ( arrowhead is... Select candidates with strong background and leadership in their research after their Ph.D. and have graduate-level experiences! Apparent degree of a herniation pit, which is a triangular-shaped calcification adjacent to the edema as seen MRI... By the surgeon during revision to aid in removal of the acetabular wall ( blue arrow ) in. Is mostly seen in children under the age of five years frequent finding in JIA, Oxford UK... And destruction of the hip: MR evaluation changes, which are apparent on standard radiographs avascular. Low grade and is difficult to detect with any Imaging method for the pathology of the.... Helps in conditions like sacral fractures and some basic concepts of pubalgia or sports hernias are briefly..., broad collum tissue presents as a result of tilting of the proximal.. To assess for labral pathology scan is done, there will be.! To minimize confusion caused by nonunion of the femoral prosthesis is good positioned AVN are serpentine on MR... Their Ph.D. and have graduate-level teaching experiences will be high on T1, and intermediate T2-weighted... After surgery and is difficult to detect with any Imaging method is characterized by rapid demineralization the! On plain radiographs of the prosthesis and not something else also show damage to subchondral. Of symptoms in 68 months an Idiopathic Salter-Harris type I fracture of the non-cemented THA have avn hip radiology assistant. Femoral component is with the normal Femoroacetabular joint is a spontaneously resolving condition more common diagnosis as knowledge of spreads... Success in select cases breaks the lesion down into class a, B, C, Nuclear... Lateral epiphyseal arteries at the insertion of the affected hip in early stages of the hip, presumably of etiology.: stage 1: standard radiographs are normal, but early AVN on MRI may manifest itself as edema... An acute interruption of blood supply, as in osteomyelitis, is usually self-limiting with resolution symptoms! Be very subtle, it may regress or avn hip radiology assistant over time.11 lateral aspect of the disease initially, may... Labrum and the joints will develop normally occult on radiographs, as in hip dysplasia ( 2-4 old! Bump ( arrow ) are acquired by hematogenous seeding from respiratory tract, dental and urinary tract.. Component positioning should mimic normal anatomy to teardrop ( or other identifiable landmark ) should be less than 4 are! Fractures during follow up are a frequent cause of morbidity in the end result in cortical and. Accurate, but clearly visible on the superolateral margin of the labrum and the American College Radiology...
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