The literature within the last 10 years on MRI use in patients with orthopedic implants is reviewed. AP view of the right elbow illustrating radial head prosthesis. Infected TKAs are often revised in a staged fashion: first, the infected TKA is removed and an antibiotic spacer is placed as illustrated, and subsequently once the infection has been eradicated with irrigation, debridement and antibiotics, the revision surgery takes place. AP view of the infected TKA with antibiotic cement spacer. either the current MR safe or MR compatible designations would be switched to MR conditional under the new standard. A literature search returned 15 relevant articles. Most intact implants are generally left in place after bony fusion due to the morbidity involved in recurrent spinal surgery. Trans-scapular Y or axillary views are also obtained to assess for dislocation. The type of fracture, anatomical site age, and comorbidities of the patient will dictate what approach the surgeon will have in treatment of the fracture. 0000001216 00000 n These components may either be cemented or noncemented. The hardware performance has direct relationship with the ultimate system overall performance. Given the large surface area contact of such side plates with the cortex, cortical blood supply may be compromised, which may result in nonunion or delayed union. There is linear soft tissue calcification incidentally noted near the medial tibial condyle. MRI Safety Information. Any gap widening or fracture of the plate is a symptom of instability (Figures 10-30 and 10-31). Although second-generation ankle prostheses have had better outcomes than first-generation prostheses, ankle arthrodesis remains the treatment of choice in managing the painful ankle joint. In such cases, it is difficult to maintain anatomic position by the use of a splint or a cast. (A) The femorotibial component should be aligned in 4–7)° of valgus, and the articular surface of the tibial component should be aligned parallel to the ground. The goal of fracture fixation is to stabilize the fractured bone in anatomic alignment in order to promote quick healing and optimal functional recovery. MR CONDITIONAL According to the new ASTM F 2503 standard, the sur- AP view of the left hip demonstrating the superior cannulated screw appears to have entered the hip joint, which puts the patient at risk of acetabular damage and subsequent osteoarthritis. There are no clear indications in management, and in most cases management often trends toward partial or total arthrodesis of the wrist and the hand. The literature within the last 10 years on MRI use in patients with orthopedic implants is reviewed. Other radiologic examinations such as arthrography, ultrasonography, computed tomography (CT), magnetic resonance imaging, and nuclear scintigraphy also have specific roles in evaluating joint replacement. The tibial component should also cover the entire surface of the tibia to provide adequate support. Infection is a serious delayed complication of any joint replacement. Figure 10-11. Figure 10-13. Arthrography can also be used to diagnose both loosening and infection. In evaluating transpedicular screws, it is important that they do not breach the pedicle and cause damage to the nerve roots that course along the pedicle.9 In addition, the tip of the vertebral body screw must not breach the anterior cortex. }�����}��?��:��[������#��s�vȔ����YZ=>x����#��Hgj�c������wN�O�z�z���#�~�Y��qL�&��ӃK���#���l�Yǩ���(��S+$_�kKzjQܗt��2�K?F�=b����%�zh?����tj�va��]aCōy(6Q��U�����O\�Q��������4`LN��N(�h��������L�Sk�W�9�J�g^�c��?�Lo� �U%�-��4L���y�G�>��_�8r��ނףM�}��q��~�9�rq��� 5� f\7�z�-H��{���EjP+\U뾁Q)�;B�%���/�����I�Tx��iIp@���1t��Û;�Cē��y8-! Another complication seen in various joint replacements is heterotopic ossification seen around the periprosthetic region. Lucency that is less than 2 mm in width and nonprogressive on follow-up radiographs is considered normal. Facet arthritis and degenerative disk and facet disease are common above and below the level of the fusion (Figure 10-22).8 Furthermore, fused bones are less mobile, making the adjacent vertebral bodies more prone to fracture in cases of trauma. AP view of the right hip demonstrating cannulated screw fixation of femoral neck fracture, with extensive heterotopic ossification (arrows) about the greater trochanter. When placed correctly, the wires convert the tensile forces of the muscle on the fracture fragments into a compressive force that promote fracture healing.10–12. However, when a fracture is surgically reduced by plates and screws, fractures heal without callus formation. Figure 10-30. h�b```b``c`c`М� Ā B�@Q�S��800�]Y/7�%*�ge�3U��Y���٭�����:4jl2y#v�5�4q����e��>���@GGGk(���. Initially a side plate is affixed to the distal femur and attached with multiple cortical screws. Fractures of hardware components include broken screws (Figure 10-20), broken wires, and fractures of the rods. This chapter reviews the basic concepts of joint replacement, spinal fusion, and fracture fixation, which are some of the most common procedures performed by orthopedic surgeons. The common artifacts in the presence of orthopedic hardware, optimization of pulse sequences to minimize metal-related artifacts, and the clinical uses of MRI following joint replacement, particularly with regard to total hip arthroplasty, total knee arthroplasty, and shoulder arthroplasty, are reviewed. If you are unsure about having any metal fragments in your body (war shrapnel or metal working injuries), you may need an X-ray prior to your MRI. "i'm wearing mri compatible pacemaker/leads (medtronic ensura). Table 1 (continued) Author Implant MRI Field Strength Deflection Angle Torque (1–4) Temperature Change ( C) Tsukimura et al,20 2017 4 Pure titanium rods 3.0 T 7.0 T 1.0 –2.0 at 3.0 T NR 0.2–0.5 at 3T Additionally, on the AP view (A), note the periprosthetic lucency (arrows) that represents hardware loosening. If there is loose metal in the body, it can move during the scan. The patella may either be simply resurfaced, or a patellar prosthesis (e.g., a button) may be attached (Figure 10-4C). AP (A) and lateral (B) radiographs of UKA. (B) The lateral view readily reveals a large posterior effusion (arrow) and bony destruction that are hallmarks of infected joint prostheses. The cup of the humeral component is connected to the stem portion of the prosthesis. g�u�m�/��||��b3�������켐v��D��gþ�^�O�� � e��0��7�ցT�#�?y�qR\(��`����Ë��I8��@���!����L��-؟0�Y^eX��w@8A�sS ��:,ҧ�4��T�� �0��E���@��s�>a(c �;w\�)�e Initially, the joint is aspirated for laboratory analysis. Bone grafts are placed within the posterior elements to facilitate osseous fusion. Next, bone graft is placed to facilitate intervertebral body fusion, with anterior plate and screws fixation for further stability. 0000032760 00000 n 1 thank. h�bb�b`b``Ń3�� 0 S�[ endstream endobj 189 0 obj <>/Metadata 52 0 R/PageLabels 48 0 R/Pages 51 0 R/StructTreeRoot 54 0 R/Type/Catalog/ViewerPreferences<>>> endobj 190 0 obj <>/Font<>/ProcSet[/PDF/Text/ImageC]/Properties<>/XObject<>>>/Rotate 0/StructParents 0/Thumb 44 0 R/TrimBox[0.0 0.0 595.276 841.89]/Type/Page>> endobj 191 0 obj <> endobj 192 0 obj <>stream Initially, there is formation of hematoma and a host inflammatory response surrounding the fracture site. With varus alignment, the lateral femoral cortex is most often injured. Next, iodinated contrast is injected into the joint. Most people who have metal rods and screws inserted during spinal surgery can have a magnetic resonance imaging (MRI) scan. Figure 10-1. Figure 10-32. Postoperative views of the shoulder prosthesis include AP view in internal and external rotation to evaluate for subsidence or upward migration of the humeral component. Note in (C), patellar resurfacing and fracture of the patella are seen. Unicompartmental patellar prostheses have been shown to result in suboptimal outcomes and are not routinely used. The radiopaque line between the femoral and tibial components seen on the AP view (A) corresponds to a metallic marker within the polyethylene component. Lumbar spinal fusion with vertebral screws and rods, and intradiscal bone graft. The disease or damaged vertebral bone is first removed. Dislocation or subluxation may occur in either the early or late postoperative period. They are made of titanium or radiolucent material such as polyether ether ketone (PEEK). In the distal femur, complications of traction pinning include damage to the quadriceps and surrounding neurovascular structures. Heterotopic ossification can also be seen with other types of hardware as well (Figure 10-16). Three types of hip prostheses exist: unipolar hemiarthroplasty, bipolar hemiarthroplasty, and total hip arthroplasty (Figures 10-1 and 10-2). Recent advances in bio-materials and joint replacement technology have led to marked improvements in the longevity of joint prostheses. H�tWˮ%� ܟ��8}��(��#1���8��Ff�x��ߧ���= �s�EI|��?��ӿ?8�����o��푎���ݷ���? Finally, interpedicular screws with vertical plates or rods are placed to reinforce stabilization (Figures 10-19 to 10-22). Improve patient care with top-quality products from MRI transport equipment to positioners, immobilizers, straps, and more. Note the formation of early bridging callus. A common example is the Harrington rod used for scoliosis of the spine. Cement is seen as a radiopaque lining surrounding the prosthesis. MRIMed's MR Adjustable Height Stretcher. Figure 10-10. The femoral component should be 90° to the long axis of the femoral shaft on the lateral view.1. Loosening, especially at the humeral component, is a major problem. Absolute contraindications for joint replacement include active local or systemic infection. Bipolar prosthesis. Another modified type of posterior approach is the transforaminal fusion that leaves the midline posterior structures intact. 0000087387 00000 n 0000032213 00000 n 0000087426 00000 n An important risk factor for loosening is osteoporosis, as it is difficult for the screw to obtain purchase in an osteoporotic vertebral body. Heterotopic ossification around the hip joint. 0000086584 00000 n A constrained prosthesis has two components that are directly linked together. MRI Med - MRI and Imaging Supplies Providing products for MRI , Cat Scan and Medical Imaging. Cortical bone is made out of multiple layers of lamellar bone with a layer of osteoclasts at the tip. Orthopedic surgeons can now choose between a vast array of prosthetic devices, many based on preference and familiarity. Various types of fracture hardware and fixation methods have been discussed. Figure 10-12. Most knee replacements are total knee replacements involving resurfacing of the femoral condyle and the tibial plateau (Figure 10-4). Alloys represent the metallic component of the prostheses. Intramedullary nails are used in the treatment of long bone fractures usually in the middiaphyseal region (Figures 10-32 and 10-33). MRI, nuclear medicine scintigraphy with WBC scan, and possibly CT-guided aspiration may be needed for further characterization of the infection.6 One other complication of spinal fusion must be noted: although fusion may be successful, it will eventually cause increased stress at levels above and below the level of surgical fixation. Although they occur more commonly in hip prostheses, particle disease can also occur in any other prostheses. The femoral component includes either a noncemented or cemented femoral stem with a femoral head that articulates directly with the native acetabulum. Loose femoral component of total knee arthroplasty (TKA). The humeral component may be cemented or noncemented, and articulate with the native glenoid. AP (A) and lateral (B) radiographs of cervical fusion instrumentation show anterior cervical fusion of C4-5 and C5-7 via plates and vertebral body screws. Bilateral laminectomies are first performed for spinal decompression. Intramedullary rod and locking screws. We will also describe current developments of utilizing MRI to evaluate implanted orthopedic hardware. Figure 10-2. AP view of the bipolar right hemiarthroplasty, with separate acetabular cup. In open fractures, there is usually significant surrounding soft tissue injury, possible vascular compromise, and increased risk of infection. As with joint replacement, and spinal fixation, many similar complications apply including infection, loosening, and hardware fracture. AP view of the left hip arthroplasty with particle disease, as evidenced by lucencies around the prosthesis components and multiple metallic particles in the joint space. Total shoulder arthroplasty. In crossing the fracture line, the screw is able to compress the fracture fragments together. There are various other indications for spinal surgery including trauma, tumors, infection, scoliosis, and spondylolisthesis. Other methods to diagnose prosthetic infection include ultrasound-guided joint fluid aspiration and nuclear scintigraphy.5. The ankle is a complex joint, and success rate for joint replacement has been suboptimal. A shoulder hemiarthroplasty is used in cases such as severe proximal humeral fractures and severe rotator cuff tear where the patient still possesses a normal glenoid. 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In ( C ) for postoperative evaluation of loosening evaluate implanted orthopedic hardware are magnetic and not compatible MRI. Spanning external fixator and K-wire fixation of olecranon and patellar fractures with the metallic cup... And cement–bone interfaces fracture callus with associated subtrochanteric fracture through fracture callus with associated varus malalignment and nonunion Figures and..., revision to a plate by threaded holes lateral radiographs of constrained left total elbow prosthesis infection... To secure the prosthesis may either be press fit into the pelvic cavity ) after device implantation elements to intervertebral...