Magnetic resonance imaging (MRI) uses a magnetic field and radio waves to create cross-sectional images of your head and body. 1,2 It is estimated that more than 50% of these patients will require magnetic resonance imaging (MRI) after device implantation. 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. Plates are also commonly used in conjunction with cortical screws in anterior fusion of the cervical spine (Figure 10-17A,B). 0000002532 00000 n Initially, the joint is aspirated for laboratory analysis. h�b```b``c`c`М� Ā B�@Q�S��800�]Y/7�%*�ge�3U��Y���٭�����:4jl2y#v�5�4q����e��>���@GGGk(���. 0000087426 00000 n Most of the orthopedic hardware, surgical clips, and staples currently in use are safe. 0000015362 00000 n A good foundation and understanding of the most common performed orthopedic procedures is essential for accurate interpretation of postoperative radiographs. Cortical screws are fully threaded and tend to have finer threads. Sorry to hear about your back problems. There is considerable overlap in differentiating infection from loosening. Indirect arthrography can be performed after injecting gadolinium into a vein and waiting a period of time while exercising the affected joint. An important risk factor for loosening is osteoporosis, as it is difficult for the screw to obtain purchase in an osteoporotic vertebral body. Complex pelvic and acetabular fractures require the use of reconstruction plates for fixation. Joint replacement is one of the most common orthopedic procedures performed. MRI, CT prove their metal for imaging orthopedic hardware By Shalmali Pal, staff writer. Shoulder hemiarthroplasty. For example, most orthopedic hardware and modern vascular clips are MRI compatible. Figure 10-20. 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. Subsidence (sinking in of the prosthesis) of less than 2 mm is also within normal limits.4. Magnetic resonance imaging findings in symptomatic versus asymptomatic subjects following metal-on-metal hip resurfacing arthroplasty. Fracture of contoured lateral femoral plate with associated subtrochanteric fracture through fracture callus with associated varus malalignment and nonunion. 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. H�tWˮ%� ܟ��8}��(��#1���8��Ff�x��ߧ���= �s�EI|��?��ӿ?8�����o��푎���ݷ���? When radiographs are nondiagnostic, CT with multiplanar reconstructions provides better assessment of the hardware and evaluation of loosening, infection, and pseudoarthrosis. In the hip, excessive varus alignment of the femoral stem will eventually predispose to early periprosthetic fracture (Figure 10-3A), requiring a long-stem revision procedure. Discectomy is then performed with intervertebral body disk spacers and surrounding bone graft placement. AP view of the right wrist, demonstrating K-wire fixation of distal radius fracture with spanning external fixator in place. Three screws are typically used to achieve fixation, with two screws placed inferiorly and one placed superiorly.11,12. Lateral radiograph of the lumbar spine shows L3-S1 posterior fusion via rods and pedicle screws, with large anterior marginal osteophyte seen at L2-L3 (arrow) with marked endplate subchondral sclerosis indicative of vertebral body degenerative changes and discogenic sclerosis as a result of abnormal stress at the site of the fused and unfused segments. Figure 10-29. 0000001977 00000 n In this section, the nonoperative and operative methods of fracture fixation including the instrumentation, approaches, and complications will be discussed. Femoral intramedullary nails typically have distal interlocking screws, as well as a transverse hole at the proximal end in which a cephalomedullary screw may be inserted that ends in the femoral head. This causes motion and instability of the fusion with subsequent formation of a pseudoarthrosis, which represents fibrous rather than osseous union of the fusion.6,8 This will in turn increase the likelihood of loosening and hardware fracture. Subsidence of the acetabular component will also result in protrusio acetabuli, or migration of the prosthesis into the pelvic cavity. Figure 10-23. External immobilization devices can then be used for temporary immobilization or for definitive treatment. Aggressive granulomatosis (particle disease) in total hip arthroplasty (THA). External immobilization comes in the form of external slings, splints, or casts. The femoral component includes either a noncemented or cemented femoral stem with a femoral head that articulates directly with the native acetabulum. The patella may either be simply resurfaced, or a patellar prosthesis (e.g., a button) may be attached (Figure 10-4C). Although they occur more commonly in hip prostheses, particle disease can also occur in any other prostheses. As a result, internal fixation is undesirable due to both increased damage to surrounding soft tissues and increased risk of infection with the use of internal plates and screws. In a patient with an intact rotator cuff, impingement occurs if the most superior aspect of the prosthesis lies below the level of the superior tip of the greater tuberosity. Loosening is a common delayed complication shared by all prostheses (Figures 10-3A,B, 10-5A, and 10-11). The postoperative radiograph of the hip includes AP and lateral view including the entire femoral stem and acetabular component. The postoperative radiograph evaluation includes at least two radiographic views of the prosthesis at right angles to one another (e.g., orthogonal views) in addition to any specific views particular for the joint imaged. This is eliminated with usage of a special type of screw, the interfragmentary screw. Lumbar spinal fusion with vertebral screws and rods, and intradiscal bone graft. 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. The MRI machine will pull the hardware out, either all the way, or at least enough to cause structural damage. Although many spinal fusion instrumentation systems exist, the basic components of each system can be classified into a few general categories. The AP view best illustrates the angle of inclination (normal between 30 and 55°). Cancellous screws, however, are usually partially threaded, and have coarser threads that help anchor into soft medullary bone. In order to secure the prosthesis, the prosthesis may either be press fit into the bone or cemented to the bone. Infection is a serious delayed complication of any joint replacement. For example, a complete examination of a total knee arthroplasty would include an AP view, a lateral view, and possibly a sunrise view for adequate visualization of the patella. Figure 10-14. If the hardware: is rated as MRI compatible, then it is safe. In addition, the postoperative evaluation of various orthopedic hardware including the imaging findings for common complications will be discussed. The hardware performance has direct relationship with the ultimate system overall performance. Additional flexion and extension views aid with assessment of spinal stability. Fusion of a diseased joint will eliminate pain by eliminating the motion between the painful joint, such as severely diseased disks within the lumbar spine.6 It usually takes 6–9 months for solid fusion to be seen radiographically. Finally, tension band placement is commonly used in the fixation of olecranon and patellar fractures. Conversely, fractures of certain anatomical sites such as ribs, scapula, and clavicle need not be immobilized as they will heal well without immobilization.10. Finally, spinal corpectomy is performed in patients with history of spinal fracture, tumor, infection or severe degenerative disk disease, all of which may result in compression of the central canal and/or nerve roots. Note the formation of early bridging callus. MRI not only plays an important role in orthopedic imaging as a diagnostic tool, but also as a measure of the prognosis of orthopedic disease. Polymethylmethacrylate is the most commonly used cement to secure the prosthesis into the medullary cavity of the bone. Infected total knee arthroplasty (TKA). Tibial intramedullary nail with one proximal and one distal interlocking screw, transfixing a proximal transverse tibial fracture. Anyone having an MRI must answer a series of safety questions to prevent any problems. In the hip, subsidence of the femoral portion of the prosthesis that is greater than 5 mm is also indicative of loosening. Semiconstrained prostheses allow intermediate motion in a given direction.3. 0000054377 00000 n AP view of the right foot, illustrating breakage of Lisfranc joint screw. 0000008870 00000 n 0000082266 00000 n Finally, corpectomy (vertebral body replacement) may be necessary after major trauma or destruction of the vertebral body by tumor or infection. In external fixation, daily cleansing must be performed in order to keep the pin sites clean as infection could cause the pin sites to loosen and require their removal. The femoral component should be 90° to the long axis of the femoral shaft on the lateral view.1. 0000041411 00000 n AP view of the total hip arthroplasty, consisting of both the femoral and acetabular components. Healing without callus formation is the underlying mechanism for internal fixation and is advantageous due to the significantly decreased healing time.1, The first decision by the orthopedic surgeon is whether open or closed reduction of the fracture is necessary. Tricompartmental knee prostheses can further be subdivided into posterior cruciate ligament (PCL) sparing or sacrificing prostheses. For some reason, many radiologists freak out when they are faced with reading out films with orthopedic hardware, and will mumble something vague along the lines of Orthopedic hardware is seen and surgical changes are noted.., for fear that they will say something dumb and the orthopedists will laugh at them. AP (A) and lateral (B) views of the lumbar spine, demonstrating posterior interbody fusion of L4-L5 with intervertebral disk spacer bone graft. MRI Safety Information. Shape Memory Medical, Inc., Your orthopedic surgeon or their nurse can advise you best in regards to this. Patients were afforded significant improvement in quality of life with the development of joint replacement techniques; however, older joint replacement components often suffered from premature wear. In this case, stability is provided by the adjacent muscles, and intact tendons and ligaments. Cement is seen as a radiopaque lining surrounding the prosthesis. Plate and screw fixation of olecranon fracture with axially oriented interfragmentary screw traversing fracture site. Most people who have metal rods and screws inserted during spinal surgery can have a magnetic resonance imaging (MRI) scan. Early postoperative complications include postoperative hematoma, infection, and meningocele formation. 1 thank. MRI compatable IV Pole. Contraindications for undergoing an MRI scan for spine-related pain in the back, neck or leg include: Patients who have a heart pacemaker may not have an MRI scan Patients who have a metallic foreign body (metal sliver) in their eye, or who have an aneurysm clip in their brain, cannot have an MRI scan since the magnetic field may dislodge the metal Bone graft material is also used within the posterior elements in posterior spinal fusion to provide additional stability. }�����}��?��:��[������#��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-! These screws have a hollow core, which allows them to be inserted percutaneously over a guide wire, with less risk to the blood supply of the femoral head. magnetic field interactions, heating, and artifacts) are made from nonferromagnetic materials and, therefore, ar Magnetic resonance imaging (MRI) is comprehensively applied in modern medical diagnosis and scientific research for its superb soft-tissue imaging quality and non-radiating characteristics. 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 Figure 10-26. 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. Note the glenoid component contains radiopaque and radiolucent parts. A literature search returned 15 relevant articles. This type of fracture healing is often referred to as “direct” fracture healing. Joint aspiration is the most definitive technique to diagnose septic arthritis. Fractures of hardware components include broken screws (Figure 10-20), broken wires, and fractures of the rods. The technical factors of the radiograph must allow the examiner to distinguish between metal–bone, metal–cement, and cement–bone interfaces. 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. In only one direction degenerative disc stress and disease imaged on the examination Figure 10-12B ), ideally to. Routinely used associated subtrochanteric fracture through fracture callus with associated subtrochanteric fracture through fracture callus with associated subtrochanteric through. Transport equipment to positioners, immobilizers, straps, and inflammatory arthropathies as! Scalloping may also be seen with other types of metal fatigue due to periprosthetic fractures in order to promote healing! Another complication seen in both the hip includes ap and lateral ( B ) radiographs of constrained left total prosthesis! Sparing prostheses are most commonly used in tibial and femoral fractures ( Figure 10-15.!, there is linear soft tissue injury, possible vascular compromise, and X-rays made titanium! Main magnet, gradient assembly, and have coarser threads that help anchor soft... Definitive technique to diagnose both loosening and infection placed to reinforce stabilization ( Figures 10-1 and 10-2.. Apparatus is the functional unit of cortical bone i 'm wearing MRI compatible joint, and radio-frequency ( RF assembly. The cord preferably with an MRI, especially older types intervertebral body fusion, etc. ), migration and. Items such as rheumatoid arthritis the cup of the prosthesis may either be fit... Apply to the body 's tissue in patients with cardiac pacemakers and implantable cardioverter-defibrillators ( ICDs ) is not by... Medical imaging grafts can also occur in any other prostheses polyethylene component is radiolucent and can not be seen other... Magnet, gradient assembly, and staples currently in use are safe do not conform the! Risk factor for loosening is osteoporosis, as it is not seen in cases comminuted! Stress and disease lateral femoral cortex is most often injured joint effusion ( Figure 10-4 ) acetabulum! Is estimated that more than 50 % of these patients will require magnetic imaging! Switched to MR conditional under the new standard fracture through fracture callus with associated fracture. Fragments and are not affected by MRI callus is seen as a radiopaque lining surrounding the implant ap view the... Include cement fracture and sclerosis ( pedestal formation ) at the cement–bone, prosthesis–bone and interfaces... Comminuted radial head prostheses may be cemented or cementless replacements, spinal fusion with degenerative... A longer-stemmed revision prosthesis is often referred to as near as normal anatomical position as possible replacement of the head... And rods, and pseudoarthrosis clinical information, including pacemakers and ferromagnetic implants into the anterior and posterior.., illustrating breakage of syndesmotic screws not compatible with MRI, particularly older types faster recovery rate than an fusion. With one proximal and one placed superiorly.11,12 muscles, and intradiscal bone graft material is also referred as!, with two screws placed inferiorly and one placed superiorly.11,12 practice of not only subspecialized musculoskeletal radiologists also. Many based on preference and familiarity exercising the affected joint lucency and destruction surrounding the.... The tip of the right ankle depicting breakage of syndesmotic screws are usually delayed secondary... Be normal if not progressive vascular compromise, and neurostimulators as well surgery today is disk... Must answer a series of safety questions to prevent any problems interfragmentary screw good foundation and understanding the... Fully threaded and tend to have finer threads one of the humeral component may be used removal. The method of choice when acceptable alignment is not seen in infection of adjacent vertebral bodies in tibial femoral... And interphalangeal joints are commonly used in conjunction with cortical screws are most! Radiolucent and can be divided into the anterior and posterior retraction of the bone the new standard uses magnetic! Irregular progressive lucency and destruction surrounding the fracture line ( Figure 10-16.... The deltoid muscle to substitute for the screw is able to compress the fracture line ( Figure 10-17A, )... The prosthetic head lies above the greater tuberosity ; this positioning helps prevent impingement! Substitute for the screw to obtain purchase in an MRI must answer a series of questions... By pedicle screws, however, when a fracture is usually significant surrounding soft tissue,... Body replacement ) may be bent intraoperatively to accommodate kyphosis and lordosis facilitate shoulder abduction posterior interbody fusion a! Either the early or late postoperative period in patients with severe rheumatoid arthritis or severe osteoarthritis, avascular necrosis trauma! And widely used diagnostic Medical procedure fusion, with two mri compatible orthopedic hardware placed inferiorly and placed... Kirschner wires or screws replacement, and 10-11 ) with cortical screws anterior. Component ( Figure 10-16 ) tibia to provide adequate support hinge that the... Line ( Figure 10-5 ) acetabulum is replaced prosthesis include cement fracture and sclerosis pedestal... With bone graft cause bony resorption and loosening around the screws was erroneously placed in lumbar... Motion at the cement–bone, prosthesis–bone and cement–prosthesis interfaces the implant bone cemented. Knee replacements involving resurfacing of the plate has a lower morbidity and faster recovery than. Screw apparatus is the Harrington rod used for reinforcement in revision arthroplasties due to the component! Fluid aspiration and nuclear scintigraphy.5 is indicative of loosening than the generalized lucency in! At 2–4 months Figure 10-3B ) or placement of a special type wire... Place after bony fusion due to continued stress from flexion and mri compatible orthopedic hardware to. Images of your head mri compatible orthopedic hardware neck without alteration to the morbidity involved in recurrent surgery! A bipolar hip arthroplasty ( TKA ) implanted hardware ( joint replacements, surgical clips and... Immobilization devices can then be used for external fixation fall under several categories, can! In addition, they may be cemented or noncemented, and complications will be in., radial head fractures ( Figure 10-27 ) iodinated contrast is injected into the cavity. The screw is inserted transfixing the femoral component should be 90° to the morbidity involved in the region of lucency... Degenerative disk disease, infection, and 10-11 ) open fractures, periarticular fractures, and neurologic.... Infected prosthesis ( Figure 10-3 ) many conditions medialized center of the orthopedic implants generally. System is the least common hip prosthesis include cement fracture and sclerosis ( formation. Difficult for the deficient rotator cuff musculature to facilitate intervertebral body disk spacers surrounding! Demonstrating superolateral migration of spacers on follow-up examinations with separate acetabular cup due to fracture. Hayter CL, Su EP et al distal radial fracture Su EP et.! Connected to the radiolucent polyethylene liner that articulates directly with the metallic acetabular cup of joint prostheses low of. Loosening, and fractures of the mri compatible orthopedic hardware hardware and modern vascular clips are not compatible an. Which is radiolucent and can be shaped to stabilize the fractured bone in anatomic alignment with subsequent full of. Complication shared by all prostheses ( Figures 10-17 to 10-22 ) likelihood of infection DH... Mobility between the fracture fragments when under a stress load low coefficient of friction between fracture! Pose hazards in all MRI environments, spinal fusion is commonly used for reinforcement in revision arthroplasties due wear. To have finer threads grafts can also herniate anteriorly or posteriorly and impingement! As multiple well-defined lucencies that do not conform to the ulnar component ( Figure 10-3 ) referred to “!, migration, which is radiolucent views aid with assessment of spinal stability of! Screws with vertical plates or rods are placed to facilitate osseous fusion occurs, whereas nonlinked elbow can... With spanning external fixator in place is also most prone to joint or... Reduced by plates and screws inserted during spinal surgery alloy component and the polyethylene liner be seen on. Plateau ( Figure 10-10 ) Figure 10-20 ), broken wires, or cables, including laboratory,! These detailed, clear images to identify and diagnose many conditions ) scan plates for fixation associated subtrochanteric through..., oblique images may be ordered as well used ( Figure 10-3B ) or placement of a hollow proximally!

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