1,2 It is estimated that more than 50% of these patients will require magnetic resonance imaging (MRI) after device implantation. Unicompartmental knee arthroplasty (UKA). Postoperative Evaluation and Complications. Intramedullary rod and locking screws. Rods can be attached to the spine by pedicle screws, wires, or cables. It is the preferred method due to the risk of cord manipulation from a posterior approach, as well as the risk to vital structures such as the trachea, the esophagus, the lungs, and the carotid artery.8 First, the herniated portion of the disk or the entire disk is removed. Click to share on Twitter (Opens in new window), Click to share on Facebook (Opens in new window), Click to share on Google+ (Opens in new window). Finally, corpectomy (vertebral body replacement) may be necessary after major trauma or destruction of the vertebral body by tumor or infection. In such cases, it is difficult to maintain anatomic position by the use of a splint or a cast. Contrast accumulation around in the region of periprosthetic lucency is suggestive of loosening (Figure 10-3B) or infection. You can have a CAT or PET scan, and X-rays. Internal fixation helps restore anatomic alignment with subsequent full function of the limb and rapid immobilization of the patient. The AP film is used to measure the angle of inclination that is optimal at 30–55° (Figure 10-2), and the lateral film is used to measure the angle of anteversion that is optimal around 15°.1,2 The femoral component should be either parallel to the femoral shaft or in slight valgus. Multiple fractures of interlocking screws. trailer <<3A8AA5B6780C4197A1A26CD0BDC54738>]/Prev 277440/XRefStm 1635>> startxref 0 %%EOF 233 0 obj <>stream A constrained prosthesis has two components that are directly linked together. Additional foci of endosteal scalloping may also be seen. 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. Shoulder hemiarthroplasty. Figure 10-7. Indirect arthrography can be performed after injecting gadolinium into a vein and waiting a period of time while exercising the affected joint. 188 0 obj <> endobj xref 188 46 0000000016 00000 n We have scanned the orthopedic hardware of over 2300 individuals at our institution, as part of an ongoing research study. Plate and screw fixation of olecranon fracture. Unlike infection, a periosteal reaction is not seen in cases of particle disease. Subsidence (sinking in of the prosthesis) of less than 2 mm is also within normal limits.4. The tibial component should also cover the entire surface of the tibia to provide adequate support. Magnetic Resonance Imaging (MRI) is a commonly accepted and widely used diagnostic medical procedure. There are various other indications for spinal surgery including trauma, tumors, infection, scoliosis, and spondylolisthesis. The function of the hardware is complete when osseous fusion occurs. Figure 10-27. Usually, the vertebral body is replaced by an expandable hollow cylinder packed with bone graft material or cement.6,7. ... Orthopedic Eval: I would strongly recommend that you go have an orthopedic evaluation, preferably with an adult hip specialist. 0000002646 00000 n Complex pelvic and acetabular fractures require the use of reconstruction plates for fixation. Most of the orthopedic hardware, surgical clips, and staples currently in use are safe. There is linear soft tissue calcification incidentally noted near the medial tibial condyle. AP view shows reverse total shoulder arthroplasty. Radiographically, solid callus is seen at this time bridging the fracture site. 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. 0000073600 00000 n 0000024110 00000 n This type of fracture healing is often referred to as “direct” fracture healing. In this case, there is a very small gap between the fracture fragments, and fracture healing is initiated by the Haversian system of remodeling. As with joint replacement, and spinal fixation, many similar complications apply including infection, loosening, and hardware fracture. The other important concept to realize is that the spinal hardware is used to provide temporary fixation and stability by immobilizing the bone. AP view of the right elbow illustrating radial head prosthesis. The superior and inferior disks are also removed, and bone graft is placed in place of the removed vertebral body, which results in fusion of the adjacent vertebral bodies. Side plates and screws are used to reinforce the fusion. Surgical approaches to the spine can be generally divided into the anterior and posterior approaches. They are commonly used for reinforcement in revision arthroplasties due to periprosthetic fractures in order to provide additional support. Infected total knee arthroplasty (TKA) with antibiotic cement spacer. Lumbar fusion with adjacent degenerative disc stress and disease. Complications of screws include loosening, fracture, and migration (Figures 10-23 to 10-27). It occurs in unstable or relatively stable mechanical conditions such as bone immobilized by a cast or a splint, or via intramedullary nail fixation or bridging plates that simply span the fracture site without screw fixation directly adjacent to the fracture site. Cortical bone is made out of multiple layers of lamellar bone with a layer of osteoclasts at the tip. Note the absence of any glenoid components. 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. AP view of the right hip. The postoperative complications will then be discussed. In addition, the postoperative evaluation of various orthopedic hardware including the imaging findings for common complications will be discussed. Lateral radiograph of the lumbar spine shows L4-S1 posterior fusion via rods and pedicle screws, exhibiting breakage of the L4 and L5 pedicle screws within the pedicle. Anyone having an MRI must answer a series of safety questions to prevent any problems. 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. Most knee replacements are total knee replacements involving resurfacing of the femoral condyle and the tibial plateau (Figure 10-4). Fractures of hardware components include broken screws (Figure 10-20), broken wires, and fractures of the rods. 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. AP view of the right foot, illustrating breakage of Lisfranc joint screw. Fracture of the femoral contoured plate. After immobilization, whether following operative or nonoperative reduction, close watch must be kept for swelling in a close fitting cast or splint as it may cause impairment to the circulation and vascular comprise to the distal part of that limb, possibly resulting in a compartment syndrome. Bilateral laminectomies are first performed for spinal decompression. Loose pedicular screws. Titanium’s nonmagnetic properties make it compatible for use with an MRI as well. 0000032481 00000 n MRI, CT prove their metal for imaging orthopedic hardware By Shalmali Pal, AuntMinnie.com staff writer. Lucency that is less than 2 mm in width and nonprogressive on follow-up radiographs is considered normal. Not all metals and not all devices cause a problem. Figure 10-20. Note the medialized center of rotation, which allows the deltoid muscle to substitute for the deficient rotator cuff musculature to facilitate shoulder abduction. TKAs may involve simple patellar resurfacing (B) or placement of a patellar button (C). Background. Figure 10-11. Plates are usually made out of titanium or stainless steel and are applicable to fixation of long bone fractures (Figures 10-28 and 10-29). Main magnet, gradient assembly, and radio-frequency (RF) assembly are main hardware in an MRI system. Tibial intramedullary nails have transverse holes at both ends that allow perpendicular interlocking screws to be placed leading to increased stability of fixation and prevention of intramedullary nail rotation. Hardware fracture is usually a result of metal fatigue due to continued stress from flexion and extension. Another important class of fractures are fractures that involve the articular surface. Additional clinical information, including laboratory analysis, is needed to assess the likelihood of infection. Heterotopic ossification around the hip joint. The femoral component should also be symmetric in the center of the acetabular component. Ankle fracture with plate and screw fixations. Cortical screws are fully threaded and tend to have finer threads. 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 In this method, cerclage wires are used to fixate the two fracture fragments and are stabilized by additional Kirschner wires or screws. Additional signs of infection include soft tissue swelling, large joint effusion (Figure 10-12B), and abscess formation. The humeral component may be cemented or noncemented, and articulate with the native glenoid. Figure 10-16. 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. In the lumbar spine, posterior interbody fusion has a lower morbidity and faster recovery rate than an anterior fusion. 0000005870 00000 n Wires are commonly used as an alternative to screws for fixation of small osseous fracture fragments. 0000032213 00000 n 0000077949 00000 n Heterotopic ossification in this region predictably results in significant deficits of hip flexion and abduction. This helps abolish motion at the fracture site and promotes faster healing without callus formation. Intervertebral spacers and bone grafts can also herniate anteriorly or posteriorly and cause neurologic compromise. The interfragmentary screw is a screw that crosses the fracture line (Figure 10-29), ideally perpendicular to the fracture line. (A) Both the femoral and tibial components of the TKA exhibit irregular periprosthetic lucency (arrows), suggestive of infection. AP (A) and lateral (B) radiographs of constrained left total elbow prosthesis. 0000008870 00000 n Constrained left total elbow prosthesis. Internal fixation is the method of choice when acceptable alignment is not possible by splinting alone. Three screws are typically used to achieve fixation, with two screws placed inferiorly and one placed superiorly.11,12. In the cervical spine, the anterior approach to fusion (Figure 10-17A,B) is usually performed for patients with painful herniated disks. Fracture nonunion leading to instability and subsequent hardware failure. The lack of success is likely due to inability to duplicate the normal mechanics of the ankle joint and inability to restore the stabilizing effect of the ligaments. Hardware fracture is usually a result of metal fatigue due to continued stress from flexion and extension. The linked portions have a rigid hinge that connects the humeral component to the ulnar component (Figure 10-9). It is important for the radiologist to have familiarity with the most common orthopedic procedures in order to better recognize complications involved with various procedures. The hardware performance has direct relationship with the ultimate system overall performance. In other words, it is not seen on the radiograph. Infected total knee arthroplasty (TKA). 0000002532 00000 n A literature search returned 15 relevant articles. In open fractures, there is usually significant surrounding soft tissue injury, possible vascular compromise, and increased risk of infection. PCL sparing prostheses are most commonly performed and have slightly improved gait. 0000077910 00000 n Over 2 million patients in the United States have implanted devices, including pacemakers and implantable cardioverter-defibrillators (ICDs). Surrounding bone graft material is also used surrounding the disk spacer to provide additional stability. 0000024222 00000 n AP view of the right hip demonstrating cannulated screw fixation of femoral neck fracture, with extensive heterotopic ossification (arrows) about the greater trochanter. AP and lateral radiographs of the spine are necessary for postoperative evaluation. Superior migration of cannulated screw. Subsidence of the acetabular component will also result in protrusio acetabuli, or migration of the prosthesis into the pelvic cavity. Lateral radiograph of the lumbar spine shows L3-S1 posterior fusion with rods and pedicle screws, exhibiting lucency surrounding the L4 and L5 screw threads (arrows) suggestive of loosening. (B) The lateral view readily reveals a large posterior effusion (arrow) and bony destruction that are hallmarks of infected joint prostheses. Other methods to diagnose prosthetic infection include ultrasound-guided joint fluid aspiration and nuclear scintigraphy.5. Another well-known plate and screw apparatus is the dynamic hip screw used to treat intertrochanteric fractures (Figure 10-26). Figure 10-19. Though it is impossible for the radiologist to become familiar with all the different devices in the market, the structural material and complications are shared among the variety of different prostheses. Figure 10-24. 0000021804 00000 n Figure 10-17. Three international standards are the most relevant in this field: the MRI standard IEC 60601–2‐33 and the implant standards ASTM F2182 and ISO/TS 10974. Another modified type of posterior approach is the transforaminal fusion that leaves the midline posterior structures intact. Migration of dynamic hip screw. AP (A) and lateral (B) views of the right ankle joint, exhibiting bridge plate fixation of oblique fibular fracture with malleolar screw fixation of medial malleolus fracture. how safe it is to perform an mri scan?" Arthrography can also be used to diagnose both loosening and infection. They are made of titanium or radiolucent material such as polyether ether ketone (PEEK). Rods are used to provide stability over short or long segments (Figures 10-17 to 10-22). h�b```b``c`c`М� Ā B�@Q�S��800�]Y/7�%*�ge�3U��Y���٭�����:4jl2y#v�5�4q����e��>���@GGGk(���. Most people who have metal rods and screws inserted during spinal surgery can have a magnetic resonance imaging (MRI) scan. Note in (C), patellar resurfacing and fracture of the patella are seen. 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. Figure 10-26. Cerclage wires are another common type of wire used in encircling and fixation of fracture fragments. Infection is an uncommon complication that usually presents with irregular progressive lucency and destruction surrounding the implant. The entire prosthesis and surrounding bone need to be imaged on the examination. Other signs of loosening in the hip prosthesis include cement fracture and sclerosis (pedestal formation) at the tip of the prosthesis.4. The side plate consists of a hollow barrel proximally, in which a screw is inserted transfixing the femoral head and neck. 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. Cancellous screws, however, are usually partially threaded, and have coarser threads that help anchor into soft medullary bone. Also note minimal lucency surrounding the radiopaque glenoid component suggestive of loosening. Most of the orthopedic implants, materials, and devices evaluated for MRI issues (i.e. Three types of surgeries exist for shoulder replacement: hemiarthroplasty (Figure 10-6), total shoulder arthroplasty (Figure 10-7), and reverse shoulder arthroplasty (Figure 10-8). Figure 10-2. MR unsafe items include magnetic items such as a pair of ferromagnetic scissors. May 4, 2007-- Musculoskeletal imaging experts may love to chew on the advantages of one imaging modality over another for assessing orthopedic hardware, but the clinicians ordering up these exams are not going to have the same enthusiasm about a rollicking MRI versus CT debate. Figure 10-29. Some types of metal implants or orthopedic hardware are magnetic and are not compatible with an MRI, especially older types. 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. AP (A) and lateral (B) views of the lumbar spine, demonstrating posterior interbody fusion of L4-L5 with intervertebral disk spacer bone graft. $8,995.00. Orthopedic/Musculoskeletal MRI is used to examine bones, joints and soft tissues such as cartilage, tendons, and muscles for the presence of structural damage, defects, infection, etc. Figure 10-18. Additionally, on the AP view (A), note the periprosthetic lucency (arrows) that represents hardware loosening. 0000063352 00000 n However, when a fracture is surgically reduced by plates and screws, fractures heal without callus formation. Six to eight screws are usually fixed to a plate by threaded holes. Broken screw. Tricompartmental knee prostheses can further be subdivided into posterior cruciate ligament (PCL) sparing or sacrificing prostheses. In crossing the fracture line, the screw is able to compress the fracture fragments together. either the current MR safe or MR compatible designations would be switched to MR conditional under the new standard. For replacement of individual carpal bones due to avascular necrosis or trauma, Silastic prostheses have been used. Heterotopic ossification can also be seen with other types of hardware as well (Figure 10-16). 0000023090 00000 n Orthopedic surgeons favor titanium implants for their strength and compatibility with body tissues. And that can cause damage to the body's tissue. Early postoperative complications include postoperative hematoma, infection, and meningocele formation. The healing process with callus formation can be divided into four stages. 0000001216 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. The osteoclasts function to resorb the end of the fracture, while osteoblasts form new bone behind the osteoclasts, thus creating numerous microscopic bony bridges across the fracture site. Linked elbow prostheses can be likened to constrained prostheses, whereas nonlinked elbow prostheses can be likened to nonconstrained prostheses. When radiographs are nondiagnostic, CT with multiplanar reconstructions provides better assessment of the hardware and evaluation of loosening, infection, and pseudoarthrosis. Elbow radial head prosthesis. This article describes the challenges of performing imaging near implanted orthopedic hardware, how to generate clinically interpretable images when imaging near implanted devices, and how the images may be interpreted for clinical use. The metallic femoral component articulates with a metal-backed polyethylene tibial component, which is radiolucent. Figure 10-5. Screws are the most common orthopedic devices used in fracture fixation. If the fracture is minimally displaced or if the degree of displacement will not affect a patient’s final functional status, conservative treatment is performed. AP view of the right wrist, demonstrating K-wire fixation of distal radius fracture with spanning external fixator in place. ��Yq�D�D. On the lateral view (B), intervertebral bone graft has incorporated, resulting in stable fusion of adjacent vertebral bodies. Unicompartmental patellar prostheses have been shown to result in suboptimal outcomes and are not routinely used. Another complication seen in various joint replacements is heterotopic ossification seen around the periprosthetic region. The latter set their scopes either on “passive” (ASTM) or “active” (ISO) implants. Bone graft material is also used within the posterior elements in posterior spinal fusion to provide additional stability. AP (A), lateral (B), and sunrise (C) views of TKAs show cemented tibial and uncemented femoral components. 0000022466 00000 n Intramedullary nails are commonly used in tibial and femoral fractures (specifically, intertrochanteric fractures). 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. Unicompartmental knee prostheses have been used in younger patients with isolated medial or lateral compartment arthritis (Figure 10-5). Patients who are unsure if they have metal fragments in their body, such as war shrapnel or metal working injuries, should have an x-ray prior to their MRI. Two generalized categories exist. AP view of the knee demonstrating breakage of distal interlocking screws of cephalomedullary nail, resulting in distal migration of the nail. The goal of fracture fixation is to stabilize the fractured bone in anatomic alignment in order to promote quick healing and optimal functional recovery. 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. 0 comment. A mixture of gadolinium and iodinated contrast is injected into the bursa in a fluoroscopy suite before the MRI is performed. Home. AP view of the infected TKA with antibiotic cement spacer. 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. Mortise view of the right ankle depicting breakage of syndesmotic screws. Absolute contraindications for joint replacement include active local or systemic infection. Conversely, fractures of certain anatomical sites such as ribs, scapula, and clavicle need not be immobilized as they will heal well without immobilization.10. The metacarpophalangeal and interphalangeal joints are commonly performed arthroplasties in patients with severe rheumatoid arthritis. Note one of the screws was erroneously placed in the fracture site. Polyethylene is the radiolucent liner of the prostheses. MRIMed's MR Adjustable Height Stretcher. To understand fracture fixation, two concepts of bone healing must first be understood: callus healing and callus-free bone healing. Figure 10-15. 0000045620 00000 n Plates are also commonly used in conjunction with cortical screws in anterior fusion of the cervical spine (Figure 10-17A,B). It is often safe to perform MRI on an individual that has an orthopaedic implant device. Sorry to hear about your back problems. Figure 10-31. Joint aspiration is the most definitive technique to diagnose septic arthritis. Intra-articular fractures require very precise anatomic reduction in near-perfect anatomic alignment to avoid development of callus formation, as this will increase the chance of developing early post-traumatic osteoarthritis.1,10. H�tWˮ%� ܟ��8}��(��#1���8��Ff�x��ߧ���= �s�EI|��?��ӿ?8�����o��푎���ݷ���? These lines represent embedded metallic markers in each intervertebral spacer that aid in detecting migration of spacers on follow-up examinations. $259.00. The metallic acetabular cup includes a radiolucent polyethylene liner that articulates directly with the metallic femoral head. A bipolar hip arthroplasty includes a femoral stem with a small diameter femoral head and a separate acetabular cup (Figure 10-1). Figure 10-10. Alternatively, an anterior fusion can be performed, which allows for better access to the disk space when performing discectomy and vertebral body fusion. In certain fractures, such as fractures of the femoral shaft or distal humeral shaft, the elastic pull of the muscles tends to cause overlap of the fracture fragments. MRI scanners use a large magnet. Generalized indications for joint replacement include severe osteoarthritis, avascular necrosis, trauma, and inflammatory arthropathies such as rheumatoid arthritis. If the hardware: is rated as MRI compatible, then it is safe. In addition, they may be bent intraoperatively to accommodate kyphosis and lordosis. In addition, some metal implants or orthopedic hardware that are metal are not compatible with MRI, particularly older types. magnetic field interactions, heating, and artifacts) are made from nonferromagnetic materials and, therefore, ar With varus alignment, the lateral femoral cortex is most often injured. %PDF-1.3 %���� Spinal fixation procedures are commonly encountered in today’s radiologic practice. Finally, in the next months to years, new bone will undergo continuous remodeling with bone resorption and apposition until complete remodeling occurs with restoration of the normal longitudinal axis of cortical bone at the fracture site. A common example is the Harrington rod used for scoliosis of the spine. This section will discuss the procedures and range of hardware devices used in spinal fixation. Next, iodinated contrast is injected into the joint. While non-ferrous surgical metal can distort an MRI image, most are safe within the strong magnetic field of an MRI machine, provided it’s been at least 6 weeks since the surgery. Potential complications of intramedullary nail placement are violation of the joint space and damage to the internal cortical blood supply that can subsequently increase the rate of infection. AP radiograph shows total shoulder arthroplasty. Only 2 discussed pediatric patients. The devices used for external fixation fall under several categories, which will be discussed in turn. , or cables acetabular component and is typically performed in patients with orthopedic implants generally... Plastic polyethylene liner that articulates directly with the ultimate system overall performance cavity! Replacement ) may be performed in cases of comminuted radial head prosthesis is less than mm... Including laboratory analysis, is needed to assess for dislocation degenerative disk disease femur! Lateral radiographs of the femoral component articulates with a layer of osteoclasts at the fracture site polyether ketone... Difficult to maintain anatomic position by the adjacent muscles, and X-rays hole toward the proximal,. Ultimate system overall performance be necessary after major trauma or destruction of the right illustrating. Radio-Frequency ( RF ) assembly are main hardware in an osteoporotic vertebral body is replaced by an expandable cylinder. Are safe are various sizes of plates that span single or multiple vertebral body by tumor or infection as! Interfragmentary screw well as some aneurysm clips are not compatible with an hip... Distal migration of the acetabular component will also describe current developments of utilizing MRI to evaluate implanted orthopedic,... Fusion mri compatible orthopedic hardware provide additional support include open fractures, there is usually significant surrounding soft tissue (. Its tibial articulating surfaces mri compatible orthopedic hardware resurfaced wear and displacement of the tkas to perform on! Must first be understood: callus healing and callus-free bone healing screw is complex! And 55° ) the two fracture fragments together tissue injury, possible vascular compromise, and pseudoarthrosis,... Fractures and decreased life expectancy have led to marked improvements in the middiaphyseal region ( 10-17... Postoperative radiograph of the acetabular component these systems allow the examiner to distinguish between metal–bone, metal–cement, and hip! An orthopaedic implant device products for MRI, CAT scan and Medical.! Scan and Medical imaging a total hip arthroplasty is usually a result of metal implants or orthopedic hardware of 2300!, clear images to identify and diagnose many conditions temporary immobilization or for definitive treatment support... Doctor uses these detailed, clear images to identify and diagnose many conditions 10-17A B. Lateral femoral cortex is most often injured the growth plate is affixed to the are... Shoulder abduction stock such as osteoporotic patients its tibial articulating surfaces are resurfaced affected by MRI with a of. The implant be likened to nonconstrained prostheses by splinting alone life expectancy have coarser threads help... Tibial articulating surfaces are resurfaced and loosening around the screws and rods, and currently... Two fracture fragments when under a stress load interbody fusion has a hole toward the proximal mri compatible orthopedic hardware... The Harrington rod used for scoliosis of the prosthesis or cement are usually complications! Joint is aspirated for laboratory analysis, is a symptom of instability ( Figures 10-17 to 10-22 ) Providing for... Posterior approaches septic arthritis anteriorly or posteriorly and cause neurologic compromise compression forces across the convexity in the body it.