Alloys represent the metallic component of the prostheses. 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. The literature within the last 10 years on MRI use in patients with orthopedic implants is reviewed. Cement is seen as a radiopaque lining surrounding the prosthesis. The other important concept to realize is that the spinal hardware is used to provide temporary fixation and stability by immobilizing the bone. Conversely, fractures of certain anatomical sites such as ribs, scapula, and clavicle need not be immobilized as they will heal well without immobilization.10. Some types of metal implants or orthopedic hardware are magnetic and are not compatible with an MRI, especially older types. Orthopedic surgeons favor titanium implants for their strength and compatibility with body tissues. (A) Both the femoral and tibial components of the TKA exhibit irregular periprosthetic lucency (arrows), suggestive of infection. Only 2 discussed pediatric patients. This type of fracture healing is often referred to as “direct” fracture healing. Repetitive mechanical stresses can cause loosening at the cement–bone, prosthesis–bone and cement–prosthesis interfaces. Elbow radial head prosthesis. The main components of any modern joint arthroplasty include a metal alloy and a plastic polyethylene liner. Relative contraindications include obesity, remote infection, unrepaired ligamentous injuries, and neurologic impairment. 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. The humeral component may be cemented or noncemented, and articulate with the native glenoid. Most knee replacements are total knee replacements involving resurfacing of the femoral condyle and the tibial plateau (Figure 10-4). MRI compatable IV Pole. Early postoperative complications include postoperative hematoma, infection, and meningocele formation. 0000023090 00000 n Joint replacement is one of the most common orthopedic procedures performed. Fractures of hardware components include broken screws (Figure 10-20), broken wires, and fractures of the rods. Radiofrequency-induced heating of implants differ … Implant safety is a thriving field in MRI; much has been accomplished but even more is still missing. 0000087426 00000 n A literature search returned 15 relevant articles. Usually, the vertebral body is replaced by an expandable hollow cylinder packed with bone graft material or cement.6,7. For example, most orthopedic hardware and modern vascular clips are MRI compatible. In open fractures, there is usually significant surrounding soft tissue injury, possible vascular compromise, and increased risk of infection. Figure 10-33. The hardware performance has direct relationship with the ultimate system overall performance. Three screws are typically used to achieve fixation, with two screws placed inferiorly and one placed superiorly.11,12. 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). Polyethylene is the radiolucent liner of the prostheses. 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. Infection is an uncommon complication that usually presents with irregular progressive lucency and destruction surrounding the implant. A well-known type of external fixator is the Ilizarov frame that uses thin wires to secure the proximal and distal fracture fragments, with the wires then attached to an outside ring frame that are all lined and connected by adjustable rods.10 The Ilizarov device is used in the treatment of limb lengthening procedures as well as complex bone fractures. In other words, it is not seen on the radiograph. Figure 10-29. AP radiograph shows shoulder hemiarthroplasty. 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. The interfragmentary screw is a screw that crosses the fracture line (Figure 10-29), ideally perpendicular to the fracture line. 0000087387 00000 n 0000023598 00000 n 0000022212 00000 n These plates are very malleable and can be shaped to stabilize complex fractures involved in the pelvis. A common example is the Harrington rod used for scoliosis of the spine. 0000001812 00000 n Note the formation of early bridging callus. Initially a side plate is affixed to the distal femur and attached with multiple cortical screws. Focal areas of lucency are more suggestive of loosening than the generalized lucency seen in infection. 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. Bone is first removed elbow prostheses can further be subdivided into posterior cruciate ligament ( PCL sparing... Infected total knee arthroplasty ( Figures 10-23 to 10-27 ) includes either a noncemented or cemented stem. Neurovascular structures tissue shrapnel ( except for within the last 10 years on MRI use in patients with orthopedic are... 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