Magnetic resonance imaging quality in the context of a knee-spanning external fixator placed inside the MR bore: a literature review.

After emergent assessment of potentially limb-threatening injuries in knee dislocation or multi-ligament knee injury patients, magnetic resonance imaging is necessary to visualize ligamentous structures and plan for soft tissue repair. However, the application of a knee-spanning external fixator may introduce artifact and reduce overall image quality, which can limit the evaluation of soft tissue injury. As a result, the utility of MRI in the context of a knee-spanning external fixator has been called into question. Signal-to-noise ratio, contrast-to-noise ratio, and qualitative scales have been used to assess image quality of MRI in the context of a knee-spanning external fixator. Despite the potential for artifact, studies have demonstrated that useful diagnostic information may be obtained from MRI in the presence of an external fixator. This review examines the general principles of anatomical assessment, magnetic field strength, device composition and design, radiofrequency coil use, and MRI sequences and artifact reduction as they pertain to MRI in the presence of a knee-spanning external fixator.

Perspectives and institutional policies on patient safety and image quality regarding the use of knee-spanning external fixators in MRI: A survey study of the Society of Skeletal Radiology.

OBJECTIVE: Concerns regarding patient safety and image quality have made the use of knee-spanning external fixators in MRI a challenging clinical scenario. The purpose of our study was to poll practicing musculoskeletal radiologists on their personal experiences regarding the use of knee-spanning external fixators in MRI in an effort to consolidate practice trends for the radiologists' benefit. METHODS: A 27-item survey was created to address the institutional use, safety, adverse events, quality, and perspectives of the radiologist related to MRI of an externally fixated knee. The survey was distributed to 1739 members of the Society of Skeletal Radiology. RESULTS: A total of 72 members of the Society of Skeletal Radiology completed the survey. Most notably, 40 of 72 (55.56%) respondents are permitted to place a knee-spanning external fixator inside the MR bore at their institution, while19 of 72 (26.39%) respondents are not permitted to do so. Fourteen of 32 (43.75%) respondents have institutional guidelines for safely performing an MRI of an externally fixated knee. Twenty-five of 32 (78.13%) respondents are comfortable permitting an MRI of an externally fixated knee. CONCLUSION: We found a general lack of consensus regarding the decision to scan a patient with a knee-spanning external fixator in MRI. Many institutions lack safety guidelines, and providers rely upon a heterogeneous breadth of resources for safety information. A re-examination of the FDA device labeling nomenclature and expectations of the individual manufacturers may be needed to bridge this gap and help direct management decisions placed upon the provider.

Paraneoplastic musculoskeletal disorders: review and update for radiologists.

Rheumatic paraneoplastic syndromes are rare syndromes that occur at distant sites from the underlying tumor and may involve the bones, joints, fasciae, muscles, or vessels. In the absence of a known tumor, early recognition of a rheumatic syndrome as paraneoplastic permits dedicated work-up for, and potentially early treatment of an occult malignancy. Although there is a continuously growing list of paraneoplastic rheumatic disorders, not all of these disorders have a well-established association with a neoplastic process. The goals of this article are to review the clinical characteristics, diagnostic work-up, and imaging findings of well-documented rheumatic paraneoplastic disorders.

Update of pediatric bone tumors: osteogenic tumors and osteoclastic giant cell-rich tumors.

There are numerous bone tumors in the pediatric population, with imaging playing an essential role in diagnosis and management. Our understanding of certain bone tumors has rapidly evolved over the past decade with advancements in next-generation genetic sequencing techniques. This increased level of understanding has altered the nomenclature, management approach, and prognosis of certain lesions. We provide a detailed update of bone tumors that occur in the pediatric population with emphasis on the recently released nomenclature provided in the 5th edition of the World Health Organization Classification of Soft Tissue and Bone Tumours.

Update of pediatric bone tumors-other mesenchymal tumors of bone, hematopoietic neoplasms of bone, and WHO classification of undifferentiated small round cell sarcomas of bone.

There are numerous bone tumors in the pediatric population, with imaging playing an essential role in diagnosis and management. Our understanding of certain bone tumors has rapidly evolved over the past decade with advancements in next-generation genetic sequencing techniques. This increased level of understanding has altered the nomenclature, management approach, and prognosis of certain lesions. We provide a detailed update of bone tumors that occur in the pediatric population with emphasis on the recently released nomenclature provided in the 5th edition of the World Health Organization Classification of Soft Tissue and Bone Tumours. We discuss other mesenchymal tumors of bone, hematopoietic neoplasms of bone, and WHO classification of undifferentiated small round cell sarcomas of bone. We have detailed osteogenic tumors and osteoclastic giant cell-rich tumors, as well as notochordal tumors, chondrogenic tumors, and vascular tumors of the bone in separate manuscripts.

Update of pediatric bone tumors-notochordal tumors, chondrogenic tumors, and vascular tumors of the bone.

There are numerous bone tumors in the pediatric population, with imaging playing an essential role in diagnosis and management. Our understanding of certain bone tumors has rapidly evolved over the past decade with advancements in next-generation genetic sequencing techniques. This increased level of understanding has altered the nomenclature, management approach, and prognosis of certain lesions. We provide a detailed update of bone tumors that occur in the pediatric population with emphasis on the recently released nomenclature provided in the 5th edition of the World Health Organization Classification of Soft Tissue and Bone Tumours. In the current manuscript, we address notochordal tumors, chondrogenic tumors, and vascular tumors of the bone.

Spectrum of imaging findings in soft-tissue necrosis.

Soft tissue necrosis can occur at different tissue levels, with numerous underlying causes. In this pictorial review, we highlight myonecrosis, and its accompanying stages, fat necrosis, devitalized soft tissue seen with infection, and necrotizing soft tissue infections. Imaging examples are provided with each entity.

Low-velocity, civilian firearm extremity injuries-review and update for radiologists.

Firearm injuries are a preventable epidemic in the USA. Extremities are commonly affected in gunshot injuries. Such injuries may be complex with concomitant osseous, soft tissue, and neurovascular components. The maximum wounding potential of a projectile is determined by its kinetic energy and the proportion of the kinetic energy that is transmitted to the target. Accurate assessment of ballistic injuries is dependent on utilizing the principles of wound ballistics, accurate bullet count, and ballistic trajectory analysis. The goals of this article are to review wound ballistics and the imaging evaluation of extremity civilian firearm injuries in the adult population, with emphasis on ballistic trajectory analysis, specific ballistic fracture patterns, and diffuse, secondary soft tissue ballistic injuries.

Update of pediatric soft tissue tumors with review of conventional MRI appearance-part 1: tumor-like lesions, adipocytic tumors, fibroblastic and myofibroblastic tumors, and perivascular tumors.

There are numerous soft tissue tumors and tumor-like conditions in the pediatric population. Magnetic resonance imaging is the most useful modality for imaging these lesions. Although certain soft tissue lesions exhibit magnetic resonance features characteristic of a specific diagnosis, most lesions are indeterminate, and a biopsy is necessary for diagnosis. We provide a detailed update of soft tissue tumors and tumor-like conditions that occur in the pediatric population, emphasizing each lesion's conventional magnetic resonance imaging appearance, using the recently released 5th edition of the World Health Organization Classification of Soft Tissue and Bone Tumors as a guide. In part one of this review, pediatric tumor-like lesions, adipocytic tumors, fibroblastic and myofibroblastic tumors, and perivascular tumors are discussed. In part two, vascular lesions, fibrohistiocytic tumors, muscle tumors, peripheral nerve sheath tumors, tumors of uncertain differentiation, and undifferentiated small round cell sarcomas are reviewed. Per the convention of the WHO, these lesions involve the connective, subcutaneous, and other non-parenchymatous-organ soft tissues, as well as the peripheral and autonomic nervous system.

Update of pediatric soft tissue tumors with review of conventional MRI appearance-part 2: vascular lesions, fibrohistiocytic tumors, muscle tumors, peripheral nerve sheath tumors, tumors of uncertain differentiation, and undifferentiated small round cell sarcomas.

There are numerous soft tissue tumors and tumor-like conditions in the pediatric population. Magnetic resonance imaging is the most useful modality for imaging these lesions. Although certain soft tissue lesions exhibit magnetic resonance features characteristic of a specific diagnosis, most lesions are indeterminate, and a biopsy is necessary for diagnosis. We provide a detailed update of soft tissue tumors and tumor-like conditions that occur in the pediatric population, emphasizing each lesion's conventional magnetic resonance imaging appearance, using the recently released 5th edition of the World Health Organization Classification of Soft Tissue and Bone Tumors as a guide. In part one of this review, pediatric tumor-like lesions, adipocytic tumors, fibroblastic and myofibroblastic tumors, and perivascular tumors are discussed. In part two, vascular lesions, fibrohistiocytic tumors, muscle tumors, peripheral nerve sheath tumors, tumors of uncertain differentiation, and undifferentiated small round cell sarcomas are reviewed. Per the convention of the WHO, these lesions involve the connective, subcutaneous, and other non-parenchymatous organ soft tissues, as well as the peripheral and autonomic nervous system.

Current concepts of spondylosis and posterior spinal motion preservation for radiologists.

Spinal fusion is performed to eliminate motion at a degenerated or unstable segment. However, this is associated with loss of motion at the fused levels and increased stress on adjacent levels. Motion-preserving implants have been designed in effort to mitigate the limitations of fusion. This review will focus on posterior spinal motion-preserving technologies. In the cervical spine, laminoplasty is a posterior motion-preserving procedure used in the management of myelopathy/cord compression. In the lumbar spine, motion-sparing systems include interspinous process devices (also referred to as interspinous process spacers or distraction devices), posterior dynamic stabilization devices (also referred to as pedicle screw/rod fixation-based systems), and posterior element replacement systems (also referred to as total facet replacement devices). Knowledge of the intended physiologic purpose, hardware utilized, and complications is important in the assessment of imaging in those who have undergone posterior motion preservation procedures.

Negative predictive value of CT for occult fractures of the hip and pelvis with imaging follow-up.

PURPOSE: To determine the negative predictive value of multidetector CT for radiographically occult fracture of the hip or pelvis in an elderly population presenting to the emergency department. METHODS: Two hundred thirty-seven elderly patients with suspected fracture were identified over a 5-year period with negative radiographs acquired in the emergency department followed by an index CT of the hip/pelvis within 24 h. There were 81 cases with a negative index CT, as determined by 2 musculoskeletal radiologists, and with some form of imaging follow-up (MRI, CT, or x-ray) performed within 18 months of the index CT. Follow-up imaging was reviewed by 2 musculoskeletal radiologists for the presence of fracture to determine the performance of the index CT. The electronic medical record was used to exclude the possibility of intervening trauma between the time of the index CT and follow-up imaging. RESULTS: There were 39 cases with follow-up imaging performed within 6 weeks of the negative index CT, and 42 with follow-up imaging within 6 weeks to 18 months of the negative index CT. Eight of 81 patients demonstrated a fracture on follow-up imaging, with 3 of 8 involving the femoral neck or intertrochanteric femur. The negative predictive value of the index CT for the detection of a radiographically occult hip or pelvic fracture was 90.1%. If considering only surgically relevant fractures (femoral neck and intertrochanteric fractures), the negative predictive value improved to 96.3%. CONCLUSION: Computed tomography for occult hip fractures has a high negative predictive value but there are cases not detected with surgical implications.

Exophytic External Occipital Protuberance Prevalence Pre- and Post-iPhone Introduction: A Retrospective Cohort.

Introduction: In controversial fashion, the presence of an enlarged external occipital protuberance has been recently linked to excessive use of handheld electronic devices. We sought to determine the prevalence of this protuberance in a diverse age group of adults from two separate time periods, before and approximately 10 years after the release of the iPhone, to further characterize this theory, as if indeed valid, such a relationship could direct preventative behavior. Materials and Methods: Eighty-two cervical spine radiographs between March 7, 2007 through June 29, 2007 and 147 cervical spine radiographs between October 25, 2017 through January 1, 2018 were reviewed for the presence or absence of an exophytic external occipital protuberance. Influence of sex and age were also assessed. Results: There were 41/82 (50%) patients within the 2007 pre-iPhone group with an exophytic external occipital protuberance, ranging from 2.7-33.8 mm in length. Twenty-seven out of 82 (32.9%) had an external occipital protuberance at or above 10 mm. There were 49/147 (33.3%) patients within the 2017 post-iPhone group with an exophytic external occipital protuberance, ranging from 4.4-53.8 mm in length. Thirty-three out of 147 (22.4%) had an external occipital protuberance at or above 10 mm. When considering accessibility to the iPhone, sex, and age to the presence of an exophytic external occipital protuberance, only sex has a statistically significant association, p=0.000000033. Conclusion: We found no significant association with iPhone accessibility and an exophytic external occipital protuberance. Due to inherent limitations in the retrospective nature of the study, future research is needed to better examine the association of handheld electronic devices with exophytic external occipital protuberances.

Surgical techniques for management of acromioclavicular joint separations: review and update for radiologists.

Imaging plays a central role in the postoperative management of acromioclavicular (AC) joint separations. There are more than 150 described techniques for the surgical management of AC joint injuries. These procedures can be categorized as varying combinations of the following basic techniques: a) soft-tissue repair, b) trans-articular AC joint fixation, c) coracoclavicular (CC) fixation, d) non-anatomic reconstruction of the CC ligaments, e) anatomic reconstruction of the CC ligaments, f) distal clavicle resection, and g) dynamic muscle transfer. The goals of this article are to describe the basic techniques for the surgical management of AC joint separations with an emphasis on technique-specific complications and postoperative imaging assessment.

External fixators: looking beyond the hardware maze.

External fixation has a wide variety of orthopedic applications. Although external fixator frames may have a complex appearance, these constructs are formed from several basic components and can be broadly categorized into unilateral, circular, or hybrid designs. The introduction of computer-aided circular external fixation devices (hexapod frames) has simplified the treatment of multiaxial and especially rotational deformities. Serial radiography plays a central role in the evaluation of callus formation (at the level of treated fracture or nonunion as well as the regenerate and docking site with distraction osteogenesis), tailoring the rate and rhythm of distraction during distraction osteogenesis, evaluation of frame complications, and determination of the timing of frame removal. The goals of this article are to review: the components, types, and relevant terminology of external fixator constructs with special emphasis on the Taylor spatial frame, the principles and techniques of distraction osteogenesis, and complications of external fixation.

Prosthetic joint infections: diagnosis, management, and complications of the two-stage replacement arthroplasty.

Despite improved strategies to prevent prosthetic joint infection, as the total number of joint replacements increases, so does the absolute number of infections. Radiography serves as the first-line imaging modality for the assessment of a suspected prosthetic joint infection. Additionally, serial radiographs acquired after a surgery to eradicate a prosthetic joint infection are an important clinical tool. Prosthetic joint infections are often treated with a 2-stage replacement arthroplasty utilizing a prosthesis with antibiotic-loaded acrylic cement. While complications are uncommon with this procedure, imaging may demonstrate periprosthetic fractures, as well as spacer migration, joint dislocation, and spacer fracture. We describe the classification of prosthetic joint infections, the clinical and imaging diagnosis, and treatment strategies. Familiarity with the hardware utilized in the management of the prosthetic joint infection, and its potential complications is fundamental to accurate imaging interpretation.

The Relevance of Ulnar-Sided Contrast Extravasation During Radiocarpal Joint Wrist Arthrography.

OBJECTIVE: Contrast material often extends from the radiocarpal joint into the proximal soft tissues adjacent to the ulnar aspect of the ulnar styloid during single-compartment radiocarpal joint MR arthrography of the wrist. The hypothesis of this study was that this is a common finding unrelated to symptoms or examination technique. MATERIALS AND METHODS: Wrist MR arthrograms were retrospectively reviewed in consensus by two radiologists. The presence or absence of ulnar-sided contrast extravasation was documented, whether this extravasation appeared contained or dispersed, as was the overall degree of proximal extension of the extravasated contrast material. Patient age, sex, wrist sidedness, volume of contrast material administered, location of symptoms reported clinically, and aberrant contrast material also apparent within the midcarpal space or distal radioulnar joint on the MR images reviewed were documented to determine potential association with ulnar-sided contrast extravasation. RESULTS: Ninety-nine examinations met the inclusion criteria. Ulnar-sided contrast extravasation after single-compartment radiocarpal joint injection was present in 56 of the 99 wrists (57%). This finding was statistically more common in right versus left wrists. No other statistically significant associations were identified. CONCLUSION: Contrast extravasation along the ulnar aspect of the distal ulna after single-compartment radiocarpal joint injection is common. In this study it had no statistically significant association with the location of a patient's wrist pain or abnormal findings evaluated at MR arthrography.

Fragility fractures of the proximal femur: review and update for radiologists.

Proximal femoral fragility fractures are common and result in significant morbidity and mortality along with a considerable socioeconomic burden. The goals of this article are to review relevant proximal femoral anatomy together with imaging, classification, and management of proximal femoral fragility fractures, and their most common complications. Imaging plays an integral role in classification, management and follow-up of proximal femoral fragility fractures. Classification of proximal femoral fragility fractures is primarily based on anteroposterior hip radiographs. Pertinent imaging features for each category of proximal femoral fractures that would guide management are: differentiating nondisplaced from displaced femoral neck fractures, distinguishing stable from unstable intertrochanteric fractures, and determining the morphology and comminution of subtrochanteric fractures. Treatment of proximal femoral fragility fractures is primarily surgical with either arthroplasty or internal fixation. Intramedullary nailing is used in the treatment of some types of proximal femoral fragility fractures and may be associated with unique complications that become evident on postoperative follow-up radiographs.

The floating shoulder.

The floating shoulder refers to a subset of complex shoulder injuries that typically occur in the setting of high-energy trauma. Identification of the full extent of complex shoulder injuries with computed tomography may have critical implications in patient management. The goals of this article are to review the anatomy, definition, imaging evaluation, and treatment of floating shoulder injuries.

Update on operative treatment of scapholunate (SL) instability for radiologists: part 1-SL ligament repair, dorsal capsulodesis and SL ligament reconstruction.

Scapholunate instability is the most common form of carpal instability. Imaging (especially radiography) plays an important role in the staging, management and post-operative follow-up of scapholunate (SL) instability. The goals of this article are to review the pre-operative staging of SL instability, the surgical options for repair and reconstruction of the SL ligament, along with the normal postoperative imaging findings as well as complications associated with these surgical options.