Total spine MRI for the preoperative evaluation of adolescent idiopathic scoliosis: part 1.

Adolescent idiopathic scoliosis is a commonly encountered condition often diagnosed on screening examination. Underlying, asymptomatic neural axis abnormalities may be present at the time of diagnosis. At certain institutions, total spine MRI is obtained preoperatively to identify these abnormalities. We provide a framework for the radiologist to follow while interpreting these studies. In part 1, we discuss Arnold Chiari malformations, syringomyelia, and the tethered cord. In part 2, we focus on spinal cord tumors, dysraphisms, to include diastematomyelia, and vertebral anomalies.

Total spine MRI for the preoperative evaluation of adolescent idiopathic scoliosis: Part 2 - spinal cord tumors, dysraphisms, diastematomyelia, and vertebral anomalies.

Adolescent idiopathic scoliosis is a commonly encountered condition often diagnosed on screening examination. Underlying, asymptomatic neural axis abnormalities may be present at the time of diagnosis. At certain institutions, total spine MRI is obtained preoperatively to identify these abnormalities. We provide a framework for the radiologist to follow while interpreting these studies. In part 1, we discuss Arnold Chiari malformations, syringomyelia, and the tethered cord. In part 2, we focus on spinal cord tumors, dysraphisms, to include diastematomyelia, and vertebral anomalies.

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.

Rare Presentation of Rosai-Dorfman Disease in Soft Tissue: Diagnostic Findings and Surgical Treatment.

Introduction and Importance. Rosai-Dorfman disease (RDD) is a rare, benign type II histiocytosis characterized by the infiltration of S100+ histiocytes and emperipolesis. The disease may present in the lymph nodes (nodal RDD), in extranodal sites, or in both nodal and extranodal sites. Among those patients who present exclusively in extranodal sites, only a minority of cases present in the soft tissue. Case Presentation. An 18-year-old female presented to orthopedic oncology clinic with a chief complaint of a mass located in her lower back. The patient underwent excision of the lumbosacral mass. Pathologic review demonstrated emperipolesis of lymphocytes and plasma cells within enlarged, eosinophilic histiocytes in a background of lymphoplasmacytic infiltration and collagenous stroma. Immunohistochemical staining demonstrated S100+ and CD163+ histiocytes, consistent with diagnosis of soft tissue RDD. Clinical Discussion. Histologically, RDD is generally characterized by emperipolesis-the presence of intact lymphocytes within the histiocyte cytoplasm-and a mixed infiltrate of S100+ histiocytes, mononuclear cells, plasma cells, and lymphocytes. Although soft tissue RDD may histologically resemble nodal RDD, soft tissue RDD also demonstrates some notable histologic differences including the lack of nodal architecture, the presence of increased fibrosis and collagen deposition, and generally fewer RDD cells. Conclusion. This case presentation demonstrates one few reports of isolated soft tissue RDD within the lumbosacral region without associated lymphadenopathy or skin changes and highlights the heterogeneity that still exists in the treatment paradigm of extranodal RDD.

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.

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.

Clinical and Anatomical Considerations for Management of a Complete Tear of the Distal Rectus Femoris Myotendinous Junction: A Rare Knee Extensor Mechanism Injury.

ABSTRACT: The knee extensor mechanism is a highly complex multilayered and reinforced structure. Quadriceps muscle injuries are considered to be common, particularly among athletes; however isolated rectus femoris injuries involving the distal myotendinous junction are considered to be exceedingly rare with very few case reports published to date. Thus, the presentation and diagnosis of this injury can be elusive and treatment is nonuniform. There is limited literature published advocating both nonsurgical and surgical management. We illustrate the clinical and radiologic presentation of a traumatic, nonsport-related distal rectus femoris muscle injury treated operatively. The presentation of this injury along with anatomical and clinical considerations is portrayed in detail. This case report contributes to the sparse literature regarding this injury and delineates management considerations.

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.

Synthesis of fracture radiographs with deep neural networks.

PURPOSE: We describe a machine learning system for converting diagrams of fractures into realistic X-ray images. We further present a method for iterative, human-guided refinement of the generated images and show that the resulting synthetic images can be used during training to increase the accuracy of deep classifiers on clinically meaningful subsets of fracture X-rays. METHODS: A neural network was trained to reconstruct images from programmatically created line drawings of those images. The images were then further refined with an optimization-based technique. Ten physicians were recruited into a study to assess the realism of synthetic radiographs created by the neural network. They were presented with mixed sets of real and synthetic images and asked to identify which images were synthetic. Two classifiers were trained to detect humeral shaft fractures: one only on true fracture images, and one on both true and synthetic images. RESULTS: Physicians were 49.63% accurate in identifying whether images were synthetic or real. This is close to what would be expected by pure chance (i.e. random guessing). A classifier trained only on real images detected fractures with 67.21% sensitivity when no fracture fixation hardware was present. A classifier trained on both real images and synthetic images was 75.54% sensitive. CONCLUSION: Our method generates X-rays realistic enough to be indistinguishable from real X-rays. We also show that synthetic images generated using this method can be used to increase the accuracy of deep classifiers on clinically meaningful subsets of fracture X-rays.

Reliability of Radiographic Union Scoring in Humeral Shaft Fractures.

OBJECTIVES: To establish the reliability of 2 radiographic union scoring systems for nonoperative humeral shaft fractures. DESIGN: Retrospective medical record review. Patients identified had humeral shaft fractures and radiographs at various follow-up time points, which were graded according to the both the standard (RUST) and modified radiographic union scoring systems (mRUST). SETTING: A single North American Level-1 Trauma center in Connecticut, including emergency department and clinic follow-up visits. PATIENTS/PARTICIPANTS: Forty-five adult patients (162 image sets) met the following inclusion criteria: diaphyseal humerus fracture, initial nonoperative management, and greater than 2 weeks of follow-up with imaging. INTERVENTION: All 162 image sets of anterior-posterior and lateral radiographs were scored and divided into 4 tiers based on increasing score. Anterior-posterior and lateral image sets were randomly selected from each tier for a total of 50 that were then scored by 7 different reviewers using both the RUST and mRUST systems. MAIN OUTCOME MEASURES: The intraclass correlation coefficients for the cortical and system scores for the RUST and mRUST systems. RESULTS: Interobserver reliability was 0.795 for the RUST system and 0.801 for mRUST. Intraobserver reliability was 0.909 for RUST and 0.949 for mRUST. For mRUST, 92% of values were within ± 1 point from each other. CONCLUSIONS: The RUST and mRUST systems can be applied to humeral shaft fractures with excellent reliability. They have the potential to assist in the diagnosis of humeral shaft union by providing an objective and standardized method to assess healing of bone over time.

Stiffness of the human foot and evolution of the transverse arch.

The stiff human foot enables an efficient push-off when walking or running, and was critical for the evolution of bipedalism1-6. The uniquely arched morphology of the human midfoot is thought to stiffen it5-9, whereas other primates have flat feet that bend severely in the midfoot7,10,11. However, the relationship between midfoot geometry and stiffness remains debated in foot biomechanics12,13, podiatry14,15 and palaeontology4-6. These debates centre on the medial longitudinal arch5,6 and have not considered whether stiffness is affected by the second, transverse tarsal arch of the human foot16. Here we show that the transverse tarsal arch, acting through the inter-metatarsal tissues, is responsible for more than 40% of the longitudinal stiffness of the foot. The underlying principle resembles a floppy currency note that stiffens considerably when it curls transversally. We derive a dimensionless curvature parameter that governs the stiffness contribution of the transverse tarsal arch, demonstrate its predictive power using mechanical models of the foot and find its skeletal correlate in hominin feet. In the foot, the material properties of the inter-metatarsal tissues and the mobility of the metatarsals may additionally influence the longitudinal stiffness of the foot and thus the curvature-stiffness relationship of the transverse tarsal arch. By analysing fossils, we track the evolution of the curvature parameter among extinct hominins and show that a human-like transverse arch was a key step in the evolution of human bipedalism that predates the genus Homo by at least 1.5 million years. This renewed understanding of the foot may improve the clinical treatment of flatfoot disorders, the design of robotic feet and the study of foot function in locomotion.

Imaging findings of anterior hip dislocations.

Anterior hip dislocations are rare orthopedic emergencies resulting from high-energy trauma and have unique imaging characteristics on radiography, computed tomography (CT), and magnetic resonance imaging (MRI). Imaging findings on CT and MRI allow for the prompt recognition and classification of anterior hip dislocations, which guides patient management and reduces complications. The purpose of this article is to review imaging findings of anterior hip dislocations, specifically focusing on CT and MRI.