Disassociation of an Anteriorly Implanted Dual-Mobility Component with Migration to the Distal Posterior Thigh: A Case Report.

CASE: Intraprosthetic dislocation, a rare complication of modular dual-mobility hip replacements, occurs when the polyethylene component becomes dislodged. Our patient sustained an intraprosthetic dislocation with subsequent implant migration to the posterior thigh. In an anterior approach revision surgery at an outside institution, the component was unable to be located. Subsequent imaging revealed marked implant migration. Computed tomography (CT)-guided needle localization was used to facilitate component removal. CONCLUSION: In the presence of different surgical approaches, dissociated polyethylene components may migrate to anatomic compartments distinct from the approach of implantation. CT and needle localization may be used to facilitate component removal.

Rare Dual Lesion: Extraskeletal Osteosarcoma Developing Within a Simple Lipoma.

Extraosseous osteosarcoma is a rare malignancy, but simple lipomas are common. This article is the first report of a case of radiation-induced extraosseous osteosarcoma that developed within a simple lipoma in a 72-year-old woman. We correlate the magnetic resonance imaging, computed tomography, positron emission tomography, and plain radiographic findings. The patient, treated with systemic therapy and wide surgical resection of the neoplasm, remained clinically free of disease during the first 22 months of follow-up.

Multimodality Approach to a Stener Lesion: Radiographic, Ultrasound, Magnetic Resonance Imaging, and Surgical Correlation.

The ulnar collateral ligament (UCL) of the thumb metacarpophalangeal joint is a static stabilizer that may rupture from a hyperabduction injury. Although some UCL tears may heal with immobilization, outcomes are worse for Stener lesions, in which the proximal ligament stump slips out from beneath the adductor pollicis aponeurosis and is entrapped proximal and superficial to the aponeurosis, preventing primary healing. We report the case of a patient with a Stener lesion with radiographic, ultrasound, and magnetic resonance imaging correlation, subsequently confirmed with intraoperative photographs. Physicians must be familiar with the regional anatomy to understand the injury pathogenesis and the need for surgical intervention to optimize patient outcomes.

Amplatzer vascular plug as an embolic agent in different vascular pathologies: A pictorial essay.

The Amplatzer Vascular Plug (AVP) is a cylindrical plug made of self-expanding nitinol wire mesh with precise delivery control, which can be used for a variety of vascular pathologies. An AVP is an ideal vascular occlusion device particularly in high-flow vessels, where there is high risk of migration and systemic embolization with traditional occlusion devices. We performed 28 embolizations using the AVP from 2009 to 2014 and achieved complete occlusion without complications.

Volumetric segmentation of ADC maps and utility of standard deviation as measure of tumor heterogeneity in soft tissue tumors.

PURPOSE: Determine interobserver concordance of semiautomated three-dimensional volumetric and two-dimensional manual measurements of apparent diffusion coefficient (ADC) values in soft tissue masses (STMs) and explore standard deviation (SD) as a measure of tumor ADC heterogeneity. RESULTS: Concordance correlation coefficients for mean ADC increased with more extensive sampling. Agreement on the SD of tumor ADC values was better for large regions of interest and multislice methods. Correlation between mean and SD ADC was low, suggesting that these parameters are relatively independent. CONCLUSION: Mean ADC of STMs can be determined by volumetric quantification with high interobserver agreement. STM heterogeneity merits further investigation as a potential imaging biomarker that complements other functional magnetic resonance imaging parameters.

Incidence of tendon entrapment and dislocation with calcaneus and pilon fractures on CT examination.

OBJECTIVE: To examine the association between tibial pilon and calcaneal fracture classification and tendon entrapment or dislocation. MATERIALS AND METHODS: After institutional review board approval, we retrospectively reviewed consecutive CT scans with calcaneal or pilon fractures from 5 years at a level 1 trauma center. We categorized calcaneal fractures according to the Sanders classification, and pilon fractures according to the Ruedi and Allgower and the Arbeitsgemeinschaft für Osteosynthesefragen-Orthopaedic Trauma Association (AO-OTA) classifications. Ankle tendons were assessed for dislocation or entrapment. Fisher's exact test was used for statistical analysis with significance at p < 0.05. RESULTS: A total of 312 fractures (91 pilon only, 193 calcaneal only, and 14 ankles with ipsilateral pilon and calcaneal fractures) were identified in 273 patients. Twenty-two pilon, 42 calcaneal, and nine combination fractures were associated with 99 occurrences of tendon entrapment or superior peroneal retinacular injury. Such findings were associated with multiple fractures (p = 0.002). Multifragmentary pilon fractures were associated with posterior tibial and flexor digitorum longus tendon entrapment (p < 0.0001 and p = 0.0003 for Ruedi/Allgower and AO-OTA, respectively), and multifragmentary Sanders type 3 or 4 calcaneal fractures were associated with superior peroneal retinacular injury (p = 0.0473) compared to simple fracture patterns. Thirty-nine percent of tendon entrapments or retinacular injuries were prospectively identified, 85 % by musculoskeletal radiologists (p < 0.0001). CONCLUSIONS: Approximately 25 % of calcaneal and pilon fractures were retrospectively identified to contain posteromedial tendon entrapment or superior peroneal retinacular injury. Radiologists should meticulously search for such injuries, particularly when analyzing multifragmentary and multiple fractures.

Benign and malignant tumors of the foot and ankle.

Pain and focal masses in the foot and ankle are frequently encountered and often initiate a workup including imaging. It is important to differentiate benign lesions from aggressive benign or malignant lesions. In this review, multiple examples of osseous and soft tissue tumors of the foot and ankle will be presented. Additionally, the compartmental anatomy of the foot and ankle will be discussed in terms of its relevance for percutaneous biopsy planning and eventual surgery. Finally, a general overview of the surgical management of benign, benign aggressive and malignant tumors of the foot and ankle will be discussed.

Epiglottic masses identified on CT imaging: A case report and review of the broad differential diagnosis.

Epiglottic masses may be cystic, granulomatous, infectious, benign or malignant neoplastic, or manifestations of a systemic disease. When large in size, the airway may become obstructed, and when accompanied by suspicious features such as cartilaginous invasion, extension to the pre-epiglottic or para-glottic spaces, or lymphadenopathy, the radiologist must consider malignancy as a primary differential diagnosis. However, when only benign features are identified, the differential diagnosis is broad. We present a 65-year-old female with an incidental 1 cm exophytic, pedunculated, papillomatous lesion on the laryngeal surface of the epiglottis discovered upon endoscopic evaluation for dyspepsia and heartburn. Because of her risk factors for malignancy, CT scan was requested and revealed only benign features. Subsequent excisional biopsy revealed a benign squamous papilloma; however, multiple additional differential considerations were entertained preoperatively.

Sonographically guided posteromedial approach for intra-articular knee injections: a safe, accurate, and efficient method.

Osteoarthritis of the knee can be a debilitating and extremely painful condition. In patients who desire to postpone knee arthroplasty or in those who are not surgical candidates, percutaneous knee injection therapies have the potential to reduce pain and swelling, maintain joint mobility, and minimize disability. Published studies cite poor accuracy of intra-articular knee joint injections without imaging guidance. We present a sonographically guided posteromedial approach to intra-articular knee joint injections with 100% accuracy and no complications in a consecutive series of 67 patients undergoing subsequent computed tomographic or magnetic resonance arthrography. Although many other standard approaches are available, a posteromedial intra-articular technique is particularly useful in patients with a large body habitus and theoretically allows for simultaneous aspiration of Baker cysts with a single sterile preparation and without changing the patient's position. The posteromedial technique described in this paper is not compared or deemed superior to other standard approaches but, rather, is presented as a potentially safe and efficient alternative.

Ischiofemoral impingement syndrome: a meta-analysis.

OBJECTIVE: The aims of this article are to review the imaging characteristics of ischiofemoral impingement (IFI), summarize measurement thresholds for radiologic diagnosis based on a meta-analysis of the literature and raise awareness among radiologists and clinicians of this entity. MATERIALS AND METHODS: A PubMed search restricted to the English language containing the keywords "ischiofemoral impingement" and "quadratus femoris MRI" was performed, and citations in these articles were also used to identify a total of 27 studies discussing ischiofemoral impingement. After excluding case reports and non-representative studies, there were five remaining articles including 193 hip MRIs of IFI in 154 subjects (133 female, 21 male) and 135 asymptomatic control hip MRIs from 74 subjects (55 female, 19 male). Additionally, we performed a retrospective database search of pelvic and hip MRI reports from our institution including the terms "quadratus femoris" or "ischiofemoral impingement" from a 9-year period and 24 hip MRIs from 21 patients (18 female, 3 male) with IFI with 5 asymptomatic contralateral control hip MRIs identified. In all, 217 hip MRIs of IFI and 140 control cases were included. A meta-analysis of these hip MRIs was conducted to determine optimal thresholds of the ischiofemoral space (IFS) and quadratus femoris space (QFS) for identifying IFI. RESULTS: Cases of IFI showed significantly smaller IFS and QFS compared to controls (14.91 ± 4.8 versus 26.01 ± 7.98 and 9.57 ± 3.7 versus 15.97 ± 6.07, measured in mm, respectively, p < 0.0001 for both). Pooled analysis revealed that for IFS, using a cutoff of ≤ 15 mm yielded a sensitivity of 76.9%, specificity of 81.0% and overall accuracy of 78.3%. For QFS, a cutoff of ≤ 10.0 mm resulted in 78.7% sensitivity, 74.1% specificity and 77.1% overall accuracy. CONCLUSION: IFI is a potential cause of hip pain that can be accurately diagnosed with MRI in conjunction with clinical findings. Using the proposed measurement thresholds may better identify patients with this impingement syndrome so that optimal treatment options can be pursued.

"Ilizarov" external fixation: what the radiologist needs to know.

Circular external fixation, including the Ilizarov method, is a complex and often long-term treatment used for various orthopedic conditions. Due to the complexity of the hardware, frequent postoperative complications, and the potential for significant radiographic changes between visits, it is important for the radiologist to have a basic understanding of ring fixators. This publication reviews indications for external fixation versus internal fixation and whether to use a circular or uniplanar construct if external fixation is elected. Indications for and characteristics of static circular frames, intercalary and non-intercalary transport frames, and deformity circular frames will also be discussed. While general similarities exist between frame types, each has unique components of which the radiologist must be aware. An emphasis is placed on the important features and complications that arise during treatment.

Sacral morel-lavallée lesion: a not-so-rare diagnosis.

Morel-Lavallée lesions are closed soft tissue degloving injuries with a propensity to become infected, arising in the lumbosacral region or even the scalp, common anatomical locations in neuroradiological studies. The radiologist must recognize this entity, its traumatic etiology, and treatment options. Our patient's Morel-Lavallée lesion was evaluated with ultrasound and MRI, demonstrating a predominantly hemorrhagic lesion successfully managed by aspiration.

Ischiofemoral impingement and the utility of full-range-of-motion magnetic resonance imaging in its detection.

Ischiofemoral impingement is a cause of hip pain resulting from compression on the quadratus femoris muscle between the ischium and femoral lesser trochanter. The most widely accepted diagnostic criterion is hip pain with isolated edema-like signal in the ipsilateral quadratus femoris muscle on magnetic resonance imaging (MRI). Additional criteria based on measurements of the ischiofemoral and quadratus femoris spaces have recently been suggested. However, because these measurements are positioning-dependent, we used full-range-of-motion MRI to increase the diagnostic yield. By evaluating through a range of motion, we detected a case of impingement involving the ischial tuberosity and the lesser trochanter, with probable contributing impingement between the ischial tuberosity and greater trochanter. In this article, we briefly review the topic of ischiofemoral impingement, provide an example of how range-of-motion MRI can improve diagnostic accuracy, describe our protocol, and propose exploring the need for an expanded definition of the impingement criteria.

Tip of the iceberg: subtle findings on traumatic knee radiographs portend significant injury.

Despite their low clinical yield, knee radiographs are among the most commonly acquired radiographic trauma studies in the emergency department. Although obvious fractures may be present, several subtler radiographic findings suggest internal derangement and significant injury. In this review, we provide an overview of traumatic knee radiography, including anatomy, acquisition techniques, and pitfalls with associated magnetic resonance imaging correlation when available.

Unusual aggressive breast cancer: metastatic malignant phyllodes tumor.

For the year of 2012, it has been estimated that breast cancer will account for the greatest number of newly diagnosed cancers and the second highest proportion of cancer related deaths among women. Breast cancer, while often lumped together as one disease, represents a diverse group of malignancies with different imaging findings, histological appearances and behavior. While most invasive primary breast cancers are epithelial derived adenocarcinomas, rare neoplasms such as the phyllodes tumor may arise from mesenchymal tissue. Compared to the breast adenocarcinoma, the phyllodes tumor tends to affect a younger population, follows a different clinical course, is associated with different imaging and histological findings and is managed distinctively. There may be difficulty in differentiating the phyllodes tumor from a large fibroadenoma, but the mammographer plays a key role in reviewing the clinical and imaging data in order to arrive at the correct diagnosis. Early diagnosis with proper surgical management can often cure non-metastatic phyllodes tumors. However, in rare cases where metastasis occurs, prognosis tends to be poor. This report describes the presentation, imaging findings and management of a metastatic malignant phyllodes tumor.