Microglial-derived C1q integrates into neuronal ribonucleoprotein complexes and impacts protein homeostasis in the aging brain.

Neuroimmune interactions mediate intercellular communication and underlie critical brain functions. Microglia, CNS-resident macrophages, modulate the brain through direct physical interactions and the secretion of molecules. One such secreted factor, the complement protein C1q, contributes to complement-mediated synapse elimination in both developmental and disease models, yet brain C1q protein levels increase significantly throughout aging. Here, we report that C1q interacts with neuronal ribonucleoprotein (RNP) complexes in an age-dependent manner. Purified C1q protein undergoes RNA-dependent liquid-liquid phase separation (LLPS) in vitro, and the interaction of C1q with neuronal RNP complexes in vivo is dependent on RNA and endocytosis. Mice lacking C1q have age-specific alterations in neuronal protein synthesis in vivo and impaired fear memory extinction. Together, our findings reveal a biophysical property of C1q that underlies RNA- and age-dependent neuronal interactions and demonstrate a role of C1q in critical intracellular neuronal processes.

Effects of anthropogenic landscapes on population maintenance of waterbirds.

Anthropogenic impacts have reduced natural areas but increased the area of anthropogenic landscapes. There is debate about whether anthropogenic landscapes (e.g., farmlands, orchards, and fish ponds) provide alternatives to natural habitat and under what circumstances. We considered whether anthropogenic landscapes can mitigate population declines for waterbirds. We collected data on population trends and biological traits of 1203 populations of 579 species across the planet. Using Bayesian generalized linear mixed models, we tested whether the ability of a species to use an anthropogenic landscape can predict population trends of waterbird globally and of species of conservation concern. Anthropogenic landscapes benefited population maintenance of common but not less-common species. Conversely, the use of anthropogenic landscapes was associated with population declines for threatened species. Our findings delineate some limitations to the ability of anthropogenic landscapes to mitigate population declines, suggesting that the maintenance of global waterbird populations depends on protecting remaining natural areas and improving the habitat quality in anthropogenic landscapes. Article impact statement: Protecting natural areas and improving the quality of anthropogenic landscapes as habitat are both needed to achieve effective conservation.

Efectos de los Paisajes Antropogénicos sobre la Conservación de Poblaciones de Aves Acuáticas Resumen Los impactos antropogénicos han reducido las áreas naturales, pero han incrementado el área de los paisajes antropogénicos. Existe un debate sobre si los paisajes antropogénicos (p. ej.: campos de cultivo, huertos, estanques de peces) proporcionan alternativas al hábitat natural y bajo cuáles circunstancias. Consideramos si los paisajes antropogénicos pueden mitigar las declinaciones poblacionales de las aves acuáticas. Recolectamos datos sobre las tendencias poblacionales y las características biológicas de 1203 poblaciones de 579 especies de aves de todo el mundo. Mediante modelos bayesianos generalizados lineales mixtos, analizamos si la habilidad de una especie para usar un paisaje antropogénico puede pronosticar las tendencias poblacionales de las aves acuáticas a nivel mundial y de las especies de interés para la conservación. Los paisajes antropogénicos beneficiaron a la conservación de las poblaciones de especies comunes, pero no para las especies menos comunes. Por otro lado, el uso de paisajes antropogénicos estuvo asociado con las declinaciones poblacionales en las especies amenazadas. Nuestros descubrimientos delinean algunas limitaciones que tienen los paisajes antropogénicos para mitigar las declinaciones poblacionales, lo que sugiere que la conservación mundial de las poblaciones de aves acuáticas depende de la protección de las áreas naturales remanentes y del mejoramiento de la calidad del hábitat en los paisajes antropogénicos.

Small sequence variations between two mammalian paralogs of the small GTPase SAR1 underlie functional differences in coat protein complex II assembly.

Vesicles that are coated by coat protein complex II (COPII) are the primary mediators of vesicular traffic from the endoplasmic reticulum to the Golgi apparatus. Secretion-associated Ras-related GTPase 1 (SAR1) is a small GTPase that is part of COPII and, upon GTP binding, recruits the other COPII proteins to the endoplasmic reticulum membrane. Mammals have two SAR1 paralogs that genetic data suggest may have distinct physiological roles, e.g. in lipoprotein secretion in the case of SAR1B. Here we identified two amino acid clusters that have conserved SAR1 paralog-specific sequences. We observed that one cluster is adjacent to the SAR1 GTP-binding pocket and alters the kinetics of GTP exchange. The other cluster is adjacent to the binding site for two COPII components, SEC31 homolog A COPII coat complex component (SEC31) and SEC23. We found that the latter cluster confers to SAR1B a binding preference for SEC23A that is stronger than that of SAR1A for SEC23A. Unlike SAR1B, SAR1A was prone to oligomerize on a membrane surface. SAR1B knockdown caused loss of lipoprotein secretion, overexpression of SAR1B but not of SAR1A could restore secretion, and a divergent cluster adjacent to the SEC31/SEC23-binding site was critical for this SAR1B function. These results highlight that small primary sequence differences between the two mammalian SAR1 paralogs lead to pronounced biochemical differences that significantly affect COPII assembly and identify a specific function for SAR1B in lipoprotein secretion, providing insights into the mechanisms of large cargo secretion that may be relevant for COPII-related diseases.

Dual threat of tidal flat loss and invasive Spartina alterniflora endanger important shorebird habitat in coastal mainland China.

China's coastal wetlands are critically important to shorebirds. Substantial loss of tidal flats, shorebirds' primary foraging grounds, has occurred from land claim and other processes, and is driving population declines in multiple species. Smooth cordgrass Spartina alterniflora was intentionally introduced to the coast of China in 1979 to promote conversion of tidal flats into dry land and has since spread rapidly. The occurrence of S. alterniflora reduces the availability of foraging and roosting habitat for shorebirds, and may be particularly detrimental in places that have experienced other tidal flat loss. However, the extent to which S. alterniflora is encroaching upon important shorebird habitat throughout coastal mainland China, and its intersection with tidal flat loss, has not been quantified. Here, we i) estimate change in the spatial extent of tidal flats between 2000 and 2015 in coastal mainland China where internationally important numbers of shorebirds have been recorded; ii) map the extent of S. alterniflora coverage in 2015 at the same set of sites; and, iii) investigate where these two threats to important shorebird habitat intersect. Our analysis of remote sensing data indicated a 15% net loss in tidal flat area between 2000 and 2015 across all sites, including a net loss in tidal flat area in 39 of 53 individual sites (74%). Spartina alterniflora occurred at 28 of 53 sites (53%) in 2015, of which 22 sites (79%) also had a net loss in tidal flat area between 2000 and 2015. Combined pressures from tidal flat loss and S. alterniflora invasion were most severe in eastern coastal China. Species highly dependent on migrating through this region, which include the Critically Endangered Spoon-billed Sandpiper and Endangered Nordmann's Greenshank and Far Eastern Curlew, may be particularly impacted. Our results underscore the urgent need to arrest tidal flat declines and develop a comprehensive control program for S. alterniflora in coastal areas of mainland China that are important for shorebirds.

Changes in area and number of nature reserves in China.

Nature reserves (NR) are the cornerstone of biodiversity conservation. Over the past 60 years, the rapid expansion of NRs in China, one of the world's megadiverse countries, has played a critical role in slowing biodiversity loss. We examined the changes in the number and area of China's NRs from 1956 to 2014 and analyzed the effect of economic development on the expansion of China's NRs from 2005 to 2014 with linear models. Despite a continuing increase in the number of NRs, the total area of China's NRs decreased by 3% from 2007 to 2014. This loss resulted from downsizing and degazettement of existing NRs and a slowdown in the establishment of new ones. Nature reserves in regions with rapid economic development exhibited a greater decrease in area, suggesting that downsizing and degazettement of NRs are closely related to the intensifying competition between economic growth and conservation. For example, boundary adjustments to national NRs, the most strictly protected NRs, along the coast of China's Yellow Sea, a global biodiversity hotspot with a fast-growing economy, resulted in the loss of one-third of the total area. One of the most important ecosystems in these NRs, tidal wetlands, decreased by 27.8% because of boundary adjustments and by 25.2% because of land reclamation. Our results suggest conservation achievement, in terms of both area and quality, are declining at least in some regions in the Chinese NR estate. Although the designation of protected areas that are primarily managed for sustainable use has increased rapidly in recent years in China, we propose that NRs with biodiversity conservation as their main function should not be replaced or weakened.

Cambios en la Superficie y el Número de Reservas Naturales en China Resumen Las reservas naturales (RN) son la piedra angular de la conservación de la biodiversidad. Durante los últimos 60 años, la rápida expansión de las RN en China, uno de los países megadiversos, ha jugado un papel crítico en la reducción de la pérdida de biodiversidad. Examinamos los cambios en el número y superficie de las RN en China de 1956 a 2014 y analizamos el efecto del desarrollo económico en la expansión de las RN en China de 2005 a 2014 mediante modelos lineales. A pesar del incremento continuo en el número de RN, la superficie total de RN en China decreció en 3% de 2007 a 2014. Esta pérdida resultó de la reducción y cambio de registro de RN existentes y una desaceleración en el establecimiento de RN nuevas. Las reservas naturales en regiones con desarrollo económico rápido presentaron una mayor disminución en la superficie, lo que sugiere que la reducción y cambio de registro de RN están relacionados cercanamente con la intensificación de la competencia entre crecimiento económico y conservación. Por ejemplo, ajustes en los límites de RN nacionales, las RN más estrictamente protegidas, a lo largo de la costa del Mar Amarillo, un sitio de importancia para la biodiversidad global con una economía en rápido crecimiento, resultó en la pérdida de un tercio de la superficie total. Uno de los ecosistemas más importantes en estas RN, humedales mareales, decreció en 27.8% debido a ajustes en los límites y en 25.2% debido a la reclamación de tierras. Nuestros resultados sugieren que los logros de conservación, en términos tanto de área como de calidad, están declinando en las RN de China. Aunque la designación de áreas protegidas administradas primariamente para un uso sustentable ha incrementado rápidamente en años recientes en China, proponemos que las RN cuya principal función es la conservación de la biodiversidad no deben ser reemplazadas o debilitadas.

The nutritional nexus: Linking niche, habitat variability and prey composition in a generalist marine predator.

Our understanding of the niche concept will remain limited while the quantity and range of different food types eaten remain a dominant proxy for niche breadth, as this does not account for the broad ecological context that governs diet. Linking nutrition, physiology and behaviour is critical to predict the extent to which a species adjusts its nutritional niche breadth at the levels of prey ("prey composition niche," defined as the range of prey compositions eaten) and diet ("realized nutritional niche" is the range of diets composed through feeding on the prey). Here, we studied adult chick-rearing Australasian gannets Morus serrator to propose an integrative approach using sea surface temperature anomalies (SSTa), geographic location and bathymetry over different years, to explore their relationship with the nutritional composition of prey and diets (i.e. prey composition and nutritional niche breadth), habitat use and foraging behaviour. We found that gannets feed on prey that varied widely in their nutritional composition (have a broad prey composition niche), and composed diets from these prey that likewise varied in composition (have a broad realized nutritional niche), suggesting generalism at two levels of macronutrient selection. Across seasons, we established "nutritional landscapes" (hereafter nutriscapes), linking the nutritional content of prey (wet mass protein-to-lipid ratio-P:L) to the most likely geographic area of capture and bathymetry. Nutriscapes varied in their P:L from 6.06 to 15.28, over time, space and bathymetry (0-150 m). During warm water events (strong positive SSTa), gannets expanded their foraging habitat, increased their foraging trip duration and consumed prey and diets with low macronutrient content (wet mass proportions of P and L). They were also constrained to the smallest prey composition and realized nutritional niche breadths. Our findings are consistent with previous suggestions that dietary generalism evolves in heterogeneous environments, and provide a framework for understanding the nutritional goals in wild marine predators and how these goals drive ecological interactions and are, in turn, ultimately shaped by environmental fluctuations.

Speciation, range contraction and extinction in the endemic New Zealand King Shag complex.

New Zealand's endemic King Shag (Leucocarbo carunculatus) has occupied only a narrow portion of the northeastern South Island for at least the past 240years. However, pre-human Holocene fossil and archaeological remains have suggested a far more widespread distribution of the three Leucocarbo species (King, Otago, Foveaux) on mainland New Zealand at the time of Polynesian settlement in the late 13th Century CE. We use modern and ancient DNA, and morphometric and osteological analyses, of modern King Shags and Holocene fossil Leucocarbo remains to assess the pre-human distribution and taxonomic status of the King Shag on mainland New Zealand, and the resultant conservation implications. Our analyses show that the King Shag was formerly widespread around southern coasts of the North Island and the northern parts of the South Island but experienced population and lineage extinctions, and range contraction, probably after Polynesian arrival. This history parallels range contractions of other New Zealand seabirds. Conservation management of the King Shag should take into account this species narrow distribution and probable reduced genetic diversity. Moreover, combined genetic, morphometric and osteological analyses of prehistoric material from mainland New Zealand suggest that the now extinct northern New Zealand Leucocarbo populations comprised a unique lineage. Although these distinctive populations were previously assigned to the King Shag (based on morphological similarities and geographic proximity to modern Leucocarbo populations), we herein describe them as a new species, the Kohatu Shag (Leucocarbo septentrionalis). The extinction of this species further highlights the dramatic impacts Polynesians and introduced predators had on New Zealand's coastal and marine biodiversity. The prehistoric presence of at least four species of Leucocarbo shag on mainland NZ further highlights its status as a biodiversity hotspot for Phalacrocoracidae.

Ultrasound Evaluation of Morton Neuroma Before and After Laser Therapy.

OBJECTIVE: The objective of our study was to retrospectively assess for differences in imaging appearances of Morton neuromas before and after laser therapy using diagnostic ultrasound (US). MATERIALS AND METHODS: A retrospective review was performed to identify patients who underwent US imaging to evaluate for Morton neuroma during the study period (June 1, 2013-July 1, 2014); of the 42 patients identified, 21 underwent US evaluations before and after laser therapy. US reports and images were reviewed and correlated with clinical history. The final study group consisted of 21 patients who had a total of 31 Morton neuromas evaluated using US after treatment. A retrospective review was then performed to characterize the appearances of these lesions before and after therapy followed by an analysis of variables. RESULTS: Retrospective US review of 31 pretreatment Morton neuromas showed fusiform, heterogeneously hypoechoic masses with well-defined borders in most cases and that pain was reported when transducer pressure was applied in 97% (30/31) of cases. After treatment, lesions showed ill-defined borders (23/31), and pain with application of transducer pressure was either significantly decreased or absent (29/31); these findings were concordant with the clinical findings. Both of these characteristics were statistically significant (p < 0.0001). In addition, more Morton neuromas occurred in the second intermetatarsal space than in the third intermetatarsal space (p < 0.0001). CONCLUSION: US may be used to identify posttreatment changes after laser therapy of Morton neuromas. Posttreatment changes include ill-defined borders and less pain or the absence of pain with the application of transducer pressure. These criteria may be applied in future clinical studies evaluating the efficacy of laser therapy for Morton neuroma.

Shear-Wave Elastography: Basic Physics and Musculoskeletal Applications.

In the past 2 decades, sonoelastography has been progressively used as a tool to help evaluate soft-tissue elasticity and add to information obtained with conventional gray-scale and Doppler ultrasonographic techniques. Recently introduced on clinical scanners, shear-wave elastography (SWE) is considered to be more objective, quantitative, and reproducible than compression sonoelastography with increasing applications to the musculoskeletal system. SWE uses an acoustic radiation force pulse sequence to generate shear waves, which propagate perpendicular to the ultrasound beam, causing transient displacements. The distribution of shear-wave velocities at each pixel is directly related to the shear modulus, an absolute measure of the tissue's elastic properties. Shear-wave images are automatically coregistered with standard B-mode images to provide quantitative color elastograms with anatomic specificity. Shear waves propagate faster through stiffer contracted tissue, as well as along the long axis of tendon and muscle. SWE has a promising role in determining the severity of disease and treatment follow-up of various musculoskeletal tissues including tendons, muscles, nerves, and ligaments. This article describes the basic ultrasound physics of SWE and its applications in the evaluation of various traumatic and pathologic conditions of the musculoskeletal system. ©RSNA, 2017.

Multi-parametric MR imaging of quadriceps musculature in the setting of clinical frailty syndrome.

OBJECTIVE: Frailty is a common geriatric syndrome associated with loss of skeletal muscle mass (sarcopenia) conferring an increased risk of rapid decline in health and function with increased vulnerability to adverse outcomes. The purpose of this study was to investigate the correlation between diffusion tensor, T2 and intramuscular fat content values of the quadriceps muscle group and clinical frailty status using diffusion tensor MR imaging. MATERIAL AND METHODS: Subjects were recruited from the Arizona Frailty cohort composed of all females with frailty status based on the Fried criteria, including 6 non-frail and 10 pre-frail/frail adults, as well as a community sample of 11 young, healthy controls. Axial images of both thighs were obtained on a 3-T magnet with T1, T2 and diffusion tensor imaging as well as intramuscular fat analysis. Diffusion tensor and T2 values were determined by region-of-interest measurements at the proximal, mid and distal thirds of both thighs. Data were evaluated to determine differences between measured values and frailty status. RESULTS: The mean fractional anisotropy (FA) values in the bilateral quadriceps muscles demonstrated significant differences (F = 7.558, p = 0.0030) between the control and pre-frail/frail and non-frail and pre-frail/frail groups. There was a significant difference in mean T2 (F = 21.675, p < 0.0001) and lipid content (F = 19.266, p < 0.0001) among all three groups in the total quadriceps muscle group. CONCLUSION: The quadriceps musculature of pre-frail/frail adults demonstrated increased FA compared to young controls and non-frail adults with increasing T2 and intramuscular fat among the control, non-frail and pre-frail/frail categories.

Accuracy of High-Resolution Ultrasonography in the Detection of Extensor Tendon Lacerations.

BACKGROUND: Lacerations to the extensor mechanism are usually diagnosed clinically. Ultrasound (US) has been a growing diagnostic tool for tendon injuries since the 1990s. To date, there has been no publication establishing the accuracy and reliability of US in the evaluation of extensor mechanism lacerations in the hand. The purpose of this study is to determine the accuracy of US to detect extensor tendon injuries in the hand. METHODS: Sixteen fingers and 4 thumbs in 4 fresh-frozen and thawed cadaveric hands were used. Sixty-eight 0.5-cm transverse skin lacerations were created. Twenty-seven extensor tendons were sharply transected. The remaining skin lacerations were used as sham dissection controls. One US technologist and one fellowship-trained musculoskeletal radiologist performed real-time dynamic US studies in and out of water bath. A second fellowship trained musculoskeletal radiologist subsequently reviewed the static US images. Dynamic and static US interpretation accuracy was assessed using dissection as "truth." RESULTS: All 27 extensor tendon lacerations and controls were identified correctly with dynamic imaging as either injury models that had a transected extensor tendon or sham controls with intact extensor tendons (sensitivity = 100%, specificity = 100%, positive predictive value = 1.0; all significantly greater than chance). Static imaging had a sensitivity of 85%, specificity of 89%, and accuracy of 88% (all significantly greater than chance). The results of the dynamic real time versus static US imaging were clearly different but did not reach statistical significance. CONCLUSIONS: Diagnostic US is a very accurate noninvasive study that can identify extensor mechanism injuries. Clinically suspected cases of acute extensor tendon injury scanned by high-frequency US can aid and/or confirm the diagnosis, with dynamic imaging providing added value compared to static. Ultrasonography, to aid in the diagnosis of extensor mechanism lacerations, can be successfully used in a reliable and accurate manner.

Normal Magnetic Resonance Imaging Anatomy of the Capsular Ligamentous Supporting Structures of the Knee.

Recognition of the normal magnetic resonance (MR) imaging appearances of the capsular ligaments of the knee is of great importance. These ligaments contribute to stability of the knee joint and are frequently injured. In this article, we describe the normal MR imaging anatomy of the capsular ligaments of the knee including the lateral and medial collateral ligamentous complexes, the extensor mechanism, and the supporting ligamentous structures of the proximal tibiofibular joint. Normal MR imaging findings and important anatomic variants of the neurovascular structures of the knee are also described.

The nuclear pore complex function of Sec13 protein is required for cell survival during retinal development.

Sec13 is a dual function protein, being a core component of both the COPII coat, which mediates protein trafficking from the endoplasmic reticulum to the Golgi apparatus, and the nuclear pore complex (NPC), which facilitates nucleo-cytoplasmic traffic. Here, we present a genetic model to differentiate the roles of these two functions of Sec13 in vivo. We report that sec13(sq198) mutant embryos develop small eyes that exhibit disrupted retinal lamination and that the mutant retina contains an excessive number of apoptotic cells. Surprisingly, we found that loss of COPII function by oligonucleotide-mediated gene knockdown of sec31a and sec31b or brefeldin A treatment did not disrupt retinal lamination, although it did result in digestive organ defects similar to those seen in sec13(sq198), suggesting that the digestive organ defects observed in sec13(sq198) are due to loss of COPII function, whereas the retinal lamination defects are due to loss of the NPC function. We showed that the retinal cells of sec13(sq198) failed to form proper nuclear pores, leading to a nuclear accumulation of total mRNA and abnormal activation of the p53-dependent apoptosis pathway, causing the retinal defect in sec13(sq198). Furthermore, we found that a mutant lacking Nup107, a key NPC-specific component, phenocopied the retinal lamination phenotype as observed in sec13(sq198). Our results demonstrate a requirement for the nuclear pore function of Sec13 in development of the retina and provide the first genetic evidence to differentiate the contributions of the NPC and the COPII functions of Sec13 during organogenesis.

High-Resolution US of Rheumatologic Diseases.

For the past 15 years, high-resolution ultrasonography (US) is being routinely and increasingly used for initial evaluation and treatment follow-up of rheumatologic diseases. This imaging technique is performed by using high-frequency linear transducers and has proved to be a powerful diagnostic tool in evaluation of articular erosions, simple and complex joint and bursal effusions, tendon sheath effusions, and synovitis, with results comparable to those of magnetic resonance imaging, excluding detection of bone marrow edema. Crystal deposition diseases including gouty arthropathy and calcium pyrophosphate deposition disease (CPPD) have characteristic appearances at US, enabling differentiation between these two diseases and from inflammatory arthropathies. Enthesopathy, which frequently accompanies psoriatic and reactive arthritis, also has a characteristic appearance at high-resolution US, distinguishing these two entities from other inflammatory and metabolic arthropathies. The presence of Doppler signal in examined joints, bursae, and tendon sheaths indicates active synovitis. Microbubble echo contrast agents augment detection of tissue vascularity and may act in the future as a drug delivery vehicle. Frequently, joint, tendon sheath, and bursal fluid aspirations and therapeutic injections are performed under US guidance. The authors describe the high-resolution US technique including gray-scale, color or power Doppler, and contrast agent-enhanced US that is used in evaluation of rheumatologic diseases of the wrist and hand and the ankle and foot in their routine clinical practice. This article demonstrates imaging findings of normal joints, rheumatoid arthritis, gouty arthritis, CPPD, psoriatic and reactive arthritis, and osteoarthritis.

Sonography of cat scratch disease.

OBJECTIVES: To characterize the sonographic features of cat scratch disease and to identify features that allow differentiation from other causes of medial epitrochlear masses. METHODS: After Institutional Review Board approval was obtained, patients who underwent sonography for a medial epitrochlear mass or lymph node were identified via the radiology information system. Patients were divided into 2 groups: cat scratch disease and non-cat scratch disease, based on pathologic results and clinical information. Sonograms were retrospectively reviewed and characterized with respect to dimension, shape (round, oval, or lobular), symmetry, location (subcutaneous or intramuscular), multiplicity, echogenicity (anechoic, hypoechoic, isoechoic, hyperechoic, or mixed), hyperechoic hilum (present or absent), adjacent anechoic or hypoechoic area, hyperemia (present or absent), pattern of hyperemia if present (central, peripheral, or mixed), increased posterior through-transmission (present or absent), and shadowing (present or absent). Sonographic findings were compared between the patients with and without cat scratch disease. RESULTS: The final patient group consisted of 5 cases of cat scratch disease and 16 cases of other causes of medial epitrochlear masses. The 2 sonographic findings that were significantly different between the cat scratch disease and non-cat scratch disease cases included mass asymmetry (P = .0062) and the presence of a hyperechoic hilum (P = .0075). The other sonographic findings showed no significant differences between the groups. CONCLUSIONS: The sonographic finding of an epitrochlear mass due to cat scratch disease most commonly is that of a hypoechoic lobular or oval mass with central hyperemia and a possible adjacent fluid collection; however, the presence of asymmetry and a hyperechoic hilum differentiate cat scratch disease from other etiologies.

Multiligamentous injuries and knee dislocations.

Complex capsular ligamentous structures contribute to stability of the knee joint. Simultaneous injury of two or more knee ligaments, aside from concurrent tears involving the anterior cruciate and medial collateral ligaments, is considered to be associated with femorotibial knee dislocations. Proximal tibiofibular joint dislocations are not always easily recognized and may be overlooked or missed. Patellofemoral dislocations can be transient with MR imaging sometimes required to reach the diagnosis. In this article, the authors describe the mechanism of injury, ligamentous disruptions, imaging, and treatment options of various types of knee dislocations including injuries of the femorotibial, proximal tibiofibular, and patellofemoral joints.

Imaging and management of thumb carpometacarpal joint osteoarthritis.

Primary osteoarthritis (OA) involving the thumb carpometacarpal (CMC) joint is a common and frequently debilitating disease. Clinical examination and radiographs are usually sufficient for diagnosis; however, familiarity with the cross-sectional anatomy is useful for diagnosis of this condition. The most widely used classification system for the radiographic staging of thumb carpometacarpal joint OA was first presented by Eaton and Littler, ranging from mild (stages I and II) to severe (stage IV) disease. If conservative treatment fails, surgical treatment is considered. A variety of surgical techniques have been developed and implemented for the management of this pervasive and disabling condition. The purpose of this article is to review the anatomy of the basal joints of the thumb, pathophysiology, preoperative imaging, and various surgical techniques that are utilized in the treatment of OA of the basal joints of the thumb with emphasis on normal postoperative radiographic findings and possible postoperative complications.

Ultrasound of the thumb ulnar collateral ligament: technique and pathology.

OBJECTIVE: The ulnar collateral ligament (UCL) serves an important role in stabilizing the thumb metacarpophalangeal (MCP) joint. The adductor pollicis aponeurosis lies superficial to the UCL, and plays an important role in the pattern of injury and treatment of UCL tears. Ultrasound is a cost-effective and accurate method to evaluate the UCL, allowing dynamic imaging and contralateral comparison in the setting of acute injury. The purpose of this video article is to show the optimal technique for sonographic evaluation of the UCL. CONCLUSION: UCL tears are common injuries involving the base of the thumb, and correct diagnosis of a Stener lesion aids in timely surgical management. Performing ultrasound evaluation in the long axis with use of dynamic imaging allows excellent visualization of the UCL and adductor pollicis aponeurosis. With application of appropriate technique, ultrasound is highly accurate in diagnosing Stener lesions.

Ultrasound of the knee.

OBJECTIVE: The purpose of this video article is to show the technique for performing an ultrasound examination of the knee, describe the anatomy of the knee as seen on ultrasound, and summarize the indications for performing ultrasound of the knee. CONCLUSION: Proper positioning of the patient is important to ensure a good quality ultrasound examination of the knee, and knowledge of the anatomy and bony landmarks makes scanning much easier. It is important to know the strengths and limitations of ultrasound with regard to examination of the knee.

Artifacts in musculoskeletal ultrasonography.

During the past 2 decades, high-resolution ultrasonography (US) has been increasingly utilized in the diagnosis of musculoskeletal trauma and diseases with results comparable with MR imaging. US has an advantage over other cross-sectional modalities in many circumstances due to its superior spatial resolution and ability to allow dynamic assessment. When performing musculoskeletal US, the examiner has to be knowledgeable in the complex anatomy of the musculoskeletal system and US imaging technique. Additionally, he or she must be familiar with several common imaging artifacts in musculoskeletal US that may be mistaken for pathology, as well as several artifacts that frequently accompany pathologic conditions. These artifacts may occur with both B-mode gray-scale and Doppler imaging. In this article, we discuss common artifacts seen in musculoskeletal US and techniques to avoid or minimize these artifacts during clinical US examinations.