Risk of wrist fracture, estimated by the load-to-strength ratio, declines following sleeve gastrectomy in adolescents and young adults.

To understand whether the bone loss which occurs after vertical sleeve gastrectomy increases the risk of fracture, we used an engineering model to estimate risk in participants before and after surgery. We found that estimated risk decreased 1 year after surgery and remained lower, though had rebounded, at year 2. PURPOSE: Vertical sleeve gastrectomy (VSG) improves metabolic health in young people with obesity but is accompanied by substantial loss of bone mass and estimated bone strength. We thus estimated fracture risk following VSG using the load-to-strength ratio (LSR), which integrates bone strength estimates with the predicted force of a fall. METHODS: Prospective 2-year study of youth ages 13-24 years with obesity undergoing VSG (n = 24) or lifestyle therapy (n = 34). We performed high-resolution peripheral quantitative computed tomography of the distal radius and microfinite element analysis to estimate bone strength and calculated LSR. RESULTS: VSG participants lost 26.4 ± 8.1% weight at year 1 (p < 0.001), which was sustained at year 2, while control participants gained weight at year 2 (4.5 ± 8.3%, p = 0.009). The predicted impact force decreased at years 1 and 2 following VSG (p < 0.001) but increased at year 2 among controls (p = 0.011). Estimated bone strength was unchanged at year 1 but decreased (p < 0.001) at year 2 following VSG, while bone strength did not change in controls. At year 1, the LSR decreased among VSG participants (p < 0.001), implying a lower risk of fracture. At year 2, the LSR was lower than baseline (p < 0.001), but higher compared to year 1 (p = 0.001). LSR did not change in the control group. CONCLUSIONS: Short-term estimated fracture risk at the radius following VSG decreases. However, ongoing bone loss despite stable weight between years 1 and 2 leads to a concerning rise in estimated fracture risk. Longer follow-up will be critical to evaluate the trajectory of fracture risk. (ClinicalTrials.gov NCT02557438, registered 9/23/2015).

Changes in serum cortisol levels after 10 days of overfeeding and fasting.

Chronic caloric deprivation and obesity are complicated by hypercortisolemia. The effects of acute overfeeding and fasting on circulating free cortisol levels and conversion of cortisone to free cortisol are unknown. We hypothesized that serum-free cortisol and free cortisol-to-cortisone ratio would increase after both overfeeding and fasting. This is a prospective study of 22 healthy volunteers who completed a 10-day high-calorie protocol followed by a 10-day fast, separated by a 2-wk washout. Morning free and total cortisol and free cortisone levels (LC/MS) were measured at baseline and after 10 days of each intervention. Both high-calorie feeding and fasting increased total and free cortisol and the free cortisol-to-free cortisone ratio (P = 0.001 to P = 0.046). There were sex interactions, with significant effects in men (P < 0.001), but not in women (P = 0.898 and 1.000, respectively) in subset analyses examining the effects of fasting on free cortisol and the free-to-total cortisol ratio. Overfeeding and fasting both increase circulating free cortisol levels and appear to alter the balance between cortisol and its inactive metabolite, cortisone. Further study is warranted to determine whether elevated cortisol levels contribute to complications of starvation and obesity, such as bone fragility.NEW & NOTEWORTHY Overfeeding and fasting both increase circulating free cortisol levels and appear to alter the balance between cortisol and its inactive metabolite, cortisone. The effect of fasting on free cortisol levels is modified by sex. Further study is needed to determine the mechanisms driving the increases in cortisol.

Relationship of Imaging-guided Corticosteroid Injections to COVID-19 Incidence in the Pandemic Recovery Period.

Background Corticosteroids injected for the treatment of musculoskeletal pain are systemically absorbed and can affect the immune response to viral infections. Purpose To determine the incidence of symptomatic COVID-19 disease in individuals receiving image-guided corticosteroid injections for musculoskeletal pain compared with the general population during the pandemic recovery period. Materials and Methods In this prospective cohort multicenter study, adults with a history of musculoskeletal pain who underwent imaging-guided intra-articular and spine corticosteroid injections from April 2020 to February 2021 were consecutively enrolled. Participants were followed for a minimum of 28 days through their electronic medical record (EMR) or by direct phone communication to screen for COVID-19 test results or symptoms. Clinical data, including body mass index (BMI), were also obtained from the EMR. The incidence of COVID-19 in the state was obtained using the Massachusetts COVID-19 Response Reporting website. The Student t test was used for continuous variable comparisons. Univariable analyses were performed using the Fisher exact test. Results A total of 2714 corticosteroid injections were performed in 2190 adult participants (mean age, 59 years ± 15 [SD]; 1031 women). Follow-up was available for 1960 participants (89%) who received 2484 injections. Follow-up occurred a mean of 97 days ± 33 (range, 28-141 days) after the injection. Of the 1960 participants, 10 had COVID-19 within 28 days from the injection (0.5% [95% CI: 0.24, 0.94]) and 43 had COVID-19 up to 4 months after the injection (2.2% [95% CI: 1.6, 2.9]). These incidence rates were lower than that of the population of Massachusetts during the same period (519 195 of 6 892 503 [7.5%], P < .001 for both 28 days and 4 months). Participants diagnosed with COVID-19 (n = 10) within 28 days from the injection had a higher BMI than the entire cohort (n = 1960) (mean, 32 kg/m2 ± 10 vs 28 kg/m2 ± 6; P = .04). Conclusion Adults who received image-guided corticosteroid injections for pain management during the pandemic recovery period had a lower incidence of symptomatic COVID-19 compared with the general population. © RSNA, 2022 Online supplemental material is available for this article.

Two-year Skeletal Effects of Sleeve Gastrectomy in Adolescents with Obesity Assessed with Quantitative CT and MR Spectroscopy.

Background Sleeve gastrectomy (SG) is effective in the treatment of cardiometabolic complications of obesity but is associated with bone loss. Purpose To determine the long-term effects of SG on vertebral bone strength, density, and bone marrow adipose tissue (BMAT) in adolescents and young adults with obesity. Materials and Methods This 2-year prospective nonrandomized longitudinal study enrolled adolescents and young adults with obesity who underwent either SG (SG group) or dietary and exercise counseling without surgery (control group) at an academic medical center from 2015 to 2020. Participants underwent quantitative CT of the lumbar spine (L1 and L2 levels) to assess bone density and strength, proton MR spectroscopy to assess BMAT (L1 and L2 levels), and MRI of the abdomen and thigh to assess body composition. Student t and Wilcoxon signed-rank tests were used to compare 24-month changes between and within groups. Regression analysis was performed to evaluate associations between body composition, vertebral bone density, strength, and BMAT. Results A total of 25 participants underwent SG (mean age, 18 years ± 2 [SD], 20 female), and 29 underwent dietary and exercise counseling without surgery (mean age, 18 years ± 3, 21 female). Body mass index (BMI) decreased by a mean of 11.9 kg/m2 ± 5.21 [SD] after 24 months in the SG group (P < .001), while it increased in the control group (mean increase, 1.49 kg/m2 ± 3.10; P = .02). Mean bone strength of the lumbar spine decreased after surgery compared with that in control subjects (mean decrease, -728 N ± 691 vs -7.24 N ± 775; P < .001). BMAT of the lumbar spine increased after SG (mean lipid-to-water ratio increase, 0.10 ± 0.13; P = .001). Changes in vertebral density and strength correlated positively with changes in BMI and body composition (R = 0.34 to R = 0.65, P = .02 to P < .001) and inversely with vertebral BMAT (R = -0.33 to R = -0.47, P = .03 to P = .001). Conclusion SG in adolescents and young adults reduced vertebral bone strength and density and increased BMAT compared with those in control participants. Clinical trial registration no. NCT02557438 © RSNA, 2023 See also the editorial by Link and Schafer in this issue.

Prognostic Significance of Percentage and Size of Dedifferentiation in Dedifferentiated Chondrosarcoma.

Dedifferentiated chondrosarcoma is rare, aggressive, and microscopically bimorphic. How pathologic features such as the amounts of dedifferentiation affect prognosis remains unclear. We evaluated the percentages and sizes of dedifferentiation in a consecutive institutional series of dedifferentiated chondrosarcomas from 1999 to 2021. The statistical analysis included cox proportional hazard models and log-rank tests. Of the 67 patients (26 women, 41 men; age, 39 to >89 [median 61] years; 2 with Ollier disease), 58 presented de novo; 9 were identified with conventional chondrosarcomas 0.6-13.2 years (median, 5.5 years) prior. Pathologic fracture and distant metastases were noted in 27 and 7 patients at presentation. The tumors involved the femur (n = 27), pelvis (n = 22), humerus (n = 7), tibia (n = 4), scapula/ribs (n = 4), spine (n = 2), and clivus (n = 1). In the 56 resections, the tumors ranged in size from 3.5 to 46.0 cm (median, 11.5 cm) and contained 1%-99.5% (median, 70%) dedifferentiated components that ranged in size from 0.6 to 24.0 cm (median, 7.3 cm). No correlation was noted between total size and percentage of dedifferentiation. The dedifferentiated components were typically fibrosarcomatous or osteosarcomatous, whereas the associated cartilaginous components were predominantly grade 1-2, rarely enchondromas or grade 3. The entire cohort's median overall survival and progression-free survival were 11.8 and 5.4 months, respectively. In the resected cohort, although the total size was not prognostic, the percentage of dedifferentiation ≥20% and size of dedifferentiation >3.0 cm each predicted worse overall survival (9.9 vs 72.5 months; HR, 3.76; 95% CI, 1.27-11.14; P = .02; 8.7 vs 58.9 months; HR, 3.03; 95% CI, 1.21-7.57; P = .02, respectively) and progression-free survival (5.3 vs 62.1 months; HR, 3.05; 95% CI, 1.13-8.28; P = .03; 5.3 vs 56.6 months; HR, 2.50; 95% CI, 1.06-5.88; P = .04, respectively). In conclusion, both the percentages and sizes of dedifferentiation were better prognostic predictors than total tumor sizes in dedifferentiated chondrosarcomas, highlighting the utility of their pathologic evaluations.

Pilot Study: Short Term Impact of Radiation Therapy on Bone Mineral Density and Bone Metabolism.

Despite the risk of complications, high dose radiation therapy is increasingly utilized in the management of selected bone malignancies. In this study, we investigate the impact of moderate to high dose radiation (over 50 Gy) on bone metabolism and structure. Between 2015 and 2018, patients with a primary malignant bone tumor of the sacrum that were either treated with high dose definitive radiation only or a combination of moderate to high dose radiation and surgery were prospectively enrolled at a single institution. Quantitative CTs were performed before and after radiation to determine changes in volumetric bone mineral density (BMD) of the irradiated and non-irradiated spine. Bone histomorphometry was performed on biopsies of the irradiated sacrum and the non-irradiated iliac crest of surgical patients using a quadruple tetracycline labeling protocol. In total, 9 patients were enrolled. Two patients received radiation only (median dose 78.3 Gy) and 7 patients received a combination of preoperative radiation (median dose 50.4 Gy), followed by surgery. Volumetric BMD of the non-irradiated lumbar spine did not change significantly after radiation, while the BMD of the irradiated sacrum did (pre-radiation median: 108.0 mg/cm3 (IQR 91.8-167.1); post-radiation median: 75.3 mg/cm3 (IQR 57.1-110.2); p = 0.010). The cancellous bone of the non-irradiated iliac crest had a stable bone formation rate, while the irradiated sacrum showed a significant decrease in bone formation rate [pre-radiation median: 0.005 mm3/mm2/year (IQR 0.003-0.009), post-radiation median: 0.001 mm3/mm2/year (IQR 0.001-0.001); p = 0.043]. Similar effects were seen in the cancellous and endocortical envelopes. This pilot study shows a decrease of volumetric BMD and bone formation rate after high-dose radiation therapy. Further studies with larger cohorts and other endpoints are needed to get more insight into the effect of radiation on bone. Level of evidence: IV.

Whole body imaging in musculoskeletal oncology: when, why, and how.

The use of whole-body imaging has become increasingly popular in oncology due to the possibility of evaluating total tumor burden with a single imaging study. This is particularly helpful in cases of widespread disease where dedicated regional imaging would make the evaluation more expensive, time consuming, and prone to more risks. Different techniques can be used, including whole-body MRI, whole-body CT, and PET-CT. Common indications include surveillance of cancer predisposing syndromes, evaluation of osseous metastases and clonal plasma cell disorders such as multiple myeloma, and evaluation of soft tissue lesions, including peripheral nerve sheath tumors. This review focuses on advanced whole-body imaging techniques and their main uses in musculoskeletal oncology.

Serum Oxytocin Levels Decrease 12 Months Following Sleeve Gastrectomy and Are Associated with Decreases in Lean Mass.

Oxytocin (OXT), an anorexigenic hormone, is also bone anabolic. Further, OXT administration results in increases in lean mass (LM) in adults with sarcopenic obesity. We examine, for the first time, associations of OXT with body composition and bone endpoints in 25 youth 13-25 years old with severe obesity who underwent sleeve gastrectomy (SG) and 27 non-surgical controls (NS). Forty participants were female. Subjects underwent fasting blood tests for serum OXT and DXA for areal bone mineral density (aBMD) and body composition. At baseline, SG vs. NS had higher median body mass index (BMI) but did not differ for age or OXT levels. Over 12 months, SG vs. NS had greater reductions in BMI, LM, and fat mass (FM). OXT decreased in SG vs. NS 12 months post-SG. While baseline OXT predicted a 12-month BMI change in SG, decreases in OXT levels 12 months post-SG were not associated with decreases in weight or BMI. In SG, decreases in OXT were positively associated with decreases in LM but not with decreases in FM or aBMD. Loss of LM, a strong predictor of BMD, after bariatric surgery may reduce functional and muscular capacity. OXT pathways may be targeted to prevent LM loss following SG.

Body composition predictors of mortality in patients undergoing surgery for long bone metastases.

BACKGROUND AND OBJECTIVES: Body composition measurements using computed tomography (CT) may serve as imaging biomarkers of survival in patients with and without cancer. This study assesses whether body composition measurements obtained on abdominal CTs are independently associated with 90-day and 1-year mortality in patients with long-bone metastases undergoing surgery. METHODS: This single institutional retrospective study included 212 patients who had undergone surgery for long-bone metastases and had a CT of the abdomen within 90 days before surgery. Quantification of cross-sectional areas (CSA) and CT attenuation of abdominal subcutaneous adipose tissue, visceral adipose tissue, and paraspinous and abdominal muscles were performed at L4. Multivariate Cox proportional-hazards analyses were performed. RESULTS: Sarcopenia was independently associated with 90-day mortality (hazard ratio [HR] = 1.87; 95% confidence interval [CI] = 1.11-3.16; p = 0.019) and 1-year mortality (HR = 1.50; 95% CI = 1.02-2.19; p = 0.038) in multivariate analysis while controlling for clinical variables such as primary tumors, comorbidities, and chemotherapy. Abdominal fat CSAs and muscle attenuation were not associated with mortality. CONCLUSIONS: The presence of sarcopenia assessed by CT is predictive of 90-day and 1-year mortality in patients undergoing surgery for long-bone metastases. This body composition measurement can be used as novel imaging biomarker supplementing existing prognostic tools to optimize patient selection for surgery and improve shared decision making.

Distal Triceps Tendon Tears: Magnetic Resonance Imaging Patterns Using a Systematic Classification.

OBJECTIVE: This study aimed to evaluate distal triceps tendon tear patterns using a systematic classification based on the tendon's layered structure. METHODS: We retrospectively identified Magnetic resonance imaging (MRI) examinations with triceps tendon tears that underwent reconstructive surgery. Magnetic resonance images were reviewed independently by 2 musculoskeletal radiologists to determine tendon layer involvement and ancillary findings, including tear size, involvement of triceps lateral expansion, and presence of olecranon bursal fluid. Surgical reports were scrutinized for level of anatomic detail and correlation with imaging findings. RESULTS: We identified 69 triceps tendon tears in 68 subjects (61 men, 7 women; mean age, 45 ± 12 years) who underwent surgical reconstruction. On MRI, the superficial layer was always involved with either a partial or full-thickness tear. The most common tear pattern was a combination of superficial layer full-thickness tear with deep layer partial tear (25 of 69 [36%]). Mean tear length was 24 ± 12 mm. We found no cases of isolated deep layer tears. Involvement of triceps lateral expansion and presence of bursal fluid correlated positively with tear severity of superficial and deep layers (P < 0.001). Detailed surgical correlation was limited, with only 9 of 69 (13%) of surgical reports containing information specifically addressing individual tendon layers. CONCLUSIONS: Triceps tendon tears show tear patterns following its layered structure and can be assessed by MRI. Radiologists and surgeons are encouraged to describe tear patterns considering both superficial and deep tendon layers.

Breast adipose tissue attenuation as a novel imaging biomarker for cardiometabolic risk.

BACKGROUND: Certain adipose tissue depots infer higher cardiometabolic risk than body mass index (BMI). PURPOSE: To assess breast adipose tissue (BrAT) attenuation as a novel imaging biomarker for cardiometabolic risk. MATERIAL AND METHODS: We studied 151 women (mean age = 56 ± 1 years) across the weight spectrum. BrAT attenuation, abdominal adipose tissue cross-sectional areas (CSA), and attenuation were quantified using non-contrast computed tomography (CT) scans. Cardiometabolic risk factors were assessed from medical records. RESULTS: BrAT attenuation was lower in obese women compared to lean women. BrAT attenuation was inversely associated with BMI, waist circumference, abdominal fat CSA, fasting glucose, and triglycerides (P ≤ 0.02), and positively associated with abdominal adipose tissue attenuation (P < 0.001). BrAT attenuation had a sensitivity of 90% but a specificity of only 35% in detecting the metabolic syndrome (area under the curve = 0.63). CONCLUSION: BrAT attenuation is associated with cardiometabolic risk markers and could serve as an imaging biomarker for opportunistic risk assessment in patients undergoing CT examination of the chest.

Role of FDG PET in the staging of multiple myeloma.

18F-Fluorodeoxyglucose (FDG) PET has been used for staging of hematologic malignancies for years. In multiple myeloma, this imaging modality can be used in many different scenarios, including initial staging, evaluation of treatment response, and investigation of residual disease or early relapse. FDG PET-CT has excellent diagnostic performance, similar to other advanced imaging modalities such as whole-body CT and MRI, and it is particularly helpful for the assessment of extramedullary disease. It also offers important prognostic information on survival and risk of relapse, both at baseline and after therapy. This review will cover the main applications, advantages, and limitations of FDG PET-CT in multiple myeloma and related clonal plasma cell proliferative disorders, such as smoldering multiple myeloma and plasmacytoma.

Diversity and perception of equity and respect in the Society of Skeletal Radiology (SSR).

PURPOSE: To assess the perception of equity and respect in the workplace and within the SSR. We hypothesized that responses would differ by gender and minorities underrepresented in medicine (URiM) status. METHODS: An electronic survey was sent to 1,531 SSR members between January 2020 and March 2020 to determine perception of equity and respect. Descriptive statistics were calculated, and analysis of differences in response by gender/minority status was performed using the Fisher's exact test. The study was exempt from IRB approval. RESULTS: There were 176 responses (11.5%). Most respondents (61.9%) were between 30 and 50 years. Members identified as male (M) in 74.4%, as female (F) in 25.0%, and as "other" in 0.6%. URiM comprised 9.1% of members. Women worked more commonly in academia (p = 0.005), had the perception of unequal opportunities for leadership positions within the institution (p = 0.006), and emphasized the importance of having a mentor of the same gender (p = 0.001). URiM members were less likely to hold a leadership position (p = 0.1, trend), had a perception of unequal opportunities for leadership positions within the institution (p = 0.06, trend), and reported the importance of having a mentor of the same race (p = 0.06, trend). There were no significant differences between gender or URiM status and perception of the SSR to provide an inclusive environment and leadership opportunities (p ≥ 0.39). CONCLUSION: While survey participation was limited and potentially biased, respondents perceived that women and minorities have fewer opportunities and are treated with lower regard in the workplace compared to male, non-minority colleagues.

Percutaneous CT-guided corticosteroid injection for the treatment of osseous Langerhans cell histocytosis: a three institution retrospective analysis.

PURPOSE: The aim of this study is to evaluate the safety and effectiveness of CT-guided corticosteroid injection for the treatment of osseous Langerhans cell histiocytosis (LCH) in a multi-institutional study. MATERIALS AND METHODS: This IRB-approved study included patients from three institutions. We retrospectively reviewed clinical, procedural, and imaging data for corticosteroid injections performed to treat osseous LCH. Location of the lesion, lesion maximum dimension and volume, corticosteroid type and dose, and time interval between injection and change in lesion size/volume and symptoms were recorded. Generalized estimating equations (accounting for multiple lesions per subject) were used to evaluate the association between predictors (dose, maximum lesion dimension, and lesion volume) and outcomes (time to partial and complete radiographic resolution, and time to pain control). This analysis was adjusted by anatomic site. RESULTS: Forty corticosteroid injections were performed in 36 patients (20 (56%) females, and 16 (44%) males, ages 12 ± 11 (2-57) years). Mean lesion maximum dimension was 3.2 ± 1.7 cm, and volume was 10 ± 17 cm3. Imaging and clinical follow-up were available for 22/40 (55%) and 34/40 (85%) of injections, respectively. All lesions responded to corticosteroid injection. Times to partial and complete imaging resolution were 13 ± 9 and 32 ± 13 weeks, respectively, and time to pain resolution was 22 ± 14 weeks. There were no complications. CONCLUSION: CT-guided corticosteroid injection is a safe and effective treatment for LCH. Pain resolution was achieved in all patients and imaging did not show progressive disease in any of the patients.

Aneurysmal bone cyst with an unusual clinical presentation and a novel VDR-USP6 fusion.

Aneurysmal bone cyst is a benign bone neoplasm that most commonly arises from the metaphyses of long bones in the first and second decades of life. Here, we describe a case of an aneurysmal bone cyst that occurred in the distal tibial diaphysis of a 72-year-old female that was concerning for malignancy on imaging, demonstrating cortical breakthrough and soft tissue extension. Histologically, the tumor showed the characteristic morphologic features of aneurysmal bone cyst. Fluorescence in situ hybridization was positive for USP6 rearrangement, and RNA sequencing revealed a USP6 gene fusion with VDR, a novel partner that encodes the vitamin D receptor and that has not been implicated previously in human neoplasia. This case highlights the diagnostic challenges presented by aneurysmal bone cyst in elderly adults, and it expands the genetic spectrum of USP6 rearrangements.

Body composition predictors of outcome in patients with COVID-19.

BACKGROUND/OBJECTIVE: Obesity is a strong risk factor for adverse outcomes in patients hospitalized with COVID-19, however, the distribution of fat and the amount of muscle mass are more accurate risk factors than BMI. The objective of this study was to assess body composition measures obtained on opportunistic abdominal CTs as predictors of outcome in patients hospitalized with COVID-19. We hypothesized that elevated visceral and intermuscular adipose tissue would be associated with adverse outcome. SUBJECTS/METHODS: Our retrospective study was IRB-approved and HIPAA-compliant. The study group comprised 124 patients (median age: 68 years, IQR: 56, 77; 59 weeks, 65 months) who were admitted with COVID-19 to a single hospital and who had undergone abdominal CT for clinical purposes. Visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), intermuscular adipose tissue (IMAT), and paraspinal and abdominal muscle cross-sectional areas (CSA) were assessed. Clinical information including prognostic factors, time of admission to the intensive care unit (ICU) and time of death within 28 days were obtained. Multivariate time-to-event competing risk models were fitted to estimate the hazard ratio (HR) for a composite outcome of ICU admission/mortality associated with a one standard deviation increase in each body compositional measure. Each model was adjusted for age, sex, race, BMI, and cardiometabolic comorbidities. RESULTS: There were 50 patients who were admitted to the ICU or deceased over a median time of 1 day [IQR 1, 6] from hospital admission. Higher VAT/SAT ratio (HR of 1.30; 95% CI 1.04-1.62, p = 0.022) and higher IMAT CSA (HR of 1.44; 95% CI 1.10-1.89, p = 0.008) were associated with a reduced time to ICU admission or death in adjusted models. CONCLUSION: VAT/SAT and IMAT are predictors of adverse outcome in patients hospitalized with COVID-19, independent of other established prognostic factors. This suggests that body composition measures may serve as novel biomarkers of outcome in patients with COVID-19.

Identification of EWSR1-NFATC2 fusion in simple bone cysts.

AIMS: Simple bone cysts are benign intramedullary tumours primarily involving the long bones in skeletally immature individuals. Several mechanisms have been proposed for their pathogenesis. Although the diagnosis is typically straightforward, the interpretation can be problematic, because of superimposed fracture causing them to resemble aneurysmal bone cysts and other tumours. EWSR1-NFATC2 or FUS-NFATC2 fusions, which are characteristic of a subset of aggressive round cell sarcomas, have been recently detected in simple bone cysts. The aim of this study was to examine the clinicopathological and molecular features in a series of simple bone cysts. METHODS AND RESULTS: Using RNA-based next-generation sequencing and/or fluorescence in-situ hybridisation, we investigated the presence of EWSR1 or FUS rearrangements in nine simple bone cysts. The patients were five females and four males, aged 3-23 years (median, 14 years); the tumours ranged from 19 mm to 160 mm (median, 46 mm) in size, and involved the femur (n = 3), humerus (n = 2), fibula (n = 2), tibia (n = 1), and iliac wing (n =1). We identified three cases with EWSR1-NFATC2 fusion (showing identical breakpoints to those in EWSR1-NFATC2 sarcomas) and one additional case with FUS rearrangement. Unlike in EWSR1-NFATC2 sarcomas, immunohistochemical expression of NKX3.1 and NKX2.2 was absent in two simple bone cysts tested. CONCLUSIONS: More than 40% of simple bone cysts harbour genetic alterations confirming that they are neoplastic, investigation of EWSR1 and/or FUS rearrangement may help to distinguish simple bone cysts from mimics, and NFATC2 rearrangement is not pathognomonic of malignancy.

Best Practices: Hip Femoroacetabular Impingement.

OBJECTIVE. Imaging plays a critical role in the assessment of patients with femoroacetabular impingement (FAI). With better understanding of the underlying pathomechanics and advances in joint-preserving surgery, there is an increasing need to define the most appropriate imaging workup. The purpose of this article is to provide guidance on best practices for imaging of patients with FAI in light of recent advances in corrective FAI surgery. CONCLUSION. Pelvic radiography with dedicated hip projections is the basis of the diagnostic workup of patients with suspected FAI to assess arthritic changes and acetabular coverage and to screen for cam deformities. Chondrolabral lesions should be evaluated with unenhanced MRI or MR arthrography. The protocol should include a large-FOV fluid-sensitive sequence to exclude conditions that can mimic or coexist with FAI, radial imaging to accurately determine the presence of a cam deformity, and imaging of the distal femoral condyles for measurement of femoral torsion. CT remains a valuable tool for planning of complex surgical corrections. Advanced imaging, such as 3D simulation, biochemical MRI, and MR arthrography with application of leg traction, has great potential to improve surgical decision-making. Further research is needed to assess the added clinical value of these techniques.

Kinematic MRI of ischiofemoral impingement.

OBJECTIVE: To examine the effect of external hip rotation on ischiofemoral (IF) and quadratus femoris (QF) spaces using real-time kinematic MRI, with the hypothesis that hips with IF and QF space narrowing have distinct motion patterns compared with control hips. MATERIALS AND METHODS: This prospective study was IRB-approved and complied with HIPAA guidelines. We recruited women (≥ 18 years) with and without ischiofemoral impingement to undergo kinematic MRI of the hips. A kinematic imaging protocol using T2-HASTE was performed beginning at maximal internal rotation followed by active external hip rotation. The duration of each acquisition was 30 s, providing 8 images/3 s. IF and QF spaces, and femoral metaphyseal and lesser trochanter centroid coordinates were measured on sequential images. Hips were classified as controls or narrowed based on IF and QF space thresholds and compared statistically throughout motion stages. RESULTS: The cohort comprised 12 women (24 hips; 10 control and 14 narrowed hips) aged 58 ± 10 years. External rotation caused IF space reduction of 59% in narrowed hips versus 41% in control hips. QF space decreased 71% in narrowed hips versus 50% in control hips. IF and QF spaces differed significantly between groups only when external rotation exceeded the neutral position (P < 0.02 for both). The lesser trochanter terminated more posteriorly in narrowed hips compared with controls (P = 0.03). CONCLUSIONS: Kinematic MRI during external hip rotation in women with narrowed and control hips reveals dynamic differences in IF and QF spaces and lesser trochanter terminal position.

Symptomatic COVID-19 infections in outpatient image-guided corticosteroid injection patients during the lockdown phase.

BACKGROUND: Musculoskeletal pain is a debilitating problem treated with image-guided corticosteroid injections. During the COVID-19 pandemic, multiple societies issued caution statements because of the unknown effect of corticosteroids on the patient's immune system. The purpose is to determine if image-guided corticosteroid injections administered during the COVID-19 lockdown phase were associated with a higher infection rate compared to the general population. MATERIALS AND METHODS: In a prospective study, patients undergoing image-guided corticosteroid injections for pain management during the lockdown phase between April 15 and May 22, 2020, were enrolled. One month after the injection, patients were surveyed by telephone for any COVID-19-related symptoms, and the electronic medical record (EMR) was reviewed for symptoms and test results. RESULTS: Seventy-one subjects were recruited, 31 (44%) females, 40 (56%) males, ages 58 ± 17 (20-92) years. Follow-up was available in 66 (93%) of subjects, 60 (91%) by phone survey and EMR, 6 (9%) by EMR only, 45 ± 22 (19-83) days after injection. One (1/66, 1.52%; 95% CI 0.04-8.2%) 25-year-old male subject developed symptomatic infection 19 days after a tibiotalar injection. The prevalence of COVID-19 cases in the state of Massachusetts was 0.91% (62,726/6,892,503) during the study period. There was no significant difference in the rate of occurrence of new cases of COVID-19 infection between the corticosteroid injection group and the general population (p = 0.44). CONCLUSION: Image-guided corticosteroid injections for pain management performed during the lockdown phase of the COVID-19 pandemic were not associated with a higher infection rate compared to the general population.