How to Best Identify Acetabular Retroversion on Radiographs: Thresholds to Guide Clinical Practice.

BACKGROUND: Acetabular retroversion is associated with impingement and instability. An adequate interpretation of acetabular version and coverage on radiographs is essential to determine the optimal treatment strategy (periacetabular osteotomy vs hip arthroscopic surgery). The crossover sign (COS) has been associated with the presence of acetabular retroversion, and the anterior wall index (AWI) and posterior wall index (PWI) assess anteroposterior acetabular coverage. However, the radiographic appearance of the acetabulum is sensitive to anterior inferior iliac spine (AIIS) morphology and pelvic tilt (PT), which differs between the supine and standing positions. PURPOSE: To (1) identify differences in the acetabular appearance between the supine and standing positions among patients presenting with hip pain; (2) determine factors (acetabular version, AIIS morphology, and spinopelvic characteristics) associated with the crossover ratio (COR), AWI, and PWI; and (3) define relevant clinical thresholds to guide management. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Patients who presented to a hip preservation surgical unit (n = 134) were included (mean age, 35 ± 8 years; 58% female; mean body mass index, 27 ± 6). All participants underwent supine and standing anteroposterior pelvic radiography to assess the COS, COR, AWI, and PWI as well as standing lateral radiography to determine standing PT. Computed tomography was used to measure supine PT, acetabular version, and AIIS morphology. Acetabular version was measured at 3 transverse levels, corresponding to the 1-, 2-, and 3-o'clock positions. The correlation between radiographic characteristics (COR, AWI, and PWI) and acetabular version, AIIS morphology, and PT was calculated using the Spearman correlation coefficient. Receiver operating characteristic curve analysis was performed to define thresholds for the COR, AWI, and PWI to identify retroversion (version thresholds: <10°, <5°, and <0°). RESULTS: The COS was present in 55% of hips when supine and 30% when standing, with a mean difference in the COR of 12%. The supine COR (rho = -0.661) and AWI/PWI ratio (rho = -0.618) strongly correlated with acetabular version. The COS was more prevalent among patients with type 2 AIIS morphology (71%) than among those with type 1 AIIS morphology (43%) (P = .003). COR thresholds of 23% and 28% were able to identify acetabular version <5° (sensitivity = 81%; specificity = 80%) and <0° (sensitivity = 88%; specificity = 85%), respectively. An AWI/PWI ratio >0.6 was able to reliably identify acetabular version <0° (sensitivity = 83%; specificity = 84%). In the presence of a COR >30% and an AWI/PWI ratio >0.6, the specificity to detect retroversion was significantly increased (>90%). CONCLUSIONS: The presence of the COS was very common among patients with hip pain. False-positive results (high COR/normal version) may occur because of AIIS morphology/low PT. Relevant thresholds of COR >30% and AWI/PWI ratio >0.6 can help with diagnostic accuracy. In cases in which either the COR or AWI/PWI ratio is high, axial cross-sectional imaging can further help to avoid false-positive results.

A Pilot Clinical and Technical Validation of an Immersive Virtual Reality Platform for 3D Anatomical Modeling and Contouring in Support of Surgical and Radiation Oncology Treatment Planning.

The aim of this study was to validate a novel medical virtual reality (VR) platform used for medical image segmentation and contouring in radiation oncology and 3D anatomical modeling and simulation for planning medical interventions, including surgery. The first step of the validation was to verify quantitatively and qualitatively that the VR platform can produce substantially equivalent 3D anatomical models, image contours, and measurements to those generated with existing commercial platforms. To achieve this, a total of eight image sets and 18 structures were segmented using both VR and reference commercial platforms. The image sets were chosen to cover a broad range of scanner manufacturers, modalities, and voxel dimensions. The second step consisted of evaluating whether the VR platform could provide efficiency improvements for target delineation in radiation oncology planning. To assess this, the image sets for five pediatric patients with resected standard-risk medulloblastoma were used to contour target volumes in support of treatment planning of craniospinal irradiation, requiring complete inclusion of the entire cerebral-spinal volume. Structures generated in the VR and the commercial platforms were found to have a high degree of similarity, with dice similarity coefficient ranging from 0.963 to 0.985 for high-resolution images and 0.920 to 0.990 for lower resolution images. Volume, cross-sectional area, and length measurements were also found to be in agreement with reference values derived from a commercial system, with length measurements having a maximum difference of 0.22 mm, angle measurements having a maximum difference of 0.04°, and cross-sectional area measurements having a maximum difference of 0.16 mm2. The VR platform was also found to yield significant efficiency improvements, reducing the time required to delineate complex cranial and spinal target volumes by an average of 50% or 29 min.

Hip Capsulolabral Complex: Anatomy, Disease, MRI Features, and Postoperative Appearance.

The hip is a uniquely constrained joint with critical static stability provided by the labrum, capsule and capsular ligaments, and ligamentum teres. The labrum is a fibrocartilaginous structure along the acetabular rim that encircles most of the femoral head. Labral tears are localized based on the clock-face method, which determines the extent of the tear while providing consistent terminology for reporting. Normal labral variants can mimic labral disease and can be differentiated by assessment of thickness or width, shape, borders, location, and associated abnormalities. The Lage and Czerny classification systems are currently the most well-known arthroscopic and imaging systems, respectively. Femoroacetabular impingement is a risk factor for development of labral tears and is classified according to bone dysmorphisms of the femur ("cam") or acetabulum ("pincer") or combinations of both (mixed). The capsule consists of longitudinal fibers reinforced by ligaments (iliofemoral, pubofemoral, ischiofemoral) and circular fibers. Capsular injuries occur secondary to hip dislocation or iatrogenically after capsulotomy. Capsular repair improves hip stability at the expense of capsular overtightening and inadvertent chondral injury. The ligamentum teres is situated between the acetabular notch and the fovea of the femoral head. Initially considered to be inconsequential, recent studies have recognized its role in hip rotational stability. Existing classification systems of ligamentum teres tears account for injury mechanism, arthroscopic findings, and treatment options. Injuries to the labrum, capsule, and ligamentum teres are implicated in symptoms of hip instability. The authors discuss the labrum, capsule, and ligamentum teres, highlighting their anatomy, pathologic conditions, MRI features, and postoperative appearance. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Which Acetabular Measurements Most Accurately Differentiate Between Patients and Controls? A Comparative Study.

BACKGROUND: Acetabular morphology is an important determinant of hip biomechanics. To identify features of acetabular morphology that may be associated with the development of hip symptoms while accounting for spinopelvic characteristics, one needs to determine acetabular characteristics in a group of individuals older than 45 years without symptoms or signs of osteoarthritis. Previous studies have used patients with unknown physical status to define morphological thresholds to guide management. QUESTIONS/PURPOSES: (1) To determine acetabular morphological characteristics in males and females between 45 and 60 years old with a high Oxford hip score (OHS) and no signs of osteoarthritis; (2) to compare these characteristics with those of symptomatic hip patients treated with hip arthroscopy or periacetabular osteotomy (PAO) for various kinds of hip pathology (dysplasia, retroversion, and cam femoroacetabular impingement); and (3) to assess which radiographic or CT parameters most accurately differentiate between patients who had symptomatic hips and those who did not, and thus, define thresholds that can guide management. METHODS: Between January 2018 and December 2018, 1358 patients underwent an abdominopelvic CT scan in our institution for nonorthopaedic conditions. Of those, we considered 5% (73) of patients as potentially eligible as controls based on the absence of major hip osteoarthritis, trauma, or deformity. Patients were excluded if their OHS was 43 or less (2% [ 28 ]), if they had a PROMIS less than 50 (1% [ 18 ]), or their Tönnis score was higher than 1 (0.4% [ 6 ]). Another eight patients were excluded because of insufficient datasets. After randomly selecting one side for each control, 40 hips were left for analysis (age 55 ± 5 years; 48% [19 of 40] were in females). In this comparative study, this asymptomatic group was compared with a group of patients treated with hip arthroscopy or PAO. Between January 2013 and December 2020, 221 hips underwent hip preservation surgery. Of those, eight were excluded because of previous pelvic surgery, and 102 because of insufficient CT scans. One side was randomly selected in patients who underwent bilateral procedure, leaving 48% (107 of 221) of hips for analysis (age 31 ± 8 years; 54% [58 of 107] were in females). Detailed radiographic and CT assessments (including segmentation) were performed to determine acetabular (depth, cartilage coverage, subtended angles, anteversion, and inclination) and spinopelvic (pelvic tilt and incidence) parameters. Receiver operating characteristics (ROC) analysis was used to assess diagnostic accuracy and determine which morphological parameters (and their threshold) differentiate most accurately between symptomatic patients and asymptomatic controls. RESULTS: Acetabular morphology in asymptomatic hips was characterized by a mean depth of 22 ± 2 mm, with an articular cartilage surface of 2619 ± 415 mm 2 , covering 70% ± 6% of the articular surface, a mean acetabular inclination of 48° ± 6°, and a minimal difference between anatomical (24° ± 7°) and functional (22° ± 6°) anteversion. Patients with symptomatic hips generally had less acetabular depth (20 ± 4 mm versus 22 ± 2 mm, mean difference 3 mm [95% CI 1 to 4]; p < 0.001). Hips with dysplasia (67% ± 5% versus 70% ± 6%, mean difference 6% [95% CI 0% to 12%]; p = 0.03) or retroversion (67% ± 5% versus 70% ± 6%, mean difference 6% [95% CI 1% to 12%]; p = 0.04) had a slightly lower relative cartilage area compared with asymptomatic hips. There was no difference in acetabular inclination (48° ± 6° versus 47° ± 7°, mean difference 0.5° [95% CI -2° to 3°]; p = 0.35), but asymptomatic hips had higher anatomic anteversion (24° ± 7° versus 19° ± 8°, mean difference 6° [95% CI 3° to 9°]; p < 0.001) and functional anteversion (22° ± 6° versus 13°± 9°, mean difference 9° [95% CI 6° to 12°]; p < 0.001). Subtended angles were higher in asymptomatic at 105° (124° ± 7° versus 114° ± 12°, mean difference 11° [95% CI 3° to 17°]; p < 0.001), 135° (122° ± 9° versus 111° ± 12°, mean difference 10° [95% CI 2° to 15°]; p < 0.001), and 165° (112° ± 9° versus 102° ± 11°, mean difference 10° [95% CI 2° to 14°]; p < 0.001) around the acetabular clockface. Symptomatic hips had a lower pelvic tilt (8° ± 8° versus 11° ± 5°, mean difference 3° [95% CI 1° to 5°]; p = 0.007). The posterior wall index had the highest discriminatory ability of all measured parameters, with a cutoff value of less than 0.9 (area under the curve [AUC] 0.84 [95% CI 0.76 to 0.91]) for a symptomatic acetabulum (sensitivity 72%, specificity 78%). Diagnostically useful parameters on CT scan to differentiate between symptomatic and asymptomatic hips were acetabular depth less than 22 mm (AUC 0.74 [95% CI 0.66 to 0.83]) and functional anteversion less than 19° (AUC 0.79 [95% CI 0.72 to 0.87]). Subtended angles with the highest accuracy to differentiate between symptomatic and asymptomatic hips were those at 105° (AUC 0.76 [95% CI 0.65 to 0.88]), 135° (AUC 0.78 [95% CI 0.70 to 0.86]), and 165° (AUC 0.77 [95% CI 0.69 to 0.85]) of the acetabular clockface. CONCLUSION: An anatomical and functional acetabular anteversion of 24° and 22°, with a pelvic tilt of 10°, increases the acetabular opening and allows for more impingement-free flexion while providing sufficient posterosuperior coverage for loading. Hips with lower anteversion or a larger difference between anatomic and functional anteversion were more likely to be symptomatic. The importance of sufficient posterior coverage was also illustrated by the posterior wall indices and subtended angles at 105°, 135°, and 165° of the acetabular clockface having a high discriminatory ability to differentiate between symptomatic and asymptomatic hips. Future research should confirm whether integrating these parameters when selecting patients for hip preservation procedures can improve postoperative outcomes.Level of Evidence Level III, prognostic study.

Prevalence of Lumbosacral Transitional Vertebral Anomalies Among Healthy Volunteers and Patients with Hip Pathology: Association with Spinopelvic Characteristics.

A lumbosacral transitional vertebra (LSTV) has been reported to be prevalent among patients with hip dysplasia. The aims of this study were to determine the (1) prevalence of an LSTV in young patients presenting with hip pain and a group of asymptomatic volunteers, (2) effect of an LSTV on spinopelvic characteristics, and (3) presence of low back pain among patients with an LSTV. Methods: This cross-sectional study included 102 patients with hip pathology and 51 asymptomatic volunteers (mean age, 33.9 ± 7.3 years; mean body mass index, 26.0 ± 5.0 kg/m2; 57.5% female). Participants underwent radiographic assessment of the lumbar spine and pelvis in standing and deep-seated positions. LSTV occurrence was classified according to the Castellvi system. Spinopelvic characteristics included lumbar lordosis (including segmental lumbar angles), pelvic tilt, and hip flexion (pelvic-femoral angle). Differences between standing and deep-seated values were calculated. Low back pain was assessed using the Oswestry Disability Index. Results: The prevalence of LSTV type ≥II was 8.5%, with no difference between patients and volunteers (p = 0.386). Individuals with an LSTV had a greater standing L1-L5 angle (mean, 51.6° ± 11.7° versus 38.9° ± 9.3°; p < 0.001). The overall spinal flexion (change in L1-S1 angle between the standing and deep-seated positions) in individuals with an LSTV was similar to that in individuals without an LSTV; restricted L5-S1 mobility was compensated for at L1-L2 (10.2° ± 5.8° in those with versus 8.4° ± 4.1° in those without an LSTV; p = 0.070). No significant difference in the presence of low back pain was found (p = 0.250). Conclusions: An LSTV was found in 8.5% of young adults, with no difference between patients with hip pathology and controls. Individuals with an LSTV have greater standing lumbar lordosis, with altered mechanics at the cephalad adjacent level, which may predispose these individuals to degenerative changes at this level. Level of Evidence: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Canadian Association of Radiologists Musculoskeletal System Diagnostic Imaging Referral Guideline.

The Canadian Association of Radiologists (CAR) Musculoskeletal System Expert Panel consists of musculoskeletal radiologists, a family physician, a sports and exercise medicine physician, emergency medicine physicians, a patient advisor, and an epidemiologist/guideline methodologist. After developing a list of 25 musculoskeletal clinical/diagnostic scenarios, a systematic rapid scoping review was undertaken to identify systematically produced referral guidelines that provide recommendations for 1 or more of these clinical/diagnostic scenarios. Recommendations from 41 guidelines (50 publications) and contextualization criteria in the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) for guidelines framework were used to develop 124 recommendation statements across the 25 scenarios related to the evaluation of the musculoskeletal system. This guideline presents the methods of development and the recommendations for imaging in the context of musculoskeletal pain, infection, tumors, arthropathies, metabolic bone disease, stress injuries, orthopedic hardware, avascular necrosis/bone infarction, and complex regional pain syndrome.

Acetabular Sector Angles in Asymptomatic and Dysplastic Hips: Defining Dysplasia and Thresholds to Guide Management.

BACKGROUND: Radiographic evaluation plays an important role in detecting and grading hip dysplasia. Acetabular sector angles (ASAs) measure the degree of femoral head coverage provided by the acetabulum on computed tomographic (CT) scans. In this study, we aimed to determine ASA values at different axial levels in a control cohort with asymptomatic, high-functioning hips without underlying hip pathology and a study group with symptomatic, dysplastic hips that underwent periacetabular osteotomy (PAO), thereby defining the ASA thresholds for hip dysplasia. METHODS: This was a cross-sectional study evaluating a control group of 51 patients (102 hips) and a study group of 66 patients (72 hips). The control group was high-functioning and asymptomatic, with an Oxford Hip Score of >43, did not have osteoarthritis (Tönnis grade ≤1), underwent a pelvic CT scan, had a mean age (and standard deviation) of 52.1 ± 5.5 years, and was 52.9% female. The study group had symptomatic hip dysplasia treated with PAO, had a mean age of 29.5 ± 7.3 years, and 83.3% was female. Anterior ASA (AASA) and posterior ASA (PASA) were measured at 3 axial CT levels to determine equatorial, intermediate, and proximal ASA. The thresholds for dysplasia were determined using receiver operating characteristic (ROC) curve analysis, including the area under the curve (AUC). RESULTS: Patients with dysplasia had significantly smaller ASAs compared with the control group; the differences were most pronounced for proximal AASAs and proximal and intermediate PASAs. The control group had a mean proximal PASA of 162° ± 17°, yielding a threshold for dysplasia of 137° (AUC, 0.908). The mean intermediate PASA for the control group was 117° ± 11°, yielding a threshold of 107° (AUC, 0.904). The threshold for anterior dysplasia was 133° for proximal AASA (AUC, 0.859) and 57° for equatorial AASA (AUC, 0.868). The threshold for posterior dysplasia was 102° for intermediate PASA (AUC, 0.933). CONCLUSIONS: Measurement of ASA is a reliable tool to identify focal acetabular deficiency with high accuracy, aiding diagnosis and management. A proximal PASA of <137° or an intermediate PASA of <107° should alert clinicians to the presence of dysplasia. LEVEL OF EVIDENCE: Diagnostic Level III . See Instructions for Authors for a complete description of levels of evidence.

MRI texture analysis of acetabular cancellous bone can discriminate between normal, cam positive, and cam-FAI hips.

OBJECTIVES: To compare the MRI texture profile of acetabular subchondral bone in normal, asymptomatic cam positive, and symptomatic cam-FAI hips and determine the accuracy of a machine learning model for discriminating between the three hip classes. METHODS: A case-control, retrospective study was performed including 68 subjects (19 normal, 26 asymptomatic cam, 23 symptomatic cam-FAI). Acetabular subchondral bone of unilateral hip was contoured on 1.5 T MR images. Nine first-order 3D histogram and 16 s-order texture features were evaluated using specialized texture analysis software. Between-group differences were assessed using Kruskal-Wallis and Mann-Whitney U tests, and differences in proportions compared using chi-square and Fisher's exact tests. Gradient-boosted ensemble methods of decision trees were created and trained to discriminate between the three groups of hips, with percent accuracy calculated. RESULTS: Sixty-eight subjects (median age 32 (28-40), 60 male) were evaluated. Significant differences among all three groups were identified with first-order (4 features, all p ≤ 0.002) and second-order (11 features, all p ≤ 0.002) texture analyses. First-order texture analysis could differentiate between control and cam positive hip groups (4 features, all p ≤ 0.002). Second-order texture analysis could additionally differentiate between asymptomatic cam and symptomatic cam-FAI groups (10 features, all p ≤ 0.02). Machine learning models demonstrated high classification accuracy of 79% (SD 16) for discriminating among all three groups. CONCLUSION: Normal, asymptomatic cam positive, and cam-FAI hips can be discriminated based on their MRI texture profile of subchondral bone using descriptive statistics and machine learning algorithms. CLINICAL RELEVANCE STATEMENT: Texture analysis can be performed on routine MR images of the hip and used to identify early changes in bone architecture, differentiating morphologically abnormal from normal hips, prior to onset of symptoms. KEY POINTS: • MRI texture analysis is a technique for extracting quantitative data from routine MRI images. • MRI texture analysis demonstrates that there are different bone profiles between normal hips and those with femoroacetabular impingement. • Machine learning models can be used in conjunction with MRI texture analysis to accurately differentiate between normal hips and those with femoroacetabular impingement.

Quantitative vs qualitative muscle MRI: Imaging biomarker in patients with Oculopharyngeal Muscular Dystrophy (OPMD).

Oculopharyngeal muscular dystrophy (OPMD) is a genetic muscle disease causing ptosis, severe swallowing difficulties and progressive limb weakness, although atypical presentations may be difficult to diagnose. Sensitive biomarkers of disease progression in OPMD are needed to enable more effective clinical trials. This study was designed to test the feasibility of using MRI to aid OPMD diagnosis and monitor OPMD progression. Twenty-five subjects with Dixon whole-body muscle MRI were enrolled: 10 patients with genetically confirmed OPMD, 10 patients with non-OPMD muscular dystrophies, and 5 controls. Using the MRI Dixon technique, muscle fat replacement was evaluated in the tongue, serratus anterior, lumbar paraspinal, adductor magnus, and soleus muscles using quantitative and semi-quantitative rating methods. Changes were compared with muscle strength testing, dysphagia severity, use of gait aids, and presence of dysarthria. Quantitative MRI scores of muscle fat replacement in the tongue could differentiate OPMD from other muscular dystrophies and from controls. Moreover, fat fraction in the tongue correlated with clinical severity of dysphagia. This study provides preliminary support for the use of Dixon-based quantitative MRI images as outcome measures for monitoring disease progression in clinical trials and provides rationale for future prospective studies aimed at methodological refinement and covariate identification.

Distal Radioulnar Joint: Normal Anatomy, Imaging of Common Disorders, and Injury Classification.

The distal radioulnar joint (DRUJ) is the distal articulation between the radius and ulna, acting as a major weight-bearing joint at the wrist and distributing forces across the forearm bones. The articulating surfaces are the radial sigmoid notch and ulnar head, while the ulnar fovea serves as a critical attachment site for multiple capsuloligamentous structures. The DRUJ is an inherently unstable joint, relying heavily on intrinsic and extrinsic soft-tissue stabilizers. The triangular fibrocartilage complex (TFCC) is the chief stabilizer, composed of the central disk, distal radioulnar ligaments, ulnocarpal ligaments, extensor carpi ulnaris tendon subsheath, and ulnomeniscal homologue. TFCC lesions are traditionally classified into traumatic or degenerative on the basis of the Palmer classification. The novel Atzei classification is promising, correlating clinical, radiologic, and arthroscopic findings while providing a therapeutic algorithm. The interosseous membrane and pronator quadratus are extrinsic stabilizers that offer a minor contribution to the joint's stability in conjunction with the joints of the wrist and elbow. Traumatic and overuse or degenerative disorders are the most common causes of DRUJ dysfunction, although inflammatory and developmental abnormalities also occur. Radiography and CT are used to evaluate the integrity of the osseous constituents and joint alignment. US is a useful screening tool for synovitis in the setting of TFCC tears and offers dynamic capabilities for detecting tendon instability. MRI allows simultaneous osseous and soft-tissue evaluation and is not operator dependent. Arthrographic CT or MRI provides a more detailed assessment of the TFCC, which aids in treatment and surgical decision making. The authors review the pertinent anatomy and imaging considerations and illustrate common disorders affecting the DRUJ. Online supplemental material is available for this article. © RSNA, 2022.

The diagnostic accuracy of MRI for evaluating the posterolateral corner in acute knee dislocation.

OBJECTIVE: To investigate the diagnostic performance of preoperative MRI in evaluating posterolateral corner (PLC) structures after acute knee dislocation (KD) and determine the correlation of MRI with operative findings for grading structure integrity. METHODS: Acute knee (femorotibial) dislocations between 2005 and 2020 with preoperative MRI and surgical posterolateral corner repair were identified from a single academic institution. From MRI, integrity was evaluated for PLC structures: lateral collateral ligament (LCL), popliteus tendon (PT), biceps femoris tendon (BFT), and ligamento-capsular complex (LCC). Frequency of injury to each structure and number of PLC structures torn in each case were tabulated. Diagnostic performance of MRI was determined using surgery as the reference standard. Correlation between MRI and surgery for each PLC structure was determined using kappa. RESULTS: Thirty-nine KD cases (19 right) in 39 patients (28 male) were included, with mean age of 33 years. Mechanism of injury was as follows: high energy 52%, low energy 38%, ultra-low energy 10%. LCL was most frequently torn, in 95% (37/39) of cases. Most commonly, three of four PLC structures were torn in 54% (21/39) of cases. Diagnostic accuracy of MRI was high for LCL 95%, BFT 87%, PT 82%, and LCC 92%. Correlation between MRI and surgical findings was variable: substantial for BFT, moderate for LCL and PT, and fair for LCC. CONCLUSION: MRI has high accuracy for detecting tears of posterolateral corner stabilizers in the setting of acute KD. However, for grading structure integrity, the correlation of MRI with surgical findings is variable, ranging from fair to substantial. KEY POINTS: • In acute knee dislocation, MRI has high diagnostic accuracy for detecting tears of posterolateral corner (PLC) structures. • Preoperative MRI should be considered by orthopedic surgeons when there is clinical concern for posterolateral corner instability following acute knee dislocation. • Although MRI is valuable in the preoperative investigation of knee dislocation, clinical assessment and intraoperative exploration may still be required for definitive diagnosis.

A Metrics-Based Research Salary Award System and Its 9-Year Impact on Publication Productivity.

RATIONALE AND OBJECTIVES: Although metrics-based systems may incentivize academic output, no prior studies have evaluated the impact on publication metrics in academic radiology. This study presents a metrics-based system of awarding research protected time, and retrospectively evaluates its 9-year impact on publication productivity and impact factor. MATERIALS AND METHODS: Based on a metrics-based algorithm to award department funded Research Protected Time (RPT), metrics pre-RPT (2003-2009) and during the RPT period (2010-2018) from an academic radiology department were retrospectively analyzed to test the hypothesis that the RPT program resulted in higher publication productivity and journal impact factor at the departmental level and for faculty members receiving the award. Comparison was made between (1) pre-RPT and RPT periods and (2) during the RPT period, between RPT and non-RPT faculty members, for annual publication productivity normalized to faculty count (Student's t test) and median impact factor (Wilcoxon rank sum test). RESULTS: For the evaluation period of 2003-2018, 724 unique publications were identified: 15% (107/724) pre-RPT period and 85% (617/724) RPT period. Normalized annual publication productivity was higher during the RPT period compared to the Pre-RPT period (1.2 vs. 0.3, p = 0.002), and within the RPT period, higher among faculty who received RPT vs. non-RPT faculty (3.5 vs. 0.4, p = 0.002). Median impact factor was higher during the RPT period compared to pre-RPT period (2.843 vs. 2.322, p = 0.044), and within the RPT period, higher in RPT vs. non-RPT faculty (3.016 vs. 2.346, p < 0.001). CONCLUSION: The implementation of a metrics-based system of funded, research protected time, was associated with increased publication productivity and increased impact factor.

MuSK not MNGIE: Atypical MuSK-antibody myasthenia presenting as a genetic disorder.

Myasthenia gravis is a treatable autoimmune disease caused by autoantibodies directed against membrane proteins at the neuromuscular junction. While acetylcholine receptor antibodies are most common, a minority of patients have antibodies directed against muscle-specific kinase (MuSK-antibody). Differentiating features often include subacute onset and rapid progression of bulbar, respiratory and neck extensor muscles, with sparing of distal appendicular muscles, most commonly in middle-aged females. Here we present an atypical presentation of MuSK-antibody myasthenic syndrome in a young male consisting of a gradual-onset, insidiously-progressive, non-fatigable and non-fluctuating ocular, bulbar and oesophageal weakness, with a normal frontalis single fibre EMG. This case clinically resembled a mitochondrial myopathy (Mitochondrial Neurogastrointestinal Encephalopathy-MNGIE) with a poor prognosis. Because of the atypical presentation, MuSK antibodies were identified very late in the disease course, at which point the patient responded very well to immunotherapy. We report an unusual presentation of an uncommon but treatable condition, illustrating significant phenotypic heterogeneity possible in MuSK-antibody myasthenic syndrome.

Hip Joint Preservation Surgery: What Every Orthopaedic Provider Needs to Know.

The understanding of the native hip's mechanics, physiology, and pathology has dramatically improved over the recent 2 decades. This was facilitated by the introduction of open and arthroscopic procedures to the native hip aimed at improving the joint's function and longevity. Associations between abnormal hip mechanics and further development of osteoarthritis are now clear. As the knowledge of hip joint mechanics has improved, other conditions around the hip have become evident, which may lead to pain but not necessarily osteoarthritis. It is important for the orthopaedic surgeon to be up to date on how the hip preservation field has evolved and the steps to consider when a painful hip presents in clinic.

Cadaveric Simulation Training Improves Residents' Knowledge and Confidence in Performing Fluoroscopic Guided Joint Injections.

RATIONALE AND OBJECTIVE: Simulation training has been strongly encouraged to enhance radiology trainees' procedural competency. We aimed to assess whether a cadaveric simulation training session was effective in improving radiology residents' subjective technical ability, knowledge and confidence in performing fluoroscopic-guided joint injections. METHODS: As part of the residency program's procedural training curriculum, first year radiology resident participated in a cadaveric, musculoskeletal injection training session including a didactic lecture followed by a practical hands-on component. Trainees performed fluoroscopic guided hip and shoulder injections on fresh cadavers, supervised by two fellowship-trained musculoskeletal radiologists. Trainees' knowledge on indications, contraindications, preprocedural care, complications, and technical ability in performing the procedures, as well as their rating of overall session experience were evaluated with pre- and post-session questionnaires (5 point Likert-scale). The mean residents' scores for pre- and post-session questionnaire items were calculated and compared using paired t-test. The magnitude of difference between mean pre- and post-session scores was compared between the items using analysis of variance. RESULTS: Results Over a 5-year period, 27 trainees participated in the joint injection simulation session. The mean pre- and post-session scores were significantly higher in the post session questionnaire for all five items pertaining to knowledge of indications, contraindications, preprocedural care, complications, and technical ability (all p < 0.0001). The magnitude of improvement was not different between the items (p = 0.45). Most of the participants rated the training facilities, contents, hands-on experience, teaching quality, and session organization as very good or excellent. CONCLUSIONS: Cadaveric joint injection simulation training significantly improved trainees' subjective knowledge, confidence, and technical ability in performing joint injections.

What Is the Correlation Among dGEMRIC, T1p, and T2* Quantitative MRI Cartilage Mapping Techniques in Developmental Hip Dysplasia?

BACKGROUND: Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) is a validated technique for evaluating cartilage health in developmental dysplasia of the hip (DDH), which can be a helpful prognosticator for the response to surgical treatments. dGEMRIC requires intravenous injection of gadolinium contrast, however, which adds time, expense, and possible adverse reactions to the imaging procedure. Newer MRI cartilage mapping techniques such as T1 rho (ρ) and T2* have been performed in the hip without the need for any contrast, although it is unknown whether they are equivalent to dGEMRIC. QUESTION/PURPOSE: In this study, our purpose was to determine the correlation between the relaxation values of three cartilage mapping techniques, dGEMRIC, T1ρ, and T2*, in patients with DDH. METHODS: Fifteen patients with DDH (three male, 12 female; mean age 29 ± 9 years) scheduled for periacetabular osteotomy underwent preoperative dGEMRIC, T1ρ, and T2* MRI at 3T with quantitative cartilage mapping. The outcomes of dGEMRIC, T1ρ, and T2* mapping were calculated for three regions of interest (ROI) to analyze the weightbearing cartilage of the hip: global ROI, anterior and posterior ROI, and further subdivided into medial, intermediate, and lateral to generate six smaller ROIs. The correlation between the respective relaxation time values was evaluated using the Spearman correlation coefficient (rS) for each ROI, categorized as negligible, weak, moderate, strong, or very strong. The relaxation values within the subdivided ROIs were compared for each of the three cartilage mapping techniques using the Kruskal-Wallis test. RESULTS: There was a moderate correlation of T1ρ and T2* relaxation values with dGEMRIC relaxation values. For the global ROI, there was a moderate correlation between dGEMRIC and T2* (moderate; rS = 0.63; p = 0.01). For the anterior ROI, a moderate or strong correlation was found between dGEMRIC and both T1ρ and T2*: dGEMRIC and T1ρ (strong; rS = -0.71; p = 0.003) and dGEMRIC and T2* (moderate; rS = 0.69; p = 0.004). There were no correlations for the posterior ROI. The mean dGEMRIC, T1ρ, and T2* relaxation values were not different between the anterior and posterior ROIs nor between the subdivided six ROIs. CONCLUSION: Quantitative T1ρ and T2* cartilage mapping demonstrated a moderate correlation with dGEMRIC, anteriorly and globally, respectively. However, the clinical relevance of such a correlation remains unclear. Further research investigating the correlation of these two noncontrast techniques with clinical function and outcome scores is needed before broad implementation in the preoperative investigation of DDH. LEVEL OF EVIDENCE: Level II, diagnostic study.

Periacetabular osteotomy with or without arthroscopic management in patients with hip dysplasia: study protocol for a multicenter randomized controlled trial.

BACKGROUND: Hip dysplasia is one of the most common causes of hip arthritis. Its incidence is estimated to be between 3.6 and 12.8% (Canadian Institute for Health Information, Hip and knee replacements in Canada, 2017-2018: Canadian joint replacement registry annual report, 2019; Jacobsen and Sonne-Holm, Rheumatology 44:211-8, 2004). The Periacetabular Osteotomy (PAO) has been used successfully for over 30 years (Gosvig et al., J Bone Joint Surg Am 92:1162-9, 2010), but some patients continue to exhibit symptoms post-surgery (Wyles et al., Clin Orthop Relat Res 475:336-50, 2017). A hip arthroscopy, performed using a small camera, allows surgeons to address torn cartilage inside the hip joint. Although both procedures are considered standard of care treatment options, it is unknown whether the addition of hip arthroscopy improves patient outcomes compared to a PAO alone. To delay or prevent future joint replacement surgeries, joint preservation surgery is recommended for eligible patients. While previous studies found an added cost to perform hip arthroscopies, the cost-effectiveness to Canadian Health care system is not known. METHODS: Patients randomized to the experimental group will undergo central compartment hip arthroscopy prior to completion of the PAO. Patients randomized to the control group will undergo isolated PAO. Patient-reported quality of life will be the primary outcome used for comparison between the two treatment groups as measured by The International Hip Outcome Tool (iHOT-33) (Saberi Hosnijeh et al., Arthritis Rheum 69:86-93, 2017). Secondary outcomes will include the four-square step test and sit-to-stand (validated in patients with pre-arthritic hip pain) and hip-specific symptoms and impairment using the HOOS; global health assessment will be compared using the PROMIS Global 10 Score; health status will be assessed using the EQ-5D-5L and EQ VAS questionnaires (Ganz et al., Clin Orthop Relat Res 466:264-72, 2008) pre- and post-operatively. In addition, operative time, hospital length of stay, adverse events, and health services utilization will be collected. A sub-group of patients (26 in each group) will receive a T1rho MRI before and after surgery to study changes in cartilage quality over time. A cost-utility analysis will be performed to compare costs and quality-adjusted life years (QALYs) associated with the intervention. DISCUSSION: We hypothesize that (1) concomitant hip arthroscopy at the time of PAO to address central compartment pathology will result in clinically important improvements in patient-reported outcome measures (PROMs) versus PAO alone, that (2) additional costs associated with hip arthroscopy will be offset by greater clinical improvements in this group, and that (3) combined hip arthroscopy and PAO will prove to be a cost-effective procedure. TRIAL REGISTRATION: ClinicalTrials.gov NCT03481010 . Registered on 6 March 2020. Protocol version: version 3.

The prevalence and characteristics of osseous erosions associated with parameniscal cysts on knee MRI.

OBJECTIVES: To determine the prevalence and characteristics of erosions associated with parameniscal cysts (PMCs) and to evaluate the profile of the associated meniscal tears MATERIALS AND METHODS: PACS database was reviewed for knee MRI scans performed over a 5-year period identifying those with PMCs in patients aged 18 years and above. The scans with PMCs were evaluated for the presence of associated osseous erosions. These erosions and PMCs were then analyzed. RESULTS: The search revealed 6773 knee MRI examinations, of which 555 had confirmed PMCs. There were 7 PMC-associated erosions for a prevalence of 1.3% (95% CI 0.6, 2.6). All erosions involved the proximal tibia. Three of 7 erosions had underlying marrow edema, and 4 out of 7 had an overhanging margin. The mean dimension of all PMCs was 13 mm (SD = 11). The mean dimension of PMCs associated with erosions was 38 mm (SD = 22), while that of PMCs without erosions was 12 mm (SD = 10) (P < 0.001, Wilcoxon rank sum test). Ninety-three percent (95% CI 90.5, 94.8) of PMCs had associated meniscal tears, most commonly of the horizontal type (57%). All PMCs with underlying erosions were associated with meniscal tears, most commonly complex type tears (5/7). CONCLUSION: Erosions can rarely be associated with contiguous parameniscal cysts (PMCs). These cysts are significantly larger compared with those without underlying erosions.