Glenoid Track Assessment at Imaging in Anterior Shoulder Instability: Rationale and Step-by-Step Guide.

Anterior shoulder dislocation is the most common form of joint instability in humans, usually resulting in soft-tissue injury to the glenohumeral capsuloligamentous and labral structures. Bipolar bone lesions in the form of fractures of the anterior glenoid rim and posterolateral humeral head are often associated with anterior shoulder dislocation and can be a cause or result of recurrent dislocations. Glenoid track assessment is an evolving concept that incorporates the pathomechanics of anterior shoulder instability into its management. Currently widely endorsed by orthopedic surgeons, this concept has ramifications for prognostication, treatment planning, and outcome assessment of anterior shoulder dislocation. The glenoid track is the contact zone between the humeral head and glenoid during shoulder motion from the neutral position to abduction and external rotation. Two key determinants of on-track or off-track status of a Hill-Sachs lesion (HSL) are the glenoid track width (GTW) and Hill-Sachs interval (HSI). If the GTW is less than the HSI, an HSL is off track. If the GTW is greater than the HSI, an HSL is on track. The authors focus on the rationale behind the glenoid track concept and explain stepwise assessment of the glenoid track at CT or MRI. Off-track to on-track conversion is a primary goal in stabilizing the shoulder with anterior instability. The key role that imaging plays in glenoid track assessment warrants radiologists' recognition of this concept along with its challenges and pitfalls and the production of relevant and actionable radiology reports for orthopedic surgeons-to the ultimate benefit of patients. ©RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center.

Determinants of in-hospital muscle loss in acute ischemic stroke - Results of the Muscle Assessment in Stroke Study (MASS).

BACKGROUND & AIMS: There is a change in the mass and composition of paretic and non-paretic skeletal muscles in the chronic phase of stroke. The multi-center, prospective, and observational Muscle Assessment in Stroke Study (MASS) was performed to evaluate the degree of muscle loss during the in-hospital acute stroke setting and determine factors contributing to this loss. METHODS: Acute dysphagic ischemic stroke patients (n = 107) admitted to neuro-intensive care units were evaluated by computed tomography on days 1 and 14 after admission to determine the cross-sectional muscle area (CSMA) at the level of the mid-humerus, mid-thigh, and third lumbar vertebra. The percentage change in CSMA and variables associated with this change were evaluated by univariate and multivariate analyses. RESULTS: There were significant reductions in CSMA in all the muscle groups analyzed; the most prominent change was observed in the arms (both: 14.2 ± 10.7%; paretic: 17.7 ± 11.6%; non-paretic: 10.1 ± 12.5%), followed by the muscles in the legs (both: 12.4 ± 8.7%; paretic: 12.9 ± 9.9%; non-paretic: 12.0 ± 9.3%) and L3-vertebra level (5.6 ± 9.8%) (P < 0.001 for all). Higher calorie (r = -0.378, P < 0.001) or protein (r = -0.352, P < 0.001) intake was negatively associated with the decrease in CSMA of upper extremities. A substantial protein (≥0.4 g/kg/d) or calorie (≥5 kcal/kg/d) gap between targeted or actual intake was related to a larger decrease in CSMA in all the anatomic regions (P ≤ 0.05 for all). Other significant predictors of muscle loss included history of diabetes mellitus, male sex, higher BMI, in-hospital infections, and the necessity for invasive mechanical ventilation. CONCLUSIONS: There is a considerable degree of loss in the global muscle mass in acute ischemic stroke patients over a two-week period. Along with several factors, falling significantly behind the daily protein or calorie targets was related to the decrease in the muscle area. TRIAL REGISTRATION INFORMATION: clinicaltrials.gov identifier NCT03825419.

Optimization of the Grashey View Radiograph for Critical Shoulder Angle Measurement: A Reliability Assessment With Zero Echo Time MRI.

Background: Suboptimal positioning on Grashey view radiographs may limit the prognosticating potential of the critical shoulder angle (CSA) for shoulder disorders. Purpose: To investigate whether radiography optimized according to the latest research is reliable for measuring CSA in comparison with magnetic resonance imaging (MRI) featuring 3-dimensional (3D) zero echo time (ZTE) sequencing, which accentuates the contrast between cortical bone and surrounding soft tissue with high fidelity. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: Patients with shoulder pain were prospectively and consecutively enrolled. All patients had Grashey view radiographs as well as 3.0-T MRI scans with isotropic 3D ZTE sequencing. Acceptable positioning on the radiographs was determined using the ratio of the transverse to longitudinal (RTL) diameter of the lateral glenoid outline; radiographs with an RTL ≥0.25 were repeated. Two observers independently measured the CSA on the radiographs and the coronal oblique reformatted ZTE images, the latter including verification of measurement points by cross-referencing against images from other planes. Reliability of measurements between observers and modalities was analyzed with the intraclass correlation coefficient (ICC). The paired-samples t test was used to compare the differences between imaging modalities. Results: Enrolled were 65 patients (35 female and 30 male; mean age, 40.2 years; range, 25-49 years). Radiographs with optimal positioning (RTL < 0.25) were attained after a mean of 1.6 exposures (range, 1-4); the mean RTL was 0.09 (range, 0-0.20). Interobserver agreement of CSA was excellent for radiographs (ICC = 0.91; 95% CI, 0.84-0.94) and good for ZTE MRI scans (ICC = 0.85; 95% CI, 0.71-0.92). Intermodality agreement of CSA between radiographs and ZTE MRI scans was moderate (ICC = 0.66; 95% CI, 0.48-0.73). The CSA was significantly different between an optimal radiograph (30.7° ± 4.3°) and ZTE MRI scan (31.8° ± 3.8) (P = .005). Subgroup analysis revealed no significant differences in CSA measurement between ZTE MRI scans and Grashey view radiographs with an RTL of <0.1 (P = .08). Conclusion: CSA measurement on ZTE MRI scans with anatomic point cross-referencing was significantly different from that on Grashey view radiographs, even with optimal positioning, and radiography may necessitate more than 1 exposure. An RTL of <0.1 ensured reliability of radiographs when other standards of sufficient x-ray exposure were met.

MRI in the Diagnosis and Treatment Response Assessment of Chronic Nonbacterial Osteomyelitis in Children and Adolescents.

PURPOSE OF REVIEW: To explain the central role of magnetic resonance imaging (MRI) in the diagnosis and follow-up of chronic nonbacterial osteomyelitis (CNO) in children and adolescents, centering on practical technical aspects and salient diagnostic features. RECENT FINDINGS: In the absence of conclusive clinical features and widely accepted laboratory tests, including validated disease biomarkers, MRI (whether targeted or covering the entire body) currently plays an indispensable role in the diagnosis and therapy response assessment of CNO. Whole-body MRI, which is the reference imaging standard for CNO, can be limited to a short tau inversion recovery (STIR) coronal image set covering the entire body and a STIR sagittal set covering the spine, an approximately 30-min examination with no need for intravenous contrast or diffusion-weighted imaging. The hallmark of CNO is periphyseal (metaphyseal and/or epi-/apophyseal) osteitis, identified as bright foci on STIR, with or without inflammation of the adjacent periosteum and surrounding soft tissue. Response to bisphosphonate treatment for CNO has some unique MRI findings that should not be mistaken for residual or relapsing disease. Diagnostic features and treatment response characteristics of MRI in pediatric CNO are discussed, also describing the techniques used, pitfalls encountered, and differential diagnostic possibilities considered during daily practice.

Anterior inferior iliac spine morphology: quantitative and qualitative assessment in an asymptomatic population.

PURPOSE: To assess the prevalence of anterior inferior iliac spine (AIIS) types, and to investigate the quantitative measurements that characterize AIIS morphology in an asymptomatic adult population. METHODS: In this prospective study, 358 hips from 179 consecutive subjects (age range, 19-82 years; 91 males, 88 females), who underwent CT examination for reasons other than hip problems and were negative for hip impingement test, were analyzed. AIIS types were determined (1, flat wall of the ilium between distal end of AIIS and acetebular rim; 2, bony eminence between distal end of AIIS and acetebular rim; and 3, extension of AIIS to the anterior superior acetebular rim) and AIIS tip angle (TA), direct distance (DD) of the anterior acetabular rim to AIIS as well as projectional distances in vertical (VD) and horizontal (HD) planes were measured. Age- and gender-related factors were searched using two-way ANOVA test under three age groups (18-39, 40-59, and ≥ 60 years). RESULTS: There were 238 (66.5%) type 1, 118 (33.0%) type 2, and two (0.5%) type 3 AIISs, with significant difference between AIIS types among age groups and genders (P < 0.001). VD and DD showed age- and gender-related (P < 0.001, P < 0.001), and TA demonstrated gender-related differences (P < 0.001). Inter-observer agreement was good for TA and moderate to poor for other measurements. CONCLUSIONS: Type 1 AIIS is the most common shape across all age groups in adult females and in young and middle-aged adult males. TA, DD, and VD might be reliably used for the evaluation of AIIS morphology.

CT assessment of asymptomatic hip joints for the background of femoroacetabular impingement morphology.

PURPOSE: The purposes of this study were to assess the presence of cam and pincer morphology in asymptomatic individuals with a negative femoroacetabular impingement test, and to determine and compare the ranges of alpha angle using two measurement methods. MATERIALS AND METHODS: In total, 68 consecutive patients who underwent abdominopelvic computed tomography (CT) for reasons other than hip problems were the patient population. Patients who had a positive femoroacetabular impingement test were excluded. Alpha angle measurements from axial oblique (AN) and radial reformat-based images (AR) from the anterior through the superior portion of the femoral head-neck junction, as well as femoral head-neck offset, center-edge angle, acetabular version angle measurements, and acetabular crossover sign assessment, were made. RESULTS: Overall prevalences of cam (increased alpha angle, decreased femoral head-neck offset) and pincer morphology (increased center-edge angle, decreased acetabular version) were 20.0%, 26.8%, 25.8%, and 10.2% of the hips, respectively. The mean AR ranged from 41.64° ± 4.23° to 48.13° ± 4.63°, whereas AN was 41.10° ± 4.44°. The values of AR were higher than AN, and the difference was statistically significant (P <0.001). The highest AR values were measured on images from the anterosuperior section of femoral head-neck junction. CONCLUSION: In asymptomatic subjects, higher alpha angle values were obtained from radial reformatted images, specifically from the anterosuperior portion of the femoral head-neck junction compared with the axial oblique CT images. Other measurements used for the assessment of cam and pincer morphology can also be beyond the ranges that are considered normal in the general population.