Diagnostic accuracy of MRI for detection of occult instability of type I anterior to posterior pelvic injuries.

Type I Young and Burgess anterior posterior compression (APC) pelvic injuries have been classically managed non operatively due to theoretical integrity of sacroiliac joint ligaments (SIJL), though examination under anesthesia (EUA) has been proven occult mechanical instability in up to 50% of these injuries.  We sought to determine the diagnostic accuracy of magnetic resonance (MRI) for detection of occult instability on APC-I injuries when compared to EUA. METHODS: Diagnostic test study of prospectively recruited patients admitted with APC-I pelvic injuries between 2015 and 2022. All patients consented to participate in this study were subjected to MRI and EUA. The evaluators of each of these tests were blinded.  On MRI evaluation, SIJL were considered compromised when unilateral injury to anterior SIJL was visualized in three or more consecutive images or in bilateral injuries, when injury to the anterior SIJL in two or more consecutive images on each side was observed. Positive EUA was considered a symphyseal diastasis over 25 mm on stress fluoroscopy. Demographic data was collected as recruited and sensitivity, specificity, accuracy, and positive and negative predictive values were calculated. Confidence interval was set at 95%. EUA was considered the gold standard in statistical analysis. RESULTS: A total of 32 patients mean aged 36 (24-61) years were included. Mean symphyseal diastasis at admission was 17.58 (11 - 25) mm. The median time from injury to EUA was 5 (0-21) days. Positive EUA was observed on 20 patients and 25 patients  presented compromised SIJL. MRI presented a sensitivity of 95% (75.13% - 99.87%), specificity of 50% (21.09% - 78.91%), positive-predictive value of 73% (60.61% to 82.93%), negative-predictive value of 87% (48.66% - 98.08%). CONCLUSION: Injury to SIJL on MRI presented an accuracy of 77% (58.29% - 89.64%) for the detection of occult pelvic instability on EUA.

Coronal displacement in proximal humeral fractures: correlation between shoulder radiographic and computed tomography scan measurements.

BACKGROUND: The purpose of this study was to analyze if there is a correlation in displacement measurements in coronal projections between shoulder radiographs and computed tomography (CT) scans in patients with proximal humeral fractures (PHFs). METHODS: A comparative, retrospective analysis of images from our database was performed. Ninety-seven cases with PHFs with radiographs and CT scans were included. Four evaluators measured PHF displacement using the following: metaphyseal extension (ME), medial calcar (MC) medialization, apex-tuberosity distance (ATD), and cervicodiaphyseal (CD) angle. Measurement reliability was evaluated with a pilot sample by performing intraclass coefficient correlation analysis. Surgery indication according to displacement (CD angle <105° or >155° and ATD <3 mm) and agreement analysis were assessed by κ tests. RESULTS: All evaluated parameters presented correlations among methods for intrarater and inter-rater reliability. All measurements showed significant differences (ME of 1.2 ± 6 mm, P = .034; MC of 1 ± 5 mm, P = .041; ATD of 2.6 ± 5 mm, P = .001; and CD angle of 9° ± 16°, P = .001). Regarding indications for treatment type relating to ATD and CD angle, there was agreement between CT scans and radiographs in 66 of 97 cases (κ = 0.351, P < .001). Twelve cases with surgical indications by CT scans had conservative indications by radiographs, whereas in 19 cases with conservative indications by CT scans, radiographic measurements suggested surgical treatment. CONCLUSION: This study documented regular concordance between radiographs and CT scans for coronal displacement measurements in PHFs. Statistical differences were documented for all measurements. Webelieve that ATD and CD angle differences are clinically relevant (mean, 3 mm and 9°, respectively) because these differences might change the type of treatment.