Can EOS Imaging Substitute for Conventional Radiography in Measurement of Acetabular Morphology in the Young Dysplastic Hip?

BACKGROUND: EOS imaging offers a low-radiation alternative to conventional radiography (CR) and has little to no magnification effects. However, it is unclear how radiographic measures may be affected using EOS. The present study aims to determine the reproducibility of measures of acetabular morphology on EOS images as compared with CR, and to directly compare the 2 imaging modalities. METHODS: A total of 21 consecutive patients (66.7% female; 14.4±4.7 y) indicated for an open hip preservation procedure with both an anterior-posterior pelvis radiograph and EOS image performed preoperatively were included. Three orthopaedic surgeons measured Tönnis angle, lateral center edge angle (LCEA), acetabular depth-width ratio (ADR), and extrusion index (EI). Measurements were performed twice, 2 weeks apart. Reliability between observers and time points was measured using intraclass correlation coefficients, and agreement between time points and modalities was measured using Bland-Altman analysis. RESULTS: On EOS images, inter-rater reliability was 0.86 for Tönnis angle, 0.86 for LCEA, 0.74 for ADR, and 0.93 for EI. On CR, inter-rater reliability was 0.86 for Tönnis anlge, 0.90 for LCEA, 0.82 for ADR, and 0.84 for EI. In the agreement analysis, biases between imaging modalities were observed. On average, raters measured Tönnis angle and EI higher on EOS images than CR (2.22 degrees, 1.09%, respectively); and LCEA and ADR lower on EOS images than CR (1.54 degrees, 1.14% respectively). Limits of agreement (LOA) between modalities were similar to that of LOA observed in intra-rater analysis. CONCLUSIONS: Measures of acetabular morphology performed on EOS images have similarly high intra-rater and inter-rater reliability compared with CR. Measures performed on EOS also have similar intra-rater agreement as compared with CR. Intermodality agreement had similar LOA as intra-rater agreement on either individual imaging modality. Small biases between imaging modalities were detected. LEVELS OF EVIDENCE: Level I-diagnostic study: investigating a diagnostic test.

Outcomes of Isolated Varus Derotational Osteotomy in Children With Cerebral Palsy Hip Dysplasia and Predictors of Resubluxation.

BACKGROUND: The appropriate intervention for hip subluxation or dislocation in children affected by cerebral palsy (CP) remains controversial. The purpose of this retrospective study was to report radiographic and clinical outcomes following isolated femoral varus derotational osteotomy (VDRO) in children with CP hip dysplasia. Risk factors for resubluxation and avascular necrosis (AVN) were also examined. METHODS: A cohort of 100 patients (199 hips) with CP treated with isolated VDRO between 2003 and 2009 was reviewed. All but 1 patient received bilateral surgery. Patients were followed for an average of 5.4 years (range, 1.03 to 10.20 y). Anteroposterior pelvic radiographs were used to assess migration percentage (MP), Shenton's line, and presence of AVN. Resubluxation was defined as a postoperative break in Shenton's line. Radiographic outcomes and risk analysis was performed in the 91 subjects (179 hips) with radiographic follow-up >1 year. RESULTS: Significant improvement was observed in MP, and all hips had a reconstituted Shenton's line following surgery. Over the course of follow-up, 16% of hips were noted to have a repeat break in Shenton's line. Univariate risk analysis showed preoperative MP, Gross Motor Function Classification System (GMFCS) level, and age at surgery were risk factors for a recurrent line break. Preoperative MP and GMFCS level were found to be predictors of resubluxation in multivariate analysis. AVN was detected in 10 hips (5.7%). GMFCS level V patients were more at risk for resubluxation, but less at risk for AVN when compared with ambulatory (GMFCS I/II/II) patients and GMFCS level IV patients. CONCLUSIONS: Performing a VDRO without additional procedures provided a stable and concentrically reduced hip joint in this population of children with CP. Attention should be paid to initial ambulatory status during the postoperative period. Concomitant procedures such as pelvic osteotomy should be considered for patients of GMFCS level IV and V, as these patients were more at risk for recurrent subluxation. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

Chest computed tomography imaging for blunt pediatric trauma: not worth the radiation risk.

INTRODUCTION: A child's risk of developing cancer from radiation exposure associated with computed tomography (CT) imaging is estimated to be as high as 1/500. Chest CT (CCT), often as part of a "pan-scan," is increasingly performed after blunt trauma in children. We hypothesized that routine CCT for the initial evaluation of blunt injured children does not add clinically useful information beyond chest radiograph (CXR) and rarely changes management. METHODS: Pediatric (<15 y) trauma team evaluations over 6 y at an academic Level I trauma center were reviewed. Demographic data, injuries, imaging, and management were identified for all patients undergoing CT. Effective radiation dose in milliSieverts (mSv) was calculated using age-adjusted scales. RESULTS: Fifty-seven of 174 children (33%) undergoing CT imaging had a CCT; 55 (97%) of these had a CXR. Pathology was identified in significantly fewer CXRs compared with CCTs (51% versus 83%, P < 0.001). All 7/57 (12%) emergent or urgent chest interventions were based on information from CXR. In 53 children (93%), the CCT was ordered as part of a pan-scan, resulting in a radiation dose of 37.69 ± 7.80 mSv from initial CT scans. Radiation dose was significantly greater from CCT than from CXR (8.7 ± 1.1 mSv versus 0.017 ± 0.002 mSv, P < 0.001). CONCLUSIONS: Clinically useful information found on CCT had good correlation to information obtained from CXR and did not change patient management, however, did add significantly to the radiation exposure of initial imaging. We recommend selective use of CCT, particularly in the presence of an abnormal mediastinal silhouette on CXR after a significant deceleration injury.