Comparison of Hip Reduction Using Magnetic Resonance Imaging or Computed Tomography in Hip Dysplasia

ArticleinJournal of pediatric orthopedics 31(5):525-9 · July 2011with4 Reads
DOI: 10.1097/BPO.0b013e31821f905b · Source: PubMed
Abstract
The purpose of this paper was to compare the use of computed tomography (CT) versus magnetic resonance imaging (MRI) to evaluate hip reduction in patients with dysplasia of the hip. A retrospective review of postoperative pelvic CT and MRI in patients <13 months of age with hip dysplasia was performed. Scanner time, anesthesia requirement, cost, and radiation dosage were recorded. Hips were classified as dislocated, subluxated, or reduced. Sensitivity and specificity of CT and MRI were calculated. The outcomes of the subluxated hips were followed. Thirty-two CT scans and 33 MRI scans in 39 patients were evaluated. CT scanner time was 2.8 minutes, which was significantly less than the 8.9 minutes required for MRI (P=0.0001). Postoperative anesthesia was only required for 1 CT case. Average cost of CT examination was $788 and $1104 for MRI. Average radiation dose with CT examinations was 1 mSv. Of the postoperative nonsubluxated hips (n=30 for CT and n=37 for MRI), CT demonstrated a sensitivity of 100% and a specificity of 96%, whereas MRI exhibited a sensitivity of 100% and a specificity of 100%. Of the postoperative subluxated hips, 66.7% spontaneously reduced, 22.2% remained subluxated, and 11.1% redislocated. This is the first study to compare these imaging modalities in the evaluation of hip reduction in DDH. This study affirms MRI as an alternative to CT scan. The sensitivity and specificity of both modalities appears excellent. Similar to other studies, a large percentage of subluxated hips in both groups reduce without additional surgical intervention. Diagnostic level II.
    • "Reports have also investigated the potential influence of factors such as the ossific nucleus at the time of reduction or the hip abduction angle in the postoperative spica cast on AVN rate [27, 32], but these results are inconclusive. Recent evidence has suggested MRI as a safe, effective, and reliable postreduction imaging modality [1, 5]. Gadolinium-enhanced perfusion MRI (pMRI) can provide the surgeon with data regarding vascular perfusion to the femoral head [2, 13]. "
    Article · Feb 2016
  • [Show abstract] [Hide abstract] ABSTRACT: Two-dimensional multiple-echo data image combination (MEDIC) images, as well as conventional T1-weighted and T2-weighted images, were obtained for 38 infants with developmental dysplasia of the hip. We retrospectively reviewed these images to evaluate subjective image quality and femoral head-to-ischium contrast. MEDIC images were considered to be of high quality compared with the conventional T1-weighted (P<0.0001) and T2-weighted images (P<0.05), as well as have a higher contrast than conventional T1-weighted and T2-weighted images (P<0.001, respectively). In conclusion, MEDIC images provide diagnostic improvement in studies on developmental dysplasia of the hip.
    Article · Sep 2013
  • [Show abstract] [Hide abstract] ABSTRACT: Closed reduction (CR) and spica casting is performed using arthrography to assess the adequacy of reduction based in part on the width of medial dye pool (MDP); however, the amount of MDP that is acceptable and its correlation to the actual anatomic position of the femoral head within the acetabulum has been poorly delineated. The purpose of this study was to determine this correlation and to explore the potential limits of acceptable MDP measurements. We retrospectively reviewed a consecutive series of patients with DDH treated at our institution by CR and immediate postoperative magnetic resonance imaging (MRI) and found 20 patients (23 hips) meeting inclusion criteria. We measured the MDP and femoral head area on the best reduced arthrographic image, the immediate postoperative mid-coronal MRI, and on 3 planes (neutral, 30-degree anterior, and 30-degree posterior) of the mid-axial MRI and compared MDP values from both imaging modalities using the Pearson correlation coefficient (R). To provide useful data for establishing intraoperative thresholds, MDP was also expressed as a percentage of femoral head width to control for fluoroscopic magnification. Twenty-two of the 23 hips were reduced on postoperative MRI; the one persistently dislocated hip was excluded from our analysis. The Pearson correlation coefficient was R=0.73 comparing arthrography and coronal MRI, indicating excellent correlation. Correlation was even stronger between arthrography and axial MRI (neutral R=0.73; 30-degree anterior, R=0.81; 30-degree posterior, R=0.81). The mean fluoroscopic MDP in the successful, fully concentric, CRs was 4.2% of the femoral head width (range, 0.6% to 15.8%). There is very strong correlation between MDP measurements on arthrography and immediate postoperative MRI in both the axial and coronal planes. On the basis of our data, an arthrographic MDP between 0.6% and 15.8% of the femoral head width always resulted in an excellent reduction, suggesting that an MDP of ≤16% of femoral head width may be a useful intraoperative criterion for determining the adequacy of CR. Level I Diagnostic Study.
    Article · Apr 2014
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