Background: Acceptable amounts of malrotation after CRPP for pediatric supracondylar humerus fracture (SCHFx) have yet to be defined. This is an attempt to correlate radiographic parameters of a malrotated SCHFx with degrees of rotational malalignment to assist intraoperative assessment of reduction. Methods: 3D models of a left distal humerus were printed, simulating a transverse SCHFx with 5, 10, 15, 20, 25, and 30 degrees of malrotation. Four different scenarios were developed: (1) lateral cortical axis of rotation, (2) medial cortical axis of rotation, (3) centroid of the humerus longitudinal axis with the medial condyle rotated posteriorly, and (4) centroid of the humerus longitudinal axis with the medial condyle rotated anteriorly. Anteroposterior and lateral fluoroscopic views were taken with a consistent image profile. Five observers measured the amount of metaphyseal overhang on the lateral view and the width of the distal humerus just proximal to the fracture to establish amount of overhang as a percentage of distal humerus width. Regression analysis established “best fit” lines for the 4 scenarios. Ten observers used the observed characteristics of each type of malrotation and “best fit” lines to estimate axis and degrees of malrotation using the same fluoroscopy of the 24 models. Results: The intraclass correlation coefficient of reliability for percentage of metaphyseal overhang ranged from 0.775 to 0.987. Observers correctly predicted axis of malrotation in 76% and correctly predicted amount of malrotation in 75% of models. Conclusions: Estimation of axis of malrotation and degrees of malrotation within 5 degrees in SCHFx can be predicted in 75% of our 3D printed models.

The purpose of this study was to quantify femoral head deformity in patients with Legg-Calvé-Perthes disease (LCPD) using a novel three dimensional (3D) magnetic resonance imaging (MRI) reconstruction and volume based analysis. Bilateral femoral heads of 17 patients (mean age 9.9 ± 2.0 years; 12 boys, 5 girls) with LCPD were scanned 1-2 times (n = 33 LCPD heads, 20 normal heads) using a 1.5T MRI scanner. Fourteen patients had unilateral and three had bilateral LCPD with five hips in the Waldenström initial stage, 9 in the fragmentation stage, 14 in the reossification stage, and 5 in the healed stage. 3D digital reconstructions of femoral heads were created using MIMICS software. Deformity was quantified using a 3D volume ratio method based on reference hemisphere volume as well as two surface geometry methods. Intra-observer analysis showed that 97% of the LCPD femoral heads were within 10% of the original value and test shapes had 99.6% accuracy. For normal femoral heads, the volume ratios of all except one were between 95 and 98% (n = 20) of a perfect hemisphere volume. For femoral heads affected with LCPD, the volume ratios ranged from 43% to 96% of a perfect hemisphere (n = 33). The volume ratio method and the two surface geometry comparison methods had high correlation (r = 0.89 and 0.96). In summary, the 3D MRI volume ratio method allowed accurate quantification and demonstrated small changes (<10%) of the femoral head deformity in LCPD. This method may serve as a useful tool to evaluate the effects of treatment on femoral head shape. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2051-2058, 2017.

These techniques may prove to be useful in the assessment of an acute disruption of the femoral head blood flow.