Automated femoral version estimation without the distal femur

Femoral version impacts the long-term functioning of the femoroacetabular joint. Accurate measurements of version are thus required for success in total hip arthroplasties and hip reconstructive surgeries. These are impossible to obtain without visualization of the distal femur, which is often unavailable preoperatively as the majority of imaging scans are isolated to the pelvis and proximal femur. We developed an automated algorithm for identifying the major landmarks of the femur. These landmarks were then used to identify proximal axes and create a statistical shape model of the proximal femur across 144 asymptomatic femora. With six proximal axes selected, and 200 parameters (distances and angles between points) from the shape model measured, the best-fitting linear correlation was found. The difference between true version and version predicted by this model was 0.00 ± 5.13° with a maximum overestimation and underestimation of 11.80 and 15.35°, respectively. The mean absolute difference was 4.14°. This model and its prediction of femoral version are a substantial improvement over pre-operative 2D or intra-operative visual estimation measures. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:3161-3168, 2018.

Normal multiplanar movement of the spinal cord during unilateral and bilateral straight leg raise: Quantification, mechanisms, and overview

The purpose of this investigation was to provide a full set of normal data describing neural biomechanics within the vertebral canal in all three planes with unilateral and bilateral SLR tests to allow for clinical comparison with clinical cases. This is done following the notion that, due to neural continuum, tensile forces are transmitted through the lumbosacral nerve roots and dura to the conus medullaris (linear dependency principle). In this controlled radiologic study 10 asymptomatic volunteers were scanned with 1.5T magnetic resonance scanner (Siemens Magnetom Aera, Erlangen, Germany) using different scanning sequences for planning and for measurement purposes. Conus displacement in both antero-posterior direction (sagittal slices) and lateral direction (axial slices) was quantified during unilateral passive left, right SLR, and bilateral SLR and compared with the position of the conus in the neutral (anatomic) position. It is shown that the conus medullaris displaced laterally and anteroposteriorly in response to unilateral and bilateral SLRs. Pearson's correlations were higher than 0.95 for both intra- and inter-observer reliability. The observed power was higher than 0.99 for all the variables tested. Following this, the authors conclude that lateral and antero-posterior displacement of conus medullaris into the vertebral canal occurs consistently with unilateral and bilateral SLRs following directions predicted by tension vectors. Summative information collected in this line of research in neuroradiology is here presented. We believe we have presented the first conclusive and complete full set of normal data on non-invasive, in vivo, normative measurement of spinal cord displacement with the SLR ever presented. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1335-1342, 2017.