Sensitivity of femoral orientation estimates to condylar surface and MR image plane location

Abstract

Purpose: To define the femoral anatomic region that provides the most reliable reference for measuring femoral orientation, from which patellofemoral and tibiofemoral orientation can be measured. Materials and Methods:After a three-dimensional imagebased osteo-alignment procedure, two independent estimates of distal femoral orientation, the anterior (AFA) and posterior femoral angles (PFA), were acquired. These sets were comprised of 31 axial femoral orientation estimates each (obtained across a region 10 mm above to 20 mm below the patellar center) from 42 normal axial magnetic resonance (MR) image sets. An analysis of variance was conducted to determine the influence of image plane location, sex, and side on femoral orientation measures. Results:The AFA presented greater variability across subjects (average SD ϭ 3.13°) as compared to the PFA (average SD ϭ 1.78°). There were significant differences in the AFA based on image plane location and sex. In contrast, no differences were found between sides, sexes, or image plane locations for the PFA. Conclusion:In total, the posterior femoral condylar surface is more reliable than the anterior condylar surface for measuring femoral orientation and is best measured at least 8 mm below the patellar center.

Three-dimensional humeral morphologic alterations and atrophy associated with obstetrical brachial plexus palsy

“…Thus, the Z-axis (superior) approximately aligned with the medulary axis. This alignment procedure minimized errors associated with visually aligning the humeri 39 and eliminated the dependency between the final measures and the image plane location/orientation 7; 16; 17; 42 . The anatomic planes were defined based on this alignment (Figure 1).…”

“…The analysis was based on the quantification of the complete bone surface, making the final measures insensitive to image plane orientation and location. This would not be the case if the measures were acquired in a single 2D slice 7; 16; 17; 42 .…”

“…Cadaver studies 14; 15; 17; 22; 25; 39 have the advantage of direct investigation of the 3D bone surfaces, which cannot be performed in living subjects. The 2D measures acquired using X-rays, computed tomography (CT), or magnetic resonance (MR) imaging 6; 8; 13; 16; 19; 46 can be severely affected by the location and orientation of the imaging plane relative to the anatomy studied 7; 16; 17; 42 . Lastly, ultrasound (US) 52–55 is non-ionizing, portable, and less expensive than MR or CT.…”

The finite helical axis of the knee joint (a non-invasive in vivo study using fast-PC MRI)

“…The entire movement cycle was used for the integration process, but all further analysis and data presentation was limited to the extension portion of the movement. The initial bone orientation was calculated using anatomically based coordinate systems (Sheehan et al, 1999;Shibanuma et al, 2004), which were identified in a single time frame only (Fig. 1).…”

Three-dimensional In Vivo Quantification of Knee Kinematics in Cerebral Palsy

“…The initial bone orientation was calculated using anatomically based coordinate systems [24,29], which were identified in one time frame only (maximum extension). Using matrix multiplication, the attitude of all three bones throughout the movement was defined relative to these anatomic coordinate systems (Fig.…”