Abstract
Though controversial, the “clock face view” of the intercondylar notch remains a way
some surgeons communicate regarding placement of the femoral tunnel in anterior cruciate
ligament reconstruction. The purpose of this study was to quantify the differences
in angle measurement between several previous descriptions of the clock face view
by using a new reference standard. Three-Tesla magnetic resonance imaging (MRI) was
used to scan 10 human knees to create three-dimensional MRI-based bony models which
were used for measurements. A standardized clock face view was developed with the
knee flexed to 90° using the junction of the cartilage and cortex of the medial and
lateral surfaces of medial and lateral femoral condyles as the 3 o'clock and 9 o'clock,
respectively, with the 12 o'clock established as the midpoint of the roof of the intercondylar
notch. With the knee viewed at 90° of flexion, an “idealized” femoral tunnel position
was plotted on the medial wall of the lateral femoral condyle at 30° (corresponding
to the 10 o'clock or 2 o'clock position). The clock faces as described by Edwards
et al, Heming et al, and Mochizuki et al were each then overlaid on this same model
and the difference in measurement calculated. The average angles measured when the
previously described clock faces were projected onto the idealized clock face view
comparing a mark made at 30° were 47.7°, 7.2°, and 49.8° for the methods described
by Edwards et al, Heming et al, and Mochizuki et al, respectively (all p < 0.001). Significant variation exists between angle measurements in simulated femoral
tunnel placement based on the varying descriptions of the intercondylar clock face.
Keywords
anatomy - anterior cruciate ligament reconstruction - clock face view - magnetic resonance
imaging
