Femoral intercondylar notch shape and dimensions in ACL-injured patients

The femoral intercondylar notch has been an anatomic site of interest as it houses the anterior cruciate ligament (ACL). The objective of this study was to arthroscopically evaluate the femoral notch in patients with known ACL injury. This evaluation included establishing a classification for notch shapes, identifying the shape frequency, measuring notch dimensions, and determining correlation between notch shape, notch dimensions, and demographic patient data. In this clinical cohort study, 102 consecutive patients underwent diagnostic arthroscopic evaluation of the notch. Several intra-operative photos, videos, and measurements were taken of the notch. Demographic data for each patient were recorded including age, gender, height, weight, and BMI. Three categories of notch shape were established: 1. A-shaped; 2. U-shaped; and 3. W-shaped. Two blinded independent orthopedic surgeons were asked to categorize the recorded notches. Notch shape, dimensions, and demographic factors were correlated. Of the 102 notches evaluated, 55 notches were found to be "A-shaped," 42 "U-shaped," and 5 "W-shaped." "A-shaped" notches were narrower in all width dimensions than "U-shaped" notches. Only patient height was found to influence notch shape with a positive association between taller patients and "U-shaped" and "W-shaped" notches (P = 0.011). Women had a smaller notch width at the base and middle of the notch. With this data, surgeons who enter the knee and appreciate an "A-shaped" notch should consider placing the arthroscope in the anteromedial portal and drill the femoral tunnel through an accessory medial portal to improve visualization and accuracy in anatomic femoral tunnel creation.