A radiographic analysis of the relationship between the size and shape of the intercondylar notch and anterior cruciate ligament injury

Notch-view radiographs were obtained from 108 persons with anterior cruciate ligament (ACL) injuries (55 women, 53 men) and 186 with intact ACL (94 women, 92 men). Notch width, femur width, and notch width index were determined from each of the 294 radiographs. The notch was also categorized as either A-shaped or non-A-shaped. Intrarater and interrater reliability ranged from 0.82 to 0.99 for notch width and femur width, respectively. Reliability within and between raters for the classification of notch shape ranged from 0.80 to 1.0. Notch width was significantly influenced by a 10 degrees change in knee angle when repeated radiographs were taken. Femur width was not affected by knee angle across this range. Analysis revealed a higher proportion of A-shaped notches among women than men. However, notch shape was not related to injury status. Results showed a smaller notch width and notch width index in ACL-injured patients regardless of notch shape or gender. A-shaped notches were smaller than non-A-shaped notches regardless of injury status or gender. Both notch width and notch width index were found to be significant indicators of ACL injury. Knowledge of the shape of the notch added no useful information in differentiating patients based on injury status. Thus, regardless of gender, individuals who possess smaller notch dimensions appear to be at greater risk of injury than individuals with larger notches.