Summary

We successfully determined injury rate of a) the anterolateral ligament (ALL) and b) the deep portions of the iliotibial tract (ITT) in pediatric patients with anterior cruciate ligament (ACL) ruptures via MRI and calculated inter- and intraobserver agreement.

Abstract

Purpose

Due to a lack of evidence it was the aim of the study to investigate injury rate of a) the anterolateral ligament (ALL) and b) the deep portions of the iliotibial tract (ITT) in pediatric patients with anterior cruciate ligament (ACL) ruptures via MRI and to calculate inter- and intraobserver agreement. It was hypothesized to find Cohen's Kappa values for intra- and interobserver reproducibility above 0.7 indicating substantial agreement between the ratings.

Methods

Knee MRI data from pediatric patients with ACL ruptures were analyzed by two musculoskeletal radiologists separately and twice. The analysis was performed as suggested by Claes et al. for ALL injury. An ALL lesion was diagnosed in case of discontinued fibers, irregular structure of the ALL or presence of intra- or peri-ligamentous edema. It was also classified whether the rupture was proximal (above meniscus level), distal (below meniscus level) or a tibial avulsion (Segond type). The same criteria were applied to the deep portions of the ITT. It was classified whether the lesion was a) proximal at the deep attachments of the ITT to the distal femur (Kaplan fibres) or b) at the capsulo-osseous layer of the ITT.

Results

25 patients (15 male, 10 female, age 14.2) were included. The proximal part of the ALL was determined ruptured in 20%. The distal part of the ALL had an injury rate of 16%. In one of the cases (4%) there was a segond lesion. The deep attachments of the ITT to the distal femur (Kaplan fibres) were found injured in 16%. The capsulo-osseous layer of the ITT was determined 'not visible' in 100% of the knees.
The inter- and intraobserver agreements were above 92% and 84% respectively (kappa values 0.756 - 1.0 and 0.519 - 1.0, respectively). Our hypothesis to find substantial agreement (kappa > 0.7) was found confirmed for all situations except intra-observer reproducibility for the distal part of the ALL (kappa 0.519).

Conclusions

The injury rate of the anterolateral extra-articular structures (ALL and deep portions of the ITT) in pediatric patients with ACL rupture could be determined with substantial inter- and intraobserver agreement with MRI (sole exception: intra-observer reproducibility for the distal part of the ALL)