title: MRI measurement of the 2 bundles of the normal anterior cruciate ligament.
abstract: Anatomical studies have shown that the normal anterior cruciate ligament (ACL) consists of 2 distinct functional bundles: the anteromedial and posterolateral bundles. To date, no study has assessed the magnetic resonance imaging (MRI) appearance of the anteromedial and posterolateral bundles. The purpose of this study was to measure the anteromedial and posterolateral bundles using high-field digital MRI. Fifty MRIs of the knees of 50 patients were prospectively collected using a 1.5-T magnet. The length and width of each ACL bundle was measured on sagittal and coronal digital MRIs, independently performed by 2 observers blinded to each other's measurements. The average length and width of the anteromedial and posterolateral bundles were determined for all patients. Intraclass correlation coefficients were calculated to determine intertester test-retest reliability. In the sagittal plane, the anteromedial bundle averaged 36.9+/-2.8 mm in length and 5.1+/-0.7 mm in width. The posterolateral bundle, by contrast, averaged 20.5+/-2.4 mm in length and 4.4+/-0.8 mm in width. In the coronal plane, the width of the anteromedial bundle averaged 4.2+/-0.8 mm and of the posterolateral bundle averaged 3.7+/-0.8 mm. Interobserver reliability for length of the ACL in the sagittal plane was 0.85, with a 95% CI of 0.75 to 0.91 for the anteromedial bundle and 0.75 with a 95% CI of 0.60 to 0.85 for the posterolateral bundle. Providing precise measurement of the ACL anteromedial and posterolateral bundles on MRI may improve the ability to detect damage to 1 or both of the bundles following injury.
authors.affiliation: Rothman Institute Orthopaedics and Department of Orthopedic Surgery, Thomas Jefferson University, 925 Chestnut Street, Philadelphia, PA 19107, USA.
authors.forename: Steven B
authors.initials: SB
authors.lastname: Cohen
authors.forename: Corinne
authors.initials: C
authors.lastname: VanBeek
authors.forename: James S
authors.initials: JS
authors.lastname: Starman
authors.forename: Derek
authors.initials: D
authors.lastname: Armfield
authors.forename: James J
authors.initials: JJ
authors.lastname: Irrgang
authors.forename: Freddie H
authors.initials: FH
authors.lastname: Fu
mesh_terms: D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult