title: MRI evaluation of the four tunnels of double-bundle ACL reconstruction.
abstract: BACKGROUND
  The double-bundle (DB) reconstruction of the anterior cruciate ligament (ACL) has gained popularity in recent years. The positioning of anteromedial (AM) and posterolateral (PL) tunnels is aimed at the anatomic femoral and tibial attachments of AM and PL bundles of the native ACL.
  
  
  OBJECTIVE
  To use magnetic resonance imaging (MRI) to evaluate the tunnel locations and tunnel findings in DB ACL reconstruction.
  
  
  METHODS
  Sixty-six patients with DB ACL reconstruction were evaluated with 1.5-T MRI 2 years postoperatively. Two musculoskeletal radiologists separately measured the locations and the diameters of the tunnels. Inter-observer agreements were estimated according to the method of Bland and Altman.
  
  
  RESULTS
  In the femur, the mean AM tunnel location was 32% from the proximal condylar surface and 18% from the notch roof. The mean PL tunnel location was 42% and 43%, respectively. In the tibia, the mean AM tunnel location was 54% of the lateral-to-medial tibial width and 42% of the anterior-to-posterior tibial depth. The mean PL tunnel location was 54% and 56%, respectively. The mean tunnel enlargement was 3.8 mm (56%). Tunnel communication was seen in seven patients (11%) in the femur and in 19 patients (29%) in the tibia. Greater femoral AM tunnel distance from the proximal condylar surface was associated with more tunnel enlargement, and more posterior tibial PL tunnel location was associated with less tunnel enlargement.
  
  
  CONCLUSIONS
  The tunnel locations of DB ACL reconstruction can be evaluated with MRI. Tunnel location was associated with tunnel enlargement that in turn was associated with tunnel communication.
authors.affiliation: Medical Imaging Centre, Tampere University Hospital, Tampere, Finland tommi.kiekara@pshp.fi.
authors.forename: Tommi
authors.initials: T
authors.lastname: Kiekara
authors.affiliation: Sports Clinic and Hospital Mehiläinen, Tampere, Finland.
authors.forename: Timo
authors.initials: T
authors.lastname: Järvelä
authors.affiliation: School of Health Sciences, University of Tampere, Tampere, Finland.
authors.forename: Heini
authors.initials: H
authors.lastname: Huhtala
authors.affiliation: Medical Imaging Centre, Tampere University Hospital, Tampere, Finland.
authors.forename: Antti
authors.initials: A
authors.lastname: Paakkala
mesh_terms: D000328:Adult; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods*; D005260:Female; D005269:Femur / Q000033:anatomy & histology; D006801:Humans; D007719:Knee Joint / Q000033:anatomy & histology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010027:Osteotomy / Q000379:methods*; D013977:Tibia / Q000033:anatomy & histology; D016896:Treatment Outcome
keywords: MRI; anterior cruciate ligament; double-bundle reconstruction; tunnel enlargement; tunnel location