title: Histological analysis of the tibial anterior cruciate ligament insertion.
abstract: OBJECTIVE
  This study was performed to investigate the morphology of the tibial anterior cruciate ligament (ACL) by histological assessment.
  
  
  METHODS
  The native (undissected) tibial ACL insertion of six fresh-frozen cadaveric knees was cut into four sagittal sections parallel to the long axis of the medial tibial spine. For histological evaluation, the slices were stained with haematoxylin and eosin, Safranin O and Russell-Movat pentachrome. All slices were digitalized and analysed at a magnification of 20×.
  
  
  RESULTS
  The anterior tibial ACL insertion was bordered by a bony anterior ridge. The most medial ACL fibres inserted from the medial tibial spine and were adjacent to the articular cartilage of the medial tibial plateau. Parts of the bony insertions of the anterior and posterior horns of the lateral meniscus were in close contact with the lateral part of the tibial ACL insertion. A small fat pad was located just posterior to the functional ACL fibres. The anterior-posterior length of the medial ACL insertion was an average of 10.8 ± 1.1 mm compared with the lateral, which was only 6.2 ± 1.1 mm (p < 0.001). There were no central or posterolateral inserting ACL fibres.
  
  
  CONCLUSIONS
  The shape of the bony tibial ACL insertion was 'duck-foot-like'. In contrast to previous findings, the functional mid-substance fibres arose from the most posterior part of the 'duck-foot' in a flat and 'c-shaped' way. The most anterior part of the tibial ACL insertion was bordered by a bony anterior ridge and the most medial by the medial tibial spine. No posterolateral fibres nor ACL bundles have been found histologically. This histological investigation may improve our understanding of the tibial ACL insertion and may provide important information for anatomical ACL reconstruction.
authors.affiliation: HKF - Center for Hip-Knee-Foot Surgery, ATOS Clinic, Bismarckstr. 9-15, 69115, Heidelberg, Germany.|Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Oka
authors.affiliation: HKF - Center for Hip-Knee-Foot Surgery, ATOS Clinic, Bismarckstr. 9-15, 69115, Heidelberg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Schuhmacher
authors.affiliation: Institute for Anatomy, Lehrstuhl I, Friedrich-Alexander-University Erlangen, Nuremberg, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Brehmer
authors.affiliation: Institute for Anatomy and Cell Biology, Ruprecht-Karls University, INF, Heidelberg, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Traut
authors.affiliation: Institute for Anatomy and Cell Biology, Ruprecht-Karls University, INF, Heidelberg, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Kirsch
authors.affiliation: HKF - Center for Hip-Knee-Foot Surgery, ATOS Clinic, Bismarckstr. 9-15, 69115, Heidelberg, Germany. rainer.siebold@atos.de.|Institute for Anatomy, Lehrstuhl I, Friedrich-Alexander-University Erlangen, Nuremberg, Germany. rainer.siebold@atos.de.
authors.forename: Rainer
authors.initials: R
authors.lastname: Siebold
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology; D000368:Aged; D016118:Anterior Cruciate Ligament / Q000033:anatomy & histology*; D002102:Cadaver; D002358:Cartilage, Articular / Q000033:anatomy & histology; D004838:Epiphyses / Q000033:anatomy & histology; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000033:anatomy & histology*; D008297:Male; D008592:Menisci, Tibial / Q000033:anatomy & histology; D008875:Middle Aged; D013194:Staining and Labeling; D013977:Tibia / Q000033:anatomy & histology
keywords: ACL; Anterior ridge; Duck-foot; Flat; Functional fibres; Histology; Posteromedial; Tibial insertion; c-shape