title: Therapeutic advantage in selective ligament augmentation for partial tears of the anterior cruciate ligament: results in an animal model.
abstract: BACKGROUND
  As a result of recent studies describing the double-bundle anterior cruciate ligament (ACL), selected ACL augmentation procedures, either anteromedial (AM) or posterolateral (PL), have been introduced as the treatment of choice for partial ACL ruptures. The preserved mechanoreceptor and vascularity of the remnant ACL are considered to provide additional biological benefits. Although enhanced knee joint proprioception in ACL augmented patients has been previously reported, there is no study assessing biological healing advantages of the graft after the ACL augmentation procedure.
  
  
  OBJECTIVE
  Selected ACL augmentation for partial tears can accelerate the healing process of the grafted tendon, which promotes better biomechanical recovery of the tendon, compared with conventional ACL reconstruction of complete tears.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Two rat models were established in this study: an ACL augmentation partial tear model and conventional ACL reconstruction for a complete tear. Biological assessments of cellularity and angiogenesis were measured by hematoxylin and eosin staining and immunostaining, respectively. Additionally, rat-specific type III collagen and α-smooth muscle actin were evaluated by immunohistochemical staining to analyze the healing process, whereas anti-rat neurofilament antigen was assessed to examine proprioceptive recovery. Biological assessments of the augmented and reconstructed grafts were conducted postoperatively at week 2, whereas biomechanical testing was performed postoperatively at week 8.
  
  
  RESULTS
  An increase in cellularity and angiogenesis was observed in the augmented grafts compared with the conventionally reconstructed grafts. Also, increased amounts of rat-specific type III collagen, α-smooth muscle actin, and anti-rat neurofilament antigen were expressed in the augmented grafts. Biomechanical testing showed that failure to load was significantly higher in the augmentation group compared with the conventional reconstruction group (augmentation, 15.9 ± 1.0; reconstruction, 7.0 ± 1.3; P < .01).
  
  
  CONCLUSIONS
  Selected ACL augmentation could be a good choice for the repair of partial ACL injury by preserving the uninjured portion of the ACL, which in turn could maintain the anatomic position of the ligament and its biomechanical function.
authors.affiliation: Stem Cell Research Center, Department of Orthopaedic Surgery, University of Pittsburgh, School of Medicine, 450 Technology Drive, 2 Bridgeside Point, Suite 206, Pittsburgh, PA 15219, USA.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Mifune
authors.forename: Shusuke
authors.initials: S
authors.lastname: Ota
authors.forename: Koji
authors.initials: K
authors.lastname: Takayama
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Hoshino
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Kuroda
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kurosaka
authors.forename: Freddie H
authors.initials: FH
authors.lastname: Fu
authors.forename: Johnny
authors.initials: J
authors.lastname: Huard
mesh_terms: D000818:Animals; D016118:Anterior Cruciate Ligament / Q000503:physiopathology / Q000601:surgery*; D000070598:Anterior Cruciate Ligament Injuries; D059549:Anterior Cruciate Ligament Reconstruction; D015415:Biomarkers / Q000032:analysis; D001696:Biomechanical Phenomena; D004195:Disease Models, Animal; D005260:Female; D051381:Rats; D017207:Rats, Sprague-Dawley; D013710:Tendons / Q000503:physiopathology / Q000637:transplantation*; D014945:Wound Healing
chemical_list: D015415:Biomarkers