title: Does fibrin clot really enhance graft healing after double-bundle ACL reconstruction in a caprine model?
abstract: OBJECTIVE
  Graft healing following anterior cruciate ligament (ACL) reconstruction is a complex process characterized by phases of healing that lead to ACL remodelling. Our hypothesis is that fibrin clot addition to ACL reconstruction will result in advanced graft remodelling and healing when compared to a control group at 12 weeks as observed by histology, immunohistochemistry and magnetic resonance imaging (MRI).
  
  
  METHODS
  Eleven Spanish Boar goats underwent double-bundle ACL reconstruction: 8 were analysed and 3 were excluded. Group 1 was treated with DB ACL reconstruction utilizing autologous fibrin clots (n = 4), and group 2 was treated with standard DB ACL-R (n = 4). Histological and radiographic analysis was performed at 12 weeks. Each animal underwent 3-T MRI immediately after euthanization for evaluation of graft signal intensity utilizing the signal noise quotient (SNQ). Specimens were then sectioned and stored for standard histological and immunohistochemistry testing.
  
  
  RESULTS
  The mean ligament tissue maturity index score was significantly higher for group 1 (15 ± 2.3) compared with group 2 (7.7 ± 5.2) (p < 0.05). The mean vascularity (cell/mm(2)) for group 1 was 7.1 ± 1.3 and 9.3 ± 3.1 for group 2 (n.s.). The mean collagen type 1 (% 50× field) for group 1 was 35.8 ± 22.1 and 19.9 ± 20.5 for group 2 (n.s.). The mean SNQ for the AM bundle was 1.1 ± 0.7 for group 1 and 3.1 ± 1.8 for group 2 (n.s.). The mean SNQ for the total PL bundle was significantly lower for group 1 (1.1 ± 0.7) compared with group 2 (3.7 ± 1.3) (p < 0.05). There was a significant correlation between the vascularity and the ligament tissue maturity index score as well as between collagen type 1 and SNQ, both AM and PL bundles (p < 0.05).
  
  
  CONCLUSIONS
  The use of fibrin clot in ACL reconstruction in a caprine model demonstrated improved healing with respect to histological analysis of the intra-articular ACL reconstruction segment and decreased signal intensity on MRI. It may lead to improved graft healing and maturation. By accelerating the intra-articular healing and ligamentization, the outcome of patients after ACL-R can be improved with faster return to sports and daily activity.
authors.affiliation: Department of Orthopaedic Surgery, University of Pittsburgh, 3471 Fifth Avenue, Pittsburgh, PA, 15213, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Hensler
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Illingworth
authors.forename: Volker
authors.initials: V
authors.lastname: Musahl
authors.forename: Zachary M
authors.initials: ZM
authors.lastname: Working
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Motoko
authors.initials: M
authors.lastname: Miyawaki
authors.forename: Stephan
authors.initials: S
authors.lastname: Lorenz
authors.forename: Michelle
authors.initials: M
authors.lastname: Witt
authors.forename: James J
authors.initials: JJ
authors.lastname: Irrgang
authors.forename: Johnny
authors.initials: J
authors.lastname: Huard
authors.forename: Freddie H
authors.initials: FH
authors.lastname: Fu
mesh_terms: D000125:Achilles Tendon / Q000637:transplantation*; D000818:Animals; D016118:Anterior Cruciate Ligament / Q000378:metabolism / Q000473:pathology / Q000601:surgery*; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods*; D015415:Biomarkers / Q000378:metabolism; D005260:Female; D005337:Fibrin / Q000627:therapeutic use*; D006041:Goats; D008279:Magnetic Resonance Imaging; D014945:Wound Healing
chemical_list: D015415:Biomarkers; D005337:Fibrin