title: Increased platelet concentration does not improve functional graft healing in bio-enhanced ACL reconstruction.
abstract: OBJECTIVE
  The use of an extracellular matrix scaffold (ECM) combined with platelets to enhance healing of an anterior cruciate ligament (ACL) graft ("bio-enhanced ACL reconstruction") has shown promise in animal models. However, the effects of platelet concentration on graft healing remain unknown. The objectives of this study were to determine whether increasing the platelet concentration in the ECM scaffold would (1) improve the graft biomechanical properties and (2) decrease cartilage damage after surgery.
  
  
  METHODS
  Fifty-five adolescent minipigs were randomized to five treatment groups: untreated ACL transection (n = 10), conventional ACL reconstruction (n = 15) and bio-enhanced ACL reconstruction using 1× (n = 10), 3× (n = 10) or 5× (n = 10) platelet-rich plasma. The graft biomechanical properties, anteroposterior (AP) knee laxity, graft histology and macroscopic cartilage integrity were measured at 15 weeks.
  
  
  RESULTS
  The mean linear stiffness of the bio-enhanced ACL reconstruction procedure using the 1× preparation was significantly greater than traditional reconstruction, while the 3× and 5× preparations were not. The failure loads of all the ACL-reconstructed groups were equivalent but significantly greater than untreated ACL transection. There were no significant differences in the Ligament Maturity Index or AP laxity between reconstructed knees. Macroscopic cartilage damage was relatively minor, though significantly less when the ECM-platelet composite was used.
  
  
  CONCLUSIONS
  Only the 1× platelet concentration improved healing over traditional ACL reconstruction. Increasing the platelet concentration from 1× to 5× in the ECM scaffold did not further improve the graft mechanical properties. The use of an ECM-platelet composite decreased the amount of cartilage damage seen after ACL surgery.
authors.affiliation: Department of Orthopaedics, Warren Alpert Medical School of Brown University, Providence, RI, USA, Braden_Fleming@brown.edu.
authors.forename: Braden C
authors.initials: BC
authors.lastname: Fleming
authors.forename: Benedikt L
authors.initials: BL
authors.lastname: Proffen
authors.forename: Patrick
authors.initials: P
authors.lastname: Vavken
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Shalvoy
authors.forename: Jason T
authors.initials: JT
authors.lastname: Machan
authors.forename: Martha M
authors.initials: MM
authors.lastname: Murray
mesh_terms: D000818:Animals; D016118:Anterior Cruciate Ligament / Q000601:surgery; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods*; D001696:Biomechanical Phenomena; D001792:Blood Platelets / Q000166:cytology* / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000378:metabolism / Q000503:physiopathology / Q000601:surgery*; D007719:Knee Joint / Q000503:physiopathology / Q000601:surgery*; D013552:Swine; D013556:Swine, Miniature; D054457:Tissue Scaffolds; D014945:Wound Healing / Q000502:physiology*