title: Collagen-platelet composites improve the biomechanical properties of healing anterior cruciate ligament grafts in a porcine model.
abstract: BACKGROUND
  The outcome of anterior cruciate ligament (ACL) reconstruction is variable, and many patients have increased joint laxity postoperatively.
  
  
  OBJECTIVE
  Placement of a collagen-platelet composite (CPC) around the graft at the time of ACL reconstruction decreases postoperative knee laxity and improves the structural properties of the graft compared with standard ACL reconstruction.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Thirteen immature pigs underwent unilateral ACL reconstruction with a bone-patellar tendon-bone allograft. In 6 pigs, a standard allograft was used to reconstruct the ACL. In 7 pigs, a CPC was placed around the allograft. After 15 weeks of healing, the animals were euthanized, and the anterior-posterior (AP) knee laxity and structural properties of the graft were measured. Qualitative histology of the grafts was also performed.
  
  
  RESULTS
  The AP laxity values of the reconstructed knees, normalized to the contralateral control, were significantly reduced by 28% and 57% at 60 degrees and 90 degrees of knee flexion, respectively, with the addition of CPC (P < .001). Significant improvements in the graft structural properties were also found; the normalized yield (P = .044) and maximum failure loads (P = .025) of the CPC group were 60% higher than the standard ACL-reconstructed group. Although cellular and vessel infiltration were observed in the grafts of both groups, regions of necrosis were present only in the standard ACL-reconstructed group.
  
  
  CONCLUSIONS
  These data demonstrate that the application of CPC at the time of ACL reconstruction improves the structural properties of the graft and reduces early AP knee laxity in the porcine model after 15 weeks of healing.
  
  
  CONCLUSIONS
  Application of a CPC to an ACL graft at the time of surgery decreased knee laxity and increased the structural properties of the graft after 15 weeks of healing.
authors.affiliation: Department of Orthopaedics, Warren Alpert Medical School, Brown University, Providence, Rhode Island, USA.
authors.forename: Braden C
authors.initials: BC
authors.lastname: Fleming
authors.forename: Kurt P
authors.initials: KP
authors.lastname: Spindler
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Palmer
authors.forename: Elise M
authors.initials: EM
authors.lastname: Magarian
authors.forename: Martha M
authors.initials: MM
authors.lastname: Murray