title: The effect of skeletal maturity on functional healing of the anterior cruciate ligament.
abstract: BACKGROUND
  The effects of skeletal maturity on functional ligament healing are unknown. Prior studies have suggested that ligament injuries in skeletally mature animals heal with improved mechanical properties. In this study, we hypothesized that skeletally immature animals have improved functional healing compared with skeletally mature animals.
  
  
  METHODS
  Twenty-one Yucatan minipigs (eight juvenile, eight adolescent, and five adult animals) underwent bilateral anterior cruciate ligament transection. On one side, the ligament injury was left untreated to determine the intrinsic healing response as a function of age. On the contralateral side, an enhanced suture repair incorporating a collagen-platelet composite was performed. Biomechanical properties of the repairs were measured after fifteen weeks of healing, and histologic analysis was performed.
  
  
  RESULTS
  Anterior cruciate ligaments from skeletally immature animals had significantly improved structural properties over those of adult animals at three months after transection in both the untreated and repair groups. Use of the enhanced suture technique provided the most improvement in the adolescent group, in which an increase of 85% in maximum load was noted with repair. The repair tissue in the adult tissue had the highest degree of hypercellularity at the fifteen-week time point.
  
  
  CONCLUSIONS
  Functional ligament healing depends on the level of skeletal maturity of the animal, with immature animals having a more productive healing response than mature animals.
authors.affiliation: Department of Orthopaedic Surgery, Children's Hospital Boston, Hunnewell 2, 300 Longwood Avenue, Boston, MA 02115, USA. martha.murray@childrens.harvard.edu
authors.forename: Martha M
authors.initials: MM
authors.lastname: Murray
authors.forename: Elise M
authors.initials: EM
authors.lastname: Magarian
authors.forename: Sophia L
authors.initials: SL
authors.lastname: Harrison
authors.forename: Ashley N
authors.initials: AN
authors.lastname: Mastrangelo
authors.forename: David
authors.initials: D
authors.lastname: Zurakowski
authors.forename: Braden C
authors.initials: BC
authors.lastname: Fleming
mesh_terms: D000367:Age Factors; D000818:Animals; D016118:Anterior Cruciate Ligament / Q000601:surgery; D000070598:Anterior Cruciate Ligament Injuries; D001696:Biomechanical Phenomena; D001846:Bone Development; D004195:Disease Models, Animal; D019651:Plastic Surgery Procedures; D013552:Swine; D013556:Swine, Miniature; D014945:Wound Healing
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