title: Lack of consensus regarding pretensioning and preconditioning protocols for soft tissue graft reconstruction of the anterior cruciate ligament.
abstract: OBJECTIVE
  Pretensioning and preconditioning of soft tissue grafts are often performed to obviate graft stress relaxation and elongation due to viscoelastic graft properties following anterior cruciate ligament (ACL) reconstruction. It was hypothesized that a consensus could be identified in the current literature regarding the biomechanical effects and clinical benefits of an optimal protocol.
  
  
  METHODS
  A systematic electronic literature search was performed by two independent reviewers to identify relevant publications. Only studies describing and/or comparing pretensioning or preconditioning protocols of soft tissue grafts or equivalent animal research models were eligible for inclusion. Study design, graft type, and protocol, including method, magnitude, mode (cyclic and/or static loading), and duration of load application, were compared. Research results and clinical conclusions were also evaluated for each study.
  
  
  RESULTS
  Five studies, including four in vitro biomechanical investigations and one histological analysis of patient tissue, met the predefined criteria for inclusion. Studies described numerous pretensioning and/or preconditioning protocols with varying force, time, and application modalities for multiple soft tissue graft types and animal models. The majority of studies (80 %) utilized at least one pretensioning or preconditioning protocol between 80 and 89 N, while only one study investigated substantially higher loads (500 N).
  
  
  CONCLUSIONS
  Despite common trends demonstrating the effects of pretensioning and preconditioning, no clear consensus regarding an optimal protocol, magnitude, or modality could be identified within the currently available relevant literature. Further multidisciplinary research is required before an optimal or consensus protocol can be established for soft tissue ACL reconstruction. Regardless, the current biomechanical literature demonstrates the potential clinically beneficial effects of pretensioning and preconditioning, including reduced graft elongation and greater preservation of graft tension and stiffness following fixation.
  
  
  METHODS
  Systematic review, Level II.
authors.affiliation: Steadman Philippon Research Institute, 181 West Meadow Drive, Suite 1000, Vail, CO, 81657, USA.
authors.forename: Kyle A
authors.initials: KA
authors.lastname: Jisa
authors.affiliation: Steadman Philippon Research Institute, 181 West Meadow Drive, Suite 1000, Vail, CO, 81657, USA.
authors.forename: Brady T
authors.initials: BT
authors.lastname: Williams
authors.affiliation: Steadman Philippon Research Institute, 181 West Meadow Drive, Suite 1000, Vail, CO, 81657, USA.|The Steadman Clinic, 181 West Meadow Drive, Suite 400, Vail, CO, 81657, USA.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Jaglowski
authors.affiliation: Steadman Philippon Research Institute, 181 West Meadow Drive, Suite 1000, Vail, CO, 81657, USA.
authors.forename: Travis Lee
authors.initials: TL
authors.lastname: Turnbull
authors.affiliation: Steadman Philippon Research Institute, 181 West Meadow Drive, Suite 1000, Vail, CO, 81657, USA. drlaprade@sprivail.org.|The Steadman Clinic, 181 West Meadow Drive, Suite 400, Vail, CO, 81657, USA. drlaprade@sprivail.org.
authors.forename: Robert F
authors.initials: RF
authors.lastname: LaPrade
authors.affiliation: Steadman Philippon Research Institute, 181 West Meadow Drive, Suite 1000, Vail, CO, 81657, USA.
authors.forename: Coen A
authors.initials: CA
authors.lastname: Wijdicks
mesh_terms: D000818:Animals; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D000070598:Anterior Cruciate Ligament Injuries; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods*; D001696:Biomechanical Phenomena; D032921:Consensus; D006801:Humans; D007718:Knee Injuries / Q000601:surgery; D023421:Models, Animal; D000078202:Systematic Reviews as Topic; D013710:Tendons / Q000637:transplantation*; D019737:Transplants / Q000601:surgery*
keywords: Anterior cruciate ligament reconstruction; Hamstring graft; Preconditioning; Pretensioning; Soft tissue grafts; Systematic review