title: Single-limb drop landing biomechanics in active individuals with and without a history of anterior cruciate ligament reconstruction: A total support analysis.
abstract: BACKGROUND
  The purpose of this study was to characterize the magnitude and distribution of the total support moment during single-limb drop landings in individuals after anterior cruciate ligament reconstruction compared to a control group.
  
  
  METHODS
  Twenty participants after reconstruction and twenty control participants matched on sex, limb dominance and activity level were recruited. Motion analysis was performed during a single-limb drop landing task. Total support moment was determined by summing the internal extensor moments at the ankle, knee, and hip. Each relative joint contribution to the total support moment was calculated by dividing each individual contribution by the total support moment. Data were captured during a landing interval that started at initial contact and ended at the lowest vertical position of the pelvis. Data were then time-normalized and indexed at 25, 50, 75, and 100% of the landing interval.
  
  
  RESULTS
  No between-group differences for total support moment magnitude were observed. At both 75% and 100% of the landing, the relative contribution of the knee joint was lower in those with a history of surgery (p<0.001). At the same instances, the relative contribution to the total support moment by the hip joint was greater in those with a history of surgery (p=0.004).
  
  
  CONCLUSIONS
  In active participants after anterior cruciate ligament reconstruction, relative contributions to anti-gravity support of the center of mass shifted from the knee to the hip joint during single-limb landing, which became evident towards the end of the landing interval.
authors.affiliation: Division of Biokinesiology and Physical Therapy, University of Southern California, USA.
authors.forename: Federico
authors.initials: F
authors.lastname: Pozzi
authors.affiliation: Sports Medicine Research Institute, The Ohio State University Wexner Medical Center, Department of Orthopaedics, The Ohio State University, USA.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Di Stasi
authors.affiliation: Department of Physical Therapy, University of Delaware, USA.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Zeni
authors.affiliation: Department of Physical Therapy, University of Dayton, Raymond L. Fitz Hall, Room 209D, Dayton, OH, 45469-2925, USA. Electronic address: jbarrios1@udayton.edu.
authors.forename: Joaquin A
authors.initials: JA
authors.lastname: Barrios
mesh_terms: D000843:Ankle Joint / Q000502:physiology*; D000070598:Anterior Cruciate Ligament Injuries / Q000503:physiopathology* / Q000601:surgery; D059549:Anterior Cruciate Ligament Reconstruction; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D005260:Female; D006621:Hip Joint / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D059385:Plyometric Exercise; D013996:Time and Motion Studies; D055815:Young Adult
keywords: Hip; Knee; Total support moment