title: Medio-lateral knee fluency in anterior cruciate ligament-injured athletes during dynamic movement trials.
abstract: BACKGROUND
  Correction of neuromuscular impairments after anterior cruciate ligament injury is vital to successful return to sport. Frontal plane knee control during landing is a common measure of lower-extremity neuromuscular control and asymmetries in neuromuscular control of the knee can predispose injured athletes to additional injury and associated morbidities. Therefore, this study investigated the effects of anterior cruciate ligament injury on knee biomechanics during landing.
  
  
  METHODS
  Two-dimensional frontal plane video of single leg drop, cross over drop, and drop vertical jump dynamic movement trials was analyzed for twenty injured and reconstructed athletes. The position of the knee joint center was tracked in ImageJ software for 500 milliseconds after landing to calculate medio-lateral knee motion velocities and determine normal fluency, the number of times per second knee velocity changed direction. The inverse of this calculation, analytical fluency, was used to associate larger numerical values with fluent movement.
  
  
  RESULTS
  Analytical fluency was decreased in involved limbs for single leg drop trials (P=0.0018). Importantly, analytical fluency for single leg drop differed compared to cross over drop trials for involved (P<0.001), but not uninvolved limbs (P=0.5029). For involved limbs, analytical fluency values exhibited a stepwise trend in relative magnitudes.
  
  
  CONCLUSIONS
  Decreased analytical fluency in involved limbs is consistent with previous studies. Fluency asymmetries observed during single leg drop tasks may be indicative of abhorrent landing strategies in the involved limb. Analytical fluency differences in unilateral tasks for injured limbs may represent neuromuscular impairment as a result of injury.
authors.affiliation: Department of Biomedical Engineering, Columbus, OH, USA, 43210.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Panos
authors.affiliation: Sports Health and Performance Institute (SHPI) OSU Sports Medicine, Columbus, OH, USA, 43210.
authors.forename: Joshua T
authors.initials: JT
authors.lastname: Hoffman
authors.affiliation: Sports Health and Performance Institute (SHPI) OSU Sports Medicine, Columbus, OH, USA, 43210.
authors.forename: Samuel C
authors.initials: SC
authors.lastname: Wordeman
authors.affiliation: Department of Biomedical Engineering, Columbus, OH, USA, 43210; Sports Health and Performance Institute (SHPI) OSU Sports Medicine, Columbus, OH, USA, 43210; The Ohio State University, Columbus, OH, USA, 43210; Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA, 44905; Departments of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA, 44905; Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, MN, USA, 44905.
authors.forename: Timothy E
authors.initials: TE
authors.lastname: Hewett
mesh_terms: D016118:Anterior Cruciate Ligament / Q000601:surgery; D000070598:Anterior Cruciate Ligament Injuries; D059549:Anterior Cruciate Ligament Reconstruction; D001265:Athletic Injuries / Q000503:physiopathology* / Q000601:surgery; D001696:Biomechanical Phenomena; D015444:Exercise / Q000502:physiology; D005260:Female; D006801:Humans; D007717:Knee / Q000503:physiopathology*; D008297:Male; D009068:Movement; D013647:Task Performance and Analysis; D055815:Young Adult
keywords: ACL injury prevention; Anterior cruciate ligament (ACL) injury; dynamic landing knee kinematics; frontal plane knee biomechanics; knee fluency