title: Effects of Prophylactic Knee Bracing on Lower Limb Kinematics, Kinetics, and Energetics During Double-Leg Drop Landing at 2 Heights.
abstract: Anterior cruciate ligament (ACL) injuries commonly occur during landing maneuvers. Prophylactic knee braces were introduced to reduce the risk of ACL injuries, but their effectiveness is debated.
  
  
  
  We hypothesized that bracing would improve biomechanical factors previously related to the risk of ACL injuries, such as increased hip and knee flexion angles at initial contact and at peak vertical ground-reaction force (GRF), increased ankle plantar flexion angles at initial contact, decreased peak GRFs, and decreased peak knee extension moment. We also hypothesized that bracing would increase the negative power and work of the hip joint and would decrease the negative power and work of the knee and ankle joints.
  
  
  
  Controlled laboratory study.
  
  
  
  Three-dimensional motion and force plate data were collected from 8 female and 7 male recreational athletes performing double-leg drop landings from 0.30 m and 0.60 m with and without a prophylactic knee brace. GRFs, joint angles, moments, power, and work were calculated for each athlete with and without a knee brace.
  
  
  
  Prophylactic knee bracing increased the hip flexion angle at peak GRF by 5.56° (P < .001), knee flexion angle at peak GRF by 4.75° (P = .001), and peak hip extension moment by 0.44 N·m/kg (P < .001). Bracing also increased the peak hip negative power by 4.89 W/kg (P = .002) and hip negative work by 0.14 J/kg (P = .001) but did not result in significant differences in the energetics of the knee and ankle. No differences in peak GRFs and peak knee extension moment were observed with bracing.
  
  
  
  The application of a prophylactic knee brace resulted in improvements in important biomechanical factors associated with the risk of ACL injuries.
  
  
  
  Prophylactic knee braces may help reduce the risk of noncontact knee injuries in recreational and professional athletes while playing sports. Further studies should investigate different types of prophylactic knee braces in conjunction with existing training interventions so that the sports medicine community can better assess the effectiveness of prophylactic knee bracing.
authors.affiliation: Department of Mechanical Engineering, Melbourne School of Engineering, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Katie A
authors.initials: KA
authors.lastname: Ewing
authors.affiliation: Gait, Balance & Falls Research Group, Institute of Sport, Exercise and Active Living, Victoria University, Footscray, Victoria, Australia.
authors.forename: Rezaul K
authors.initials: RK
authors.lastname: Begg
authors.affiliation: Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Mary P
authors.initials: MP
authors.lastname: Galea
authors.affiliation: Department of Mechanical Engineering, Melbourne School of Engineering, The University of Melbourne, Parkville, Victoria, Australia pvlee@unimelb.edu.au.
authors.forename: Peter V S
authors.initials: PV
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D000070598:Anterior Cruciate Ligament Injuries / Q000517:prevention & control*; D001696:Biomechanical Phenomena; D001915:Braces; D005260:Female; D005528:Foot / Q000502:physiology; D006615:Hip / Q000502:physiology; D006801:Humans; D007717:Knee / Q000502:physiology; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D059385:Plyometric Exercise; D016059:Range of Motion, Articular; D055815:Young Adult
keywords: anterior cruciate ligament (ACL) injury; injury prevention; knee bracing; landing biomechanics