title: Do ground reaction forces during unilateral and bilateral movements exhibit compensation strategies following ACL reconstruction?
abstract: OBJECTIVE
  The aims of the study were (1) to evaluate the leg asymmetry assessed with ground reaction forces (GRFs) during unilateral and bilateral movements of different knee loads in anterior cruciate ligament (ACL) reconstructed patients and (2) to investigate differences in leg asymmetry depending on the International Knee Documentation Committee Subjective Form (IKDC) in order to identify potential compensation strategies.
  
  
  METHODS
  The knee function of 50 ACL reconstructed (patella tendon) patients was examined at 31 ± 7 months after the surgery. GRFs were quantified during the sit-to-stand and stand-to-sit test, the step-up and step-down test, and the two- and one-leg vertical jump. Further, the IKDC score, the anterior-posterior knee laxity, and the concentric torque of the quadriceps and hamstring muscles were evaluated.
  
  
  RESULTS
  Differences between the operated and non-operated leg were found in the knee laxity, the quadriceps torque, and GRFs. The patients with low IKDC scores demonstrated greater leg asymmetries in GRFs compared to the patients with high IKDC scores.
  
  
  CONCLUSIONS
  ACL reconstructed patients showed GRF asymmetries during unilateral and bilateral movements of different knee loads. Three compensation strategies were found in patients with low subjective knee function: (1) a reduced eccentric load, (2) an inter-limb compensation during bilateral movements, and (3) the avoidance of high vertical impact forces. These compensation strategies may be indicative of a protective adaptation to avoid excessive ACL strain. GRF measurements are practicable and efficient tools to identify individual compensation strategies during early rehabilitation.
authors.affiliation: Department of Movement and Training Science, University of Wuppertal, Fuhlrottstraße 10, 42119, Wuppertal, Germany. baumgart@uni-wuppertal.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Baumgart
authors.affiliation: Clinic of Trauma Surgery and Orthopedics, HELIOS Klinikum Wuppertal, Heusnerstraße 40, 42283, Wuppertal, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Schubert
authors.affiliation: Department of Movement and Training Science, University of Wuppertal, Fuhlrottstraße 10, 42119, Wuppertal, Germany.
authors.forename: Matthias W
authors.initials: MW
authors.lastname: Hoppe
authors.affiliation: Center for Human Movement Sciences, University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, 9713 AV, Groningen, The Netherlands.
authors.forename: Alli
authors.initials: A
authors.lastname: Gokeler
authors.affiliation: Department of Movement and Training Science, University of Wuppertal, Fuhlrottstraße 10, 42119, Wuppertal, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Freiwald
mesh_terms: D000328:Adult; D016118:Anterior Cruciate Ligament / Q000503:physiopathology* / Q000601:surgery; D000070598:Anterior Cruciate Ligament Injuries / Q000503:physiopathology* / Q000534:rehabilitation / Q000601:surgery; D059549:Anterior Cruciate Ligament Reconstruction / Q000534:rehabilitation*; D001696:Biomechanical Phenomena; D005080:Exercise Test; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology* / Q000601:surgery; D007719:Knee Joint / Q000503:physiopathology* / Q000601:surgery; D008297:Male; D009068:Movement / Q000502:physiology*; D052097:Quadriceps Muscle / Q000503:physiopathology; D020127:Recovery of Function; D019415:Torque; D055815:Young Adult
keywords: Asymmetry; Biomechanics; IKDC; Jump test; Knee joint; Rehabilitation