title: Periarticular muscle stimulation controls anterior tibial laxity after experimental ACL section: an experimental study.
abstract: OBJECTIVE
  Besides current strategies to treat potentially disabling anterior cruciate ligament (ACL) injury, a new and innovative approach was designed based on electrical stimulation of the muscle to prevent unwanted displacement of the tibia relative to the femur. Our aim was to measure muscular strain and anterior tibial translation (ATT) in a controlled study using an animal model of ACL-deficient knee undergoing muscular electric stimulation.
  
  
  METHODS
  Seventeen cat knees under tibial anterior traction of 24.5 N were studied before and after ACL transection. Muscular fiber length variation was obtained by ultrasonomicrometry and ATT by video recordings at the beginning, during, and at the end of the movement. Square pulses of 0.2 ms with 5 V were applied in trains of 500, 100, and 20 ms simultaneously to both the quadriceps and hamstrings before and immediately after traction.
  
  
  RESULTS
  Electric stimulation of ACL-deficient knees normalized muscular strain to values of control knees. An increased resistance to muscular lengthening was observed in stimulated knees. Stimulation before traction maintained similar ATT than control knees during the subsequent traction.
  
  
  CONCLUSIONS
  Electric muscular stimulation in the ACL-deficient knee provoked periarticular muscle contraction, controlling ATT when time-adjusted stimulus (before traction) was used. This suggested that artificially inducing the muscular response could help to control anterior knee laxity after ACL injury.
authors.affiliation: Unidad de Ortopedia Pediátrica, Hospital Infantil, Hospital Universitario La Paz, Paseo de la Castellana, 261, 28046, Madrid, Spain. nuria.bonsfills@gmail.com
authors.forename: Nuria
authors.initials: N
authors.lastname: Bonsfills
authors.forename: Angel
authors.initials: A
authors.lastname: Nuñez
authors.forename: Enrique
authors.initials: E
authors.lastname: Gomez-Barrena
mesh_terms: D000818:Animals; D000070598:Anterior Cruciate Ligament Injuries; D002415:Cats; D004599:Electric Stimulation Therapy; D007593:Joint Instability / Q000209:etiology / Q000628:therapy*; D007718:Knee Injuries / Q000150:complications*; D007719:Knee Joint; D009119:Muscle Contraction; D018482:Muscle, Skeletal; D013977:Tibia