title: Characterisation of in-vivo mechanical action of knee braces regarding their anti-drawer effect.
abstract: BACKGROUND
  The knee joint is vulnerable to various injuries and degenerative conditions, potentially leading to functional instability. Usual treatments involve knee orthoses to support the joint. However, the level of mechanical action of these devices remains controversial despite high prescription and demand.
  
  
  METHODS
  The mechanical ability of three commercial hinged knee braces and one sleeve to prevent a static drawer was evaluated using a GNRB arthrometer. The testing of both pathological and healthy joints was performed on 16 patients with documented injuries involving the ACL, and an original method allowed decoupling the contribution of the brace.
  
  
  RESULTS
  The mean stiffness of the three hinged braces ranged between 2.0 and 7.1 N/mm. The most efficient brace was able to exert a restraining force on the joint equivalent to the one exerted by a healthy ACL, up to a 2.8 mm anterior displacement of the tibia. For higher anterior displacements, the restraining force of the brace dropped below the level of action of the intact ACL because of the particular non-linear behaviour of this structure. Finally, the most efficient brace was found to vary from subject to subject.
  
  
  CONCLUSIONS
  This study confirmed that fabric-based knee braces may effectively replace the passive mechanical role of the ACL within the low stiffness region of this structure. Although bracing may have other benefits (e.g., proprioception), this shows that they act as an effective passive restraint to low grade anterior laxities. Besides, a high patient-specificity of their effects highlighted the need of personalised objective testing for brace selection.
authors: Ecole Nationale Supérieure des Mines, CIS-EMSE, CNRS:UMR5307, LGF, F-42023 Saint-Etienne, France; Pôle des Technologies Médicales, F-42000 Saint-Etienne, France. Electronic address: baptiste.pierrat@gmail.com.
authors: B
authors: B
authors: Pierrat
authors: Department of Clinical Physiology of Exercise, Units of Sport Medicine and Myology, Bellevue Hospital, University Hospital Center, Saint-Etienne, France; University of Lyon, Physiology of Exercise Laboratory, Saint-Etienne, France.
authors: R
authors: R
authors: Oullion
authors: Ecole Nationale Supérieure des Mines, CIS-EMSE, CNRS:UMR5307, LGF, F-42023 Saint-Etienne, France.
authors: J
authors: J
authors: Molimard
authors: Ecole Nationale Supérieure des Mines, CIS-EMSE, CNRS:UMR5307, LGF, F-42023 Saint-Etienne, France.
authors: L
authors: L
authors: Navarro
authors: Orthopaedic surgery department, North Hospital, 42055 Saint Etienne, Cedex 2, France.
authors: M
authors: M
authors: Combreas
authors: Ecole Nationale Supérieure des Mines, CIS-EMSE, CNRS:UMR5307, LGF, F-42023 Saint-Etienne, France.
authors: S
authors: S
authors: Avril
authors: Orthopaedic surgery department, North Hospital, 42055 Saint Etienne, Cedex 2, France.
authors: R
authors: R
authors: Philippot
authors: Physical Medicine and Rehabilitation Department, Bellevue Hospital, University Hospital Center, Saint-Etienne, France; University of Lyon, Physiology of Exercise Laboratory, Saint-Etienne, France.
authors: P
authors: P
authors: Calmels
mesh_terms: D000293:Adolescent; D000328:Adult; D000070598:Anterior Cruciate Ligament Injuries; D053587:Arthrometry, Articular / Q000379:methods*; D001696:Biomechanical Phenomena / Q000502:physiology; D001915:Braces; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology / Q000628:therapy*; D007719:Knee Joint / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D055815:Young Adult
keywords: ACL; Arthrometer; Instability; Knee brace; Knee orthosis