title: [Muscular control of scapholunate instability. An experimental study].
abstract: OBJECTIVE
  As long as the neuromuscular stabilizers are intact, a lesion of the scapholunate ligament may or may not progress to a carpal instability. The mechanisms by which the muscles compensate this defect are not very well known. We designed an experimental study with the aim of clarifying these mechanisms.
  
  
  METHODS
  Using 10 fresh wrists, with no pre-existing lesions, we studied the movements of the scaphoid, triquetrum and capitate produced by the isometrical loading of the muscles which move the wrist, each of them isolated or combined, before and after cutting off the scapholunate ligaments. To do this, we placed sensors in each of these bones and used the Fastrack system to record these movements.
  
  
  RESULTS
  The simultaneous loading of the muscles of the wrist produce rotational movements in flexion and supination of the proximal carpal row. After cutting off the scapholunate ligaments, the scaphoid rotates in pronation and flexion, while the triquetrum rotates in pronation and extension. In this situation of a scapholunate lesion, the muscles that worsen the carpal dexasation are the extensor carpi ulnaris and flexor carpi ulnaris. On the other hand, the isolated loading of the radial muscles reduce the scapholunate diastasis, thus improving the carpal alignment.
  
  
  CONCLUSIONS
  In dynamic scapholunate instabilities, isometric contraction of the ulnar carpal muscles must be avoided, as it promotes the scapholunate diastasis. The rest of the muscles have the opposite effect, stabilizing the carpus when primary stabilizers have failed.
authors.affiliation: Departamento de Traumatología, Hospital Can Misses, Ibiza, España. Electronic address: mayteleonlopez@gmail.com.
authors.forename: M M
authors.initials: MM
authors.lastname: León-López
authors.affiliation: Institut Kaplan, Barcelona, España.
authors.forename: M
authors.initials: M
authors.lastname: García-Elías
authors.affiliation: Departamento de Cirugía de la Mano y Microcirugía, Hospital Son Llàtzer, Palma de Mallorca, España; Institut Ibacma, Palma de Mallorca, España.
authors.forename: G
authors.initials: G
authors.lastname: Salvà-Coll
authors.affiliation: Unidad de Mano, Departamento de Traumatología, Hospital de Vall d'Hebron, Barcelona, España; Departamento de Anatomía, Facultad de Medicina, Universidad de Barcelona, Barcelona, España.
authors.forename: M
authors.initials: M
authors.lastname: Llusá-Perez
authors.affiliation: Unidad de Mano, Departamento de Traumatología, Hospital de Vall d'Hebron, Barcelona, España; Departamento de Cirugía, Unidad de Traumatología y Ortopedia, Universidad Autónoma de Barcelona, Barcelona, España.
authors.forename: A
authors.initials: A
authors.lastname: Lluch-Bergadà
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D050824:Carpal Joints; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D008023:Ligaments, Articular / Q000503:physiopathology; D012667:Lunate Bone; D008297:Male; D018482:Muscle, Skeletal / Q000503:physiopathology*; D021361:Scaphoid Bone; D014955:Wrist Joint
keywords: Biomechanics; Biomecánica; Carpo; Carpus; Cinética; Escafolunar; Estabilidad; Kinetic; Propiocepción; Propioception; Scapholunar; Stability