title: Contribution of denervated muscle to contractures after neonatal brachial plexus injury: not just muscle fibrosis.
abstract: BACKGROUND
  We investigated the contribution of muscle fibrosis to elbow flexion contractures in a murine model of neonatal brachial plexus injury (NBPI).
  
  
  METHODS
  Four weeks after NBPI, biceps and brachialis fibrosis were assessed histologically and compared with the timing of contracture development and the relative contribution of each muscle to contractures. Modulus of elasticity and hydroxyproline (collagen) content were measured and correlated with contracture severity. The effect of halofuginone antifibrotic therapy on fibrosis and contractures was investigated.
  
  
  RESULTS
  Elbow contractures preceded muscle fibrosis development. The brachialis was less fibrotic than the biceps, yet contributed more to contractures. Modulus and hydroxyproline content increased in both elbow flexors, but neither correlated with contracture severity. Halofuginone reduced biceps fibrosis but did not reduce contracture severity.
  
  
  CONCLUSIONS
  Contractures after NBPI cannot be explained solely by muscle fibrosis, arguing for investigation of alternate pathophysiologic targets for contracture prevention and treatment.
authors.affiliation: Division of Orthopaedics, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, Ohio, 45229-3026, USA.
authors.forename: Sia
authors.initials: S
authors.lastname: Nikolaou
authors.forename: Hu
authors.initials: H
authors.lastname: Liangjun
authors.forename: Lori J
authors.initials: LJ
authors.lastname: Tuttle
authors.forename: Holly
authors.initials: H
authors.lastname: Weekley
authors.forename: Wylie
authors.initials: W
authors.lastname: Christopher
authors.forename: Richard L
authors.initials: RL
authors.lastname: Lieber
authors.forename: Roger
authors.initials: R
authors.lastname: Cornwall
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000933:Antifibrinolytic Agents / Q000627:therapeutic use; D001696:Biomechanical Phenomena; D020516:Brachial Plexus Neuropathies / Q000150:complications*; D003094:Collagen / Q000378:metabolism; D003286:Contracture / Q000188:drug therapy / Q000209:etiology* / Q000473:pathology*; D003714:Denervation; D004195:Disease Models, Animal; D005355:Fibrosis / Q000188:drug therapy / Q000473:pathology; D007839:Functional Laterality; D051379:Mice; D018482:Muscle, Skeletal / Q000503:physiopathology*; D012018:Reflex / Q000502:physiology; D013997:Time Factors; D034941:Upper Extremity / Q000294:innervation
chemical_list: D000933:Antifibrinolytic Agents; D003094:Collagen
keywords: brachial plexus; contracture; fibrosis; muscle; neonatal