title: Muscle, tendons, and bone: structural changes during denervation and FES treatment.
abstract: OBJECTIVE
  This paper describes a novel approach to determine structural changes in bone, muscle, and tendons using medical imaging, finite element models, and processing techniques to evaluate and quantify: (1) progression of atrophy in permanently lower motor neuron (LMN) denervated human muscles, and tendons; (2) their recovery as induced by functional electrical stimulation (FES); and (3) changes in bone mineral density and bone strength as effect of FES treatment.
  
  
  METHODS
  Briefly, we used three-dimensional reconstruction of muscle belly, tendons, and bone images to study the structural changes occurring in these tissues in paralysed subjects after complete lumbar-ischiadic spinal cord injury (SCI). These subjects were recruited through the European project RISE, an endeavour designed to establish a novel clinical rehabilitation method for patients who have permanent and non-recoverable muscle LMN denervation in the lower extremities. This paper describes the use of segmentation techniques to study muscles, tendons, and bone in several states: healthy, LMN denervated-degenerated but not stimulated, and LMN denervated-stimulated. Here, we have used medical images to develop three-dimensional models and advanced imaging, including computational tools to display tissue density. Different tissues are visualized associating proper Hounsfield intervals defined experimentally to fat, connective tissue, and muscle. Finite element techniques are used to calculate Young's modulus on the patella bone and to analyse correlation between muscle contraction and bone strength changes.
  
  
  RESULTS
  These analyses show restoration of muscular structures, tendons, and bone after FES as well as decline of the same tissues when treatment is not performed. This study suggests also a correlation between muscle growth due to FES treatment and increase in density and strength in patella bone.
  
  
  CONCLUSIONS
  Segmentation techniques and finite element analysis allow the study of the structural changes of human skeletal muscle, tendons, and bone in SCI patient with LMN injury and to monitor effects and changes in tissue composition due to FES treatment. This work demonstrates improved bone strength in the patella through the FES treatment applied on the quadriceps femur.
authors.affiliation: Department of Development and Consultancy UTS, Landspitali-University Hospital, Reykjavik, Iceland. paologar@landspitali.is
authors.forename: Paolo
authors.initials: P
authors.lastname: Gargiulo
authors.forename: Páll Jens
authors.initials: PJ
authors.lastname: Reynisson
authors.forename: Benedikt
authors.initials: B
authors.lastname: Helgason
authors.forename: Helmut
authors.initials: H
authors.lastname: Kern
authors.forename: Winfried
authors.initials: W
authors.lastname: Mayr
authors.forename: Páll
authors.initials: P
authors.lastname: Ingvarsson
authors.forename: Thordur
authors.initials: T
authors.lastname: Helgason
authors.forename: Ugo
authors.initials: U
authors.lastname: Carraro
mesh_terms: D000328:Adult; D015519:Bone Density; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000473:pathology*; D004599:Electric Stimulation Therapy / Q000379:methods*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D016472:Motor Neuron Disease / Q000473:pathology / Q000628:therapy*; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000473:pathology*; D013119:Spinal Cord Injuries / Q000473:pathology / Q000628:therapy*; D013710:Tendons / Q000000981:diagnostic imaging / Q000473:pathology*; D036542:Tomography, Spiral Computed