title: The 'functional muscle-cartilage unit': a reasonable approach to describe a putative relationship between muscle force and longitudinal growth at the forearm in children and adolescents?
abstract: BACKGROUND
  Several reports give evidence that the perichondral ossificiation of bone tubes (modeling) strongly depends on muscular forces in children and adolescents. The present analyses intend to investigate the hypothesis that muscular forces also partly determine enchondral ossification and, therefore, longitudinal growth of bone tubes.
  
  
  METHODS
  Analyses were based on a single cross-sectional investigation with peripheral quantitative computed tomography in 296 individuals (age 5-19 years) participating in the Dortmund Nutritional and Anthropometric Longitudinally Designed (DONALD) study.
  
  
  RESULTS
  Forearm length (FL) was correlated with body height in gender-related subgroups of prepubertal and pubertal individuals (rs between 0.76 and 0.86). Cross-sectional muscle area (MA) increased faster than FL and faster than cross-sectional bone area (BA) close to the distal growth plate in puberty. Close to the growth plate, longitudinal growth was faster than perichondral ossification in females. The ratio MA/BA (surrogate of pressure on the distal growth plate) was correlated with FL in prepubertal boys (r = -0.249, p = 0.043) and pubertal individuals (r = 0.153, p = 0.051).
  
  
  CONCLUSIONS
  Results support the hypothesis that longitudinal growth precedes modeling at the distal forearm. Confounding variables such as puberty may modify the relationship between muscle forces and longitudinal growth at the forearm in boys.
authors.affiliation: Children's Hospital, University of Cologne, Cologne, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Fricke
authors.forename: Ralf
authors.initials: R
authors.lastname: Beccard
authors.forename: Oliver
authors.initials: O
authors.lastname: Semler
authors.forename: Christof
authors.initials: C
authors.lastname: Land
authors.forename: Angelika
authors.initials: A
authors.lastname: Stabrey
authors.forename: Baerbel
authors.initials: B
authors.lastname: Tutlewski
authors.forename: Thomas
authors.initials: T
authors.lastname: Remer
authors.forename: Eckhard
authors.initials: E
authors.lastname: Schoenau
mesh_terms: D000293:Adolescent; D055592:Biophysical Phenomena; D001827:Body Height; D015519:Bone Density; D002356:Cartilage / Q000254:growth & development; D002648:Child; D002675:Child, Preschool; D005260:Female; D005542:Forearm / Q000000981:diagnostic imaging / Q000254:growth & development*; D006132:Growth Plate / Q000502:physiology; D006801:Humans; D007537:Isometric Contraction; D008297:Male; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000254:growth & development*; D011627:Puberty / Q000502:physiology; D014057:Tomography, X-Ray Computed; D055815:Young Adult