title: Healing of human Achilles tendon ruptures: radiodensity reflects mechanical properties.
abstract: OBJECTIVE
  This study tests the idea of using radiodensity from computed tomography to quantitatively evaluate the healing of ruptured Achilles tendons.
  
  
  METHODS
  The radiodensity of the healing tendons in sixty-five patients who were treated for Achilles tendon rupture was measured. The hypothesis was that density would correlate with an estimate for e-modulus, derived from strain, measured by radiostereometry with different mechanical loadings.
  
  
  RESULTS
  Radiodensity 7 weeks after injury was decreased to 67 % (SD 11) of the contralateral, uninjured tendon. There was no improvement in radiodensity from 7 to 19 weeks, whereas at 1 year, it had increased to 106 % (SD 7). Only 2 of 52 measured values at 1 year were lower than the highest value at 19 weeks, i.e. there was minimal overlap. The variation in radiodensity could explain 80 % of the variation in e-modulus, but radiodensity correlated only weakly with e-modulus at each time point separately. At 1 year, both radiodensity and e-modulus correlated with functional results, although weakly.
  
  
  CONCLUSIONS
  From 19 weeks onwards, radiodensity appears to reflect mechanical properties of the tendon and might to some extent predict the final outcome. Radiodensity at 7 weeks is difficult to interpret, probably because it reflects both callus and damaged tissues.
authors.affiliation: Orthopedics, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, 58185, Linköping, Sweden, thorsten.schepull@lio.se.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Schepull
authors.forename: Per
authors.initials: P
authors.lastname: Aspenberg
mesh_terms: D000125:Achilles Tendon / Q000000981:diagnostic imaging* / Q000293:injuries / Q000503:physiopathology / Q000601:surgery; D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020127:Recovery of Function; D012421:Rupture; D013708:Tendon Injuries / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery; D014057:Tomography, X-Ray Computed; D014945:Wound Healing; D055815:Young Adult