title: Ossification of Achilles tendon--report of three cases.
abstract: BACKGROUND
  Ossification of the Achilles tendon is reportedly an unusual condition. The microscopic features of such ossifications have been not well documented.
  
  
  METHODS
  We treated three patients with bilateral ossification of the Achilles tendon and examined the specimens microscopically. The patients were all male. Their ages ranged from 41 to 59 years with an average of 48 years. The chief complaint was pain in two cases and rupture of the Achilles tendon in one case. The ossification site was near the insertion in five feet and in the tendon body in one foot. They had no laboratory abnormalities.
  
  
  RESULTS
  Removal was performed in two cases. Microscopic examination revealed no active inflammation of the ossified tendon. Lamellar bone formation with bone marrow continuous with the extensive cartilage metaplasia, namely enchondral ossification, and osteoid formation in the granulation tissue, namely intramembranous ossification, were observed.
  
  
  CONCLUSIONS
  Judging from the heavy work and bilateral occurrence in the present cases, repetitive microtrauma to the Achilles tendon and some predisposition are implicated as causative factors in the ossification.
authors.affiliation: Department of Orthopaedic Surgery, Tohoku University School of Medicine, 1-1 Seiryomachi, Aobaku, Sendai, Japan 980-8574. mhato@mail.cc.tohoku.ac.jp
authors.forename: Masahito
authors.initials: M
authors.lastname: Hatori
authors.forename: Michimasa
authors.initials: M
authors.lastname: Matsuda
authors.forename: Shoichi
authors.initials: S
authors.lastname: Kokubun
mesh_terms: D000125:Achilles Tendon / Q000000981:diagnostic imaging / Q000293:injuries / Q000473:pathology*; D000328:Adult; D006801:Humans; D008297:Male; D008875:Middle Aged; D009999:Ossification, Heterotopic / Q000209:etiology*; D011859:Radiography; D012421:Rupture; D013708:Tendon Injuries / Q000473:pathology