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Bony island within the articular cartilage of the knee in a child: a rare condition for early osteoarthritis

Taku Hatta, Takehiko Sugita, Toshimi Aizawa, Masahiro Ohnuma, Atsushi Takahashi, Eiji Itoi
  • Taku Hatta
    Affiliation not present
  • Takehiko Sugita
    Affiliation not present
  • Masahiro Ohnuma
    Affiliation not present
  • Atsushi Takahashi
    Affiliation not present
  • Eiji Itoi
    Affiliation not present


Articular cartilage is a specific type of connective tissue composed of hydrated proteoglycans within a matrix of collagen fibrils. In the elderly population, it shows degenerative changes that may results in osteoarthritis. The more severe form of osteoarthritis occasionally demonstrates bone formation within the cartilage, which is designated as a bony protuberance, however, such lesions are rare in children. This report presents the case of a 10-year-old boy with a bony protuberance within the articular cartilage of the knee. The patient initially complained of knee pain and he subsequently developed flexion contracture. Radiological and arthroscopic examinations revealed a bony protuberance in the articular cartilage and degenerative changes of the cartilage above it. He was successfully treated by the removal of the bony protuberance and osteochondral grafting. The bony protuberance may have caused cartilage degradation since the thickness of the cartilage above it was thinner than that around the lesion. The bony protuberance within the articular cartilage formed in the younger population may be a possible cause of osteoarthritis. This case is a noteworthy with regard to the pathogenesis of osteoarthritis.


Bone protuberance;, Articular cartilage; Osteoarthritis, Child

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Submitted: 2010-12-28 00:03:37
Published: 2011-04-01 07:48:59
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