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Year |
2002 |
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Question Number |
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Category |
Orthopaedic Science |
Question
Which of the following is considered a typical characteristic of deep lesions in articular cartilage that cross the tidemark in adults?
1- Heals with intramembranous ossification
2- Heals with hyaline cartilage.
3- Contains abundant type I collagen at 1 year
4- Predominantly repopulated from surrounding chondrocytes
5- Contains abundant aggrecan at 1 year
Figures
Answer (click for answer)
Correct Answer: 3- Contains abundant type I collagen at 1 year
The given references are a pretty good review of articular cartilage healing. In full-thickness injuries (i.e., past the tidemark), there is recruitment with subsequent proliferation and differentiation of mesenchymal cells into chondrocyte-like cells. Cells in the deeper layer undergo endochondral ossification to heal the subchondral bone defect. This all seems to take place in the first 6 to 8 weeks. Unfortunately there is subsequent degeneration of this matrix with replacement of the chondroid-like tissue with fibrocartilage. By one year out from injury, the repair tissue seems to be a mix of hyaline cartilage and fibrocartilage. By this point it contains a significant amount (20% to 40%) of type I collagen.
Reference: (1)Am J Orthop 1999;28:31-33. (2) Am J Orthop 1999;28:88-96.