A 66-Year-Old Man Who Suffered from Severe Osteoarthritis Is Referred

A 66-year-old man who suffered from severe osteoarthritis is referred to an orthopedic surgeon for replacement of his right knee. He had been actively involved in both high school and intercollegiate football and had continued running until about the age of 45 as a form of relaxation and exercise. With the patient's permission the removed joint is used by investigators performing a proteomic analysis of different joint tissues. The meniscus was found to contain almost exclusively type I collagen and aggrecan was undetectable. What is the most likely explanation for this result?

A) The meniscus normally consists of dense regular connective tissue, which contains primarily type I collagen.
B) The meniscus normally consists of fibrocartilage, which contains only type I collagen.
C) The meniscus had undergone repeated rounds of repair due to wear-and-tear during which its hyaline cartilage component was replaced by dense connective tissue.
D) Osteoarthritic injury in the knee resulted in the chondrocytes of the meniscus switching from expression of genes for type II collagen to type I collagen.
E) Elastic cartilage is normally replaced by fibrocartilage during aging and this process can be accelerated by exercise.