What is osteonecrosis?

Osteonecrosis refers specifically to the death of bone tissue that occurs due to a lack of blood supply. This condition can lead to the collapse of bone structure and may cause severe pain and loss of function in the affected area. The lack of blood flow deprives the bone of essential nutrients and oxygen, leading to cellular death and eventual structural failure.

In this context, the other options describe distinct orthopedic conditions but do not relate to osteonecrosis. For instance, a fracture of the pars interarticularis pertains to a specific type of spinal fracture, while the forward slipping of one vertebra over another (spondylolisthesis) involves vertebral alignment issues, and the degeneration of intervertebral discs focuses on spinal disc health. Thus, the unique characteristic of osteonecrosis being directly linked to compromised blood supply to the bone substantiates why the identification of it as the death of bone tissue due to insufficient blood supply is accurate.