Where does osteosarcoma most commonly occur in children and young adults?

Osteosarcoma most commonly occurs in the metaphyses of long bones, particularly around the knee, such as in the distal femur or proximal tibia. The metaphysis is the region of long bones where the growth plates are located, and this area experiences rapid growth, making it more susceptible to the development of tumors like osteosarcoma during periods of skeletal growth that are prevalent in childhood and adolescence.

The metaphysis is characterized by the presence of actively growing bone tissue, which is believed to contribute to the tumor's increased occurrence in this location. This tumor's aggressive nature, typical in young patients, aligns with the growth dynamics of the metaphysis, as it is more biologically active during the time when osteosarcoma typically manifests, usually in the second decade of life.

In contrast, other regions such as the diaphysis and epiphysis are less commonly involved due to their different roles in bone growth and development. Therefore, recognizing that osteosarcoma favors the metaphysis provides important insight into its epidemiology and helps guide clinical diagnosis and management.