The main cause of osteosarcoma is not well-known, yet. However, a number of risk factors have been identified in this regard. Osteosarcoma can involve any bone but it usually affects the extremities of long bones near metaphyseal growth plates. The most common sites include
Femur 42% of cases ( the distal femur had around 75% of involvement).
Tibia 19% of cases ( the proximal tibia had around 80% of involvement).
Humerus 10% of cases  ( the proximal humerus had around 90% of involvement).
Skull and jaw 8% of cases.
Pelvis 8% of cases.
Osteosarcoma pathophysiology
Osteoma pathophysiology
Osteochondroma pathophysiology
Osteosarcoma risk factors
Bone metastasis
Osteochondroma risk factors
Osteosarcoma staging
Chondroma pathophysiology