Osteosarcoma is a malignant tumour of mesodermal connective tissue generally originating from bone and rarely in soft tissue (Dahlin, 1975). It is defined by the presence proliferating malignant mesenchymal cells that produce osteoid and/or immature bones (Gaeta, 1988). Osteosarcoma is most frequently found in the medullary cavity of the metaphysis of a growing long tubular bone. However, it can also appear on the surface of a bone (Gurfunkle, 2007). Most osteosarcoma’s develop in the appendicular skeleton with only 10% developing in axial skeleton. Aproximatly 50% originate around the knee area, the most common cyctes are the distal femur, proximal tibia and proximal hummerus (Kumar, 2014). Tumour growth often extends though the cortex stimulating the periosteum. Although osteosarcoma usually arises in the medullary cavity of the metaphysis of a growing long tubular bone, it also may arise on the surface of a bone, it may be confined tothe cortex, or it even may arise in an extraskeletal site (Gaeta, 1988).
Aetiology and Prevalence
It is estimated that within the general population there are 2-3 cases of Osteosarcoma per million per year. Within the population of 15-19 year olds the rate is a higher 8-11 per million each year. Osteosarcoma accounts for 15% of all solid extra-cranial cancers of the 15-19 year old age group. The rate of occurrence is approximately 1.4 more frequent in males than in females (Gurfunkle, 2007). The aetiology of osteosarcoma is unclear. However, suggested factors include trauma, pre-existing diseases, rapid bone growth, carcinogens, radiation exposure and hereditary disorders (e.g hereditary retinoblastoma and the Li-Fraumeni cancer family syndrome) (Gaeta, 1988).
Osteosarcoma is most frequently is found in the medullary cavity of the metaphysis of a growing long tubular bones its frequent cyctes are the distal femur, proximal tibia and proximal hummerus. The medullary cavity of the metaphysis in children and adolescences contains the epitheal growth plate (Dahlin, 1975)
There is a suggested link between rapid bone proliferation and the occurrence of malignant mesenchymal cells. Adolesces, generally experience a period of rapid bone growth (Ritter, 2010). The timing of the adolescent growth spurt matches the peak rate of from bone tumours. In adolescence death rate of bone tumors of 11 cases per million is four times more than that of children (Ritter, 2010).
The relationship between mean height being greater in paients with Osteosarcoma compared patients with nonosseous malignancies also suggests a relationship between with bone growth and presence of mesenchymal cells. (Ritter, 2010)
• Local pain and tenderness for weeks or months. (Klien, 2006)
• Pain at rest as well as pain during weight bearing activities such as when lifting with arm or standing (National Library of Health, 2012)
• Often Palpable firm mass at site of involvement. (Tebbi, 1988)