Osteosarcoma of the knee

Osteosarcoma is a type of tumor with a relatively high incidence rate. Usually, osteosarcoma can be divided into several types, such as primary and secondary. Patients can choose the appropriate method for treatment according to their actual physical condition. Generally, osteosarcoma mainly occurs in adolescents between the ages of 10 and 20. A small number of patients develop the disease after the age of 30. It is more common in men than in women and in large bones. The first symptom is pain, which worsens as the disease persists.

Osteosarcoma is a malignant bone tumor characterized by the direct formation of bone or bone-like tissue by tumor cells, and its incidence ranks first among malignant bone tumors. Osteosarcoma can be divided into two types: primary and secondary. Primary osteosarcoma can be further divided into intraosseous osteosarcoma occurring in bones and extraosseous osteosarcoma occurring in soft tissues. The latter is extremely rare. Secondary osteosarcoma is osteosarcoma that occurs after certain bone tumors, bone diseases, or radiotherapy of certain lesions. It is extremely rare clinically.

According to the location of the tumor, it can be divided into central osteosarcoma and surface osteosarcoma. The former, in addition to the most common common (or classic) osteosarcoma, also includes subtypes such as telangiectatic osteosarcoma, intramedullary well-differentiated osteosarcoma and small (round) cell osteosarcoma; the latter is further divided into paraosteal (juxtacortical) osteosarcoma, periosteal osteosarcoma and high-grade surface osteosarcoma. According to the histological characteristics of the tumor, it can be divided into osteoblastic, chondroblastic, and fibroblastic osteosarcoma types.

Osteosarcoma generally refers to the common (classic) osteosarcoma. right

1. Clinical characteristics

age

It is more common in adolescents aged 10 to 20 years old and rarely seen before the age of 10 or after the age of 30.

gender

There are more male patients than female patients, with a ratio of about 3:2.

Location

It is common in the epiphysis of the long bones of the limbs and the pelvis, among which the distal femur, proximal tibia and proximal humerus are the most common, accounting for 3/4 of all osteosarcomas. The most common sites of osteosarcoma in long bones are the epiphysis and the diaphysis.

Symptoms and Signs

The earliest clinical symptom is local pain, which is mild at first, gradually worsens, and is more obvious at night. It is easy to be attributed to injury and ignored by patients. This is followed by soft tissue swelling or lumps, tenderness, and some patients experience limited joint movement. Increased skin temperature and distended subcutaneous veins may occur locally in the tumor. A small number of patients develop pathological fractures at an early stage due to rapid progression of the disease.

Laboratory tests

Serum alkaline phosphatase may be normal in the early stages of osteosarcoma, sclerotic osteosarcoma, parosteal osteosarcoma, and low-grade osteosarcoma, but may exceed the normal value by more than 10 times when the tumor is huge or metastases appear. After high-dose chemotherapy or surgery, alkaline phosphatase levels tend to decrease, but will increase again when the tumor recurs or metastasizes. Therefore, alkaline phosphatase can be used as a sensitive indicator to judge the efficacy of chemotherapy and monitor tumor recurrence or metastasis.

2. Imaging characteristics

The X-ray manifestations of osteosarcoma are diverse: sclerotic osteosarcoma with bone formation as the main feature; osteolytic osteosarcoma characterized by simple bone destruction; and mixed osteosarcoma with a mixture of bone destruction areas and osteoblastic areas. The boundaries of the lesions are unclear, and periosteal reaction can be seen in most cases, manifested as Codman's triangle or solar radiant periosteal reaction. When the tumor penetrates the bone cortex, a soft tissue mass shadow may be seen.

CT and MRI findings are not specific, but they can clearly show the extent of tumor invasion and adjacent relationships. In particular, MRI can show the extent of tumor invasion in the medullary tissue and surrounding soft tissues, which helps determine the osteotomy level and surgical plan.

DSA examination can help understand the blood supply of the tumor and its relationship with the main blood vessels, which is of great significance for formulating surgical plans. Interventional treatment and placement of arterial infusion chemotherapy devices can also be performed after DSA examination.

ECT is an important examination method for early detection of osteosarcoma and its distant metastases, and it is also of certain value in evaluating the efficacy of chemotherapy for osteosarcoma.