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Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Job Classification

In most duration tables, five job classifications are displayed. These job classifications are based on the amount of physical effort required to perform the work. The classifications correspond to the Strength Factor classifications described in the United States Department of Labor's Dictionary of Occupational Titles. The following definitions are quoted directly from that publication.

Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Bone Tumors (Benign and Malignant)


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Overview

A bone tumor is an abnormal growth of cells within the bone that may be noncancerous (benign) or cancerous (malignant). A bone tumor may be primary, originating within the bone itself, or secondary, resulting from the spread (metastasis) of cancer elsewhere in the body, such as from the lung, breast, or prostate.

Benign bone tumors occur more frequently than malignant bone tumors. Benign bone tumors do not spread (metastasize) to other tissues or organs but remain localized within the bone. They are named according to the cell type of origin: bone cells (osteoblasts) may produce osteomas, cartilage cells (chondroblasts) may produce chondromas, and tumors arising from both bone and cartilage produce osteochondromas, which are the most common type of benign bone tumor. The majority of benign bone tumors require no treatment, and the remainder can usually be cured with surgical resection.

Malignant bone tumors may be primary or secondary. They rarely occur as a primary bone tumor (less than 1% of all malignant tumors) but more frequently result from metastasis (secondary bone cancer) from cancer originating elsewhere in the body. Primary bone cancer, or sarcoma, can originate in different types of bone or adjacent soft tissues (muscle, cartilage, nerves, fat, and connective tissue) anywhere in the body.

The most common types of sarcoma are osteosarcoma, chondrosarcoma, fibrosarcoma, and Ewing's sarcoma (the latter belongs to the Ewing family of tumors, which also includes peripheral primitive neuroectodermal tumors and extraosseous Ewing tumors). Osteosarcomas, the most common type, are bone-forming sarcomas that develop primarily at the ends of the bones at the growth plates of children and young adults and affect the knees, upper arms, and pelvis. Chondrosarcomas arise from cartilage and develop in the legs, arms, pelvis, and ribs; they may also develop from benign enchondromas and osteochondromas. Fibrosarcomas arise from connective tissue (muscle, ligament, or tendon) but may affect the bones of the jaw, arms, and legs. Ewing's sarcoma, the second-most-common type of bone cancer in children, develops most frequently in the middle (shaft) of long bones, and affects hips, long bones in the thigh and upper arm, and pelvis. The increased incidence of osteosarcomas and Ewing's sarcomas in teenagers supports the idea that bone neoplasms develop during rapid growth and that growing bone is susceptible to transformation (Baker). There are several other types of sarcoma, such as malignant giant cell tumors and chordoma; these rare tumors occur most often in adults over the age of 30.

Osteosarcomas, the most common type of malignant bone cancer, are classified according to the cells of origin, their size and appearance, and their degree of proliferation (mitoses). A low-grade tumor has few dividing cells and a mature cell matrix as viewed under the microscope; it is unlikely to spread to other parts of the body and carries an excellent prognosis. A high-grade tumor has multiple dividing cells and an immature cell matrix, indicating rapid proliferation; these tumors have a high likelihood of metastasis and usually require both surgery and chemotherapy. Intermediate-grade tumors have a variable prognosis.

Secondary bone cancer occurs when malignant cells from a primary cancer site, such as the kidney, lung, prostate, breast, or thyroid, spread (metastasize) to the bones; although cancer is present in the bones, the malignant cells are those of the organ of origin. Therefore, these secondary cancers are not referred to as bone cancer but instead reference the original organ from which it metastasized, such as metastatic lung cancer. Common sites of secondary bone cancer include the ribs, skull, pelvis, and vertebrae. These bone tumors may not be treated in the same way as primary bone tumors because they occur in the later stages of metastatic cancer of other organ systems. Sometimes, when metastasis of the primary tumor involves bone and other organ systems, only palliative treatment is given.

Two additional types of cancer may also develop within the bones: non-Hodgkin's lymphoma of the bone, and multiple myeloma, which develops in the plasma cells of the bone marrow.

Malignant bone tumors are staged using the American Joint Commission on Cancer (AJCC) tumor/node/metastasis staging system. Stages for tumor characteristics, the possible spread to lymph nodes, and metastasis to distant organs (TNM) are shown in increments, including T0 (no tumor evident), T1 (8-cm tumor), T2 (tumor larger than 8 cm), and T3 (tumor in more than one place on same bone); N0 (no spread) to N1 (spread to lymph nodes); and M0 (no distant spreading) or M1 (distant metastasis) ("Detailed Guide"). An alternate grouped TNM staging system uses Roman numerals I through IV, ranging from the absence of to incremental increases in metastasis. A grade will also be assigned, including G1 through G4, with lower numbers indicating low-grade tumors, and higher numbers indicating high-grade tumors ("Detailed Guide").

Incidence and Prevalence: According to the American Cancer Society, an estimated 2,570 new cases of malignant bone tumors would be diagnosed in 2009 in the US, with an estimated 1,470 deaths ("Detailed Guide").

The two most common types of primary bone cancer are osteosarcoma and chondrosarcoma, with each accounting for about 35% of primary bone cancers (“Detailed Guide”). In the US each year, 400 new cases of osteosarcoma are diagnosed, or 4.8 cases per 1 million individuals younger than age 20; the incidence among blacks is 5.2 cases per 1 million each year, and among whites it is 4.6 cases per 1 million each year (Mehlman).

Fibrosarcoma and malignant fibrous histiocytoma account for 2% of primary bone cancer, and chordoma accounts for 5%. Ewing's sarcoma of bone accounts for 10% of cases of primary bone cancer (“Detailed Guide”); about 2.9 cases are diagnosed per 1 million individuals, with the incidence in whites about 9 times that in blacks (Toretsky). Rare tumors, such as giant cell tumors, make up the remainder of primary bone cancers.

Source: Medical Disability Advisor