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Prosthetics that Grow

Orthopedic Surgeons Expand Possibilities with an Implant that Grows with the Patient

March 1, 2009

Orthopedic surgeons are sparing children with osteosarcoma from a series of implant surgeries. In order to remove the cancer, the bone is often removed, leaving the patient with a prosthesis that requires several surgeries during the child's growth. With a new experimental device, the arm or leg implant expands as the child grows, eliminating the need for multiple surgeries. The implant consists of a coiled spring encased in a hard plastic. Outside the leg, an electromagnetic device heats up a metal bar under the plastic, melting it over time and slowly releasing the spring and expanding the implant.

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HOW IT WORKS: A musculoskeletal oncologist specialist replaced a boy's femur with an expandable bone prosthesis because of bone cancer. Doctors use electromagnetism to heat and melt plastic, which allows a spring to expand and lengthen the bone prosthesis. In the past, similar procedures had required the use of bone cement, which could create irreversible damage. As the child's other leg grows, surgery to lengthen the prosthesis is unnecessary, because with a simple visit to the doctor, kids can have their prostheses lengthened. A bit of muscle stretching is the only side effect of this outpatient procedure.

CHILDHOOD CANCERS: The most common form of cancer in children is childhood acute lymphocytic leukemia, or ALL. Lymphocytes, a type of cell that helps fight infection, develops in bone marrow. If the lymphocytes grow too quickly and do not fully mature, the child has ALL. It can cause anemia, easy bruising or bleeding and swollen lymph nodes. Doctors use a blood test to count the numbers of different types of blood cells ý too many white blood cells can indicate leukemia.

A RARE DISEASE: In the United States in 2005, approximately 9,510 children under age 15 will be diagnosed with cancer. But cancer is still relatively rare in this age group with, on average, 1 to 2 children developing the disease each year for every 10,000 children in the United States.

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More information on this story

On The Web: Expandable High-Tech Bone Implants 'Grow' As Children Do

To Go Inside This Science:
Joel Mayerson, M.D.
Columbus, Ohio
614-293-4420
Joel.Mayerson@osumc.edu


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