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When 3-year-old Mark Blinder developed pain in his right arm, doctors diagnosed him with Ewing’s sarcoma, a rare bone tumor. Chemotherapy wasn’t working and radiation would have destroyed the growth plates in his bones. So instead of amputating the arm, doctors tried an experimental approach–implanting an artificial, expandable bone made of titanium and cobalt chrome, designed specifically for Mark. The bone, produced by the company Biomet Inc., is small enough to fit inside the 3-year-old’s arm, but should be sturdy enough to last his entire life.  Most artificial bones are used to replace only part of a bone, so they are glued securely to remaining bone. In Mark’s case, the entire humerus was being removed, so the prosthetic had to be attached to soft tissue [Los Angeles Times].

To install the bone, doctors first had to remove the tumor by carving out the fat around it, a process one of the doctor’s likened to carving out a peach pit without ever touching the pit. The surgery was a success but Mark, who is now 4 years old, underwent chemotherapy as a precaution. Mark is gradually relearning how to use his arm. He’s moving his wrist and fingers, can pick up small objects, and is receiving physiotherapy to rebuild strength and flexibility in the elbow and shoulder. He won’t ever regain full function in those joints, but he is using the arm more each day, his mother said [Los Angeles Times]. He will have to undergo three or four minor surgeries over the years so doctors can extend the prosthetic bone as he grows–but since the only other option open to Mark was amputating his arm completely, he probably won’t complain.

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Image: iStockphoto

This can only lead to a summer blockbuster. Researchers implanted tiny electrodes in two monkeys’ brains, allowing them to move robotic arms with their thoughts.

To motivate the monkeys to perform, they were encouraged to feed themselves marshmallows and pieces of fruit with the robotic arms, which had joints and “grippers” that roughly replicated fingers. According to the research team’s report in Nature [subscription required], the arms’ movements were fluid and natural, and the monkeys continuously adjusted the speed and direction of their robotic limbs.

While the technology isn’t yet ready for human testing, scientists are hopeful that it can eventually be applied to prosthetic limbs for people with spinal cord injuries, strokes, and other paralyzing conditions.

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