CHILDREN suffering from the spinal condition scoliosis face the prospect of major surgery with lifelong complications. To try to avoid this, a new corrective implant is under development that 鈥済rows鈥� with the child, harvesting the energy it needs from its host鈥檚 movements.
Scoliosis affects as many as 1 in 50 adult women and 1 in 200 men, causing their spines to curve from side to side into unnatural 鈥淐鈥� or 鈥淪鈥� shapes. In severe cases, it is treated by grafting sections of bone or metallic fixators onto the spine to help straighten it. But this 鈥渟pinal fusion鈥� surgery usually cannot be done until a child is almost fully grown, by which time the symptoms are already advanced.
The technique has other drawbacks, too: it restricts movement, and can cause surrounding muscles and ligaments to atrophy. 鈥淰ertebral fusion drastically [weakens] the strength of the skeleton,鈥� says Jose Alvarez Canal, a mechanical engineer who has been working on the new implant at NADAR Computerized Medical Systems in Langreo, Spain.
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Canal says that controllable machines are needed that progressively manipulate the spine over time. The new implant, developed in collaboration with spineexperts from Spain and France, uses a hydraulic piston to apply a force between two points along the spine, gradually correcting its curvature.
鈥淎 hydraulic piston applies a force between two points along the spine鈥�
The device can be fitted to relatively young children, but as they grow and the piston moves, the force it exerts inevitably reduces. To correct this, doctors need to top up the pressure on the piston. The NADAR device is designed to allow some free movement of the spine, some of which it harnesses to pump hydraulic fluid from a low-pressure reserve within the device into a high-pressure reservoir. When adjustment is needed, the doctors use wireless telemetry to open a valve that releases fluid from the reservoir into the piston. The device is removed completely once the spine is straight, reducing the risk of complications.
Tests on goats have been very promising, Canal says, but it will be at least three years before it鈥檚 ready to be tried in humans (Mechatronics, ).
