Nerve damage can leave no sense of when the bladder is full or control over when the contents are released.
A study, published in Science Translational Medicine, showed a device to read the remaining nerves’ signals could be used to control the organ.
The charity Spinal Research said this was “impressive and important” work.
The loss of bladder, bowel and sexual function after spinal cord injury is often rated by patients as having the biggest impact on quality of life.
When the spinal cord is injured, signals passing up from the bladder cannot tell the brain when the bladder is full. Going the other way, signals from the brain cannot tell the bladder when it is time to go to the toilet.
Researchers at the University of Cambridge have devised a solution that uses the nerves still around the bladder.
Electrodes wrapped around bundles of nerves can interpret signals that say the bladder is full.
Stimulating other sets of nerves can get the bladder to contract on demand and prevent it emptying of its own volition.
One of the researchers, Dr Daniel Chew, told the BBC the device had worked on rats.
“It is very effective. The feasibility studies are done, we’re now limited by miniaturisation of the technology,” he said.
While the components that fit inside a rat could be converted for human use, the rest of the technology to process the information recorded currently needs a 6ft (2m) stack of equipment.
This needs to shrunk down to a handheld device that can inform a patient when the bladder is full and a trigger button to contract the bladder.
Dr Chew added: “This device is not the ultimate goal, the ultimate aim is to regenerate the spinal cord. What we’re doing is restoring some function, not curing spinal cord injury.”
Dr Mark Bacon, the director of research at the charity Spinal Research, told the BBC: “Bladder dysfunction blights the life of many with spinal cord injuries and has a very major impact on their health and quality of life.
“This is impressive and important work addressing one of the major limitations found with existing options for electrical stimulation to control bladder emptying, namely the need to surgically destroy the sensory fibres coming from the bladder.
“Sparing and making use of sensory signals from a filling bladder adds a welcome degree of sophistication to elective voiding whilst retaining other functions normally lost such as erectile function – a distressing consequence of current methods.”
By James Gallagher
Health and science reporter, BBC News