Given the length of time it takes for nerves to grow back, scientists have turned to other types of procedures to try to repair damaged nerves. These are often grafts, which are nerves taken from other, healthy places in the body and positioned around the damaged nerves to take their place. But these procedures aren’t ideal because the patient needs two surgeries, often feels pain at the donor site, and sometimes the patient's body even rejects the graft. More recently, researchers have experimented with nerve guidance channels, which are cylinders made of bio-compatible materials that encourage nerve grow. Though these have more flexibility than nerve grafts, they can only help nerves grow in a straight line, which doesn’t help nerves damaged in “large, geometrically complex injuries,” the study authors write.