Spondylosis is a stress fracture usually in the 5th lumbar vertebrae (bone) in the lower spine. When that stress fracture weakens the bone and it moves, the condition is called spondylolithesis. These are common conditions for some athletes like gymnasts and weightlifters, with symptoms ranging from no signs to pain and spasms. Some people are born with thinner vertebrae, making them susceptible to this type of fracture with injury.