The evolution of spondylolysis into spondylolisthesis during adult age

Over a period of two and a half years 7 cases of isthmic spondylolisthesis in adults were observed. Radiographs which had been taken from 7 to 28 years previously, when the patients were aged 27 to 44 years, revealed a spondylolysis in which slipping was either absent or almost imperceptible. In 5 cases the radiographs revealed a gradual increase of vertebral slipping over the years and in all these cases the onset and progression of the listhesis was associated with a decrease in the height of the underlying disc. These observations do not support the widely held view that spondylolysis gradually evolves into spondylolisthesis only during childhood or adolescence. On the contrary, they indicate that it may be initiated and become progressive during adult age.