A series of 202 patients (133 men, 69 women) with lumbar spondylolysis were examined radiographically on two occasions, first at the time of diagnosis and later at a follow-up, after an observation period of. 20 years or more.The films from patients in groups without and with moderate and severe olisthesis were evaluated with respect to variables describing lumbosacral lordosis, wedging of the spondylolytic vertebra, lengths of the transverse processes and iliolumbar ligaments, disk height, progression of slipping, and influence on measured olisthesis of lumbar spine flexion and extension at the radiographic examination. The evaluation was made with special attention to possible signs which could be predictive for the prognosis of vertebral slipping.Progession of slipping did not differ between patients diagnosed as adults or adolescents. Reduction of disk height was correlated to the degree of slipping present at the initial examination and to the progression of olisthesis. Flexion and extension of the lumbar spine did not modify the degree of olisthesis. Data concerning the lengths of the transverse processes and the iliolumbar ligaments, and lumbar lordosis, cannot be used for prognostic purposes. The lumbar index reflecting the degree of wedge deformity of the spondylolytic vertebra was shown to be the only variable of prognostic value for the development of vertebral slipping.Radiographically demonstrable lumbar spine instability in spondylolytic patients has been suggested as a cause of olisthesis (12). Other studies did not confirm the existence of instability, although a large range of mobility, characteristic of any spine with disk degeneration, could be recorded at the olisthetic level (14,15,16). The clinical significance of instability recorded radiographically has not been critically evaluated. Marked lumbosacral lordosis (2, 11), backward displacement of the sacrum (22), increased wedging of the spondylolytic vertebra (21, 23), and iliolumbar ligament laxity (1,4,8), have all been proposed as risk factors for spondylolisthesis. These factors and their relative importance for the development of olisthesis have, however, not been analysed in any larger series for spondylolytic patients.The present investigation was designed against this background. Its aim was to explore the possible existence, at diagnosis, of predictive radiographic abnormalities related to the slipping of the vertebra. The investigation forms a part of a more extensive work on the prognostic and therapeutic aspects of spondylolysis and spondylolisthesis in patients with a follow-up time of more than 20 years.
MaterialDefinitions. Spondylolysis is here defined as a defect in the pars interarticularis of the vertebra, and spondylolisthesis (olisthesis, slipping) as an anterior displacement (forward slipping) of the lytic vertebra in relation to the vertebra below.Basis for the investigation. A series of 383 consecutive patients with bilateral lumbar spondylolysis, radiographically diagnosed not later than 1961 at Karolinska Sjukhuset...
