Vertebral displacement in spondylolisthesis.

The causes of sagittal displacement in 162 patients with isthmic spondylolisthesis and 81 with degenerative spondylolisthesis have been assessed. The slip ratio was compared with joint mobility, the presence of spina bifida, the lumbosacral angle, a self-assessment of previous athletic ability at school and childhood injuries. There was a correlation between the slip ratio and the lumbosacral angle in isthmic spondylolisthesis ( = 0.39, p < 0·01); but this may be secondary. Metacarpophalangeal joint hyperextension correlated with slip ratio (r = 0·26, p < 0·05). There was no significant difference in slip ratio between the patients with and without spina bifida. Those patients with a childhood injury before 11 years of age had greater displacement than those with a later injury, but this did not reach statistical significance. Many patients with degenerative spondylolisthesis rated their athletic ability at school as 'poor'.