Stress views in the comparative assessment of spondylolytic spondylolisthesis.

Patients with spondylolytic spondylolisthesis were examined in six different positions to detect segmental instability. The amount of displacement was determined on lateral spot radiographs, taken in recumbent, standing, flexion, extension, axial compression, and traction positions in each patient. An error analysis was also performed. Examination in axial compression-traction was found to be a significantly better method for detection of segmental instability compared with standing-recumbent, or flexion-extension radiographs. In addition, the compression-traction method exhibited a higher sensitivity for identification of instability (73%) than standing-recumbent (33%) or flexion-extension (20%) views. The total error in the determination was small, +/- 2.5% (95% CL), providing a careful and controlled technique was used.