Kinematic analysis of posterolateral fusion in the lumbosacral spine.

Three cases operated upon with posterolateral fusion in the lumbosacral spine have been subjected to a kinematic postoperative analysis with the aid of a roentgen stereophotogrammetric method. The primarily diseased intervals became comparatively rigid in spite of significant residual mobility, in two of the patients, not until 174 days postoperatively. Three levels of operation displayed unrestricted residual mobility.