In the experiments in which the spinous processes alone were fused, there were practically no changes in the articular facets.

When, in addition to the fusion of the spinous processes, sections of bone were thrown up from the laminae and over the articular facets, secondary changes took place in the facets that had not been destroyed. In one experiment of 205 days' duration, several of the articulations were partially arthrodesed.

If, in conjunction with the fusion of the spinous processes, the articular facets were destroyed on one side, marked changes took place in the articular facets of the opposite side. After 160 days very slight remnants of articular cartilage were found in some of the undestroyed articulations. No signs of joint spaces were found, although some joints showed the persistence of two articular cartilages.

There was marked distortion of the plane of the facets with heaping up of bone about them on the side which had not been operated upon, as well as on the side upon which an operation had been performed.

The changes described took place in normal spines. One would expect greater changes if a diseased condition or abnormal pressure as in scoliosis were present.