1. The percentage of pseudarthrosis developing in spine-fusion operations in the lumbosacral region may be reduced by an adequate amount of bone of good texture, firmly implanted and free from infection.
2. The possibility of pseudarthrosis should be discussed with the patient before operation in every instance, so that he is forewarned, and so that consent for repair may more readily be obtained, when necessary.
3. One should avoid covering any greater number of spinal intervals than are absolutely essential in performing a fusion at the lumbosacral juncture, but the fusion should always extend to and include the sacrum.
4. For statistical and practical purposes, it is useless to report a series of spine fusions at the lumbosacral juncture without control of the series by biplane roentgenograms, taken with the patient in flexion and extension, and with right and left bends. The roentgenograms should then be accurately superimposed. Furthermore, even with such roentgenograms, a few instances of pseudarthrosis in any series will fail to be recognized.