Total facetectomy and pars excision at surgery destabilize the spine and must be added to the preoperative risk factors for instability. Calcified annulus, capsule and ligamentum flavum, or complete disc resorption may offer some protection from postoperative instability. The level of instability may be preselected by the proximity to the intercrestal line. It is recommended that during surgical decompression for spinal stenosis, the posterior elements be spared as much as possible to avoid instability after surgery. Factors suggesting instability noted preoperatively or decompression which produces instability suggest that fusion should be combined with decompression.
Spinal fusion is the treatment for postoperative instability.