The use of mechanical etiology to determine the efficacy of active intervention in single joint lumbar intervertebral...

A group of patients were matched for clinical diagnosis, severity of symptoms, and duration and type of preoperative management. The patients all had intractible sciatica. They were submitted to this study by nine participating authors working independently in various centers in North America. Of these patients, those with spondylolysis or spondylolisthesis or those who had had previous surgery were excluded. The patients were treated by chemonucleolysis or by surgery. The information in the various parts of the protocol allowed: (1) identification of the joint at risk, (2) the generic type of injury (torsion or compression), and (3) the procedure of choice for each patient. The outcome was predicted from the operation report using a demerit system for each deviation from the procedure of choice. It was possible to predict from this information only, with a high degree of accuracy (94%), the outcome 2 years later. It was also possible to compare the efficacy of the various types of intervention, especially chemonucleolysis versus a variety of surgical procedures.