Safety is reported as the number and types of complications and reoperation encountered.
Efficacy is measured in terms of a 10-point combined pain and function scale score and the fusion status. Results will only be reported for 12 and 24 months. There were 47 males and 65 females with an average age of 51. The outcome was rated as excellent if the combined score was 9 or 10, good if the score was 7 or 8, fair if the score was 5 or 6, and poor if the score was 4 or less. Fusion was based on radiographic evaluation by the investigator.