G2143 Fs odi 9-15mo > 22Functional status measured by the oswestry disability index (odi version 2.1a) at one year (9 to 15 months) postoperatively was greater than 22 and functional status measured by the odi version 2.1a within three months preoperatively and at one year (9 to 15 months) postoperatively demonstrated an improvement of less than 30 points