Table 3.

Depicts overall preoperative, postoperative values, difference between preoperative and postoperative values and statistical significance of the change in the value of outcome instruments (SD = standard deviation). Mean of change in score obtained by subtracting mean final follow-up score from mean preoperative score. (ODI = Oswestry disability index; RMDQ = Roland Morris Disability Questionnaire; SF-12 PCS = Physical component of Short Form-12; SF-12 MCS = Mental component of Short Form-12).

Outcome instrument	Preoperative mean ± SD	Final follow-up mean ± SD	Mean of change in score ± SD	95% Confidence interval of change in score	P - value
ODI	45.8 ± 15.6	21.1 ± 18.5	24.0 ± 20.5	19.0 to 29.1	<0.0001
RMDQ	12.8 ± 4.8	5.6 ± 5.5	7.1 ± 5.8	5.7 to 8.5	<0.0001
SF-12 PCS	30.2 ± 6.0	41.2 ± 11.0	−11.1 ± 11.1	−13.8 to −8.3	<0.0001
SF-12 MCS	45.6 ± 12.0	51.4 ± 10.9	−6.1 ± 13.0	−9.3 to −2.9	<0.0001