Two level pedicle substraction osteotomies for the treatment of severe fixed sagittal plane deformity: computer software-assisted preoperative planning and assessing

To evaluate the efficacy of two level pedicle substraction osteotomies (PSOs) planned preoperatively with a computer software, in the patients with severe fixed sagittal plane deformities. In the literature, there are studies indicating that two level PSOs may be required in severe cases. However, the results of two level PSOs preoperatively planned with computer software-assistance have not yet been reported in the English literature. Severe fixed sagittal plane deformities of 11 patients are described. Preoperative surgical planning was done with the aid of a computer software. Two level PSOs were indicated after the process. After the application of the indicated surgical technique, clinical and radiological results were evaluated in the preoperative, the early postoperative periods and during the last follow-up. The mean sagittal vertical axis was found as 190.5 (range 161-220) mm in the preoperative period, 23.5 (range -27 to 61) mm in the early postoperative period (P < 0.001) (87.7 % correction) and 34.5 (range -3 to 55) mm during the last follow-up (P < 0.001). The mean pelvic tilt (PT) significantly decreased from 38.3A degrees (range 21A degrees-63A degrees) preoperatively to 23.8A degrees (range 18A degrees-42A degrees) postoperatively (P = 0.008) and to 27.5A degrees (range 17A degrees-42A degrees) during the last follow-up (P = 0.042). The mean lumbar lordosis (LL) was 2.8A degrees (range -29A degrees to 20A degrees) preoperatively, -35.6A degrees (range -54A degrees to 23A degrees) early postoperatively (P < 0.001) and -33.6A degrees (range -52A degrees to 20A degrees) during the last follow-up (P < 0.001). The average amount of bleeding was 5345 (range 2600-7415) ml. Although a statistically significant correction was obtained, the mean PT and PI-LL value could not be restored in physiological limits during the last follow-up. Thus, two level PSOs performed after computer software (surgimap) assisted preoperative planning failed to correct severe fixed sagittal plane deformities. Besides, this procedure is of possible risks for major complications such as a result of excessive bleeding. We recommend that two level PSOs should be rarely indicated, but preferred as an alternative technique only in the most severe cases.