Radiological and functional outcomes of high-grade spondylolisthesis treated by intrasacral fixation, dome resection and circumferential fusion: a retrospective series of 20 consecutive cases with a minimum of 2 years follow-up.

PURPOSE

Major concern during surgery for high-grade spondylolisthesis (HGS) is to reduce lumbosacral kyphosis and restore sagittal alignment. Despite the numerous methods described, lumbosacral fixation in HGS is a challenging technique associated with high complication rate. Few series have described outcomes and most of the results are limited to lumbosacral correction without global sagittal alignment analysis. This study aims at analyzing clinical and radiological outcomes of HGS patients treated with intrasacral rods on full spine radiographs.

METHODS

HGS patients (Meyerding III or higher) operated between 2004 and 2014 were reviewed. All patients underwent full spine stereoradiographic images. After L5 and S1 decompression, reduction and circumferential fusion with intrasacral rod fixation and fusion up to L4 were performed under fluoroscopy. The entry points for S1 screws were located 3-5 mm above and 5 mm lateral to the first sacral hole, toward the promontory. The two short distal fusion rods were then positioned into the sacrum guided by anteroposterior fluoroscopy using Jackson's technique. Then, sacral dome resection was performed and a PEEK cage was impacted in L5S1 after reduction. Postoperatively, the hip and knee were kept flexed at 45° for 1 week and extended progressively. Preoperative, 3 months postoperative and last follow-up (> 2 years minimum) clinical and radiographic data were collected. Sagittal parameters included lumbosacral angle (LSA), olisthesis, T1 spinopelvic inclination (T1SPi) and spinopelvic parameters.

RESULTS

20 HGS patients were included (8 ptosis, 5 Meyerding IV). The mean age was 14 years. At final FU (7.2 years ± 3), LSA kyphosis and olisthesis were reduced (65° ± 14 vs 99° ± 11, p < 0.001 and 81% ± 19 vs 45% ± 18, p < 0.001, respectively). While L1L5 lordosis decreased, T1T12 kyphosis increased. At FU, global alignment with T1SPi was - 6° ± 3. No significant loss of correction was observed. Regarding complications, ten patients presented transient L5 motor deficit that occurred when patients were put in standing position. However, all recovered before 3 months postoperatively.

CONCLUSION

Intrasacral rod fixation appears to be an effective technique to correct LSA kyphosis, compensatory hyperlordosis and restore global sagittal alignment with a postoperative T1SPi corresponding to the value of the asymptomatic subject and achieve fusion. However, it remains a demanding technique with high risk of transient neurologic complications.