Mid- and long-term outcomes of hybrid surgery combined Dynesys fusion and non-fusion stabilization in the treatment of degenerative lumbar diseases / 中华骨科杂志

ABSTRACT

Objective:To evaluate the mid- and long-term outcomes of Dynesys hybrid surgery (in some segments act as a non-fusion device, in other segments act as an alternative of rigid fixation in combination with interbody fusion) in the treatment of multi-segmental lumbar degenerative disease (LDD).Methods:The data of 27 patients who received Dynesys hybrid surgery (hybrid group) for the treatment of LDD from May 2011 to September 2016 and completed the follow-up were retrospectively analyzed. Among them, there were 8 males and 19 females; their average age was 59.1±11.9 years (23-78 years). Main diagnosis: 13 cases of lumbar spinal stenosis, 14 cases of lumbar disc herniation; 4 cases of combined lumbar dynamic position instability, 7 cases of combined lumbar spondylolisthesis. There were 15 cases of two-segment disease, 11 cases of three-segment disease, and 1 case of four-segment disease. Segments distribution: 9 cases of L 3-L 5, 6 cases of L 4-S 1, 7 cases of L 3-S 1, 4 cases of L 2-L 5, and 1 case of L 2-S 1. Midline incision was used to exposure, followed by bilateral pedicle screws implantation, and interbody fusion cage with bone grafting were performed at the fusion level. Twenty-seven patients who underwent TLIF+rigid internal fixation during the same period were included as the control group. Clinical outcomes were measured by visual analog scale (VAS) for low back pain and leg pain, and Oswestry disability index (ODI). Radiological outcomes included fusion rate, intervertebral disc height (DH) of surgical segments and the proximal adjacent segment, range of motion (ROM) of non-fusion segments and the proximal adjacent segment. At the same time, the occurrence of complications was observed. Results:Patients of Hybrid group and control group were followed up for an average of 83.8±20.9 months (48-112 months) and 87.3±16.2 months (53-114 months), respectively. Baseline data of the two groups (average follow-up time, age, gender, surgical level, diagnosis) showed no significant difference. The operation time (183.0±27.8 min) and intraoperative blood loss (301.9±178.9 ml) in the hybrid group were significantly lower than those in the control group (operation time t=2.337, P=0.023; blood loss t=2.706, P=0.01). At the final follow-up, the VAS scores of low back pain and leg pain (low back pain t=12.164, P<0.001; leg pain t=20.603, P<0.001), as well as ODI were significantly improved ( t=22.827, P<0.001). A total of 32 segments received TLIF+Dynesys stabilization and 35 segments received Dynesys non-fusion stabilization in the hybrid group, with 28 segments (87.5%) achieved solid fusion at 1-year follow-up. There were 67 fusion segments in the control group, and the fusion rate at 1-year follow-up was 85.1%. DH of non-fusion segments were lower than that before surgery with statistical significance at final follow-up ( t=2.647, P=0.012), while DH of the fusion segments in the hybrid group and the surgical segments in the control group increased compared with that before surgery at the final follow-up. A certain degree of ROM (2.4°±1.5°) was retained of the non-fusion segments at the final follow-up; the ROM of proximal adjacent segments of non-fused segments was significantly smaller than that of proximal adjacent segments of fused segments ( t=2.126, P=0.044). In the hybrid group, screw loosening occurred in 4 patients (8 screws) and adjacent segment degeneration (ASD) occurred in 5 patients. In the control group, screw loosening occurred in 3 patients (6 screws), while ASD occurred in 8 patients. No screw fracture was observed during the follow-up period and no patients received reoperation. Conclusion:Hybrid surgery of Dynesys stabilization combined with interbody fusion is a safe and effective method for the treatment of multi-segmental LDD. Compared with multi-segmental fusion, this lumbar hybrid surgery has the advantages of less trauma and retaining partial segmental ROM.