[Different interbody fustion cages and combined fixation through intermuscular approach for lumbar diseases:a case control study].

To explore the clinical effect of combined fixation and interbody bone grafting through intermuscular approach with different fusion cages in the treatment of single segment lumbar diseases.

From June 2014 to December 2016, the clinical data of 123 cases of single segment lumbar diseases were analyzed retrospectively, including 44 males and 79 females, aged 22 to 60 years old, with the diseases course of 6 to 84 months. The disease types involved lumbar disc degeneration in 65 cases, lumbar spinal stenosis in 30 cases, MeyerdingⅠslip in 21 cases, giant lumbar disc herniation in 7 cases. Lesions was L_{3, 4} in 5 cases, L_{4, 5} in 101 cases, L₅S₁ in 17 cases. According to the application of different interbody fusion cage, patients were divided into single common cage group, double common cage group and banana type cage group. The operation time, intraoperative hemorrhage, postoperative incision drainage fluid and incision length were observed in three groups; VAS score of lumbar incision and JOA score of preoperative and final follow up were recorded 72 hours after operation;the intervertebral space height, Cobb angle of lumbar coronal and sagittal plane before and after operation, and interbody fusion 12 months after operation were observed by imaging data.

There was no significant difference in incision length, operation time, intraoperative bleeding volume, postoperative drainage volume and VAS score of lumbar incision 72 hours after operation among three groups (P>0.05). All cases were followed up for 12 to 36 (23.70±4.52) months. The height of intervertebral space in three groups recovered significantly (P<0.05), at the last follow-up, there were different degrees of loss, the loss degree of single common fusion cage group>banana type fusion cage group>double common fusion cage group. At the last follow-up, the Cobb angle in the coronaland sagittal planes of the three groups were significantly improved (P<0.05). During the follow-up, there were 42 cases of fusion cage subsidence, including 26 cases in the single common cage group, 5 cases in the double common cage group, 11 cases in the banana cage group, the difference was statistically significant (P<0.05). At 12 months after operation, the interbody fusion rate was 83% in the single common cage group, 95% in the double common cage group and 90% in the banana cage group, the interbody fusion rate in the two common cage group and the banana cage group was better than that in the single common cage group. No obvious degeneration was observed in the adjacent segments. At the last follow-up, the JOA scores of the three groups were statistically significant (P<0.05). The incidence of single common fusion cage group was 10%(4 / 42), that of double common fusion cage group was 9%(4 / 43), and that of banana fusion cage group was 10%(4 / 39). There was no significant difference among the three groups.

Through the intermuscular approach, single pedicle screw and contralateral facet screw were used for fixation, and single common fusion cage, double common fusion cage or banana type fusion cage were used for interbody grafting to treat single segment lumbar disease. Although the application of different fusion cage could not increase the axial strength of fixed segment, the speed of fusion was accelerated by increasing the contact area, and the quality of the fusion cage reduces the settlement of the cage and the loss of the height of the intervertebral space. Therefore, two interbody fusion cages implanted in one side are of positive clinical significance for the fixation of unilateral pedicle screw combined with contralateral facet screw, without prolonging the operation time and increasing the complications.