Effectiveness Of Nano-Hydroxyapatite/Polyamide-66 Cage In Interbody Fusion For Degenerative Lumbar Scoliosis

Objective: To explore the effectiveness of nano-hydroxyapatite/polyamide66(n-HA/PA66)cages in interbody fusion for degenerative lumbar scoliosis(DLS).Methods: A retrospective case-control analysis was designed and conducted for 70 patients(68 intervertebral spaces were fused with n-HA/PA66 cages in 43 patients and 39 intervertebral spaces were fused with PEEK cages in 27 patients)who underwent posterior decompression and interbody fusion with correction of deformity for DLS between January 2013 and August 2016.There was no significant difference in gender,age,weight,body mass index,direction of convex,degree of apical rotation,fusion level,osteoporosis,pre-operative intervertebral height of fusion segments,coronal cobb angle,visual analogue score(VAS),and modified Oswestry Disability Index(ODI)between 2 groups(P>0.05).The operation time,intraoperative blood loss,postoperative drainage,hospital stay,and complications of the operation were recorded.Modified ODI,VAS,and MacNab criterion were adopted to assess clinical outcomes.Radiographic indexes,including intervertebral height of fusion segment,coronal cobb angle,disc insertion depth,and the bone graft fusion rate,were also evaluated.Results: There was no significant difference in operation time,intraoperative blood loss,postoperative drainage,hospital stay and the incidence of perioperative complications between 2 groups(P>0.05).Patients in n-HA/PA66 cage group were followed up 18-62 months(mean,30.9 months)and the patients in PEEK cage group were followed up20-58months(mean,33.0 months).There was no significant difference in follow-up time(P>0.05).There was one patient suffered from cage retropulsion with symptoms in n-HA/PA66 group.The intervertebral height of fusion segments after operation were significantly improved when compared with preoperative ones in both groups(P<0.05).The loss of the intervertebral height was 0.50±1.79 mm and 1.72±1.43 mm in n-HA/PA66 cage group and PEEK cage group,respectively,and there was significant difference in the loss of the intervertebral height between groups(P<0.05).The coronal Cobb angle after operation were significantly improved when compared with preoperative ones(P<0.05),and no significant difference was found between 2 groups at each time point(P>0.05).The disc insertion depth showed no significant difference between each time point after operation in 2 groups(P>0.05)and between 2 groups in each time pointafter operation(P>0.05).Bony fusion were obtained in all patients at last follow-up.The VAS score and modified ODI in both groups were improved after operation compared with those before operation(P<0.05),and no significant difference was found in VAS score and modified ODI between 2groups at each time points.According to the MacNab criteria,the excellent and good rates at last follow-up was 88.4% and 85.2% in n-HA/PA66 cage group and PEEK cage group,respectively,and no significant difference was found between 2 groups(P>0.05).Conclusion: The n-HA/PA66 cage can effectively restore and maintain the IH of fusion segment with favorable clinical effects in surgical treatment for DLS.It is an optional substitute material for interbody fusion.