Efficacy comparison of posterior atlas uniaxial and polyaxial screw instrumentation and fusion with bone graft for Gehweiler type IIIb atlas fracture / 中华创伤杂志

ABSTRACT

Objective:To compare the efficacy of posterior atlas uniaxial and polyaxial screw instrumentation and fusion with bone graft for Gehweiler type IIIb atlas fracture.Methods:A retrospective cohort study was performed to analyze the clinical data of 36 patients with Gehweiler type IIIb atlas fracture admitted to Henan Provincial People′s Hospital from January 2015 to October 2020. There were 29 males and 7 females, with age range of 23-82 years [(48.8±15.5)years]. All patients were treated with posterior atlas screw-rod internal fixation and fusion with bone graft, of which 14 received atlas uniaxial screw internal fixation (uniaxial screw group) and 22 received atlas polyaxial screw internal fixation (polyaxial screw group). The operation time and intraoperative blood loss were compared between the two groups. The atlas fracture union rate and atlantoaxial posterior arch bone fusion rate were compared between the two groups at 3 months and 6 months after operation. The anterior atlantodental interval (ADI), basion-dens interval (BDI) and lateral mass displacement (LMD) were compared between the two groups to evaluate the reduction of fracture fragments before operation, at 1, 3, 6 months after operation and at the last follow-up. At the same time, the visual analogue scale (VAS) and neck dysfunction index (NDI) were compared between the two groups to evaluate neck pain and functional recovery. The postoperative complications were observed.Results:All patients were followed up for 12-44 months [(27.2±9.9)months]. There was no significant difference in operation time or intraoperative blood loss between the two groups (all P>0.05). The atlas fracture union rate and atlantoaxial posterior arch bone fusion rate were 85.7% (12/14) and 78.6% (11/14) in uniaxial screw group at 3 months after operation, insignificantly different from those in polyaxial screw group [72.7% (16/22) and 77.3% (17/22)] (all P>0.05). All patients in the two groups achieved bone union and fusion at 6 months after operation. There was no significant difference in ADI between the two groups before and after operation (all P>0.05). The BDI in the two groups did not differ significantly before operation ( P>0.05), but a significantly higher value was found in uniaxial screw group at 1, 3, and 6 months after operation and at the last follow-up [(5.9±1.3)mm, (5.8±1.3)mm, (5.9±1.2)mm and (5.8±1.2)mm] than in polyaxial screw group [(3.1±0.6)mm, (3.1±0.6)mm, (3.1±0.6)mm and (3.1±0.6)mm] (all P<0.01). The two groups did not differ significantly before operation ( P>0.05), but LMD at 1, 3, and 6 months after operation and at the last follow-up was (1.6±0.8)mm, (1.5±0.8)mm, (1.5±0.7)mm and (1.5±0.9)mm in uniaxial screw group, significantly lower than that in polyaxial screw group [(4.8±1.6)mm, (4.6±1.6)mm, (4.9±1.6)mm and (4.9±1.6)mm] (all P<0.01). There was no significant difference in VAS between the two groups before operation ( P>0.05). The VAS at 1, 3, and 6 months after operation and at the last follow-up was 3.0(3.0, 4.0)points, 2.0(1.0, 2.0)points, 1.0(0.8, 2.0)points and 1.0(0.0, 1.3)points in uniaxial screw group and was 3.5(3.0, 4.0)points, 2.0(2.0, 3.0)points, 2.0(1.0, 2.0)points and 2.0(1.0, 3.0)points in polyaxial screw group. In comparison, the VAS scored much lower in uniaxial screw group than in polyaxial screw group at 6 months after operation and at the last follow-up (all P<0.01). There was no significant difference in NDI between the two groups before operation ( P>0.05). The NDI at 1, 3, and 6 months after operation and at the last follow-up was 34.9±6.3, 23.4±6.2, 13.9±2.7 and 9.4±2.8 in uniaxial screw group and was 33.2±6.1, 24.4±6.3, 18.1±4.1 and 12.7±3.2 in polyaxial screw group, showing a significantly lower NDI in uniaxial screw group than in polyaxial screw group at 6 months after operation and at the last follow-up (all P<0.01). The complication rate was 21.4% (3/14) in uniaxial screw group when compared to 22.7% (5/22) in polyaxial screw group ( P>0.05). Conclusion:For Gehweiler type IIIb atlas fracture, both techniques can attain atlas fracture union and atlantoaxial posterior arch bone fusion, but the posterior atlas uniaxial screw instrumentation and fusion is superior in reduction of atlas fracture displacement and lateral mass separation, neck pain relief and functional improvement.