| Objective(s): The purpose of this study is to evaluate and analyze the clinical efficacy of lamina screws in patients with basilar invagination(BI)with High-Riding Vertebral Artery(HRVA)and to provide some basis for the selection of the posterior approach C2 screw placement.Methods: A retrospective analysis of 54 BI patients who underwent occipitocervical fusion(OCF)at our hospital from January 2019 to March 2022 was performed,and clinical indicators such as age,gender,height,weight,operative time,intraoperative blood loss,and JOA score at preoperative and final follow-up were counted.The imaging parameters measured included: Cervicomedullary Angle(CMA)and Basion-dental Interval(BDI)before surgery and at the last follow-up,the internal height of the C-2 lateral mass and the isthmus widths,the pedicle width,distance from the apex of vertebrae artery groove to the upper facet joint surface(a)and horizontal distance from the entrance of VAG to the vertebrae canal(e)and the screw offset distance.Patients were divided into: non-HRVA and HRVA groups according to the presence or absence of HRVA,where the HRVA group could be further divided into HRVA pedicle screw group and HRVA lamina screw group,and the clinical efficacy and screw accuracy of each group were analyzed.At the same time,the pedicle can be divided into types I-IV according to the pivotal vertebral artery foramen typing,and the precision of pedicle screws was analyzed in the presence or absence of HRVA and stenosis of the pedicle,respectively.The data were statistically analyzed using chisquare test,paired t-test,and χ2 test to assess the clinical efficacy of lamina screw and the precision of pedicle screw placement.Results: 1.general results: of the 54 patients,20(37%)were male and 34(63%)were female,with a mean age of 45.1±10.1 years and a mean follow-up time of20.6±8.0 months.of the 108 pedicles,46(45.6%)were HRVA pedicles and 62(57.4%)were non-HRVA pedicles;60(55.6%)were stenotic pedicles and 48(44.4%)were non-stenotic pedicles.No vertebral artery injury,nail dissection,or revision was observed in all cases;wound infection was observed in one case and cerebrospinal fluid leakage was observed in two cases.2.Efficacy results: CMA,BDI,and JOA scores improved in the three groups at the last follow-up compared with preoperative scores(P < 0.05),and there was no significant difference in improvement between groups(P > 0.05).The operative time and intraoperative bleeding in the non-HRVA and HRVA pedicle screw groups were smaller than those in the HRVA pedicle screw group(P < 0.05).3.Screw precision results: 1)Overall screw precision: the HRVA pedicle screw group had the highest precision,the non-HRVA group had the second highest precision,and the HRVA pedicle screw group had the lowest precision(P < 0.05).2)Pedicle screw precision: the precision of non-HRVA pedicle screws was higher than that of accompanying HRVA pedicle screws(P < 0.05),and the precision of nonstenotic pedicle screws was higher than that of stenotic pedicle screws(P <0.05).The accuracy of type III tight low-infraction pedicle screws was significantly lower than that of type I loose low-infraction type(P < 0.05).Conclusion(s): The use of pedicle screws for fixation in patients with basilar invagination with high-riding vertebral artery is an acceptable alternative in cases where pedicle screws cannot be implanted.In patients with basilar invagination with type III narrow and low pedicles who also have stenotic pedicles,translaminar screws or other nailing methods that can reduce damage to the vertebral artery can be chosen to avoid damage to the vertebral artery due to low screw accuracy. |
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