A Novel Staging Method Based On The Spatial Distribution Pattern Of Cement In The Vertebral Body

Objective:To summarize the spatial distribution pattern of cement in the vertebral body after vertebroplasty,a new and relatively accurate and simple typing method reflecting threedimensional space was constructed by using postoperative ortho-lateral radiographs,so as to better describe the spatial distribution of cement in the vertebral body and provide a more reliable basis for further basic research and clinical work.Methods:A total of 180 patients who underwent percutaneous vertebroplasty(PVP)or percutaneous kyphoplasty(PKP)in the Department of Spine Surgery,Second Hospital of Jilin University from April 2014 to September 2018 were retrospectively analyzed.Patients.Patients’ gender,age,bone mineral density(T-Score),body mass index,duration of symptoms,number of fractured vertebrae,location of fractured vertebrae,anterior margin compression of injured vertebrae,middle compression of injured vertebrae,posterior convexity angle of injured vertebrae,volume of cement injected,cement leakage,and postoperative frontal and lateral views were collected.The basic clinical characteristics of the patients in the cohort were reviewed by statistical description and based on 2 markers in the postoperative orthopantomogram: the midline of the spinous process(A line)and the line connecting the upper and lower endplates(B line);and 1 marker in the lateral view: the line connecting the anterior and posterior edges of the vertebral body(C line).Most of the cement contact markers were recorded as 1(A1,B1,and C1),and the uncontact markers were recorded as(A2,B2,and C2),and the diffusion pattern of cement in the vertebral body was divided into 8 types by these markers: Type Ⅰ(A1B1C1),Type Ⅱ(A1B1C2),Type Ⅲ(A1B2C1),and Type Ⅳ(A1B2C2),Type Ⅴ(A2B1C1),Type Ⅵ(A2B1C2),Type Ⅶ(A2B2C1),and Type Ⅷ(A2B2C2).The number and proportion of different distribution patterns of postoperative frontal and lateral radiographs were analyzed in 180 patients.The postoperative slices of 180 patients were classified according to this typing method after1,4,and 6 weeks of training by three doctors with different levels of spinal surgery.The consistency,accuracy,and correctness of the typing were evaluated by several physicians separately.Results: Out of a total of 180 patients with a total of 291 vertebrae included.Of these,146(50.17%)were type Ⅰ;52(17.87%)were type Ⅱ;18(6.19%)were type Ⅲ;28(9.62%)were type Ⅳ;8(2.75%)were type Ⅴ;52(6.87%)were type Ⅵ;6(2.06%)were type Ⅶ;and 4(4.47%)were type Ⅷ.Bone cement leakage was observed in 14 cases of type Ⅰ(9.59%);4 cases of type Ⅱ(7.69%);4 cases of type Ⅲ(22.22%);7 cases of type Ⅳ(25.00%);0 cases of type Ⅴ(0.00%);3 cases of type Ⅵ(12.50%);1 case of type Ⅶ(16.67%);and 22.22% of type Ⅷ 2.Adjacent vertebral fractures type Ⅰ 8(5.48%);type Ⅱ 3(5.77%);type Ⅲ 3(16.67%);type Ⅳ 5(17.86%);type Ⅴ 0(0.00%);type Ⅵ 2(8.33%);type Ⅶ 1(16.67%);Ⅷ 2(22.22%).3 subtypes of Kendall’s W test results: the Kendall’s W coefficients were 0.94(P<0.01),0.90 P<0.01,0.80(P<0.01).the mean accuracy,recall and correctness of Doctor1 in the 3 typings were0.70,0.76 and 0.86.The mean accuracy,recall and correctness of Doctor2 in 3 fractions were 0.66,0.75 and 0.81.The mean accuracy,recall and correctness of Doctor3 in 3fractions were 0.68,0.74 and 0.79.Conclusions:1.The typing method reflects the diffusion pattern of cement and the relative spatial distribution in the vertebral body relatively accurately and easily through the postoperative frontal and lateral radiographs.2.The overall accuracy and correctness of the classification by several doctors were relatively high,reflecting the more rigorous and precise definition of the typing method.3.The typing method has high reliability from the methodological point of view,and there is strong consistency in the observation results between different observers.The method is stable and reliable,easy to master after simple training,with low learning costs and a gentle learning curve,which is conducive to promotion.4.Types Ⅲ,Ⅳ,Ⅶ and Ⅷ have relatively the highest incidence of cement leakage and adjacent vertebral re-fracture,and the formation of such a distribution should be avoided as much as possible in clinical practice.