髋臼后柱骨折经皮逆行拉力螺钉固定的三维重建模型研究

目的 为髋臼后柱骨折经皮逆行拉力螺钉固定提供应用解剖学基础. 方法 收集60个正常成人骨盆的螺旋CT扫描数据,重建骨盆三维模型.模拟逆行拉力螺钉固定,在髋臼后柱置入虚拟三维圆柱体.计算其最大直径、长度、置入角度以及置入点(A)到坐骨结节远端(B)的距离.同时在相同的三维重建骨盆模型上,垂直髋臼内侧面对后柱进行重切,每间隔1 cm取一个截骨面,测量每个截骨面的内外径和上下径. 结果 男性半骨盆58个,女性半骨盆62个.虚拟三维圆柱体的平均最大直径为(13.16±1.45)mm,虚拟三维圆柱体与水平面、冠状面和矢状面的夹角分别为72.02°±6.05°、14.71°±6.98°和8.61°±3.96°,置入点位于坐骨结节内外侧缘的中线上,AB间距离为(15.18±1.97)mm.平均最小内外径和上下径分别为20.11 mm、19.19 mm,明显大于虚拟三维圆柱体的平均最大直径.虚拟三维圆柱体的直径、长度、与矢状面的夹角在男女之间的差异有统计学意义(P＜0.001). 结论 髋臼后柱可容纳7.3 mm的拉力螺钉,但男女的进针角度不同.螺钉的直径不能仅仅靠截骨面的直径确定.

Percutaneous retrograde screw fixation for posterior column fractures of acetabulum: a study by virtual three-dimensional model

Objective To provide evidence of applied anatomy for the placement of pereutaneoas retrograde lag screws in the treatment of posterior column fractures of acetabulum. Methods Virtual three-dimensional models were reconstructed from computed tomography (CT) scans obtained from 60 adult patients without any bony problem. Virtual cylindrical implants were placed intraosscously into the posterior column of acetabulum. The maximum diameter, length and insertion direction were determined for screws.The distance between the insertion point (A) of virtual cylindrical implant and the distal end of the ischiadic tuberosity (B) was measured. In the same model, cross-sections of the pelvic posterior column was made at interval of 1 cm to measure their diameters. Results One hundred and twenty (58 male, 62 female) hemi-pelvic models were obtained. The mean maximum diameter of virtual cylindrical implant was 13. 16 ±1.45 mm and the mean angles to the transverse, coronal and sagittal planes were 72.02°± 6. 05°, 14. 71°±6. 98° and 8.61°±3.96° respectively. The insertion point was on the central line between the medial and lateral margins of ischiadic tuberosity. The distance between points A and B was 15.18 ± 1.97 mm. The smallest diameter of the posterior column was larger than the maximum diameter of the corresponding virtual cylindrical implant. Differences in the diameter, length, angle to sagittal plane of virtual cylindrical implant between the male and female were of statistical significance ( P ＜ 0. 001 ). Conclusions The posterior column can accommodate screws of 7.3 mm, but the insertion angle should vary from the male to female. The screw size for percutaneous fixation of posterior column fractures of aeetabulum should not be based solely on the measurement of cross-sectional diameter.