通过数字化分析对髋臼下螺钉最大通道参数的测量和置钉可行性的评估

Measurement of the maximum corridor parameters of infra-acetabular screw and evaluation of the feasibility of screw insertion by digital analysis

目的:通过对髋臼结构的数字化分析,测量髋臼下螺钉最大通道的参数,并评估髋臼下螺钉置入的可行性。方法:回顾性分析2013年4月至2015年6月行骨盆CT平扫100例患者的骨盆CT数据,男50例,年龄20~84(48.42±17.48)岁,女50例,年龄18~87(55.02±19.54)岁,髋臼骨折、髋关节发育不良和髋臼有金属植入物的患者除外。将CT数据以DICOM格式导入Mimics软件中,生成三维模型,在骨盆入口位找到髋臼下通道在耻骨中段的轴向投影区,在投影区置入虚拟螺钉,分别测出髋臼下最大通道的直径、髋臼下最大通道的长度、入钉点到耻骨联合的距离、入钉点到髂前上棘的距离以及入钉点到骨盆内侧边缘的距离。再将骨盆模型导入3-matic软件中,建立骨盆模型的骨盆前平面及正中矢状面,测量螺钉轴线与2个平面的角度。以5 mm作为置入3.5 mm螺钉的标准,计算螺钉的置入率。结果:在100例病例中,有49%的患者存在直径≥5 mm的髋臼下通道,其中男性置钉率明显高于女性。髋臼下最大通道的平均直径(4.86±1.72)mm,平均长度(94.04±8.29)mm,入钉点到耻骨联合平均距离(60.92±4.84)mm,到髂前上棘平均距离(85.15±6.85)mm,到骨盆内缘平均距离(6.12±3.32)mm。螺钉轴线与正中矢状面的平均角度(-1.38±4.74)°,与骨盆前平面的平均角度(56.77±7.93)°。男女性测量参数除螺钉轴线与骨盆前平面夹角差异无统计学意义外,其余测量结果差异均有统计学意义。骨盆双侧髋臼下最大通道参数差异无统计学意义。结论:所测患者中髋臼下螺钉置入率较低,术前应充分评估置钉可行性。

Objective:To measure the maximum corridor parameters of the infra-acetabular screw and evaluate the feasibility of screw insertion through digital analysis of the acetabular structure.Methods:The pelvic CT data of 100 patients who received plain pelvic CT scan from April 2013 to June 2015 were retrospectively analyzed.There were 50 males,aged 20 to 84 years,with an average age of(48.42±17.48)years,and 50 females,aged 18 to 87 years,with an average age of(55.02±19.54)years.Patients with acetabular fractures,hip dysplasia,and metal implants in the acetabulum were excluded.Import CT data into Mimics software in DICOM format to generate a three-dimensional model,and find the axial projection of the infra-acetabular corridor in the middle of the pubis ramus in the inlet view.A virtual screw was placed in the infra-acetabular space and measure the parameters including the diameter and the length of the maximum corridor,the distance from the insertion point to the pubic symphysis,to the anterosuperior iliac spine and to the medial edge of the pelvis.Then import the pelvic model into 3-matic software,establish the pelvic model anterior pelvic plane and median sagittal plane,and measure the angle between the screw axis and the two planes.A minimum corridor diameter of at least 5 mm was defined as a cutoff for placing a 3.5 mm screw,and calculate the screw insertion rate.Results:In 100 cases,49%of patients had a infra-acetabular corridor with a diameter≥5 mm,and the rate of screw placement in men was significantly higher than that in women.The average diameter of the maximum corridor of infra-acetabular screw was(4.86±1.72)mm,the average length was(94.04±8.29)mm,the average distance from the insertion point to the pubic symphysis was(60.92±4.84)mm,to the anterosuperior iliac spine was(85.15±6.85)mm,and to the medial edge of the pelvis was(6.12±3.32)mm.The mean angle between the axis of the screw and the median sagittal plane was(-1.38±4.74)°,and the mean angle between the axis of the screw and the anterior pelvic plane was(56.77±7.93)°.There are significant differences between male and female measured parameters,except for the angle between the screw axis and the anterior pelvic plane.There was no statistically significant difference in the maximum corridor parameters of infra-acetabular screw on both sides of the pelvis.Conclusion:This study shows that the insertion rate of infra-acetabular screws is low in local patients,and the feasibility of screw insertion should be fully evaluated before surgery.