A standard canulated screw may not fit up to 1/3 of the patients treated percutaneously for anterior column acetabular fractures-A pilot study

Abstract

A proper evaluation of the narrowings and length of the anterior acetabular column would offer better predictability and precision for implant insertion in the case of an acetabular fracture.

Objective: To determine the diameter and length of the safety corridor of the anterior column of the acetabulum in patients with available pelvic computed tomography (CT), analyze the obtained measurements against those of a standard 6.5-mm implant, and verify possible sex differences regarding these measurements. A secondary aim was to develop a method for measurement of the anterior column of the acetabulum based on CT images.

Materials and methods: In 200 CT scans of hemipelvises we measured the diameter of two areas of narrowing and the length of the safety corridor of the anterior column. The images were submitted to multiplanar reformatting adjusted to a plane orthogonal to the bone corridor, drawn at the level of the superior pubic ramus.

Results: Measurement #1 had a mean value of 8.12 (2.27) mm in the overall sample and median values of 9.03 (7.76-10.48) mm in men and 6.77 (5.44-7.19) mm in women. Measurement #2 had a mean value of 7.29 (2.19) mm and median values of 8.23 (7.18-9.82) mm in men and 5.9 (4.65-7.19) mm in women. Measurement #3 had a mean value of 109.53 (13.66) mm in the overall sample and median values of 117.17 (112.9-122.9) mm in men and 100.91 (90.95-111.17) mm in women (p<0.001 all three measurements). Measurement #1 was smaller than 6.5 mm in 22.5% of the patients (of whom 90% were women). Measurement #2 was smaller than 6.5 mm in 35% of the patients (of whom 80% were women).

Conclusions: This study proposed an anatomic evaluation of the anterior column of the acetabulum using conventional CT images The areas of narrowing in the anterior column had an average of 8.12 mm at the level of the pubic tubercle and 7.29 mm at the level of the acetabular fossa. The mean length of the safety corridor was 109.53 mm. In 35% of the cases, a 6.5 mm percutaneous screw would have violated the cortical bone of the safety corridor.

Keywords: Acetabular anatomy; Acetabular fracture; Anterior acetabular column; Anterior acetabular fixation; Anterior column anatomy; Anthropometric measurement; Computed tomography; Minimally invasive fixation; Percutaneous fixation; Preoperative planning; Safety acetabular corridors; Template.