Reexamination of Pelvic Inlet and Outlet Images Using 3-Dimensional Computed Tomography Reconstructions

Abstract

This study demonstrated that the ideal angle to obtain inlet views should be approximately 25 degrees and to obtain outlet views should be approximately 45 degrees during screening x-rays to evaluate patients who were diagnosed with pelvic injuries. Application of these new values in the clinical practice would provide higher rates of adequate studies and further prospective clinical studies should be performed to validate these parameters.

Radiological evaluation of pelvic inlet and outlet radiographic view in Indian population

“…However, if the views are not orthogonal, there may be a large area, which is not visualized unless the image intensifier is further tilted until the second view is orthogonal to the first one. 12 In a study done by Ricci et al 7 in 2010, the inlet angle was 25 and outlet angle was 60 , which suggests greater variation in the inlet angle whereas similar result for outlet view as compared to present study. Also, the data of Ricci et al was re-evaluated by Pekmezci et al 12 using 3D reconstruction suggesting the ideal inlet angle to be 25 and ideal outlet angle to be 45 .…”

“…12 In a study done by Ricci et al 7 in 2010, the inlet angle was 25 and outlet angle was 60 , which suggests greater variation in the inlet angle whereas similar result for outlet view as compared to present study. Also, the data of Ricci et al was re-evaluated by Pekmezci et al 12 using 3D reconstruction suggesting the ideal inlet angle to be 25 and ideal outlet angle to be 45 . Though these data from the study may have variations from the current study but it does reinforce the fact that there is significant deviation of the inlet and outlet angle from the traditional practice.…”

The Utility of the Hyperinlet View in Posterior Fixation of Pelvic Ring Injuries

“…The traditional inlet angle is defined as the angle formed by the line tangent to the anterior border of the upper and second sacral segments and the anteroposterior plane in the center of the sacrum. [9][10][11] To date, there have been numerous studies describing the ideal angle used in the acquisition of the inlet view with values ranging from 19.4 to 33 degrees. [9][10][11] However, considering the inlet view establishes the anterior margin of the osseous fixation pathways in the posterior pelvic ring; it provides poor visualization of the spinal canal, which is the posterior limit of the osseous fixation pathway.…”

“…[9][10][11] To date, there have been numerous studies describing the ideal angle used in the acquisition of the inlet view with values ranging from 19.4 to 33 degrees. [9][10][11] However, considering the inlet view establishes the anterior margin of the osseous fixation pathways in the posterior pelvic ring; it provides poor visualization of the spinal canal, which is the posterior limit of the osseous fixation pathway. The hyperinlet angle is formed by the posterior border of the upper and second sacral segment and the anteroposterior plane.…”

“…7,8 The inlet view is used to profile the anterior body of S1 and has been shown to be between 19 and 33 degrees of cranial tilt. [9][10][11] The outlet view is defined to be perpendicular to the body of S1 and S2 and has been shown to be between 42 and 60 degrees of caudal tilt. [9][10][11] The lateral sacral view can provide additional information and help define the alar bodies and the osseous upper sacral nerve root tunnels but can be challenging in the obese patient.…”