Review Question - QID 3571

The obturator oblique-inlet view, as seen in Illustration A, best demonstrates the position of a supra-acetabular screw or pin relative to the tables of the ilium.

Starr et al review their initial results and technique of closed or limited open reduction and percutaneous fixation of acetabular fractures. They defined two groups of patients who may benefit from this technique; elderly patients with multiple comorbidities to facilitate early mobilization and restore hip morphology, and young patients with elementary fracture patterns and multiple associated injuries.

Starr et al describe their operative technique and outcomes for a case series of 3 patients using percutaneous acetabular fixation to augment open reduction of acetabular fractures. The authors state that, for placement of an anterior colum ramus screw, an iliac oblique-inlet (not obturator oblique-inlet) will ensure that the screw is within the medullary canal of the ramus and does not exit anterior or posterior.

Gardner and Nork describe a technique for placement of a large femoral distractor in the supra-acetabular region to compress displaced posterior pelvic ring injuries. They note that the obturator oblique-inlet view is necessary to view the entire length of the pin as well as to ensure that pin remains in bone.

Incorrect answers:
Answer 1: Relationshiop of the screw to the acetabulum is best evaluated with the obturator oblique-outlet view as well as the iliac oblique view
Answer 2: The iliac oblique view is used to ensure the trajectory of the screw is superior to the sciatic notch
Answer 3: The Obturator oblique-outlet view, otherwise known as the "teepee" or "tear drop" view, is used to identify the start for supra-acetabular implant placement
Answer 4: The gluteal pillar is not utilized as a start point when placing supraacetabular fixation, and the obturator oblique-inlet view would not be ideal to visualize this region of the pelvis