This 1990 cadaveric and CT study by Wasielewski et al. defines which acetabular zones are safe for transacetabular screw placement during cementless THA. Using vascular injection, CT imaging, and anatomic dissection of seven cadaver pelves plus CT review of 25 normal patients, the authors mapped neurovascular proximity relative to four surgeon-visible quadrants defined from the ASIS.
When placing screws through a cementless acetabular shell, your only reliable intraoperative guide to intrapelvic neurovascular anatomy is the quadrant system defined by this paper. The ASIS is palpable through virtually any approach — use it to construct Line A and commit your screws to the posterior half.
Avoid the anterior quadrants entirely if possible. The external iliac vein sits 4 mm from the anterior column at the dome level, tethered by peritoneum with no room for error. The polar position carries the same risk. A 15 mm screw can reach the obturator bundle through the paper-thin quadrilateral surface.
In revision cases where the fovea is absent or the acetabulum is distorted, the ASIS alone reconstructs the quadrant system. This is why the technique remains applicable even in the most deformed cups. Drill plunging is the most common mechanism of intraoperative vascular injury. Knowing the safe zone does not eliminate risk if technique is imprecise.
This 1990 cadaveric and CT study by Wasielewski et al. defines which acetabular zones are safe for transacetabular screw placement during cementless THA. Using vascular injection, CT imaging, and anatomic dissection of seven cadaver pelves plus CT review of 25 normal patients, the authors mapped neurovascular proximity relative to four surgeon-visible quadrants defined from the ASIS.
When placing screws through a cementless acetabular shell, your only reliable intraoperative guide to intrapelvic neurovascular anatomy is the quadrant system defined by this paper. The ASIS is palpable through virtually any approach — use it to construct Line A and commit your screws to the posterior half.
Avoid the anterior quadrants entirely if possible. The external iliac vein sits 4 mm from the anterior column at the dome level, tethered by peritoneum with no room for error. The polar position carries the same risk. A 15 mm screw can reach the obturator bundle through the paper-thin quadrilateral surface.
In revision cases where the fovea is absent or the acetabulum is distorted, the ASIS alone reconstructs the quadrant system. This is why the technique remains applicable even in the most deformed cups. Drill plunging is the most common mechanism of intraoperative vascular injury. Knowing the safe zone does not eliminate risk if technique is imprecise.