Mapping the columns of the acetabulum--implications for percutaneous fixation.

Knowledge of the bony thickness of the acetabular columns is one requisite for safe execution of percutaneous fixation of acetabular fractures. We performed a cadaveric study to determine anatomical dimensions of the columns of acetabulum with reference to percutaneous screw fixation. Twenty-two hemipelves (11 pairs) from 6 male and 5 female cadavers were measured and statistically analysed. In the anterior column, the psoas groove displayed the least vertical thickness of 15.1mm (range, 12.1-18.2mm), followed by the obturator canal with 15.9 mm (range, 12.2-20.6mm). The mean thickness of the posterior column wall of the acetabulum along the screw path displayed 21.3mm (range, 16.5-30.3mm). This study provides a clinical map for safe passage of both antegrade and retrograde percutaneous screws. Anatomic data suggests that 7.3mm cannulated screws can be safely accommodated by the anterior and posterior columns of the acetabulum.