[Anatomic measurements and quantitative analysis of posterior acetabular wall]

To explore morphological character and clinical significance of superior-posterior acetabular wall by anatomically measuring and quantitatively analyzing thickness of posterior acetabular wall, then provide a theoretical reference for clinical treatment of acetabular fracture.

Fifteen adult formalin-preserved cadaveric pelvises (8 males and 7 females) were used for this investigation. Excess soft tissue was removed and the whole acetabular posterior walls were marked with "angle" sector method and the thickness was measured with caliper in different levels of the different split points. The measurement results were validated and analyzed statistically.

At 5 mm away from acetabular rim, the average thickness of superior-posterior acetablar wall fluctuated between (6.47±0.61) mm and (7.43±0.71) mm; the average thickness of inferior-posterior acetabuluar wall fluctuated between (5.62±0.51) mm and (6.33±0.61) mm; the average thickness of acetabular roof fluctuated between (7.71±0.74) mm and (8.27±0.99) mm. There was no statistical difference between average thickness of superior-posterior wall of acetabulum and inferior-posterior wall of acetabulum (P>0.05), but the average thickness of acetabular roof was significantly larger than superior-posterior acetabular wall (P<0.05). At 10 mm away from the acetabular rim, the average thickness of superior-posterior acetabular wall fluctuated between (8.81±0.67) mm and (13.35±0.89)mm; the average thickness of inferior-posterior acetabular wall fluctuated between (7.02±0.63) mm and (7.66±0.69) mm; the average thickness of acetabular roof fluctuated between (14.46±0.97) mm and (17.05±1.35) mm. Comparatively, the average thickness of superior-posterior acetabular wall was significantly larger than inferior-posterior wall of acetabulum (P<0.05), and the average thickness of acetabular roof was significantly larger than superior-posterior acetabular wall (P<0.01). At 15 mm away from the acetabular rim, the average thickness of superior-posterior acetabular wall fluctuated between (12.08±0.78) mm and (19.84±1.03) mm; the average thickness of inferior-posterior acetabular wall fluctuated between (10.17±0.76) mm and (11.12± 0.77) mm; the average thickness of acetabular roof fluctuated between (23.23±1.12) mm and (26.01±1.53) mm. Comparatively, the average thickness of superior-posterior wall of acetabulum was significantly larger than inferior-posterior acetabular wall (P<0.01), and the average thickness of acetabular roof was significantly larger than superior-posterior acetabular wall (P< 0.01).

The thickness of entire acetabular posterior edge revealed an increasing tendency from inferior-posterior wall to the superior-posterior wall to acetabular roof. And this trend became more obvious with increasing distance away from acetabular rim. Therefore, the superior-posterior acetabular wall could not only maintain the stability of hip joint but also bear loading.