Abstract: Objective To evaluate the stability of the pelvic ring reconstruction using fibular autograft for periacetabular tumor type Ⅱ resection. Methods 6 adult cadaveric specimens were tested. The periacetabular tumor resection models were established according to Ennecking's type Ⅱ resection. The resected pelvic rings were reconstructed with double-fibular graft fixed by four internal fixation techniques including plates, pedicle-rods (PR), lateral-rods (LR) or sacral-iliac rods (SIR). Axial loading from the proximal L3 vertebral body was applied by MTS load cell in the gradient of 0～500 N in the double feet standing state. Images in front view were obtained using CCD camera. Based on Image J software, displacement of the first sacral vertebrae （S₁） of the reconstructed pelvis and intact pelvis were calculated using digital maker tracing method with center-of-mass algorithm. Results The rotational movements and vertical displacement of S1 around the normal side femoral head of the reconstructed pelvis in coronary plane were found in simulated bilateral leg standing position. The average vertical load-displacement and load-angular rotation curve of S₁ in coronary plane were approximately linear behavior under the vertical load 500 N. The average vertical displacement and angle of S₁ in coronary plane had not overacted. The stability of axial direction and rotation had not changed significantly when reconstructed by LR or Plates compared with the intact pelvis, but the SIR did. Conclusion Plates and LR fixation were more stabile for periacetabular tumor type Ⅱ resection.

Key words: bone neoplasms, pelvis, type Ⅱ resection and reconstruction