Strain Analysis of Pelvis After Iliac Bone Tumor Resection

The purpose of this study is to analyze the pelvic strain behavior after iliac tumor type I resection. Six adult cadaveric specimens were tested. The iliac subtotal resection models were established according to Ennecking´s type I resection. The surficial strains of the defect pelvis and the intact pelvis were measured using 6 strain gauges attached to the key regions of pelvis including the site of lateral sacral mass, iliac arcuate line and the superior ramus of pubis. Axial loading from the proximal lumbar was applied by MTS load cell in the gradient of 0 N to 500 N in the double feet standing state. Much change of the strains was found of the pelvis after type I resection. Compared with the intact pelvis, the remarkable change of strain values was found on both side of the superior ramus of pubis, compressive strain altering to tensile strain. In addition, the average strain values on the normal sites of lateral sacral mass (-554.5plusmn251.2 ^muepsiv ) and iliac arcuate line(-1105.5plusmn352.7 ^muepsiv) under vertical load of 500 N were enlarged, which were 2.86 times and 3.77 time as much as the those in the corresponding sites of the intact pelvis. The differences of strain values on this two sites between the defect pelvis and the intact pelvis were statistically significant (p<0.05). Biomechanical model of iliac tumor type I resection were established. In the defect pelvis , strain values on the normal side of the sacrum and the ilium which conduct compressive stress are enlarged. Strain values are also enlarged in the region of pubic symphysis, which conducts tensile stress. Essential pelvic reconstruction must be introduced to recover the normal pelvic stress conduction. The strain gauge method is simple and efficient, which can be used extensively in pelvic biomechanical research.