A comparison of methods of repairing the symphysis pubis in bladder exstrophy by tensile testing

Objective. To compare the efficacy of several fixation techniques in the reconstruction of diastasis of the symphysis pubis in bladder exstrophy. Materials and methods. The symphyses of 32 pelves removed from piglets about 1 month old were disrupted and repaired using one of eight methods. After repair, each pelvis was tested biomechanically for load-to-failure, stiffness and energy-to-failure. The various repair techniques were compared with one another and to a group of six pelves tested intact. Results. Four of the methods tested, including a no. 2 nylon suture placed through bone in a horizontal mattress arrangement, several loops of no. 2 nylon suture tied around the pubes, Mersilene tape tied around the pubes, and Mitek G-II suture anchors placed into the superior pubic rami, showed the highest stiffness and load-to-failure. All methods were very weak compared with the intact symphysis; the best load-to-failure (no. 2 nylon horizontal mattress suture) was less than half of that for intact bone, and the best stiffness (mersilene tape) was less than one-third that for the intact symphysis. Conclusion. The repairs varied greatly in the variables tested and those which are most promising merit further investigation to assess methods of improving their performance.