I am not sure exactly what the concern is that underlies this thread. Football players and hockey players have had their spleens ruptured during games. I would think a ruptured spleen could happen with any contact sport and I am not sure why that would be less of a concern than an injury to a J Pouch. This is not to mention injuries to other parts of the body which could occur and necessitate surgery like ACL tears in the knees, rotator cuff tears in the shoulder, etc. Regarding girls playing basketball, they tear their ACLs in their knees all the time. It is a common injury in girl's and women's basketball due to the different configuration of a woman's body than a man's and resultant stresses placed on the body and the knees. As a huge fan of the UConn women's basketball team I have seen many of their star players suffer this injury. I believe former UConn All American Shea Ralph had 5 ACL tears in her knee, one of them sustained playing with her dog. These injuries all required surgical repair, and ended her basketball career. Shea is now an assistant coach at UConn.
Someone recently posted a thread about his J Pouch having perforated, apparently for no reason at all or from turning the wrong way. I would think that once the pouchogram has been passed this is a rare event, but the poster of that thread said he had a J Pouch for 8 years.