A transverse fracture means the break went through the sacral bone in a horizontal fashion. It can be nondisplaced (fracture has not separated) or displaced (separated or shifted apart). In severe injuries, the separated pieces of the sacrum can shift apart and then overlap one another. Any change in the normal anatomical alignment in this area can put pressure on the cauda equina (nerve tissue at the end of the spinal cord). Serious neurologic problems such as loss of sensation and/or loss of bowel and/or bladder function can develop.
Surgery is done right away when there is a need to protect the cauda equina before neurologic these problems develop or become permanent. The surgeon removes a portion of the sacrum that is pressing on the nerve tissue. This procedure is called a decompression surgery. If the fracture can’t be reduced (bone fragments put back together), then a metal plate and/or screws are used to hold it together.
Surgery isn’t always required with transverse sacral fractures. If the fracture isn’t displaced (separated) and the patient doesn’t have any neurologic damage, then conservative (nonoperative) care may be all that’s needed. But severe fractures with displacement, bony malalignment, and/or any sign of neurologic compromise warrants an immediate surgical procedure.
Some experts suggest that surgery can be preventive in a way. If the fracture looks stable but develops a large bone callus during the healing phase that presses on nerve tissue, then it would have been better to operate early on. The same thing applies if the bone fragments move after the imaging study showed they were lined up and stable.
These cases are so rare, no one knows how to predict when those complications might occur and prevent them in any other way than by doing early surgery. This is especially true when you consider that these fractures are difficult to treat and displacement of the bones only makes it that much harder to realign and stabilize them.