Review Question - QID 211135

This patient has sustained a U-type sacral fracture. The most stable fixation is triangular osteosynthesis, also referred to as lumbopelvic fixation.

This patient has sustained a spinopelvic dissociation, which occurs when there are multiplanar fracture lines in both the horizontal and vertical planes. This creates an unstable situation with the upper part of the sacrum attached to the lumbar spine and the lower part of the sacrum remaining attached to the pelvis. There are many treatment options for this condition including open or percutaneous iliosacral screw osteosynthesis, tension band transiliac plate osteosynthesis, transiliac bars, and local plate osteosynthesis. If a neurologic defect is present, a sacral decompression with laminectomies is recommended.

Schildhauer et al. performed a retrospective study to report the results of sacral decompression and lumbopelvic fixation in neurologically impaired patients with highly displaced, comminuted sacral fracture-dislocations resulting in spinopelvic dissociation. They found 19 patients who were treated with open reduction, sacral decompression, and lumbopelvic fixation. They concluded that lumbopelvic fixation provided reliable fracture stability, and that neurological outcomes were influenced by the completeness of the injury and the presence of sacral root disruption.

Schildhauer et al. performed a biomechanical comparison of triangular osteosynthesis and the standard iliosacral screw osteosynthesis for unstable transforaminal sacral fractures in both the immediate postoperative situation and in the early postoperative weight-bearing period. They concluded that triangular osteosynthesis for unstable sacral fractures provided significantly greater stability than iliosacral screw fixation under in vitro cyclic loading conditions.

Figure A is an AP radiograph of the pelvis demonstrating a paradoxical inlet that occurs due to the kyphotic deformity of the sacrum. Figure B is an axial CT demonstrating a U-type sacral fracture. Figure C is a sagittal CT demonstrating the same U-type sacral fracture. The kyphotic deformity is well visualized on this image. Illustration A is an AP radiograph of the same patient after surgical treatment with triangular osteosynthesis. Illustrations B & C are coronal and sagittal CTs demonstrating the same. Illustration D is a volume-rendered 3D image of the same patient demonstrating a U-type sacral fracture. Illustration E demonstrates the various multiplanar sacral fractures: A: H-Type, B: Y-Type, C: T-Type, D: U-Type.

Incorrect Answers:
Answers 2, 3, 4, & 5: Though all of these may be treatment options for treating this injury, triangular osteosynthesis is the most stable fixation construct.