Triangular Osteosynthesis and Lumbopelvic Fixation

Abstract

Lumbopelvic fixation and triangular osteosynthesis of the posterior pelvic ring are elaborated fixation techniques, which create mechanical stability at the complex lumbopelvic junction by counteracting multidirectional forces. These are rather reconstructive procedures for specific surgical indications. The term triangular osteosynthesis describes a lumbopelvic fixation combined with an iliosacral screw in a unilateral application. The term lumbopelvic fixation is used for any bilateral application of the triangular osteosynthesis concept. Lumbopelvic fixation does not only counteract cephalad migration but also flexion of the injured hemipelvis when a long ilium screw is used. Timing of surgery is determined according to the optimal preparation of the patient and surgical environment. However, in patients with deteriorating neurologic examination, progressive pain or impaired dorsal integument, more urgent operative intervention is recommended. Highly unstable situations, such as displaced fractures, fractures with comminuted zones of osteoporotic bone, fractures with progressive displacement or secondary loss of reduction after percutaneous or other fixation techniques, and posterior pelvic ring pseudarthroses may be good indications for unilateral or bilateral lumbopelvic fixation. In patients with an onset of neurologic symptoms consistent with cauda equina or lumbosacral plexus encroachment secondary to instability at the lumbopelvic junction and posterior pelvic ring, neural decompression is indicated. A clear understanding of the fracture type and its associated instability is required to plan for the appropriate osteosynthesis technique. In fractures and instabilities involving the anterior and posterior pelvic ring and lumbopelvic junction, the anterior pelvis may need to be considered for fixation as well. Preoperative planning, positioning of the patient, intraoperative imaging and the different steps of the surgical technique are explained in detail. Postoperatively, it is advisable to get an early CT scan to allow for assessment of neural element passage, lumbosacral alignment in three planes, and check on hardware placement. Triangular osteosynthesis and lumbopelvic fixation promise a stable fixation at the lumbopelvic junction, which allows for immediate patient mobilization with full weight-bearing. Some authors recommended hardware removal after fracture healing between 6 and 12 months postoperatively.