Reconstruction of a Pelvic Nonunion Secondary to Metastatic Breast Cancer and Palliative Radiation

Pathologic pelvic nonunions are uncommon, although they remain a difficult problem and require meticulous surgical planning and execution for desired outcomes. In this paper, we discuss a patient who sustained a pathologic pelvic insufficiency fracture secondary to radiation therapy for metastatic breast cancer, who subsequently developed a symptomatic nonunion that required surgical intervention secondary to debilitating pain and inability to ambulate. We also discuss the classification of insufficiency fractures of the pelvis to guide treatment, in addition to complications associated with surgical intervention. A 51-year-old female with a 12-year history of metastatic breast cancer. She presented to an outside facility where she was diagnosed with a nondisplaced left superior pubic ramus and iliac wing fracture with lytic lesions throughout her pelvis (Rommens fragility fractures of the pelvis (FFP) type IVc). Follow-up at our institution with updated imaging demonstrated a windswept pelvis, left iliac crescent fracture, and bilateral parasymphyseal fracture involving the superior and inferior rami, with a right-sided zone 1 sacral fracture. Discussion with the patient was made regarding conservative nonoperative management, as well as operative management; the patient wished to proceed with surgery, given her debilitating pain and inability to ambulate. The patient was placed into the supine position on a radiolucent table. A urinary catheter was placed. A stoppa approach was performed to access bilateral pelvic brims and the symphysis, along with a lateral window. The left hemi-pelvis was reduced with lateral bookwalter traction. The iliac crest was reduced and stabilized with a 6-hole 3.5 mm recon locking plate and a 7.3 mm fully treated cannulated screw across the LC-2 corridor. A 20-hole 3.5 mm recon plate was used to stabilize the anterior pelvis. Two right-sided 7.3 mm fully threaded cannulated trans-sacral screws with a washer were placed through the S1 and S2 corridors to stabilize the posterior pelvic ring. A mixture of 20cc of demineralized bone matrix (DBX) and allograft was used over the fracture sites. Two months postoperatively, she had increased pain in the right buttocks and had audible clicking with ambulation. Imaging demonstrated a broken S1 transsacral screw and plate anteriorly. The patient then underwent multiple revision surgeries, given hardware failure and progression of her fragility fractures, which are further discussed in the case report. This case is unique as there are no reported cases to our knowledge on the clinical outcome after reconstruction of pelvic nonunion cases secondary to radiation therapy for metastatic breast cancer.