Risk of cement leakage and pulmonary embolism by bone cement-augmented pedicle screw fixation of the thoracolumbar spine

Background: Cement-augmented pedicle screw instrumentation (CAPSI) of the thoracolumbar spine is indicated in osteoporosis or osteopenia to improve pullout strength and biomechanical stability of pedicle screws (PS). Only a few studies report on the incidence of pulmonary cement embolism or other complications associated with CAPSI.

Purpose: The aim of this retrospective study was to assess the rate of CAPSI-associated complications.

Study design: Retrospective cohort study.

Patient sample: Patients who underwent CAPSI due to spinal tumors or degenerative spine disease.

Outcome measures: Cement leakage, pulmonary cement embolism (PCE), mortality rate.

Methods: Our clinical database was reviewed for patients who underwent CAPSI between January 2012 and June 2015. A total of 165 patients (mean age 71±11.2; range: 46 to 93 years; m=62, f=103) were included. Indications were osteoporotic fractures (n=40), spinal metastases (n=57), degenerative (n=49) or infectious spine disease (n=5), and traumatic vertebral fractures (n=14) with an associated osteoporosis. Every patient received between 2 and 21 (mean 8±3.3) cement-augmented pedicle screws in the thoracolumbar and lumbosacral spine. Both intraoperative cement leakage in prevertebral veins, the inferior vena cava, and/or pulmonary arteries, and leakage detected on postoperative imaging were evaluated. We assessed the incidence of clinically symptomatic and asymptomatic events.

Results: In 29 of 31 patients with intraoperative suspicion of cement leakage into prevertebral veins or the inferior vena cava on lateral fluoroscopy, which were without hemodynamic relevance, cement extrusion was confirmed on postoperative X-ray or computed tomography (CT) scan. In three of eight patients with suspicion of PCE, PCE was verified on thoracic CT. Four patients experienced life-threatening intraoperative hemodynamic reactions, either due to cement embolism (n=2; 1.2%) or anaphylactic shock (n=2; 1.2%) with need for intraoperative cardiopulmonary resuscitation in three cases. Two patients died due to fulminant PCE. Three patients with dyspnea 1 day after surgery were also confirmed with PCE on chest CT. In five patients, an asymptomatic PCE was found incidentally on postoperative imaging. In addition, 68 patients with cement leakage into prevertebral veins or the ascending cava vein were found incidentally on postoperative spine X-ray or CT. Two of 10 patients with intraspinal epidural cement leakage required revision surgery. One hundred ten of 165 patients (66.7%) had clinically asymptomatic cement leakage. Thirteen patients had PCE (7.9%), of whom five (3.0%) were symptomatic. Two patients experienced intraoperative cement-induced anaphylaxis (1.2%). The overall symptomatic complication rate was 5.5% (n=9). The 30-day mortality rate was 1.8% (n=3).

Conclusions: CAPSI bears a high risk of asymptomatic cement leakage. The risk for associated severe complications was also relatively high and probably underestimated considering the retrospective nature of the present study. A strict indication for cement augmentation, especially in patients with cardiac predisposition, should be the consequence. We doubt that technical aspects of cement application and/or different types of cement are capable of reducing the risk of these complications substantially.