Pulmonary cement embolism following transpedicular screws placement for thoracolumbar fractures.

BACKGROUND: Symptomatic pulmonary cement embolism in patients undergoing thoracic transpedicular fenestrated screw placement is rare. Here, we have added a 64-year-old female undergoing transpedicular screw placement for a T11 fracture who developed a pulmonary cement embolism intraoperatively and add this case to 13 others identified in the literature. CASE DESCRIPTION: A 64-year-old female presented with a type "C", ASIA "E" T11 fracture. The thoracolumbar pedicle screw fixation was supplemented with bone cement due to her underlying severe osteoporosis. During the fluoroscopy-guided supplementation with bone cement, a leak through the paravertebral venous system was noted. Thirty minutes later, the patient acutely developed extreme respiratory failure and required mechanical ventilation for the next 2 days. The diagnosis of pulmonary embolism due to bone cement was confirmed on a contrast computed tomography study of the chest.
CONCLUSION: Symptomatic pulmonary cement embolization supplementing transpedicular screws placement for osteoporotic bone is rare. Here, we present a 64-year-old female who during transpedicular fixation of a T11 fracture developed an acute pulmonary embolism from the bone cement resulting in the need for 2 days of postoperative artificial ventilation. Copyright:

INTRODUCTION

Polymethylmethacrylate (PMMA) bone cement improves immediate stability and increases pullout resistance from 173% to 244% for patients with osteoporosis undergoing thoracic fracture transpedicular fixation.[4,14,19]

Potential locations of bone cement leakage include perivertebral, disc intracanalicular, foraminal, local perivertebral venous system cement leakage, and critically, as in this case, leakage to the central vascular system with migration to the cardiac or pulmonary system with risk of pulmonary embolism (2.1–26%).[2,3,8,17,18]

The presence of pulmonary embolism correlates with instrumentation of >7 levels.[16] Notably, patients with anterior or posterior wall fractures or burst fractures and accompanying cortical destruction are at increased risk of pulmonary cement embolization.[8]

CASE REPORT

A 64-year-old female with osteoporosis, presented with a non-penetrating T11 traumatic spinal injury as a result of falling backwards downstairs. The computed tomography (CT) scan showed a T11, AO spine C classification, without a neurological deficit, ASIA – E [Figure 1].

Figure 1:

(a) Computed tomography, sagittal view, transverse fracture of T11, subluxation of the vertebral body. (b) T2-weighted magnetic resonance imaging, sagittal view, injury of the posterior ligament complex. (c) Computed axial tomography, axial view, double image of vertebral laminae due to subluxation.

Surgery

Three days later, she underwent a T11 hemilaminectomy to remove an epidural hematoma with T9 - T10 (5.5 mm × 40 mm screws) to T12 - L1 (6.5 mm × 45 mm screws) transpedicular instrumented fusion. Vertebral body augmentation with 1.5 mL of PMMA bone cement per transpedicular screw (distally fenestrated) was performed due to her underlying osteoporosis. When the fourth screw was placed, fluoroscopy showed leakage of PMMA cement into the paravertebral system [Figure 2]. We briefly stopped applying bone cement, but then resumed its application when we observed no intraoperative cardiorespiratory compromise. Fracture reduction was then performed with bilateral 5.5 mm × 36 cm rod placement. The intraoperative arterial blood gas showed respiratory acidosis with a moderate “oxygenation disorder” (pH, 7.31; pO2, 100 mmHg; pCO2, 48 mmHg; HCO3, 24 mEq/L; O2 saturation, 96%; PaO2/FiO2, 178 mmHg; lactate, 1 mmol/L, hemoglobin 11.5 g/dL). Thirty minutes after transfer to the recovery room, however, she suddenly developed hypoxemia with oxygen saturation of 45%, requiring ventilatory support.

Figure 2:

(a) Intraoperative, instrumental placement for cement application. (b) Fluoroscopy, sagittal view, transpedicular screw placement. (c) Augmentation begins, bone cement at the level of the vertebral body. (d) Suspected bone cement leakage through the paravertebral venous system.

The CT angiogram of the chest documented a cement pulmonary embolism [Figure 3]. She remained intubated for the next 2 days and was started on low molecular weight heparin 4 days postoperatively. Nine days later, she had a postoperative Chest X-ray that showed a radiopaque image in the right lung associated with cement emboli [Figure 4]. She was then discharged without supplemental oxygen or on anticoagulation.

Figure 3:

Computed axial tomography Angiography, (a-c) Coronal, sagittal, and axial view (yellow circle), respectively where high density material is observed in the paravertebral venous system, is suggestive of cement embolus. (d) Presence of the high density material occupying the lumen of the subsegmental arterial vessels, in the apicoposterior segment of both upper lobes, anterior segment of the right upper lobe, lingula lobe, middle lobe, posterior and medial basal, segment of the right lower lobe.

Figure 4:

Follow-up at 1 week after surgery. Instrumentation with transpedicular screws at T9, T10, T12 and L1 with polymethylmethacrylate augmentation. (a) Anteroposterior view, radiopaque image in right lung associated with cement emboli. (b) sagittal view radiopaque image which is correlated with cement leakage through the paravertebral venous system.

DISCUSSION

Symptomatic pulmonary embolism due to bone cement utilized to perform transpedicular screw fixation is rare, occurring in 1.4% of isolated cases.[6,7,9,11,13,20] Currently, ten publications have reported 13 cases of patients with symptomatic pulmonary embolism due to bone cement.[1,5,9-12,14-16,20] Most of the patients reported were over 64 years of age and had instrumentation of the lumbar spine [Table 1]. Of the 13 cases, one had a fatal outcome, and two required open embolectomy; Where pulmonary cement embolisms involve main arterial trunks or are located in cardiac cavities but the patient is asymptomatic, anticoagulation is recommended for 6 months.[1,5,10,12,15] In this case, due to clinical improvement and lack of level A evidence, the cardiology department did not recommend continuing anticoagulation. Follow-up was performed 15 days, 1 month, and 6 months after discharge.

Table 1:

Case Reports of Symptomatic Pulmonary Embolism After Transpedicular Cemented Screw Instrumentation.

CONCLUSION

PMMA cementation continues to be a used in osteoporotic patients to increase pull-out resistance when placing transpedicular screws for thoracolumbar fractures/ fusions. Although cement leakage resulting in symptomatic pulmonary embolization following cemented PMMA transpedicular screw fixation is rare, it should be aggressively diagnosed and medically managed in every patient individually by an interdisciplinary team.