Thoracic Vertebroplasty and Kyphoplasty

25 Thoracic Vertebroplasty and Kyphoplasty

Justin Schwarz, Srikanth Boddu, Ibrahim Hussain, Alejandro Santillan, and Athos Patsalides

Summary

Thoracic vertebroplasty and kyphoplasty are vertebral augmentation procedures (VAPs) that are safe and effective minimally invasive treatments of symptomatic mechanically stable thoracic vertebral compression fractures (VCFs). VCFs are a highly prevalent disease that cause significant morbidity, especially in the elderly and cancer populations. VAPs have shown significant utility in treating symptomatic VCFs with a relatively recent paradigm shift toward early surgical intervention. In this chapter, appropriate patient evaluation and patient selection are discussed, as well as the indications and contraindications of VAP. Detailed step-by-step VAP instructions are provided, specifically highlighting the key to maximizing a favorable clinical outcome while avoiding potential complications.

Keywords: vertebral compression fractures (VCFs) vertebral augmentation procedure (VAP) osteoporosis kyphosis vertebroplasty kyphoplasty polymethylmethacrylate (PMMA)

25.1 Introduction

Vertebral compression fractures (VCFs) are a highly prevalent disease affecting approximately 700,000 people in the United States each year.1^,² These fractures have a profoundly negative impact on patient function and quality of life with approximately 30 to 40% of VCF patients developing disabling pain, resulting in 150,000 annual hospitalizations.³^,⁴ Vertebroplasty and kyphoplasty are vertebral augmentation procedures (VAPs) that are effective percutaneous minimally invasive techniques for treating VCF and ameliorating symptoms. In both procedures, cement is injected into the fractured bone where it hardens and congeals the fracture fragments, providing immediate stability and pain relief.⁵^,⁶^,⁷ Kyphoplasty includes an additional step prior to cement injection where a balloon is gently inflated within the fractured vertebral body to create a cavity for the cement and restore vertebral body height.⁸

25.2 Indications

Thoracic VCF with symptoms that are not adequately controlled on oral pain medications are considered for kyphoplasty or vertebroplasty. The typical presentation of a symptomatic thoracic compression fracture is an acute onset of mechanical back pain that roughly correlates with the vertebral level of the osteoporotic or pathologic VCF. This mechanical back pain is often accompanied by muscle spasm pain and pain that radiates along the respective spinal level’s intercostal distribution.

The majority of patients who suffer from osteoporotic or pathologic VCF are elderly and have multiple medical comorbidities, such as arthritis or metastatic cancer, which may make the assessment of pain difficult. In such cases, it may be difficult to determine if a newly diagnosed compression fracture is truly symptomatic. A thorough clinical history is necessary to determine the time frame and potential mechanism of injury, which can help ascertain if a VCF is the etiology of a patient’s pain. Determining the chronicity of symptoms and correlating the clinical history with physical examination and radiographic findings are important. A dedicated thoracic spine computed tomography (CT) or magnetic resonance imaging (MRI) is preferred for diagnosis. Plain films are inadequate for proper diagnosis, but have limited utility as an initial screening tool. The time frame of injury can be determined by comparing current imaging with past radiologic studies, including previous X-rays, CT, or MRI. If no comparison imaging is available, an MRI is obtained to determine acuity. Short tau inversion recovery (STIR) hyperintensity within the vertebral body of interest suggests a relatively recent fracture, and identifies a vertebral body that is amenable to intervention. Subacute and acute compression fractures respond well to VAP, whereas chronic fractures are unlikely to have a favorable response. MRI aids in the assessment of the stability of the fracture, as well as the chronicity. A1, A2, and A3 fractures in the AO classification scheme respond well to VAP. A4 fractures can also be good candidates for VAP as long as there is no symptomatic retropulsion or significant alignment abnormalities that would suggest disruption of the posterior tension band. In regard to the thoracolumbar injury classification and severity score (TLICS) classification, vertebroplasty can be attempted in patients with a TLICS 4 injury to achieve symptom improvement, but results can be highly variable. If vertebroplasty is to be attempted in such a case, care needs to be taken during the procedure to ensure that there is no leakage of cement into the spinal canal.

25.3 Contraindications

Vertebroplasty and kyphoplasty are typically reserved for patients with osteoporotic or pathologic VCF that are mechanically stable. Patients with unstable thoracic fractures do not respond to VAP and continue to have significant pain despite VAP. These patients, with unstable as opposed to stable fractures, typically require open surgical intervention for stabilization. Retropulsion with symptomatic cord compression is an absolute contraindication to VAP, as these patients require open surgical intervention for decompression and stabilization. Asymptomatic patients with retropulsion are still candidates for vertebroplasty. In this patient population, cement injection is performed cautiously to avoid any worsening of the retropulsion and prevent any neurologic deterioration. Other absolute contraindications to VAP include active osteomyelitis at the fracture area or an allergy to cement, polymethylmethacrylate (PMMA).

Typically, fractures involving T5 through T12 are amenable to VAP because the vertebral anatomy is easily visualized using frontal and lateral fluoroscopy for these spinal levels. In certain situations, T3 and T4 can be visualized well enough to attempt VAP, but this is dependent upon the patient’s body habitus and anatomy. In these situations, the operator often will not know if the T3 or T4 level can be successfully visualized to perform VAP until the patient is positioned.

25.4 Preoperative Planning

25.4.1 Anesthesia Planning

VAP is performed with the assistance of an anesthesiologist. Ideally, the procedure is performed under monitored anesthesia care (MAC), but endotracheal intubation with general anesthesia is used in select patients. MAC is used for relatively healthy and cooperative patients undergoing a one- or two-level kyphoplasty or vertebroplasty. General anesthesia is used if three or more levels are being treated, the patient is unable to cooperate, or systemic medical issues necessitate endotracheal intubation with general anesthesia.

25.4.2 Procedure Location

Thoracic VAP is most efficiently performed using biplane fluoroscopy, but can also be performed using single-plane fluoroscopy in either an interventional procedure room or the operating room using “C-arm” fluoroscopy or two C-arms simultaneously (AP and lateral views). Biplane fluoroscopy typically reduces the procedural time significantly by obviating the need for equipment repositioning, especially when switching between anterior-posterior and lateral fluoroscopic projections.

25.4.3 Unipedicular versus Bipedicular Approach

An effective result can be obtained utilizing either a uni- or bipedicular approach. In the majority of cases, a bipedicular approach is preferred to allow for maximal and uniform distribution of cement. A unipedicular approach is used in certain situations, such as when one of the pedicles is destroyed by tumor invasion or is significantly fractured, the vertebral body is sufficiently small to allow for adequate cement filling through one cannula, or when the patient’s anatomy allows for an appropriate transpedicular trajectory into the medial and anterior vertebral body. The unipedicular approach has the advantage of reducing procedure time because only one cannula needs to be navigated into the affected vertebral body. For this reason, the unipedicular technique may be used in patients needing treatment of multiple levels, or those with significant medical comorbidities where minimizing procedural time is imperative.

25.5 Patient Positioning

Patients are placed in the prone position on the procedure table prior to the administration of moderate sedation or following endotracheal intubation and administration of general anesthesia. Two large bolsters are placed transversely for adequate support during the procedure. One large bolster is placed at the level of the iliac crest and the second is placed at the level of the chest, typically just superior to the nipple line. The exact position of these bolsters varies slightly depending upon body habitus. A pillow is placed under the patient’s head, with the head rotated toward the anesthesia team for easy access during the procedure. The arms are positioned above the head, with the elbows bent at approximately 90 degrees with the forearms overlapping above the patient’s head. An additional bolster, or multiple pillows, is placed under the distal shins, just proximal to the patient’s ankles to minimize pressure on the patient’s feet. Pressure points, including the forearms, elbows, knees, and abdomen, are carefully inspected and padded. It is important to prevent any excessive rotation of the patient’s spine that could make visualization with fluoroscopy more difficult. The patient is then secured in position with a safety belt across the buttocks and fabric tape across the waist, shoulders, and elbows to minimize movement during the procedure (Fig. 25.1a). The procedure and its important steps are narrated and illustrated in Video 25.1.