11.1 Introduction

Vertebral augmentation is a category of surgical procedures used to treat vertebral fractures and includes vertebroplasty, kyphoplasty, and implants. The goal of any vertebral augmentation procedure is the minimally invasive reduction and stabilization of a painful vertebral compression fracture (VCF). Unique to balloon kyphoplasty is restoration of vertebral body height and reduction of kyphotic angulation through the use of inflatable bone tamps. The balloon tamps reduce the risk of cement leakage by facilitating an injection that follows the path of least resistance into and around the cavity created by the balloon.

11.2 Materials

The surgical equipment is available through numerous sources. A comprehensive list of manufacturers, materials, and equipment for kyphoplasty can be found in ▶Table 11.1. Components available from Medtronic Kyphon are listed in the following sections and shown in ▶Fig. 11.1.

11.3 Diagnosis and Preoperative Preparation

A patient with an acute or subacute vertebral body compression fracture will almost always complain of severe back pain. Physical examination will reveal tenderness to palpation and percussion over the corresponding spinous process. Subsequent radiographs, CT, MR, and/or nuclear bone scan imaging are used to confirm and characterize a fracture. Short tau inversion recovery (STIR) and T1-weighted sequences on MR imaging are considered the gold standard for evaluating VCFs. There is a high degree of correlation between increased STIR signal and a pain-generating fracture and the T1-weighted images well demonstrate fracture lines and marrow signal changes (▶Fig. 11.2). If MR imaging is not possible, nuclear bone scan imaging may be used to demonstrate radionuclide uptake in an acute or subacute fracture and can be used in combination with CT scanning for accurate anatomic characterization of the fracture.

Patients undergoing kyphoplasty are often elderly, are deconditioned, and have inherent vulnerability to perioperative stress. For example, inhalation agents are affected by the minimum alveolar anesthetic concentration, which decreases approximately 6% for every decade. Clearance and the volume of the central compartment decrease with age. Metabolism of medications and their durations of action depend on renal or hepatic excretion. It is important to titrate doses and prudent to use short-acting drugs. Preoperative assessment of organ function and reserve is essential to know how the patient might react with anesthesia. ³ Although preoperative laboratory studies and testing will vary from patient to patient, we routinely include CBC with differential, chemistries, coagulation studies, anteroposterior (AP) chest radiograph, and an ECG.

11.4 Indications and Contraindications

Indications for kyphoplasty include intractable severe pain or moderate to severe persistent pain associated and correlating with a VCF. In 2017, a multidisciplinary expert panel of orthopaedic and neurosurgeons, interventional radiologists, and pain specialists, using the RAND/UCLA Appropriateness Method (RUAM), developed the Clinical Care Pathway (CCP), defining patient-specific recommendations for vertebral fragility fractures (VFF). The panel assessed the relative importance of signs and symptoms for the suspicion of VFF, the relevance of diagnostic procedures, and the appropriateness of vertebral augmentation versus nonsurgical management for a variety of clinical scenarios (▶Fig. 11.3). Their report included the following guidelines for relative and absolute contraindications (▶Table 11.2).

Absolute contraindications include active infection at the surgical site and untreated blood-borne infections. Strong contraindications include osteomyelitis, pregnancy, allergy to fill material, coagulopathy, spinal instability, myelopathy from the fracture, neurologic deficit, and neural impingement. Although dependent on degree, fracture repulsion and canal compromise are not generally a contraindication. Relative contraindications include cardiorespiratory compromise such that safe sedation or anesthesia cannot be achieved and in such cases the procedure may need to be done under local anesthesia. Breach of posterior vertebral cortex by tumor and tumor extension into the spinal canal are also relative contraindications for percutaneous vertebral augmentation techniques due to the potential for leakage of cement and/or displacement of tumor posteriorly.

11.5 Procedure

Kyphoplasty may be performed under general anesthesia or monitored anesthesia care (MAC) with conscious sedation and local anesthetic. In our practice, with rare exceptions, we perform kyphoplasty under general endotracheal anesthesia. In patients who cannot tolerate general anesthesia due to severe cardiopulmonary disease, for example, sedation with MAC is used with caution to avoid oversedation and respiratory compromise.

The patient is positioned prone on the operating table with shoulder and hip bolsters to aid in spinal extension and vertebral height restoration. All pressure points are padded and checked. With fluoroscopic guidance for localization, the area of planned surgery is prepped and draped in the usual sterile fashion. Appropriate prophylactic antibiotics are administered. Fluoroscopy is used to identify the pedicles and fractured vertebral body. Fluoroscopic views include true AP and lateral views. Another technique includes the en face view, directed down the longitudinal axis of the pedicle (▶Fig. 11.4).

Local anesthetic is injected and a small stab incision is made with a no. 15 or a no. 11 blade approximately 1 cm superior and 2 cm lateral to the superior pedicle border. For a standard transpedicular approach, the Jamshidi needle is inserted and guided under direct fluoroscopy through the pedicle into the vertebral body. Other approaches and access techniques may also be used (see Chapter 6). The inner cannula is removed and replaced with a K-wire. Using the Seldinger technique, the Jamshidi cannula is removed and the cannulated osteointroducer is passed over the K-wire and advanced through two-thirds of the AP vertebral body diameter. The K-wire and inner cannula are removed when the outer cannula position is confirmed. The drill is passed manually with fluoroscopic guidance to create a void for the bone tamp and to obtain biopsy material for pathology. Core bone biopsies may be obtained through the introducer or a biopsy cannula (▶Fig. 11.1).

Next, a 10- or 15-mm bone tamp connected to a syringe prefilled with iodinated contrast is inserted through the cannula and, under direct fluoroscopic guidance, guided into the tract created by the drill. The radiopaque markers on the balloon tamp are visualized distal to the cannula sheath in both AP and lateral fluoroscopic images. When a bilateral approach is used, this procedure is repeated identically on the contralateral side.

The use of balloon tamps allows for safe and gentle end plate reduction, displacement of trabecular bone, and the creation of a void. The balloon tamps are incrementally inflated while being monitored with AP and lateral imaging. Digital manometers incorporated into the inflation devices demonstrate increases in pressure with each increase in volume. The pressure then gradually diminishes as the trabecular bone is displaced. This process is repeated as safely tolerated. Fracture reduction is guided by the degree of end plate distraction, height restoration, and reduction of kyphotic angulation. Pressure, volume, and fluoroscopic images will all dictate an endpoint. There should be no breach of lateral wall or anterior cortex of the vertebral body. The final balloon volume is recorded and one or both tamps are deflated and removed. The cement-delivery cannula is inserted through the working channel and advanced until the tip of the cannula reaches the anterior extent of the void created by the tamp, preferably just posterior to the anterior cortical wall of the vertebral body. The rod is used to expel cement from the cannula. As cement is delivered, the cannula and rod are retracted gently to allow room for the cement to fill the void. As the cement extends posteriorly, the injection should be slow to watch for extravasation. The cement should extend from superior to inferior end plate and be located between the pedicles. The cement can extend up to the posterior vertebral body wall, but it is important to watch for and recognize extension of cement beyond this margin. This process is repeated on each side until an adequate fill is achieved. As the cement begins to harden, the cannulas are removed. The internal fixation and stabilization of the vertebrae is achieved through the hardening of the cement injected into the vertebral body. Final fluoroscopic images are taken to document the final cement position. Wounds are dressed with Dermabond or Steri-Strips (▶Fig. 11.5).

Related posts:

4 Physical Examination Findings in Patients with Vertebral Compression Fractures 13 Radiation Exposure and Protection: A Conversation Beyond the Inverse Square Law, Thermoluminescent Dosimeters, and Lead Aprons 14 Appropriateness Criteria for Vertebral Augmentation 18 Predisposing Factors to Vertebral Fractures 23 Number of Levels Appropriately Treated with Vertebral Augmentation 30 Vertebral Augmentation in Instrumented Spinal Fusions

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