Introduction

Vertebral compression fractures (VCFs) have a high incidence in the elderly population and are the most common fractures in osteoporotic bones. The majority present without a history of major trauma.¹ The incidence of VCF is increased in patients with a prior vertebral compression fracture, with studies indicating that nearly 20% of patients who have an osteoporotic VCF will develop a second fracture within a year of the first.² Not only do these fractures cause significant morbidity in terms of pain, loss of mobility, and kyphosis, but the relative risk of death after a vertebral fracture is nearly nine times greater than in people without a vertebral fracture.²

Percutaneous vertebroplasty (PVP) was introduced in France in 1984 by Galibert and Deramond as a treatment for a malignant aggressive hemangioma.¹ It is a therapeutic procedure performed to reduce pain and perhaps to stabilize vertebral lesions. Subsequently PVP was used to treat painful lesions such as hemangiomas, metastasis, multiple myeloma, and osteoporotic fractures. Today most patients undergoing PVP suffer from vertebral osteoporotic compression fractures. PVP is generally seen as a safe and efficient procedure for treatment of painful osteoporotic fractures.

Vertebral augmentation using balloon kyphoplasty and vertebroplasty³ is traditionally performed with polymethyl methacrylate (PMMA) cement. Clinical studies have demonstrated the efficacy of both methods in reducing fracture-related pain.^2,4 However, there have also been reports of complications: extrusion of cement into surrounding tissue, vascular embolism in the corresponding vascular system, adverse systemic reactions to unpolymerized toxic monomers, and thermal damage to adjacent structures. The two latter complications are specific to PMMA. For this reason, and because PMMA does not become osseointegrated, attempts have been increasingly made in recent years to explore the possibilities of alternative cements by looking into biomaterials based on calcium phosphate (CaP). The properties of such bone cements, however, would have to fit a specific profile that takes into account the following parameters: setting behavior, mechanical fitness, and biological behavior.

There is a new vertebral augmentation device, the Kiva VCF Treatment System (Benvenue Medical, Santa Clara, Calif.), that can be used in the treatment of patients sustaining painful VCFs. Unlike the traditional balloon kyphoplasty procedure that pushes cancellous bone peripherally to form a repository for bone cement, the Kiva device preserves cancellous architecture using a percutaneously introduced Poliether etherKetone implant in a continuous loop to form a nesting, cylindrical column. The implant is delivered over a removable guide wire to provide structural support to the vertebral body, and it is a conduit for bone void filler placement. Vertical displacement by the column results in endplate re-elevation and fracture reduction. Bone cement is delivered through the lumen of the implant, which provides contained interdigitation into the cancellous bone thus stabilizing the fracture and minimizing the risk of extravasation.

Indications

The Kiva system is indicated for the management of pathological compression fractures of the vertebral body that may result from osteoporosis, in segments T10 to L5 of the spine. It can also used to treat benign or malignant lesions, by creating a transpedicular channel through which a PEEK implant is inserted into the vertebral body.

Contraindications

Contraindications include the following:

Precautions

Precautions that should be taken include the following:

Description of the Device

The Kiva system is packaged as a single-use, sterile device incorporating an implantable PEEK distraction sleeve. It is a surgical instrument designed to provide percutaneous access and channel creation in the cancellous bone of the spine followed by delivery of a PEEK distraction sleeve implant into that channel. The Kiva system consists of five primary components: