Comparison of Balloon Kyphoplasty and Vertebroplasty in Subacute Osteoporotic Vertebral Fractures

Overview

This study aims to compare two treatments in subacute (more than 6 week duration) non-traumatic (usually osteoporotic) vertebral fractures. The two treatments are the following: 1. Vertebroplasty consisting in the percutaneous injection into the fractured vertebra of polymethylmetacrylate cement (the cement used to fix prosthesis in joint replacement) through a posterior route through the vertebral pedicles under radiological guidance. 2. Balloon Kyphoplasty which consists of placing through a percutaneous posterior approach under radiological guidance, into the fractured vertebra a balloon which is inflated with fluid and creates a cavity. This may restore part of the vertebral height loss due to the fracture. In addition, after balloon deflation, polymethylmetacrylate cement is injected with low pressure into the created cavity to fix fracture reduction. The study will indicate if balloon kyphoplasty is able to restore vertebral height of the fractured vertebra better than vertebroplasty.

Vertebral compression fractures can occur at any level in the vertebral column but the most frequent ones occur at the thoracic (T8-T12) and lumbar spine (L1 and L4). Multiple vertebrae are often concerned. Vertebral fractures are characterized by height reduction of the involved vertebral bodies and very often also by kyphosis and laterally dorsal pain laterally irradiating towards the two sides of the back. A spontaneous improvement of this pain can occur spontaneously within 6 to 12 weeks, but a large number of patients develop a chronic pain and associated morbidity, due to the side effects caused by the fractureThe main cause (85%) of non-traumatic vertebral compression fractures is osteoporosis, in particular in elderly patients. In osteoporotic vertebral fractures older than 6 weeks, conservative management is purely symptomatic, with no effect on the compression fracture itself. Two alternatives are available: Percutaneous Vertebroplasty and Percutaneous Balloon Kyphoplasty 1. Percutaneous Vertebroplasty is a percutaneous treatment of vertebral fractures which is used now for more than 25 years. It was first reported in aggressive vertebral hemangiomas and vertebral malignancies and than in osteoporotic vertebral fractures. More recently, vertebroplasty was used in traumatic vertebral fracture.Vertebroplasty is performed under fluoroscopic guidance with the patient in prone position under general or local anesthesia and conscious sedation. A trocar needle is inserted through a posterior approach into the vertebral neural arch and pedicle, up to the fractured vertebral body. Depending on cases a unilateral or bilateral approach is used. A bilateral approach is used in the cases of traumatic fractures. Once the needle is well positioned into the vertebral body as checked on apical and Lateral views, a radio-opaque cement, in a viscous phase, is slowly injected into the vertebral body under continuous fluoroscopic control. The injection is stopped in case of cement leakage outside from the vertebral body. Polymethylmetacrylate is the most commonly used cement. Its biologic compatibility is well established since used in orthopedic surgery for many decades. Some operators are reluctant to use a non-resorbable cement in young patients. However, to date, the ideal resorbable injectable cement to be discovered. Vertebroplasty allows rapid fracture fixation and decrease in pain, thus allowing the patient to resume walking and daily activities in the days following the procedure. Vertebroplasty does not reduce significantly the kyphosis angle due to the fracture unless nonunion is present in the fracture line. 2. Percutaneous Balloon Kyphoplasty is a variant of vertebroplasty which is performed under general anaesthesia using the KyphX® System (Medtronic, Sunnyvale, California). Balloon kyphoplasty aims at restore vertebral height of the fractured vertebra using an inflatable balloon prior to inject surgical cement (PMMA) into the vertebral body and fix the fracture. It is an expensive technique costing around 4,000 euros for up to 2 vertebrae in the same patient. The surgical technique for the procedure has been described by Lieberman et al. A bilateral approach is chosen to insert working cannulas into the posterior part of the vertebral body. Fluoroscopy is used to insert the tools and control the procedure. With reaming tools, two working channels are created and the balloons are inserted. The balloons are available in lengths of 10, 15 and 20 mm.The two balloons(one on each side) should ideally be centered at middle height between the superior and inferior endplates and in the anterior two-thirds of the vertebral body. Balloon placement into the vertebral body is checked using radiopaque markers at the two extremities of the balloon. Once inserted, the balloons are inflated using visual, volume and pressure control to create a cavity. Inflation is stopped when one of the following inflation endpoints is reached: pressure raised over 400 psi, balloon contacts one of the cortical bone of the vertebra or reaching maximal balloon inflation volume. The balloons are then deflated and removed. The mean balloon inflation volume is 2 to 3ml. The Bone Filler Device, filled before with 1.5 ml of polymethylmethacrylate (PMMA), is then advanced through the working cannula towards the anterior part of the cavity and cement is slowly extruded by a stainless steel stylet, acting as a plunger. When the amount of cement from the first Bone Filler Device is delivered in the cavity, it is removed and another Bone Filler Device is advanced through the working cannula. This step is repeated till a complete fill of the cavity is obtained. The same procedure is repeated through the other working cannula at the contra-lateral pedicle. Filling of the cavity with highly viscous PMMA is performed under continuous fluoroscopic control.