Explaining their recent study, Alexis Kelekis and Dimitrios Filippiadis write that the use of augmented vertebroplasty could offer improved mechanical and structural support when compared with standard vertebroplasty in the treatment of extreme vertebral fractures. The study was presented at the Radiological Society of North America Annual Meeting (30 November–5 December 2014, Chicago, USA).
Traumatic fractures can be classified according to the Magerl classification based on the injury’s pathologic and morphological characteristics. There are three main injury mechanisms that give name to three major categories (type fractures): A for compression, B for distraction and C for rotation. Specific morphologic criteria for each fracture lead to further classification in subgroups.
Throughout the literature there are numerous studies (both prospective and retrospective) with both small and larger patient samples evaluating the efficacy of percutaneous vertebroplasty for the treatment of vertebral compression fractures with resultant significant pain reduction and mobility improvement. However, in the literature there are a limited number of studies reporting moderate efficacy of standard percutaneous vertebroplasty for the treatment of split/incomplete burst fractures or vertebral compression fractures with large osteonecrotic cavities (AO-Magerl A2/A3). In these types of fractures, potential displacement of the fractured fragments seems to limit the efficacy of the technique.
In our study, we attempted to test whether augmented vertebroplasty with a PEEK polymer cage (Kiva; Benvenue Medical) is a better choice for these extreme fractures compared with standard percutaneous vertebroplasty.
Patients were enrolled in the study if they had symptomatic AO-Magerl A2/A3 vertebral fractures, split or incomplete burst vertebral fractures or large osteonecrotic vertebral cavities at one or more levels with back pain and minimum visual numeric scale score of 4/10. Overall, 24 patients were enrolled in the study, randomised to group A (standard vertebroplasty) and group B (augmented vertebroplasty) with implantation of a biocompatible PEEK cage. Standard X-rays and CT scans were performed during follow-up. Pain prior, the morning after and at the last follow-up (average follow-up 12 months) were compared by means of a visual numeric scale questionnaire. Cement or implant migration were recorded.
Standard vertebroplasty technique was performed according Cardiovascular and Interventional Radiological Society of Europe and Society of Interventional Radiology standards of practice. Augmented vertebroplasty with a Kiva system is a percutaneous technique during which a trocar is inserted in the vertebral body through a transpedicular access, used with a working cannula over a Kirschner wire. Through the working cannula, a nitinol coil is deployed inside the vertebral body. The PEEK polymer cage is deployed inside the vertebral body over the coil, after which the nitinol coil is removed. Finally, a PEEK polymer cage is filled with PMMA under fluoroscopy.
In the standard vertebroplasty group, there was progression of the vertebral body damage (including widening of the fracture line or PMMA migration and subsequent vertebral fracture) in three patients (25%) with two being surgically operated on (16.7%). In the PEEK cage group there was no implant change or migration observed. No symptomatic or clinically significant extravasation occurred in either group. The vertebroplasty group presented a mean pain value of 9±1 prior to and 2.3±3.7 visual numeric scale units post-treatment, with a mean decrease of 6.7±1.5 visual numeric scale units (p=0.005). The PEEK cage group presented a mean pain value of 8.7±1 prior to and 1.3±1.5 visual numeric scale units post treatment, with a mean decrease of 7.33±1.49 units (p=0.002). Pain reduction difference between the two groups was not statistically significant (p=0.545). PMMA versus implant migration in the two groups was marginally insignificant in the statistic analysis (p=0.064), while overall mobility improved in 10 (83%) patients in the vertebroplasty group and in all patients in the PEEK cage group.
Looking at the results of our study, both standard and augmented vertebroplasty seem to be effective in reducing pain in patients with split or incomplete burst vertebral fractures or large osteonecrotic vertebral cavities. However, preliminary results show potential tendency for widening of fracture line or PMMA migration and subsequent vertebral fracture in the vertebroplasty group. In contrast, in augmented vertebroplasty, the implant seems to function as an internal cast providing mechanical and structural support and height restoration for the vertebra.
Alexis Kelekis is an interventional radiologist at the Univeristy Hospital of Athens, Greece. Dimitrios Filippiadis is an interventional radiologist at Attikon University Hospital, Greece