Connolly, M. Nilsson, T. McGrath, D. Needleman (Santa Clara, USA)
INTRODUCTION: Vertebral compression fractures (VCF) are increasingly treated interventionally compared to conservatively. There are several reasons for the increase, but the immediate pain relief that the patient experiences after the interventional treatment is probably the strongest proof and incitement for active treatment. Today vertebroplasty and kyphoplasty are the two most common techniques for treatment of VCF. A new alternative is the KIVATM VCF Repair System1, which utilizes a coil-like PEEK implant to reduce and stabilize the fracture. This device may be used in combination with a small volume of cement and acts to prevent extravasation by directing and containing the cement. In this study a biphasic, highly flowable and resorbable ceramic cement2 (Cerament™, Bonesupport AB) was evaluated against PMMA cement (Benvenue). Compressive stiffness and mechanical strength of the repaired vertebrae were compared and cement distribution evaluated.
METHODS: 12 cadaveric vertebral bodies (VB’s) harvested from three human cadaveric spines were used for the study. BMD was measured and specimens randomly assigned to either a PMMA or Cerament™ repair group. Group assignment was made such that there was no difference in mean BMD between groups. The KIVATM device was implanted in all VB’s, then cement injected according to group assignment.
Prior to implantation, all VB’s were compressed until failure, with a 10mm anterior offset load to create a wedge fracture. Per the KIVATM procedure, each VB was cannulated unipedicularly, and a coiled nitinol guide wire deployed into the cancellous bone. The implant was then advanced over the guide wire to form a coiled construct. After removing the guide wire, 2 to 3 mL of cement was injected into the VB through the fenestrated implant. Each specimen was then tested at least 24 hours post-treatment to measure compressive stiffness and failure strength.
RESULTS: Both Cerament™ and the PMMA cement were easily injected through the KIVATM implant. They displayed similar radiopacity and similar distribution within the implant and into the surrounding cancellous bone.
The failure strength post treatment exceeded the load required to induce fracture in all specimens, with a mean increase of 151% with PMMA and 124% with Cerament™.
Both procedures significantly increased compressive stiffness from the fractured state (Fig. 1).
CONCLUSIONS: The presented technique using the KIVATM VCF Repair System in combination with a ceramic cement may be a good alternative to vertebroplasty and kyphoplasty for treatment of vertebral compression fractures. The PEEK implant in conjunction with a biphasic ceramic cement yields augmented vertebral stiffness and strength comparable to PMMA solutions yet offers a unique, resorbable option with reduced potential for complications associated with PMMA3
REFERENCES:
1. Wilson DC et al., Proc ORS 2009, Las Vegas.
2. Hierholzer J et al., Proc C119, Spineweek 2008, Geneva.
3. Schmidt R et al., Eur Spine J 2005;14:466-73.