Vertebral augmentation treatment of painful osteoporotic compression fractures with the Kiva VCF Treatment System

Abstract

Background: Vertebral compression fractures (VCFs) can cause significant pain and functional impairment, and their cumulative effect can lead to progressive morbidity. This single-arm, prospective feasibility trial, conducted at 4 clinical sites, was undertaken to evaluate the clinical outcomes associated with the use of an innovative vertebral augmentation device, the Kiva VCF Treatment System (Benvenue Medical, Santa Clara, California), in the management of symptomatic VCFs associated with osteoporosis.

Methods: Vertebral augmentation treatment was performed for persistent back pain symptoms in 57 patients (mean age, 71.9 ± 10.4 years), including 46 women, with radiologically confirmed VCFs; 36 of these patients (63%) had reached 12 months of follow-up at this data analysis. There were 51 one-level cases, 5 two-level cases, and 1 three-level case, representing 64 treated levels. Back pain severity and condition-specific functional impairment were evaluated with a standard 100-mm visual analog scale and the Oswestry Disability Index (ODI), respectively, before device implantation as well as at 6 weeks, 3 months, and 12 months.

Results: Marked clinical improvements were realized in back pain severity and functional impairment through 12 months of follow-up. The mean back pain score on the visual analog scale improved from 79.3 ± 17.2 before treatment to 21.9 ± 21.3, 21.9 ± 24.6, and 23.2 ± 23.3 at 6 weeks, 3 months, and 12 months, respectively. The mean decrease at 12 months was 49.9 ± 30.3 mm, or approximately 66% (P < .0001). Similarly, the mean ODI score improved from 68.1% ± 16.9% before treatment to 27.4% ± 17.2%, 23.8% ± 18.7%, and 23.3% ± 15.5% at 6 weeks, 3 months, and 12 months, respectively, representing a mean change of 39.2 ± 19.6 percentage points, or approximately 63%, at 12 months. Overall clinical success rates based on a 30% improvement in pain severity or greater and maintenance or improvement in the ODI were 91%, 88%, and 89% at 6 weeks, 3 months, and 12 months, respectively. The vertebral augmentation procedure required injection of a mean of 2.2 ± 0.12 mL of cement per vertebral body. There were 5 levels (8%) where cement extravasation was identified radiographically, and none were related to clinical symptoms.

Conclusions: These pilot findings are encouraging, suggesting robust and durable clinical improvement after this novel vertebral augmentation procedure in patients with painful VCFs.

Keywords: Cement augmentation; Kiva; Osteoporosis; Vertebral compression fracture.

Figures

Fig. 1

Graphical illustration of VCF Treatment System, consisting of a percutaneously introduced nitinol coil guidewire advanced through a deployment cannula (A) and then fully coiled within the cancellous portion of the fractured vertebral body (B). A radiopaque polyetheretherketone implant is delivered incrementally over the removable coil (C) in a continuous loop to form a nesting, cylindrical column providing vertical displacement that may result in endplate re-elevation and fracture reduction (D).

Fig. 2

Fluoroscopic images illustrating deployment of the implant into a vertebral body over the removable guidewire in a coiled manner (A). After removal of the coil, the implant is fully deployed (B) to provide structural support to the vertebral body and serve as a conduit for bone cement placement. After bone cement delivery through the lumen of the implant, lateral (C) and anteroposterior (D) fluoroscopic images show contained interdigitation of cement into the adjacent cancellous bone, and the fracture is fully stabilized in situ.

Fig. 3

Line graph showing mean (± SE) VAS pain and ODI scores at baseline and each follow-up interval after vertebral augmentation.

Fig. 4

Box-and-whisker plots indicating the upper (75th) and lower (25th) quartiles and the median value for percent improvement in VAS back pain severity (left) and ODI (right) scores at 6 weeks, 3 months, and 12 months after vertebral augmentation. The points at the end of the “whiskers” represent the 90th and 10th percentile values.

Fig. 5

Mean and 95% confidence interval values for improvement in back pain severity by VAS derived from 4 separate meta-analyses of balloon kyphoplasty studies compared with the 12-month mean reduction in VAS pain scores for patients treated with the VCF Treatment System.

Fig. 6

(A) Intraoperative lateral fluoroscopic image showing moderate vertebral wedging with percutaneous initial catheter introduction. (B) Immediate postoperative image in the same patient showing complete implant deployment with cement containment.