A prospective, international, randomized, noninferiority study comparing an implantable titanium vertebral augmentation device versus balloon kyphoplasty in the reduction of vertebral compression fractures (SAKOS study)

Abstract

Background context: Balloon kyphoplasty (BKP) is a commonly performed vertebral augmentation procedure for painful osteoporotic vertebral compression fractures (OVCFs).

Objective: This study aimed to support a non-inferiority finding for the use of a titanium implantable vertebral augmentation device (TIVAD) compared to BKP.

Study design: Prospective, parallel group, controlled comparative randomized study.

Patient sample: Patients who presented with one or two painful OVCFs located between T7 and L4 aged <3 months, failed conservative treatment, and had an Oswestry Disability Index (ODI) score ≥30/100 were eligible for the study.

Outcome measures: The primary composite endpoint was defined as: reduction in VCF fracture-related pain at 12 months from baseline and maintenance or functional improvement (ODI) at 12 months from baseline, and absence of device-related adverse event or surgical reintervention. If the primary composite endpoint was successful, a fourth component (absence of adjacent level fracture) was added for analysis. If the analysis of this additional composite endpoint was successful, then midline target height restoration at 6 and 12 months was assessed. Secondary clinical outcomes included back pain intensity, ODI score, EQ-5D index score (range 0=death to 1=full health) and EQ-VAS score (range 0-100).

Methods: Patients were recruited in 13 hospitals across 5 countries and were randomly assigned (1:1) to either TIVAD or BKP with electronic randomization as described in the protocol. A total of 152 patients with OVCFs were initially randomized. Eleven patients were excluded (six met exclusion criteria, one with evidence of tumor, and four patients had T score out of requested range). Anterior vertebral body height ratio, midline vertebral body height ratio, and Cobb angle were measured preoperatively and postoperatively by an independent imaging core lab. Adjacent and subsequent fractures and safety parameters were recorded throughout the study. Cement extravasation was evaluated on X-rays. All patients were followed at screening at 5 days, 1 month, 6 months, and 12 months postoperatively. This study was supported by Vexim SA. Seven authors received study-specific support less than $10,000 per year and seven authors received no study-specific support.

Results: Among the 141 patients (78.7% female, mean age 73.3±9.5 years) who underwent surgery (TIVAD=68; BKP=73), 126 patients (89.4%) completed the 12-month follow-up period (TIVAD=61; BKP=65). The analysis of primary endpoint on the ITT population demonstrated non-inferiority of the TIVAD to BKP. The analysis of the additional composite endpoint demonstrated the superiority of TIVAD over BKP (p<0.0001) at 6 months (88.1% vs. 60.9%) and at 12 months (79.7% vs. 59.3%). Midline VB height restoration was more improved for TIVAD than for BKP at 6 months (1.14±2.61 mm vs. 0.31±2.22 mm); p=0.0246) and 12 months after surgery (1.31±2.58 mm vs. 0.10±2.34 mm; p=0.0035). No statistically significant differences were shown between procedures for improvement in functional capacity and quality of life. Pain relief was significantly more marked in the TIVAD group compared to the BKP group at 1 month (p=0.029) and at 6 months (p=0.021) after surgery. No patient required surgical reintervention or retreatment at the treated level. No symptomatic cement leakage was reported. Adverse events were similar for both groups (41.2% in the TIVAD group and 45.2% in the BKP group). The incidence of adjacent fractures was significantly lower after the TIVAD procedure than after BKP (12.9% vs. 27.3%; p=0.043).

Conclusions: Study results demonstrated non-inferiority of the TIVAD to the predicate BKP with an excellent risk/benefit profile for results up to 12 months.

Keywords: Adjacent fractures; Balloon kyphoplasty; Height restoration; Osteoporosis; Percutaneous vertebral augmentation; Prospective randomized study; Spine surgery; SpineJack® system; Vertebral compression fracture.