Results, experience and technical points learnt with use of the SKy Bone Expander kyphoplasty system for osteoporotic vertebral compression fractures: a prospective study of 40 patients with a minimum of 12 months of follow-up

Abstract

To describe our centre's results, experience and technical points learnt with the SKy Bone Expander System for osteoporotic vertebral compression fractures (VCFs). Forty consecutive patients with painful single level T12 or L1 osteoporotic VCF who had failed conservative management for more than 3 months had 40 single level SKy Bone Expander kyphoplasties performed. Using local anaesthesia with patients in a prone, hyper-lordotic position, a unilateral, percutaneous, intra-pedicular approach was employed. Once correctly positioned, the SKy Bone Expander was expanded, creating a void. It was subsequently contracted, removed and bone cement injected. Pre-kyphoplasty and 12-month post-kyphoplasty radiological and functional outcomes were recorded. Statistical analysis was by Wilcoxon Signed Ranks Test. Median percentage increase in anterior, middle and posterior vertebral body heights at 12-month post-operative was 51.25% [inter-quartile range (IQR) 17.21-93.22], 52.29% (IQR 26.50-126.17) and 9.84% (IQR 4.94-19.26) respectively, while median percentage decrease in kyphotic angle was 30.77% (IQR 17.06-46.61). There was no significant vertebral body correction loss at 12-month post-operative. Visual analogue score, North American Spine Society and Short Form-36 scores for physical functioning and bodily pain scores improved by medians of 5.0 (IQR 3.0-8.0), 1.45 (IQR 0.68-2.90), 20.5 (IQR 0.0-40.8) and 10.0 (IQR 0.0-20.0) respectively. All P-values were <0.001. There were eight adjacent/remote level VCFs, three cases of cement extravasation and one case of the SKy Bone Expander being unable to be contracted and withdrawn from the vertebral body. It was left in situ. This is the first reported incidence of such a complication. The SKy Bone Expander System appears to be a viable alternative to balloon tamp kyphoplasty. Important technical considerations include proper device positioning within the vertebral body before expansion, single use of devices, familiarity with salvage procedure and injection of bone cement under close image intensifier guidance to prevent cement extravasation.