Cement augmentation in spinal tumors: a systematic review comparing vertebroplasty and kyphoplasty

Study design: Comparative effectiveness review. Study rationale: The spine is among the most common location for bony metastases. In many cases these metastases cause fractures leading to increased morbidity. Percutaneous cement augmentation techniques have been developed over the past decades for the treatment of these fractures; however, there are little data comparing these interventions. Clinical question: Do comparative studies of vertebral cement augmentation for fractures caused by spinal tumors provide evidence of improved patient outcomes? Methods: A systematic search and review of the literature was undertaken to identify studies published through June 8, 2011. Two individuals independently reviewed articles based on inclusion and exclusion criteria which were set a priori. Each article was evaluated using a predefined quality-rating system and an overall strength of evidence determined. Results: The literature consists primarily of case series. Only two studies comparing vertebroplasty with kyphoplasty were found. Pain scores in both treatment groups were significantly decreased relative to preoperative scores and appear to have been sustained at follow-up times to 1 year. It is unclear whether one treatment provided superior pain relief than the other. Both studies reported decreased analgesic use after both treatments but neither study compared use between treatment groups. Balloon rupture occurred in one kyphoplasty patient in one study and extravasation of polymethylmethacrylate (PMMA) cement into the anterior perivertebral soft tissue was seen in another patient in the vertebroplasty group and no patients in the kyphoplasty group in the other study. No other intraoperative or postoperative complications occurred. Conclusions: There is only limited evidence from comparative studies (two small retrospective cohort studies) regarding the benefits of vertebroplasty versus kyphoplasty in patients with spinal fractures caused by tumors. Both appear to be effective in reducing pain with relatively few complications. Whether one method provides superior results over the other cannot be determined from the available evidence. Study limitations preclude making definitive conclusions. The overall strength of evidenced is very low.