Initial outcome and efficacy of “kyphoplasty” in the treatment of painful osteoporotic vertebral compression fractures.
Purpose of Study
Kyphoplasty was first described in 1987. This paper by Lieberman et al was a phase I efficacy study looking at the use of kyphoplasty in the treatment of symptomatic osteoporotic compression fractures. The study included 70 consecutive kyphoplasty procedures in 30 patients over the course of 11 months.
Based on a review of the study, there are several concerns. First, while the authors clearly state that the data is based on consecutive patients, there is no discussion on whether any initial cases or patients were excluded and whether all of the cases were performed by one or multiple surgeons. As we know, selection bias can be easily introduced in a prospective cohort study. Since this was a phase I study, these may have been the first training cases for a particular surgeon or surgeons. A relatively new procedure with limited training certainly may have skewed the overall results.
In regards to outcome measures, one of the primary measures was measurement of height restored. The authors did clearly describe the procedure for calculating this measurement, but in the results section state that this was in some cases difficult to obtain so an estimate was used or no value at all was obtained for a particular level (potential for detection bias). The duration of symptoms ranged from 0.5 to 24 months for this cohort. The authors did not take into account age (chronicity) of fracture which would ultimately effect the degree of height restoration in some patients. The authors do concede this in the discussion. Taking this information into account combined with the small sample size and the potential detection bias, the overall conclusions supporting restoration of vertebral body height may not be valid.
Since this published in 2001, further studies looking at the efficacy and outcomes from kyphoplasty have appeared in the literature, but no definitive conclusions have been made. Gov V. et al (Spine 2015) looked at outcomes and trends in utilization of kyphoplasty from 2005 to 2010. This review of the literature and a national inpatient database included 81,790 kyphoplasty procedures. It was noted that vertebral augmentation procedures (includes vertebroplasty and kyphoplasty) have seen a significant decrease in utilization since 2009 where two controversial prospective randomized control trials were published in the New England Journal of Medicine. When compared with vertebroplasty, kyphoplasty had a lower mortality rate and higher overall costs. A previous randomized control trial from Sweden (Spine 2011) compared kyphoplasty to standard medical (conservative) treatment for fractures less than 3 months old. Using the EQ-5D to assess quality of life and QALYs to evaluate cost effectiveness, the authors were unable to conclude that Kyphoplasty was cost effective when compared to standard medical treatment. Multiple other studies including randomized trials and meta-analysis have failed to show superior efficacy in many regards for Kyphoplasty over vertebroplasty in treatment of osteoporotic vertebral compression fractures. There may be benefits in regards to short term pain relief and lower rates of cement leakage for kyphoplasty.
The study by Lieberman did not state whether any funding was received for this prospective study, however, the kyphoplasty device manufacturer, Kyphon Inc, was recognized for providing equipment and technical support.