1. 2015;18;E805-E814Effect of the Location of Endplate Cement Extravasation on Adjacent Level Fracture in Osteoporotic Patients Undergoing Vertebroplasty and Kyphoplasty
   Prospective Study
   Deborah Glueck, PhD, Brian Petersen, MD, Mary Kristen Jesse, MD, and Sarah Kriedler, PhD.

BACKGROUND: The most widely researched risk/complication following vertebroplasty (VP) or kyphoplasty (KP) is that of adjacent level fracture (ALF). Current literature results regarding the effect of intradiscal extravasation of cement on the risk of ALF is conflicting with about half of the studies concluding there is no added risk with endplate extravasation and half of the studies reporting opposite conclusions.
OBJECTIVE: The purpose of the study is to further stratify the data to determine whether specifically the location and extent of endplate cement extravasation more strongly affect ALF risk in osteoporotic patients following either VP or balloon KP.
STUDY DESIGN: Retrospective cohort study.
SETTING: University teaching hospital
METHODS: One hundred and fifty-six cemented levels in 80 patients, treated at a single center between 2008 and 2012 were reviewed. Age, gender, T-score, body mass index, and osteoporosis type (primary or secondary) were recorded. An ALF was defined as a fracture: 1) in a non-cemented vertebra; 2) adjacent to a cemented level; and 3) not due to trauma or malignancy. Location of the cement extravasation (anterior, middle, or posterior third of the vertebral body) and extravasation extent (percentage of the intervertebral disc height occupied by the bolus) were measured. A logistic modeling strategy permitted examining the association between the location and extent of extravasation and the odds of ALF.
RESULTS: ALF occurred in 14 of the 52 patients (27%) and 20 of the 98 levels (20.4%) remaining after exclusions. Odds of ALF were 5.9 times higher (95% CI: 1.6 to 21.2, P = 0.008) with extravasation when compared to no leakage. Odds of ALF in a given patient were 22.6 times higher (95% CI: 3.0 to 170.9, P = 0.003) with anterior extravasation when compared to no leakage. Leakage in the middle or posterior thirds and extent of extravasation were not associated with ALF.
LIMITATIONS: Limitations of the study include the retrospective study design and small sample size as well as the retrospective implementation of follow-up criteria posing risk of selection bias.
CONCLUSIONS: Cement endplate extravasation isolated to the anterior third of the vertebral body is associated with is significantly higher odds of ALF after VP or KP in patients with osteoporosis.