Fluid sign in the treated bodies after percutaneous vertebroplasty.

INTRODUCTION: The aims of this study are to describe non-healing in the treated vertebral body after percutaneous vertebroplasty and analyze the influence of vacuum cleft, location, and severity of collapse on the development of nonunion cement.
MATERIALS AND METHODS: Of 208 patients (266 treated vertebral bodies) who were treated with percutaneous vertebroplasty from September 2002 to May 2006, 23 patients (41 treated levels) with residual or recurrent pain underwent follow-up magnetic resonance imaging (MRI) study. Retrospective chart review with analysis of preoperative and postoperative MRIs were performed in these 23 patients.
RESULTS: In the 41 treated vertebral bodies, 22 of 41 bodies had vacuum cleft found in the preoperative MRI study. Eight of the 22 treated vertebral bodies with preoperative vacuum clefts were found to have fluid between the interface of cement and the residual bone in the collapsed vertebral bodies on follow-up MRI. The adjacent discs of these treated vertebral bodies were upward/downward displaced. The endplate of the adjacent vertebral body exhibited fibrotic change. Treated bodies with vacuum clefts and level A location (T9, T11, T12, and L1) had higher probability of developing nonunion of the cement with statistical significance. The probability of nonunion cement in severe collapsed bodies might be higher than that of union cement in mild collapsed ones, but was not statistically significant.
CONCLUSIONS: Fluid sign in the treated body represents unhealed bone-cement interface. The location of the treated vertebral body and existence of vacuum cleft in the treated bodies may be important factors influencing the nonunion of cement.