In vivo temperature profile of intervertebral discs and vertebral endplates during vertebroplasty -: An experimental study in sheep

Study Design. Experimental study of temperature profiles during vertebroplasty. Objectives. To define accurate temperature profiles during vertebroplasty in an in vivo animal model. Summary of Background Data. Controversy still exists whether vertebroplasty achieves its analgesic effect by stabilizing fracture fragments or due to thermal damage of sensory nerves inside the vertebral body. Furthermore, the energy release during cement polymerization may cause thermal injury to the spinal cord or intervertebral discs. Methods. A total of 4.0 mL PMMA was injected into three lumbar vertebrae of four skeletally mature mixed-bred ewes. Nine separate K-type thermocouples were placed into 12 vertebrae and their adjacent intervertebral discs. Temperature changes were recorded continuously before, during, and after the injection. Results. The highest peak temperatures were measured at the cranial endplate (mean 42.4 +/- 8.8 C) and in the center of the vertebral body (mean 43.3 +/- 6.9 C). Temperatures stayed above 40 C for approximately 2.5 minutes. Peak temperatures in the discs and at the dorsal wall (closest to spinal cord) did not exceed 41 C and 47 C and stayed above 40 C for approximately 1.5 minutes. Conclusions. The intervertebral discs and the spinal cord do not seem to be in danger of thermal damage during vertebroplasty. The measured energy does not seem to be sufficient for the palliative effect achieved by vertebroplasty.