Intravertebral pressure gradient during vertebroplasty.

Objective: Intravertebral pressure (IP) is considered a possible factor influencing cement leakage in vertebroplasty (VP). Reports of measuring IP during the injection of the cement reveal rather low values in the periphery of the vertebral body but fail to determine the situation in the center. Hypothesizing there is a significant IP gradient between both areas intravertebral pressure measurements were conducted in a comparative biomechanical study.

Methods: VP was performed in ten lumbar cadaveric spines. A pressure sensor was either placed in the center or in the periphery of the vertebral body, while bone cement was delivered in 1.5-cc increments. Volume flow, cement mixing time, and room temperature were standardized and kept constant during cement injection.

Results: During the administration of the first 1.5 cc of bone cement, the central IP (C-IP) increased to 23.6 kPa and the peripheral IP (P-IP) to 0.9 kPa on average. With the second injection, the mean C-IP was 42.8 kPa while the mean P-IP was 3.8 kPa. During the 3rd filling, C-IP averaged 69.9 kPa and P-IP 12.8 kPa, respectively. At the last increment, C-IP was at 70.7 kPa and P-IP at 24.5 kPa on average.

Conclusions: A centroperipheral IP gradient (∆IP) was monitored during cement delivery in VP. ∆IP decreases with increasing bone cement charge of the vertebra, but C-IP stays significantly higher than P-IP at all times. C-IP was consistently higher than IP values reported for VP so far.