Biological cement extravasation into the spinal canal following kyphoplasty. Long-term follow-up. Report of one case and review of the literature

Vertebroplasty and kyphoplasty are minimally invasive percutaneous techniques indicated in the treatment of some somatic vertebral fractures. Both are based on the introduction of a substance, called cement, inside the vertebral body. We can choose acrylic or biological cement. These techniques are not risk-free, cement extravasation being the main complication. Due to the short experience in the use of the biological cements, nowadays there are a lot of unresolved doubts about the long-term behaviour of these materials, especially in the case of leakage. We report a case of biologic cement extravasation into the spinal canal during a kyphoplasty in a 23 year old man and its long-term follow-up (3 years), performing a review of the scientific literature related to the topic. Most of the papers in the literature discuss the behaviour of the reinforcement material inside a bony environment, but they do not refer to the evolution of the cement outside the vertebral space. We have appreciated in our case that the leaked cement is not being substituted for bone but it suffers a process of progressive resorption. The extravasation of the vertebral reinforcement material is an important and potentially serious complication of the vertebral augmentation techniques. To avoid this, a very precise chirurgical technique is necessary, under radiological guidance. Biocompatibility, biodegradability and osteoconductivity are the main advantages of biological cements. We base the choice of the cement on the balloon/trabeculae interaction.