Two of the most common newer minimally invasive spine procedures are vertebroplasty and kyphoplasty, both of which are used for treating osteoporotic vertebral body fractures and vertebrae affected by metastatic cancer. Unsurprisingly, many people first hear of these terms when back pain and other symptoms of spinal compression or fracture bring them to the office of an orthopedic surgeon.
Vertebroplasty is a type of minimally invasive procedure that involves bone cement being injected into a fractured vertebrae in order to seal and stabilize the fracture. This also helps relieve pain caused by a compression fracture. In most cases, candidates for vertebroplasty are those who are suffering from intense pain and difficulty walking and standing due to a compression fracture.
Kyphoplasty meanwhile, is a procedure used to correct kyphosis, or excessive curvature of the spine. Kyphosis caused by a compressed vertebra may be treated by inserting a deflated balloon into the compressed vertebra, inflating the balloon to restore the proper height of the vertebra and then injecting bone cement into the space created by the balloon to make the decompression more permanent.
Problems with Vertebroplasty and Kyphoplasty
Both of these procedures make use of bone cement, a substance that quickly hardens to provide a stable, resilient part of the restructured spine. Although bone cement is considered safe and effective for the most part, there are two main causes of problems with bone cement, or polymethylmethacrylate (PMMA) cement: thermal and chemical necrosis of surrounding bone.
Chemical necrosis is caused by the release of unreacted monomer and thermal necrosis by the high temperature generated during polymerisation. Vertebroplasty and kyphoplasty have been around for just over 15 years and in that time the techniques have been refined in order to make them safer and less liable to lead to complications from back surgery.
The degree of heat likely produced during these back surgeries was recently studied by Wegener and colleagues (2012), who found that the temperature did indeed rise during polymerisation of the bone cement, with a peak temperature of 43.16°C reached after a few minutes and lasting only for a few seconds. These researchers concluded that when vertebroplasty and kyphoplasty are performed correctly there is no generation of heat that would cause spinal cord or spinal nerve damage.