Bone cement augmentation of the pedicle screw in spinal surgery

Osteoporosis is a common metabolic bone disease in the elderly. It may be one of the factors which contributes to instrumentation failure in spinal surgery. Bone cement augmentation of the pedicle screw is a technique to enhance fixation strength, and it is now mainly applied in patients with osteoporosis and revision surgery, as well as spinal tumor surgery. According to clinical studies, bone cement augmentation can decrease screw loosening rate, prevent correction loss of the spine deformity, and increase the fusion rate. Pedicle screw fracture and pulloutare rare following screw augmentation surgery. The pedicle screw loosening rates following screw augmentation surgery with bone cement are higher in patients with osteoporotic vertebral fracture and lower in patients with spinal degenerative diseases. The main material for bone cement augmentation is Polymethylmethacrylate, and the volume for each screw is about 1-3 ml. Some researchers suggest less volume use in thoracic vertebrae than lumbar vertebrae. Both traditional and cannulated screws can be applied as the augmented pedicle screws, as well as the expandable pedicle screw. Cannulated screws can decrease the risk of bone cement extravasation compared with traditional screws. The mini-mally invasive technique of screw augmentation with bone cement can be used both in primary spinal surgery and augmentation of loosed screws. The main complications of the bone cement augmentation technique are cement leakage and pulmonary cement em-bolism. X-ray fluoroscopy is generally used to detect cement extravasation during the bone cement procedure. The 3D navigation and neurological monitoring are also recommended to reduce cement leakage in some studies. Most local cement leakage events are asymptomatic and need no treatment. Management of pulmonary cement embolism depends on the clinical presentation and the position of the emboli, including regular follow-up, oxygen inhalation, anti-coagulation therapy and embolectomy.