Vertebral augmentation, including vertebroplasty and kyphoplasty, refers to similar percutaneous spinal procedures in which bone cement is injected through a small hole in the skin into a fractured vertebra in order to relieve back pain caused by a vertebral compression fracture. After decades of medical research into the efficacy and safety of vertebral augmentation, there is still a lack of consensus regarding certain aspects of vertebroplasty and kyphoplasty.
Procedure
Vertebroplasty and kyphoplasty are the two most common procedures for spinal augmentation. These medical terms are classical compounds of the suffix -plasty meaning "molding or shaping surgically" (from Ancient Greek plastós "molded, formed") and the prefixes vertebro- "vertebra" (from Latin [[wikt: vertebra#Etymology 1|vertebra]] "joint, joint of the spine") and kypho- "humped; stooping forward" (from Ancient Greek kyphos "crooked").
Vertebroplasty
Vertebroplasty is typically performed by a spine surgeon or interventional radiologist. It is a minimally invasive procedure and patients usually go home the same or next day as the procedure. Patients are given local anesthesia and light sedation for the procedure, though it can be performed using only local anesthetic for patients with medical problems who cannot tolerate sedatives well.
During the procedure, bone cement is injected with a biopsy needle into the collapsed or fractured vertebra. The needle is placed with fluoroscopic x-ray guidance. The cement (most commonly poly methyl methacrylate (PMMA), although more modern cements are used as well) quickly hardens and forms a support structure within the vertebra that provide stabilization and strength. The needle makes a small puncture in the patient's skin that is easily covered with a small bandage after the procedure.
Kyphoplasty
Kyphoplasty is a variation of a vertebroplasty which attempts to restore the height and angle of kyphosis of a fractured vertebra (of certain types), followed by its stabilization using injected bone cement. The procedure typically includes the use of a small balloon that is inflated in the vertebral body to create a void within the cancellous bone prior to cement delivery. Once the void is created, the procedure continues in a similar manner as a vertebroplasty, but the bone cement is typically delivered directly into the newly created void.
In a 2011 review Medicare contractor NAS determined that there is no difference between vertebroplasty and kyphoplasty, stating, "No clear evidence demonstrates that one procedure is different from another in terms of short- or long-term efficacy, complications, mortality or any other parameter useful for differentiating coverage."
Effectiveness
As of 2019, the effectiveness of vertebroplasty is not supported. A 2018 Cochrane review found no role for vertebroplasty for the treatment of acute or sub-acute osteoporotic vertebral fractures. The subjects in these trials had primarily non-acute fractures and prior to the release of the results they were considered the most ideal people to receive the procedure. After trial results were released vertebroplasty advocates pointed out that people with acute vertebral fractures were not investigated. A number of non-blinded trials suggested effectiveness, but the lack of blinding limits what can be concluded from the results and some have been criticized because of being funded by the manufacturer. One analysis has attributed the difference to selection bias.
Some have suggested that this procedure only be done in those with fractures less than 8 weeks old; however, analysis of the two blinded trials appear not to support the procedure even in this acute subgroup. Others consider the procedure only appropriate for those with other health problems making rest possibly detrimental, those with metastatic cancer as the cause of the spine fracture, or those who do not improve with conservative management.
Evidence does not support a benefit of kyphoplasty over vertebroplasty with respect to pain, but the procedures may differ in restoring lost vertebral height, and in safety issues like cement extravasation (leakage). As with vertebroplasty, several unblinded studies have suggested a benefit from balloon kyphoplasty. , no blinded studies have been performed, and since the procedure is a derivative of vertebroplasty, the unsuccessful results of these blinded studies have cast doubt upon the benefit of kyphoplasty generally.