The positive correlation between upper adjacent vertebral fracture and the kyphosis angle of injured vertebral body after percutaneous kyphoplasty: An in vitro study

• OVCF model was used to stimulate the recovery of vertebral kyphosis angle by PKP.
• Stiffness and fracture load in group A were better than those in group B.
• Angle of kyphosis decreased may reduce the risk of adjacent vertebral fracture.

ObjectiveTo investigate the correlation between the kyphosis angle of injured vertebral body and the risk of upper adjacent vertebral fracture after percutaneous kyphoplasty (PKP) using an osteoporotic vertebral compressed fracture model.Materials and methods24 functional spinal units (FSUs, T9 to L4) were selected from 6 elderly formalin preserved vertebral specimens to build the vertebral compressed fracture model. According to the kyphosis angle between the upper plate of upper vertebral body and the horizontal plane, group A (0°) and group B (20°) were defined, with each group comprised with 12 FSUs. The stiffness and fracture load were measured in both groups.ResultsAfter PKP, the stiffness was (571.513 ± 83.373)N/mm and the fracture load was (1751.659 ± 112.291)N in group A, with both significantly higher than those of group B (stiffness, (307.706 ± 46.723)N/mm; fracture load, (1128.011 ± 125.417)N).ConclusionsTo reduce the risk of upper adjacent vertebral fracture, it is better to restore the height of injured vertebral body and decrease the angle of kyphosis to increase the capability of upper adjacent vertebral body against fracture.