Finite element analysis of the lumbar destabilization following pedicle subtraction osteotomy

• Spinal osteotomies are complex procedures with a high-rate of complications.
• PSO performed both on L3 and L4 induce a major destabilization of the lumbar spine.
• The osteotomy in L3 may reduce the overload acting on the device.

This study aims to analyze the destabilization produced following a pedicle subtraction osteotomy (PSO), with a calibrated numerical model. A 30° resection was created on L3 and L4. Range of Motion (ROM) and the force acting on the vertebral body were calculated. Osteotomies consistently increased the ROMs. In the intact model, 87% of the compressive load was acting on the vertebral bodies whereas in the destabilized models all the load was on the fractured surface. Osteotomies at both levels induced a marked instability but the PSO at L4 seemed to have a greater influence on the ROM. Despite the significant deformity corrections which could be achieved with PSO, this technique needs further analyses.