Effect of Severity of Rod Contour on Posterior Rod Failure in Setting of Lumbar Pedicle Subtraction Osteotomy (PSO): A Biomechanical Study

Pedicle subtraction osteotomy (PSO) is a powerful technique to correct flat back deformity in the lumbar spine. Because corrections as great as 30–40 degrees can be achieved with this technique, contouring of the fusion rods can be quite extreme in PSO constructs. Rod failure (Figure 1) during the late post-operative period (<1 year) has been reported clinically and is commonly associated with pseudoarthrosis. In fact, instrumentation failure following PSO occurs frequently enough that several studies have reported and investigated revision strategies.