Overall complication rate was 39%, and 26% of the patients were reoperated for mechanical or neurological complications. Risk factors include number of instrumented vertebra, fusion to the sacrum, PSO, and preoperative pelvic tilt of 26° or more. There is a 44% risk of a new operation in the 6-year-period after the primary procedure.

The instability observed after a PSO is mainly rotational and increases with disc degeneration. Shape of rod contour affects the location of maximum stress in the constructs. These findings may explain different instrumentation failures.

Level IV.

No abstract