Case 3. A 44-year old woman with a progressive thoracolumbar kyphotic deformity caused by ankylosing spondylitis was treated by a 40 degree closing wedge lumbar osteotomy at level L4. Unfortunately, the pedicle screw fixation in S1 broke out, resulting in loss of deformity correction at L4. Revision surgery was performed to restore the deformity correction with bilateral iliac screws in a FB construct. Figure 4a: Pre-operative lateral radiograph. Note the loss of correction and S1 screw failure. Figure 4b: Postoperative lateral radiograph. Figure 4c: Postoperative anteroposterior radiopgraph.