To analyze the results of radiologic and clinical outcomes after pedicle subtraction osteotomy in iatrogenic flat back syndrome.

We reviewed 12 surgical cases of iatrogenic flat back syndrome from January 1998 to July 2001 with a follow-up of more than 12 months. All cases were females and an average age was 59.8 years (48-66 years). An average follow-up period was20.4 months (12-37 months). Initial diagnosis were as follows: lumbar degenerative kyphosis, in 5 cases; spinal stenosis, in 5 cases; spondylolisthesis, in 2 cases. For clinical evaluation, 10-point pain scale and 5-point scale for activity level, cosmesis and subjective satisfaction were used. Lumbar lordotic angles and sagittal vertical axis (SVA) were measured.

In radiologic results, an average lumbar lordotic angle at preoperative, postoperative and the last follow-up were 5.13±21.69 degree, -31.33±16.32 degree, -27.50±16.73 degree respectively. And average SVA at preoperative, postoperative and the last follow-up were 8.46±6.04 cm, 0.62±2.24 cm, 2.82±2.81 cm respectively. In clinical results, preoperative pain (6), activity (2) and cosmesis (1.8) were improved to 3.2, 3 and 3.2respectively at the last follow-up. Subjective satisfaction was 3.9.

Pedicle subtraction osteotomy seemed to be very useful surgical option for improvement of clinical results through recovering of lumbar lordotic angle and sagittal balance in cases of iatrogenic flat back syndrome.