Complications (Pseudarthrosis, Neurologic Deficit) of Pedicle Subtraction Osteotomies for Fixed Sagittal Imbalance
Methods: Full data on 33 consecutive pts (done 1995-1999) with sagittal imbalance treated with lumbar pedicle subtraction osteotomy (PSO) at 1 institution (all L1, L2, or L3). Data collected prospectively. Minimum 2-yr follow-up (2-5 yrs). The largest series reported with minimum 2-yr follow-up that encompasses mostly diagnoses other than ankylosing spondylitis [2 ankylosing spondylitis, 10 degenerative sagittal imbalance (DSI), 17 idiopathic scoliosis, 4 post-traumatic kyphosis]. 27 females, 6 males, average age 51 yrs (34-75). 30 had previous fusion/spine surgery. Also neurologic complications recorded prospectively for 60 consecutive [33 with 2-5 yr followup, 23 (done 2000-2002) with <2 yr followup].
Purpose: To fully report these complications with this procedure plus the anticipated 2-5 yr follow-up result.
Early Complications: 1 pt had cauda equina syndrome (out of the first 33) at 1 week postop which responded to central canal decompression. Also 5 pts in the subsequent 27 cases had positive wake-up tests not predicted by SEP, MEP-> responded to long central decompressions.
Late Complications: 6 pts with pseudo/implant failure in the distal thoracic spine and 1 pt with pseudo/implant failure in the upper lumbar spine through a PSO where previous pseudo/laminotomy (all DSI pts). For those pts having PSO done through a previous fusion mass (n=20 out of 33), there were no pseudos. No permanent neuro deficits (0 out of 60).
Radiographic results/clinical data (33 pts with 2-5 year followup):
| C7 Plumb | Lordosis | PSO angle | OWSTY | Pain Score | |
| Preop | 17cm | -15° | +2° | 53 | 7 |
| Postop ultimate | 4cm | -48° | -32° | 34 | 4 |
| p value | <0 .0001 | <0 .0001 | <0 .0001 | <0 .0001 | 0.0001 |
Conclusion: We now always enlarge the canal centrally and do intra-operative wake-up tests. Achieving a solid fusion seems to be a given if the osteotomy is done through a previous fusion mass (n=20 out of 33). Consider anterior and posterior fusion in the distal thoracic spine for pts with purely degenerative etiologies.