Surgical Treatment of Fixed, Unbalanced Adult Spinal Deformities

Presentation

 

This is a 46-year-old female who is status post posterior fusion and instrumentation from the upper thoracic spine to her sacrum.  (See figures 1A and 1B below for the upright AP and lateral x-rays on presentation to this institution.)  Note she has broken implants and an element of coronal and sagittal imbalance. 

Figure 1A                                                         Figure 1B

 

                                                           

See figures 2A and 2B for her clinical appearance in both planes.  Note the clinical coronal and sagittal imbalance.  She is trying to stand as erect as possible.

Figure 2A                                 Figure 2B

 

                                               

We know that it is very hard to get a long fusion down to the sacrum solid.  The literature suggests that the necessary minimum requirements for having any hope of getting a long fusion to the sacrum solid include the following:

1.      Segmental fixation at all levels.  See Saer, Winter et al.⁴

2.      Putting the patient in neutral or negative sagittal imbalance.  See Dekutoski et al.¹

3.      Some form of protection and back up to the S1 screws.

4.      Structural grafting for L4-L5 and L5-S1.

In many cases, anterior fusion of all the lumbar segments is helpful as well.

In this particular case, many “rules” were broken.  First off, the fixation was not adequate.  Bilateral implants were not used and enough fixation points were not employed.  There were too many gaps between the fixation points.  Also, the sacral screws were not backed up or protected in any way, shape or form by either second fixation points in the sacrum or an intrasacral rod technique such as that described by Jackson et al² or a combination of sacral screws and iliac screws that have been described by many, most recently Kuklo et al.³  Also, no anterior surgery was performed and, as you can see, the patient is in positive sagittal balance now.

Surgical Reconstruction/Revision

A revision procedure first included doing a posterior exploration from top to bottom to identify the levels with pseudarthrosis.  It was determined that all levels from T10 to the sacrum were without solid fusion and had motion.  The fusion was solid from T7 to T10 but then all levels above T7 were not solidly fused.  The previous implants were removed.  New fixation points were achieved from top to bottom, including bicortical S1 sacral screws and bilateral iliac screws.  She then had an anterior procedure performed from T10 to the sacrum placing morselized autogenous rib graft at all levels and placing structural grafts in the lower lumbar segments.  She then had the posterior portion of her spine opened again.  In order to achieve adequate lordosis in her lumbar spine, a pedicle subtraction procedure was performed and she was then definitively instrumented from the upper thoracic spine down to the sacrum and pelvis.  Autogenous iliac bone graft was used posteriorly as well as local bone graft.

Discussion

She is now three years postop.  See the 3-year upright AP and lateral x-rays (Figure 3A and 3B) and see her clinical appearance at three years postop as well (Figures 4A and 4B). 

Figure 3A                                                                     Figure 3B

 

            Figure 4A                                                         Figure 4B

A note of caution here.  Just because she is over three years postop doesn’t mean that she necessarily has a solid fusion from top to bottom.  I have seen late pseudarthrosis present in adult patients between 5-10 years postop.  She is doing significantly better than she was preoperatively based on her Oswestry scores and the scores from the SRS-24.   In an effort to give her a competitive chance of getting a solid fusion, four point sacral pelvis fixation was used, structural grafting was used in the distal lumbar spine, anterior fusion was used for all the lumbar segments, and segmental fixation with multiple fixation points with a minimum of jumps and gaps and bilateral implants were used.  Wherever possible autogenous bone graft was used as well.

Bibliography

1. Dekutoski MB, Cohen M, Schendel MJ, Transfeldt EE, Wood KB, Ogilvie JW. Fusion to the sacrum in adult idiopathic scoliosis:  The role of sagittal balance. Orthopaedic Transactions 1993;17:125.

2.Jackson RP, McManus AC. The iliac buttress. A computed tomographic study of sacral anatomy.  Spine 1993;18:1318-1328.

3.   Kuklo TR, Bridwell KH, Lewis SJ, Baldus C, Blanke K, Iffrig TM, Lenke LG: Minimum two-year analysis of sacropelvic fixation and L5/S1 fusion utilizing S1 and iliac screws.  Spine (in press).

4.   Saer EH III, Winter RB, Lonstein JE. Long scoliosis fusion to the sacrum in adults with nonparalytic scoliosis.  An improved method.  Spine 1990;15:650-653.