Minimally Invasive Treatment of Adjacent Segment Disease
The patient is a 67-year-old female who presented two years after an open L4-S1 posterior decompression and instrumented fusion at an outside institution. Her chief complaints were progressive mechanical back pain and neurogenic claudication. She had attempted non-operative measures with minimal relief.
There was a well-healed midline lumbar incision. Motor exam was normal in the upper and lower extremities. Reflexes were symmetric and brisk. There was no clonus and negative Babinski sign. Sensation was normal. She had excellent standing posture without obvious sagittal or coronal plane deformity on physical examination. Her back and leg numeric pain score (NPS) was 6.5 out of 10.
MRI of the lumbar spine demonstrated L3-L4 stenosis above the previous construct (Figures 1A and 1B). Dynamic x-rays showed a mild spondylolisthesis (Figure 2A and 2B).
Adjacent segment stenosis and disease of the lumbar spine
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Minimally invasive lateral indirect decompression and fusion with stand-alone interbody device.
A single-stage, MIS lateral approach afforded adequate indirect decompresion and stabilization and obviated the need to open the previous posterior incision and remove the old hardware. Operative time was under two hours with minimal blood loss, and the patient was discharged on post-operative day one.
A growing body of literature supports the option of lateral lumbar interbody techniques for treatment of degenerative disease and deformity. It must be emphasized, however, that understanding the global spinal balance and spinopelvic parameters (best determined with 36" standing scoliosis films) is essential to integrate the lateral approach into the surgical plan. Whether to use stand-alone interbody devices, or in conjunction with lateral and posterior instrumentation relies on the appreciation of this global spinal balance.
Post-operative Imaging at 6 Months
The patient had no post-operative complications and no thigh pain or parasthesias. Her symptoms drastically improved by her first post-operative visit, and at the most recent visit (6 months post-op) she was symptom free with a NPS of 0/10 in both the back and legs.
This is a very interesting case of junctional stenosis in a patient with at least some significant loss of lumbar lordosis. As the author notes, the best assessment of sagittal alignment should be done with long-standing films assessing pelvic incidence, overall lumbar lordosis, and overall balance. We do not have this in this case. What remains to be answered is, “Will this strategy for treatment decrease the chance of further junctional degeneration?” The clinical results are excellent. I would also question the need for posterior stabilization, as the healing potential is challenged by the construct being placed adjacent to a solid fusion.