Lumbar Degenerative Scoliosis in a 69-year-old Female
The patient is a 69-year-old Asian female who presents with progressively more severe low back pain. She was unable to walk from the car to the clinic for her appointment.
She has a prior history of kidney resection for cancer.
Her neurological exam was normal.
To treat her low back pain, the patient has tried:
- pain medication
- physical therapy
- chiropractic manipulation
- epidural steroid injections
AP coronal (Fig. 1) balance shows primary lumbar scoliosis at 47-degrees, concave to the right. Compensated with a 21-degree lumbosacral curve and a 13-degree thoracic curve.
Figure 2: Sagittal balance was nearly normal
Figure 3: Bending x-ray
Primary lumbar degenerative scoliosis
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The patient had T10-L5 MIS correction. That procedure was chosen because it was completely muscle sparing and it dropped blood loss to 250cc.
The MRI demonstrated the preserved disc space at L5-S1, so it wasn't necessary to go all the way to the sacrum.
The patient was in the hospital for 5 days. She didn't need a transfusion. She no longer complains of pain, and she's able to walk 2 to 3 miles.
AP x-ray (Fig. 4) showing correction of coronal balance. This is 18 months postop.
The operative management of degenerative scoliosis is characterized by significant variability in approaches and choice of levels. Improtant decisions in surgical strategy include consideration of how high and how low to instrument and fuse the spine, and when to use a circumferential arthrodesis. Factors including regional alignment of the spine, goals for deformity correction and host variables including bone quality and comorbidities have important influences on the choice of a surgical strategy.
The patient is a 69-year-old female with significant deformity in the coronal plane and important regional sagittal plane abnormality. She presents with significant low back pain without neural dysfunction. The goal of surgery is to improve her pain and function. Global alignment in the sagittal and coronal planes remains well-balanced, although the patient has significant hyperkyphosis at the thoracic spine and hyperlordosis in the lumbar spine. These regional alignments may have important implications for the probability of adjacent level degeneration.
In choosing how high to extend instrumentation and fusion, sagittal and coronal considerations may guide informed decision-making. In the coronal plane, fusion to a neutral and stable upper level may reduce the rate of adjacent segment deformity. In the sagittal plane, junctional kyphosis is a common and significant potential complication. Instrumentation and fusion to a segment that is neutral or lordotic in the sagittal plane may limit the rate of proximal junctional kyphosis. This patient has significant thoracic hyperkyphosis, and she may be at risk of sagittal plane decompensation above her fusion. Extension of fusion and instrumentation to T3 may be a reliable strategy to avoid thoracolumbar junctional complications, but may also increase surgical morbidity.
The choice of a lower level for instrumentation and fusion remains controversial. Fusion to L5 may be unreliable in patients with poor bone quality, sagittal plane malalignment, and long fusions extending into the thoracic spine. Fusion to L5 may limit the magnitude of surgery and permit some motion at the lumbosacral junction. However, the incidence of subsequent advanced degeneration at L5-S1 is significant and may lead to progressive sagittal plane deformity, loss of fixation at L5, and symptomatic changes including pain. Extending fusion to S1 with iliac fixation may be a more reliable strategy for maintenance of deformity correction and improvement of lumbosacral pain.
The surgical strategy of a posterior-only MIS approach was effective in this case. This case was done with limited blood loss, and the patient has a good functional result at 18 month follow-up. Further follow-up of sagittal plane alignment, arthrodesis, and junctional changes will be required to assess the durability of this surgical strategy.
The advantages of minimally invasive surgical techniques are well-suited for this population of patients who tend to be older, suffer a higher proportion of medical co-morbidities, tend to be less physically fit, and additionally require significantly more complex surgery. By decreasing surgical trauma, blood loss, and post-operative recovery, the morbidity of surgical intervention in this frail group of patients can be significantly decreased. However, minimally invasive spine (MIS) surgery techniques remain technically challenging and its application in multi-level reconstruction is a newly emerging field.
Dr. Fessler's considerable experience and expertise in these techniques have led to a remarkable result in this patient. There is excellent coronal plane realignment and excellent function at 18 months postop. Other MIS surgeons, who focus on adult deformity, have obtained similar good results. However, the long-term results (greater than 5 years) remain to be seen. It is clear from traditional open surgery that a key factor of long-term success is sagittal balance. At present, this is best assessed using lateral radiographs that contain sufficient information to assess the pelvic incidence and location of the C7 plum line.
With traditional open posterior surgery, the posterior musculature necessary for dynamic postural stability is adversely affected. This places greater emphasis on static postural stability, which is achieved through radiographic sagittal balance. With MIS techniques that preserve posterior musculature function, it is possible that patients may tolerate greater degrees of radiographic sagittal malalignment. This is an important consideration if it avoids the necessity to extend the fusion to the upper thoracic spine.
It is intriguing to consider the possibility that muscle-preserving MIS techniques will allow for long-term clinical success with markedly shorter fusions than with traditional open surgery. To adequately address this vital question, it will be necessary to obtain long scoliosis images that include the C7 plum line and the hips to assess radiographic sagittal alignment. The Society for Minimally Invasive Spine Surgery (SMISS), of which Dr. Fessler is a past-President, has developed a prospective registry of MIS surgeries that will strive to answer this important clinical question.