Severe Sagittal Imbalance and Lumbar Spinal Stenosis in a Patient with Multiple Medical Comorbidities
The patient is a 50-year-old male with end-stage renal disease (ESRD), on dialysis, and presents with a 10-year history of low back pain. He was a successful engineer. However, he had to go on disability starting two years ago due to progression of his symptoms.
Despite all non-operative measures, his pain has become severe and unremitting. Over the past two years, he has developed leg pain, numbness, and weakness with walking. He has developed a progressive left foot drop and now requires a cane to ambulate even short distances.
Previous surgical, medical, and social history:
- Right total knee arthroplasty
- Coronary artery disease status post quadruple bypass
- ESRD on dialysis
- On disability
- Height: 5 feet 7 inches tall
- Weight: 155 pounds
- Ambulates with good balance but a flexed forward posture
- Foot drop evident on ambulation
- Tenderness to palpation in the lumbar spine in the midline and paraspinal muscles
- Pain free lumbar flexion
- Lumbar extension is limited to 0 degrees due to increasing pain
- Left foot drop
- Left foot: 3/5 Tibialis Anterior (TA), 0 Extensor Hallucis Longus (EHL)
- Right foot: 4/5 TA, 3/5 EHL
- Full strength in remaining distributions
- Sensation intact to light touch throughout lower extremities
- Diminished patellar reflexes, absent Achilles reflexes
He has had multiple epidural injections, physical therapy, and attempts at activity modification.
The imaging studies revealed significant spondylosis changes throughout the lumbar spine, particularly from L3 to the sacrum. The lumbar flexion view shows Grade I spondylolisthesis noted at L3-L4 and L4-L5. His lumbar spine is significantly flat with loss of lumbar lordosis, and shows a degenerative scoliosis from L2 to the sacrum.
Pre-operative sagittal balance parameters are as follows (Figs 3-5):
MRI shows very severe stenosis at both L3-L4 and L4-L5; L5-S1 with significant left side foraminal stenosis.
The patient has a very severe lumbar stenosis at multiple levels with spondylolisthesis at L3-L4 and L4-L5 with generalized deformity of the lumbar spine including scoliosis and flatback.
- Flatback syndrome may be partially related to lumbar stenosis.
- Sagittal alignment is decompensated requiring increasing amounts of pelvic tilt to maintain upright posture.
- Stenosis is severe enough that he is developing neurologic deficits, including a left foot drop.
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Optimal treatment is surgery for both decompression and sagittal realignment. To address the stenosis the patient requires decompressive laminectomy from L3-L5. His sagittal alignment is severely decompensated. Guidelines for selecting the amount of correction can be determined by comparing his lumbar lordosis to his pelvic incidence. The difference between those two parameters is approximately 42⁰, which suggests that an osteotomy achieving approximately that amount of correction is required.
Decompressive laminectomy and pedicle subtraction osteotomy at the L3 level was performed. Instrumentation was placed from T12 to S1. The goal for correction was to achieve approximately an additional 42⁰ of lumbar lordosis. The pedicle subtraction osteotomy can achieve approximately 30⁰ correction, as some of the deformity is non-structural and due to the spinal stenosis. An additional 10⁰-15⁰ can be achieved by laminectomy and positioning during surgery.
Authors' Treatment Rationale
The patient presented with a combination of structural deformity due to degenerative changes, as well as some non-structural deformity related to compensation due to spinal stenosis. The patient was not able to extend through the lumbar spine voluntarily, partly due to severe multi-level stenosis. During surgery, some correction of lordosis occurs due to decompression and positioning. In some cases, it may not be necessary to perform a three-column osteotomy if there is significant correction of deformity with positioning and decompression of the stenosis. In this case, the combination of a three-column osteotomy, along with the additional correction that occurred after decompression was required to achieve a goal of approximately 42⁰ of correction.
Final x-rays show significant improvements in sagittal alignment parameters. The patient is doing much better with resolution of his pain and improved walking ability. His left foot drop has not resolved and may be permanent.
This is a patient with significant comorbidities and a long history of low back pain. Like many patients, it is the onset of leg complaints with neurologic deficit that leads him to seek surgical intervention. The surgeons achieved a very nice clinical result in this patient who presented with multiple deficits and challenges. The patient has spinal stenosis, spondylolisthesis at two levels and sagittal malalignment. Full-length standing radiographs are reviewed pre-operatively. There is a markedly abnormal sagittal vertical axis and even more significantly a mismatch between lumbar lordosis and pelvic incidence.
The goal of surgery is to decompress the neural elements, stabilize the spine, and improve the sagittal balance while doing so in a manner, which considers the patient's co morbidities and surgical risk factors. With a pre-op 0/5 EHL strength little to know improvement in neurologic function is anticipated. However, the patient does have bilateral anterior tibialis weakness due to mechanical compression. Improvement in strength and function would be anticipated.
It is recognized that some of the patient's sagittal imbalance is due to his spinal stenosis and compensatory mechanisms. This will improve following decompression but not to the extent that the pelvic incidence lumbar lordosis mismatch will be corrected. Therefore, attempts to improve sagittal alignment need to be considered. With the degree of mismatch, a pedicle subtraction osteotomy was performed and parameters improved. Other considerations would be to consider interbody stabilization and correction with a hyperlordotic spacer. This can be pursued best through an extreme lateral and/or anterior lumbar approach. Implants providing up to 30-degree lordosis are available.
Finally, the fusion levels both cephalad and caudal are considered. The considerations include the patient's comorbidities and ability to tolerate the procedure as well as the post-op rehab. Some might consider extending the fusion above the thoracolumbar junction to diminish the risk of breakdown at the junction and proximal junctional kyphosis. Caudally, for fusions from the sacrum to L2 or above the addition of pelvic fixation is a consideration. This patient has Modic changes at the lumbosacral junction with foraminal stenosis and chronic low back pain, and the level was appropriately included.
Following consideration of each of these issues the surgeons achieved a very successful result following neurologic decompression, improvement of sagittal alignment and surgical stabilization.