Direct Lateral Interbody Fusion for Degenerative Disc Disease and Degenerative Scoliosis
This surgeon is a consultant of Medtronic, but received no compensation for this case discussion.
The patient is a 63-year-old female who presents with low back pain and bilateral leg pain approximately 18-months after a motor vehicle accident. Back pain was worse than her leg pain and was associated with bilateral leg numbness, but no weakness. Her left leg is slightly worse than her right leg. Otherwise, she actively cares for and rides horses while managing a small ranch. Pain limits her activity.
Her medical history includes hypertension, coronary artery disease, atrial fibrillation that requires Coumadin, depression, osteoporosis, and fibromyalgia.
Physical therapy, acupuncture, spinal manipulation, opiate analgesics, and subsequent translaminar epidural steroid injections brought minimal relief. She did report modest and short-term relief from bilateral L2-L3, L3-L4 transforaminal epidural steroid injections and L2-L3, L3-L4 bilateral medial branch facet blocks and radiofrequency rhizotomies.
The patient has moderate scoliosis with tenderness across the mid-lumbar spine and paraspinal region. Her neurological examination was normal.
Figure 1A. Standing anteroposterior x-ray
Figure 1B. Standing lateral x-ray
Figure 2A. Sagittal CT myelogram
Figure 2B. Axial CT myelogram through the L2-L3 disc space
Figure 2C. Axial CT myelogram through the L3-L4 disc space
Figure 3A. Three-dimensional (3D) reformatted CT image, left
Figure 3B. 3D reformatted CT image, right
Degenerative scoliosis with multi-level degenerative disc disease at L2-L3, L3-L4, bilateral foraminal stenosis, mild central stenosis
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The patient was treated with a 2-stage approach during a single general anesthetic. She underwent a minimal access, direct lateral transpsoas right-sided approach with interbody fusion using CLYDESDALE™ Spinal System interbody spacers.
Triggered electromyography (EMG) and spontaneous EMG monitoring were used. This was followed by image-guided, percutaneous placement of pedicle screw instrumentation using CD HORIZON® SEXTANT® II Spinal System titanium screw and rod system.
The patient wore a lumbar corset for 6 weeks and an external bone stimulator for 6 months due to her underlying history of osteoporosis.
Author's Discussion: Rationale for Selected Treatment
This operative approach was selected to maximize the improvement in the patient's coronal plane imbalance. In addition, the direct lateral approach was selected to maximize the interbody graft size and minimize soft tissue exposure and retraction for a 2-level lumbar fusion.
Percutaneous, image-guided placement of pedicle screw instrumentation was selected to maximize the benefits of a minimally invasive surgical approach through multiple small incisions.
Note to patients
As you read this please keep in mind that all treatment and outcome results are specific to the individual patient. Results may vary. There are some risks associated with minimally invasive spine surgery, including transitioning to a conventional open procedure, neurological damage, damage to the surrounding soft tissue, and instrument malfunction such as bending, fragmentation, loosening, and/or breakage (whole or partial). Other risks associated with implants used include device migration, loss of spinal curvature, correction, height, and/or reduction. Please consult your physician for a complete list of indications, warnings, precautions, adverse events, clinical results, and other important medical information.
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DIRECT LATERAL System
CLYDESDALE™ Spinal System
CD HORIZON® SEXTANT® II System
*NIM-Eclipse® Spinal System
Figure 4A. Standing anteroposterior x-ray at 3-months
Figure 4B. Standing lateral x-ray at 3-months
The patient was discharged home the day after surgery. She was not taking any opiate analgesics at her 3-week follow-up visit. The patient continues to do well more than 2 years after surgery. She reports only occasional complaint of muscle tightness across her lumbar spine and continues to ride and train horses, and manages a ranch.
This is an interesting case of a 63-year-old female who presents with primary complaints of low back and bilateral leg pain. Her symptoms developed after a motor vehicle accident that occurred about a year and a half previous to treatment. Significant co-morbidities include hypertension, coronary artery disease, atrial fibrillation, fibromyalgia, and depression. She takes Coumadin. Patients who present with such conditions can be challenging to treat because of:
1. The ubiquitous nature of low back pain.
2. The need for a definitive diagnosis of the pain generator prior to consideration of any focal surgical intervention.
It appears the patient underwent appropriate conservative care. The transforaminal epidural steroid injections were of diagnostic value and provided short-term relief of lumbar symptoms as did the medial branch blocks and facet injections in the area of the apex of the lumbar scoliosis. These results help to determine the area of localized pain generation and provide some indication of the primary pathologic region.
Review of the radiographs reveal there appears to be a lumbar scoliotic curve, quite degenerative, and focused at the apex in the area of the L3 vertebral body with multi-level adjacent segment degeneration. The CT myelogram confirms significant degeneration at L2-L3, L3-L4, and unfortunately at L5-S1. There appears to be a vacuum disc sign at L2-L3 and L3-L4 with some stenosis at L3-L4, and slight stenosis at L2-L3.
The three-dimensional (3D) x-rays reveal good pictures of the patient's 3D spinal deformity. Full-length scoliosis films could lend to understanding the full nature of the deformity as it relates to overall balance. It is not clear if the deformity extends up into the thoracic spine, if its development is in a compensatory manner, or whether or not the coronal plane of the head is balanced over the pelvis.
The patient's symptomatology implies she is most likely in overall global balance in the coronal plane. Again, the lateral x-ray does not reveal a head to pelvic view so it is difficult to state whether or not there is positive sagittal balance. However, the lack of lordosis throughout the lumbar spine suggests there may be some sagittal imbalance with positive sagittal balance.
Based on the patient's symptoms and unsuccessful non-surgical care, a surgical intervention could be offered with the caveat that surgery may not completely eliminate pain. My preference would be to see a complete set of x-rays to determine overall global coronal and sagittal balance before definitive treatment. However, based on the images limited to the lumbar spine, it appears there is coronal and sagittal imbalance of the lumbar spine.
Direct spinal decompression or a realignment procedure would certainly help relieve some of the stenosis. Perhaps, realignment with fusion through the degenerative levels could relieve a component of back pain. The goal of surgery should include restoring some of the sagittal balance and attempt to correct the coronal plane deformity without causing overall imbalance or over alignment.
There are many ways to approach surgery versus a posterior approach, interbody cages and fusions, releases, and corrections through facet resections. An anterior or anterior/posterior combined approach could be considered. Discography (discogram), although controversial, could provide valuable information as to whether the L5-S1 level is contributing to pain; as this segment does look degenerated with some mild stenosis and a vacuum disc sign.
The severest degeneration appears to be at L2-L3 and L3-L4, which probably is the focus of the patient's pain based on the short-term relief from the epidural and facet injections at these levels. One could consider deformity correction through a decompression and fusion via potential realignment at L2-L3 and L3-L4, or include levels extending down to the sacrum to incorporate L5-S1 to potentially restore more sagittal balance.
In this case, it appears the surgeons chose a lateral interbody fusion at L2-L3 and L3-L4 with percutaneous pedicle screws for spinal stabilization. Reviewing the post-operative images, the authors have done a tremendous job to restore some of the sagittal balance and to recreate some lordosis through the use of lordotic cages implanted at L2-L3 and L3-L4. In addition, it appears this resulted in some coronal plane deformity correction. Overall, the alignment looks very good.
Some concerns exist about problems at the L5-S1 level, although based on the outcome at 2-years after surgery the patient is doing quite well and such implies that L5-S1 is not a significant pain generator. The alignment and balance in the sagittal and coronal planes appears to be significantly improved. I deem this a very successful surgery, especially given the fact it was performed using a minimally invasive approach with spinal realignment. I commend the authors for the results of this case.
*The NIM-ECLIPSE® Spinal System is manufactured by Axon Systems, Inc. Distributed by Medtronic.