Degenerative Disc Disease at L4-L5 and L5-S1
This 44-year-old female patient, previously a professional water skier, presents with 80% low back pain and 20% leg pain demonstrating a L5 distribution. Her symptoms have been severe for more than two years, but low back pain has been modest for more than 5 years.
Seven years ago she underwent a L5-S1 laminotomy / microdiscectomy with an excellent result.
She presents with isolated back pain over the L4-L5 and L5-S1 facet joints. Flexion is 60% of normal. Extension is limited to 20% of normal because of severe back pain. Straight leg raising tests are bilaterally negative. Strength is normal, but slightly diminished right to L5 light-touch sensation.
Although a L5 selective nerve root block provided short-term relief, there was no response to facet injections.
The sagittal MRI (Fig. 1) demonstrates disc desiccation with narrowing at L4-L5 and L5-S1. There is a component of contained disc protrusion at both levels. A high intensity zone (HIZ) is seen at L4-L5.
Figure 1. Sagittal MRI
The lateral x-ray (Fig. 2) demonstrates moderate narrowing at L4-L5 and L5-S1 without evidence of instability.
Figure 2. Lateral x-ray
L4-L5, L5-S1 degenerative disc disease, status post L5-S1 laminotomy / microdiscectomy
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I elected to proceed with a mini-open ALIF at L4-L5 and L5-S1 using dual acid-etched titanium implants (Endoskeleton® Titan Spine, LLC) filled with INFUSE® Bone Graft (rh-BMP-2) (Medtronic, Inc.). The patient then underwent a minimally invasive posterior decompression and pedicle screw instrumentation and fusion at L4-L5 and L5-S1. She was discharged home on the third postoperative day.
Paul J. Slosar, Jr., MD serves as a consultant to Titan Spine, LLC.
The patient was pain free and off all medications at 6 weeks. She resumed full workouts at 3 months and was back to water skiing at 5 months.
The figures below are the patient's postoperative films at 3 months. The sagittal and coronal CT images (Fig. 5A, 5B) demonstrate excellent endplate-implant osseous integration and bridging bone. There is no subsidence. The axial CT image (Fig. 5C) demonstrates bone within the cage, midline positioning of the implant, with substantial endplate coverage.
This is not an uncommon presentation for patients with previous successful discectomies who years later develop chronic pain unresponsive to conservative care. They, in my opinion, are the best patients for fusion or disc replacement (provided they have no contraindications). With the advent of rh-Bone Morphogenetic Protein-2 (BMP) and percutaneous screws, these patients undergo surgery much faster with much less postoperative pain and an extremely high fusion rate. They also recover and return to activities much faster as this case illustrates. This is in marked contrast to fusions done years ago when it took 6 months or more for a fusion to heal. With anterior posterior constructs patients are stable immediately. In general, we do not carry out posterior decompressions and just utilize MIS pedicle screws.
We have also utilized this technique for patients with degenerative spondylolisthesis and stenosis by achieving an indirect decompression with anterior reduction and fusion followed by percutaneous screws without a posterior decompression.
Finally, I caution the readers that it is very important to select these patients carefully. We routinely utilize discography to make certain we are identifying the pain generator. We also utilize presurgical psychological screening to maximize patient success and to aid in determining if the patient is a good surgical candidate.