L4-L5 Foraminal Spinal Stenosis in an Elderly Male
The patient is a 77-year-old male who underwent laminectomy at L4-L5 and L5-S1, which was complicated by a cerebrospinal (CFS) fluid leak. The laminectomy was performed at another center. He presents with persistent right lumbar radiculopathy.
His past medical history includes asthma, prior right knee replacement, and hypothyroidism.
- Positive straight leg raise on right
- Motor function: full bilateral lower extremities
- Reflexes: +1 at bilateral knees and ankles
The sagittal lumbar MRI (Fig. 1) demonstrates multilevel degenerative disc disease (DDD).
Figure 2 (below) shows right-sided L4-L5 severe foraminal stenosis and DDD.
Physical therapy and repeated spinal injections have failed to resolve the patient's right lumbar radicular symptoms.
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L4-L5 oblique lumbar interbody fusion with pedicle screws in the lateral position.
Surgeons' Treatment Rationale
- Primary pathology is foraminal stenosis; therefore restoration of foraminal height is critical, which is best achieved through placement of a large interbody graft
- Desire to avoid working through the previous scarred posterior surgical field with prior CSF leak
- Avoidance of dissection through the psoas muscle at L4-L5 with the potential risk to the femoral nerve and lumbar plexus
- Screw placement in the lateral position saves operative time as it avoids the need to reposition the patient from lateral to prone
The photos (below) demonstrate pedicle screw placement in the lateral position.
The patient experienced immediate resolution of leg pain. He was discharged on post-operative day one.
OLIF (Oblique Lumbar Interbody Fusion)
1. Creates a surgical corridor anterior to the psoas muscle, avoiding dissection of the muscle and mitigates potential trauma to the femoral nerve and lumbar plexus
2. Also, rotates the axis of approach anterior to the illiac crest facilitating access to L4-L5
3. Given the large graft size that can be placed via OLIF, significant disc height restoration and, therefore, foraminal expansion can be achieved
4. Graft placement on the cortical rims of the vertebrae helps to resist subsidence
5. Given the large graft footprint, in our experience, unilateral pedicle screw fixation appears adequate in single-level procedures
The surgeons in this case present a novel solution to a complicated clinical case—how to revise a failed decompression in the face of a previous CSF leak and a severely degenerative lumbar level. No doubt this patient needed a lumbar fusion and a revision decompression; the question is how?
The authors rightfully pointed out that their technique avoids a lateral approach through the psoas and its comorbidities while at the same time achieving the same result of an indirect decompression, restoration of foraminal height and stabilizing the segment. This solution avoids performing a revision decompression through an area that experienced a CSF leak and also avoids having to perform a posterolateral fusion and instrumentation with its associated blood loss and increased operative time.
The main concern of this approach is whether or not unilateral screws are able to create a construct that is stable enough. The authors point to their experience to give a positive answer to this question. The authors additionally claim that the large graft size (height and footprint) used can give stability to the anterior column therefore, making bilateral pedicle screws redundant.
In 2012, Xue et al1 came to a similar conclusion pointing out the advantages of unilateral pedicle screws in a TLIF approach. These advantages include: decreased operative time, diminished blood loss, decreased implant cost while noting no decrease in fusion rates or any increase in complication rates.
Overall, the author's solution to this difficult clinical case is creative, thoughtful and provides a template for other surgeons to emulate in treating similar difficult cases.
1. Xue H, Tu Y, Cai M. Comparison of unilateral versus bilateral instrumented transforaminal lumbar interbody fusion in degenerative lumbar diseases. Spine J. 2012;12:209-15.