Adjacent Segment Degeneration after Previous Decompression and Fusion
The patient is a 59 year-old male, non-smoker, and of acceptable weight level. The patient presented in 2006 with severe, “unacceptable” low back pain, and early fatigue marked by diminished endurance when walking or standing. The patient’s Oswestry Disability Index was greater than 50. On presentation, the patient had completed one year of nonoperative treatment, including physical therapy, injections, and non-narcotic and narcotic medication.
In 1996 the patient underwent laminectomy and posterolateral spinal fusion from L3-S1. The patient reported reasonable benefit from the surgery.
By 2003, adjacent segment degeneration was apparent, and the patient underwent a TLIF procedure at L2-L3. The patient again reported reasonable benefit from the surgery and became satisfactorily functional. However, within three years, the patient presented with unacceptable pain and diminished endurance described above.
Physical examination showed limited lumbar range of motion, and flat back and buttock. The patient was neurologically intact.
The patient’s AP lumbar X-ray showed solid fusion from the previous surgery and good coronal alignment (Fig. 1). The lateral X-ray showed L1-L2 disc height loss with anterior and posterior bone spurs (Fig. 2).
Flexion and extension films showed hypermobility and vacuum disc phenomenon (Figs. 3-4). Discogram results showed nonconcordant 5/10 pain at T11-T12 and T12-L1, and 10/10 concordant pain at L1-L2 (Fig. 5).
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The patient underwent bilateral TLIF with SPO at L1-L2, with the objectives of:
- Removing the presumed pain generator of the disc
- Improving sagittal contour to deal with the anticipated kyphosing process of aging in the remaining mobile spine
Figs. 6 A-B. Anterior placement (on flexed Wilson Frame) of interbody spacer. Good disc clearance. Anterior placement enables spacer to operate as a pivot point.
Figs. 6 C-D. Pedicle screw placement prior to compression and, after Wilson Frame was extended, compression was applied to enhance lordosis.
Nine months postop, the patient reported an 80% reduction in pain and similar improvement in walking and standing endurance.
Films showed good lordosis and apparently solid / progressive arthrodesis (Figs. 7-8).
This case involves a 59 year-old male with severe low back pain and a history of multiple lumbar surgeries. His pre-operative AP and lateral plain films demonstrate a satisfactory posterolateral fusion extending from L2 to his sacrum. Pedicle fixation is positioned at L2-L3. The lateral films show a rather limited lumbar lordosis.
In patients with a history of multiple lumbar surgeries, the source of back pain can be difficult to identify. Pseudoarthrosis, ongoing degenerative changes, segmental instability, as well as myofascial inflammation should all be considered. Additionally, as with all patients being managed for low back pain, psychosocial factors need to be assessed and a rigorous conservative management regimen carried out.
Presuming this patient to be a reasonably healthy individual who is motivated to improve and is unresponsive to conservative management measures, the next step would be to obtain flexion-extension films to assess the previous fusion, the integrity of the pedicle screws at L2-L3 and the spinal segments adjacent to the fusion. These were obtained and clearly demonstrate degenerative changes at the adjacent L1-L2 disc space. In particular, on the extension view, the anterior disc space at L1-L2 widens or “fish mouths.” This finding represents a clear sign of segmental instability and is a strong indicator that implicates the L1-L2 disc space as the source of this patient’s back pain.
Although I do not commonly use discography in my practice, I would use it in this case to confirm or refute the findings of the flexion-extension films. The presence of concordant pain at the L1-L2 disc space on the discogram, as well as the lack of similar findings at the control levels, provides further evidence of the L1-L2 disc space being the most likely cause of this patient’s back pain.
Given the findings presented in this case, I would proceed with a transforaminal interbody fusion (TLIF) at the L1-L2 level. Another option for this patient would be a lateral interbody fusion but, in my hands, a TLIF provides the best chance for a successful outcome.
With a satisfactory fusion noted at the L2-L3 level, I would remove the pedicle screws at L3. I would leave in the screws at L2 and insert screws into the L1 pedicles to supplement the TLIF at that level. I would do the TLIF from a unilateral approach inserting a single interbody cage filled with local autograft. I do not feel that the lack of lordosis needs to be addressed given the evidence supporting the L1-L2 disc as the primary pain generator in this case, as well as the magnitude of the surgery needed to correct the lumbar alignment in this patient.