Low Back Pain Two Years Post Recurrent Disc Excision

History

The patient is a 36-year-old female who presents with worsening low back pain and bilateral buttock pain that radiates down her posterior / posterolateral thighs to the calves in typical L5 and S1 dermatomal distributions.

Two years ago, she underwent L5-S1 recurrent disc excision that provided excellent relief of radicular pain.

Presently, back pain is significantly more severe compared to any leg pain.

Examination

She is 5'3" and weighs 134 pounds. No motor or sensory deficit. Negative straight leg raises. Decreased active range of motion primarily in flexion and rotation; extension and lateral bending in the lumbar spine is maintained.

Oswestry Disability Index (ODI) is 40. Visual Analog Score (VAS) is 87.

Prior Treatment

• Organized physical therapy with focus on core strengthening
• Oral anti-inflammatory, muscle relaxants, and narcotics for pain

Images

MRI scans reveal severe desiccation of L5-S1 with some lateral gutter and foraminal stenosis. Other levels are completely normal. (Figs. 1A, 1B)

Figure 1A. T2 sagittal MRI. Note Modic changes at the L5-S1 endplates.

Figure 1B. T1 sagittal CT. Note Modic changes at the L5-S1 endplates

Posterior anterior and lateral radiographs demonstrate normal sagittal alignment with decreased disc height of L5-S1 and no obvious spondylolisthesis (Figs. 2A, 2B).

Figure 2A

Figure 2B

Other test results:

• CT scans show no occult pars defects. The facet joints are in reasonably good health and graded I-II on the I-IV arthrosis scale.
• Bone density testing: 2.1 standard deviations above the adult mean.
• Provocative discography: Normal nucleogram at L4-L5. L5-S1 shows degenerative dye pattern and markedly positive with concordant pain reproduction.

Diagnosis

Discogenic low back pain, recurrent left L5 radiculopathy secondary to foraminal stenosis, and L5-S1 disc degeneration.

Selected Treatment

The Charité® Artificial Disc (DePuy Spine, Inc.) was implanted at L5-S1. Estimated blood loss was 100 cc and surgical time was 113 minutes. There were no adverse events.

Figure 3A. Flexion

Figure 3B. Extension

Outcome

Twenty-four months after surgery, the patient is doing well.

	ODI	VAS
Postoperative	40	87
12-months postop	0	23
24-months postop	10	8

At 24-months, no re-operation.

Case Discussion

This is a patient who had surgery years ago for recurrent disc herniation at L5-S1 and is now complaining of primarily low back pain and, to a lesser extent, leg pain. The images show disc height collapse, endplate changes, and foraminal narrowing at L5-S1. Given the positive discogram and all of the other information, discogenic low back pain with associated radiculopathy at L5-S1 has been diagnosed. Given failure of nonoperative treatment, this patient has become a candidate for surgery.

Prior to embarking on descriptions of surgical options to the patient, I would still include continued nonoperative treatment as an option to discuss with the patient. I always counsel my patients that the clinical outcome of surgery for primarily low back pain tends to be somewhat unpredictable and that if symptoms and lifestyle allow, nonoperative treatment is always preferred. However, there comes a time, when the symptoms are severe enough that surgical options come to the forefront.

Prior to the advent of artificial discs, the principles for treatment would include stabilization of the motion segment (preferably with an interbody fusion) to address the back pain and decompression of the L5 nerve root to address the leg pain. This can be accomplished with PLIF/TLIF or ALIF approaches. The advantage of a PLIF/TLIF approach is the possibility of direct decompression of the nerve root. However, this patient, who had a prior discectomy, is most likely to have significant scarring around the nerve root that may require significant manipulation of the nerve root to mobilize it enough to perform the PLIF/TLIF. The ALIF approach is advantageous in that there is less paraspinal soft tissue disruption compared to a posterior approach (facilitating faster recovery), and that there is an excellent fusion bed. The decompression of the foramen would be achieved by disc space distraction or performing a foraminotomy from the anterior approach. I feel that the both the posterior- and anterior-based approaches are reasonable, and the choice can be made based on surgeon or patient preferences.

Dr. Knight has chosen a more avant-garde technique by choosing the artificial disc approach. This approach is similar to ALIF, but has its own unique advantages and disadvantages. As with ALIF, both indirect and direct decompression of the foraminal stenosis can be achieved. By avoiding fusion, disc replacement patients can be allowed to be physically active earlier. I would not list the preservation of motion to be a major advantage of disc replacement surgery, as a few degrees of motion at the L5-S1 level is unlikely to be of functional benefit to the patient. A possible disadvantage of artificial disc replacement surgery is that a more ideal (wider) exposure of the disc is required to place the artificial disc in the most suitable position. This can make the surgery potentially more difficult. Furthermore, the Charité® device used by Dr. Knight is typically placed with significant mobilization posterior to the vertebral endplates and with significant distraction, and some surgeons have reported nerve root irritation in post-discectomy patients.

In the hands of a good surgeon most of these procedures can work. My particular preference would have been ALIF with anterior decompressive discectomy.