Degenerative Disc Disease: Lumbar Interbody Fusion or Artificial Disc?
The patient is a 46-year-old female who rates her lower lumbar pain as 7/10. There is no history of spinal surgery.
She is 5'2" and weighs 124 pounds. There is decreased active lumbar range of motion in all planes. Her lower extremity examination shows that she is neurologically intact; 5/5 motor strength, light touch intact L3-S1, and equal symmetrical patellar and ankle reflexes.
Oswestry Disability Index (ODI) is 50. Visual Analog Score (VAS) is 58/100.
The patient underwent L4-L5 epidural steroid injections and L4-L5 facet joint injections.
MRI scans reveal moderate to severe degenerative disc disease at L4-L5 (Fig. 2), central bulge and high intensity zone (HIZ). There is moderate bilateral L4-L5 facet arthropathy.
Figure 1. Posterior anterior x-ray (Circle denotes radiologist's localizer)
Figure 2. Sagittal MRI; HIZ at L4-L5
Other test results:
- Bone density testing: Normal
- Provocative discography: Normal nucleogram at L3-L4. L4-L5 revealed a degenerative dye pattern and markedly positive with concordant pain reproduction.
Discogenic low back pain secondary to L4-L5 degenerative disc disease.
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The Charité® Artificial Disc (DePuy Spine) was implanted at L4-L5. Estimated blood loss was 100-cc and surgical time was 124 minutes. There were no adverse events.
Figure 3A. Postoperative anterior posterior x-ray
Figure 3B. Postoperative lateral x-ray
Twenty-four months after surgery, the patient is doing well.
|12 months postoperative||
|24 months postoperative||
At 24 months, no re-operation.
This case illustrates the surgical treatment of a single-level painful degenerated disc disease, with early MRI findings of degeneration. The clinical issues raised in the case illustrate the difficulty of diagnosing someone with primary back pain and a "black disc." Our current diagnostic tools, including MRI and provocative discography, are often inaccurate and inconsistent. The question of if she would even be considered a surgical candidate is open for debate. It appears, with her pre and postoperative outcome measures, Dr. Knight did indeed make the correct determination that surgery would be helpful. However, a different outcome would not have been unexpected and may not necessarily be a failure of the surgical technology, but more of patient selection.
With regard to the choice of surgery, the options include either fusion of the L4-L5 level via a number of different methods versus lumbar arthroplasty. This again is a second area of debate within spine surgery. The choice of lumbar arthroplasty would not have been my choice for this patient. In my mind, is the added risk of lumbar arthroplasty (more difficult surgery, durability, and revision strategy) is not offset by the theoretical advantage of a reduction in adjacent level disease. Currently, there are no data that would support that lumbar arthroplasty will actually reduce the rate of adjacent level disease. I would have recommended a fusion surgery for L4-L5 either MIS TLIF or DLIF, if I were convinced this was the source of her chronic back pain.
Dr. Liu's concerns regarding the choice of care for this patient are well-founded. Debate regarding the pros and cons of lumbar arthroplasty will continue until definitive evidence for or against arthroplasty's reduction of junctional degeneration and improved revision strategies are established.
Cadaveric studies have suggested that motion preservation at the index disc level reduces mechanical stress on the cranial, caudal and/or distant disc levels. At this point, the body of literature does have level one, randomized prospective trials to suggest equivalence of arthroplasty to fusion. Only continued use of early technology will give the weighted evidence needed for clear conclusions regarding efficacy.
Surgical treatment of discogenic back pain should be an option of last resort, fusion or arthroplasty. Exhaustive, organized physical therapy and thorough patient education aid in patient selection; the key to any operative success. At this point; arthroplasty remains an option for properly selected patients in my practice.