New Onset of Low Back Pain
The patient is a 42-year-old male truck driver who presents with a new onset of low back pain with bilateral buttock pain that radiates down his posterior / posterolateral thighs.
He is two years status post a work-related fracture at T12 that was treated by posterior spinal fusion of T10-T12 with excellent results.
He is 5'11" and weighs 210 pounds. His thoracolumbar scar from prior spine fusion is well-healed. There is decreased active lumbar range of motion in all planes. Plus bilateral paraspinal lumbar muscle spasm. His lower neurovascular extremities are intact with 5/5 motor strength, light touch intact L3-S1, reflexes 2+, and symmetrical patella and ankle.
Rest, oral pain medications, physical therapy
Plain posterior anterior and lateral x-rays (Figs. 1A, 1B) reveal degenerative disc disease at L5-S1 with posterior spinal implants consistent with his prior fusion for T12 fracture.
The MRI scan reveals an isolated degenerative disc at L5-S1 without junctional stenosis below the prior fusion. (Fig. 2)
Provocative discography: Normal nucleogram at L3-L4. L5-S1 degenerative dye pattern is markedly positive with concordant pain reproduction (Figs. 3A, 3B).
Mechanical low back pain secondary to L5-SI degenerative disc
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The ProDisc®-L (Synthes Spine, Inc.) was implanted at L5-S1. Estimated blood loss was 100-cc and surgical time was 105 minutes. There were no adverse events.
The patient returned to work six weeks after surgery. At 24 months, he remains gainfully employed as a truck driver, off narcotic medication, with no re-operation.
This 42-year-old male presents with symptoms that are attributable to his L5-S1 degenerative disc disease. He does not have evidence of any significant degeneration of any of the levels between the symptomatic L5-S1 and his prior fusion. Any prior surgery should always be considered while developing a treatment strategy.
The change in overall stress and motion at the segments below or above a prior fusion can often cause us to alter our treatment strategy to prevent early breakdown of additional segments. In this case, the prior fusion is several motion segments removed from the pathology. The prior fusion will not cause significant alteration in force at the L4-L5 level, which is the level of concern if we are treating L5-S1. As such, the relevant discussion is that of treatment of degenerative disc disease in a relatively young male.
When a patient fails nonsurgical treatment for single-level degenerative disc disease, surgery is a reasonable option. Current strategies include anterior or posterior fusion, as well as disc arthroplasty. Planning the appropriate approach involves a thorough examination of the risks and benefits to the patient. One consideration, in this relatively young male, is the potential for small, but still relevant risk of retrograde ejaculation with an anterior approach. For that reason, in this population, my preference is often a minimally invasive TLIF.
Disc arthroplasty has excellent early results in this patient, but I do have some concerns for the long-term durability in this 210-pound patient over the next 40 years. As we continue to accrue follow up in these patients, I hope we will continue to see good results and potentially avoid breakdown at the adjacent segment.
Dr. Koski is correct in suggesting that the long-term effects of disc arthroplasty remain unclear. There a growing body of evidence to suggest that properly selected patients can expect an equivalent, if not superior, outcome comparing disc arthroplasty to single-level anterior interbody fusion at L5-S1.
A key to any surgical procedure is patient selection. A major part of that process involves thorough patient education regarding the potential risks and benefits of surgical options and continued nonoperative treatment. In this 42-year-old male, the risk of retrograde ejaculation was discussed and fortunately not encountered. Following lengthy discussions with the patient and review of biomechanical data documenting reduced stress on adjacent disc spaces, a decision was made to proceed with disc arthroplasty.
Early results have been encouraging. We continue to monitor the L5-S1 arthroplasty for any signs of failure and the L4-L5 disc space of symptomatic degenerative changes.