In the July 2004 Edition of the Journal of Bone and Joint Surgery, Dr. Ghiselli et al performed a retrospective review on patients that had undergone lumbar fusions by primarily by the Late Dr. Edgar Dawson, distinguished professor and spine surgeon affliated with UCLA. The goal was to establish the rate of developing symptomatic adjacent level degeneration that required surgical management. The journal article details the indications for the fusion procedure. Most patients had posterior intertransverse process spinal fusion for spondylolithesis, post-laminectomy instability, or recurrent discectomy. Patients excluded from the study included those with history of neoplasm, acute fracture of dislocation, or were scheduled to have an additional anterior surgical procedure.
Total number of patients reviewed are 215 patients that have had posterior lumbar fusion between April of 1983 to August of 1994. As we know, the article was written in 2004. The surgical procedures included about 50% of the patients that had non-instrumented fusion ( no plates, screws or other hardware).
The study concluded that 16.5% of these patients had additional decompression or fusion within 5 years. 36.1% of these patients had additional decompression or fusion within 10 years. The theory is that these patients developed symptomatic disk degeneration that required surgery at a rate of 3.9% a year.
Of course, while the study did present some numbers, this was a retrospective review, and the multiple different indications for the primary lumbar fusion was not well stratified. We do no know if patients that had recurrent disk herniations, versus patients that had post-laminectomy instability versus spondylolisthesis had more or less numbers of patients with development of symptomatic adjacent level disease. We do not know if there was a difference of outcome based on the surgical technique utilized (instrumentation, vs non-instrumentation). Also, there was no matched pair of non-surgically treated patients to see if there is an statistical difference in adjacent level disease in non-surgically treated patients. What if the adjacent level degeneration is not because of the surgery, but rather, because the patients who need surgery also are the ones who develop rapid degeneration that would be considered surgically treatable? The authors themselves stated the limitation of the study is that the endpoint for symptomatic adjacent level disease is the additional surgery. There can also be a population that develops surgically treatable adjacent level disease, but chose not to have surgery. There are too many unanswered questions to conclude the rates and percentages are accurate. But, as a spine surgeon, we do know that adjacent level degeneration is a real issue that must be measured, and counseling on the potential for further surgery should be discussed with all patients undergoing lumbar spinal fusion.
While some will use this data to discredit spinal fusion, most clinicians know that spinal fusion still has a role. Further studies will hopefully give us better information, so we can inform patients, families, insurers, etc the potential for more surgery in this population.
- Wang MY, Vasudevan R, Mindea SA. Minimally invasive lateral interbody fusion for the treatment of rostral adjacent-segment lumbar degenerative stenosis without supplemental pedicle screw fixation. J Neurosurg Spine. 2014 Dec;21(6):861-6. PubMed PMID: 25303619
- Sander AL, Lehnert T, El Saman A, Eichler K, Marzi I, Laurer H. Outcome of traumatic intervertebral disk lesions after stabilization by internal fixator. AJR Am J Roentgenol. 2014 Jul;203(1):140-5. PubMed PMID: 24951207