Many people who reach out to our office write to us after they have undergone a spinal surgical procedure with less than hoped for results. They write us about their continued pain and are looking for help. These people now realize the complexities of spinal surgery, especially in patients with numerous procedures. Some have been offered another surgery others not because they and their doctors have agreed that further surgery would likely do no good. Therefore another treatment or pain management program would need to be put in place. Following failed back surgery the patient may be sent to physical therapy, be prescribed stronger painkillers, and, or a spinal cord stimulator. Sometimes these treatments work, sometimes they do not. Let’s start exploring the research on adjacent segment disc degeneration following fusion surgery and the current recommendations.
Lumbar adjacent segment disease is a complication of lumbar spinal fusion surgery. The adjacent segments are above and or below the fusion levels. A L3-L4 fusion would have adjacent levels at L2 and L5 for instance.
Radiculopathy, stenosis and instability – preoperative risk factors for Lumbar adjacent segment disease
An October 2021 paper wrote (1) : “Spinal fusion is the most widely accepted treatment for lumbar disc degenerative disease. However, it has been associated with adjacent segment degeneration as a potential long-term sequel especially in those with preoperative risk factors, which may cause aberrant stress forces in these segments and lead to adjacent level degeneration. Adjacent segment pathology can include adjacent segment degeneration and adjacent segment disease, although a clear and consensual definition of adjacent segment disease is missing. In most studies, adjacent segment degeneration is defined as radiographic changes in the intervertebral discs adjacent to the surgically treated levels, whereas adjacent segment disease is defined as the pathologic process associated with disc degeneration leading to clinical symptoms, such as radiculopathy, stenosis and instability. Nevertheless, there are a few reports considering reoperation rate as being the most reliable parameter to define adjacent segment disease, despite clinical symptoms.”
Transforaminal lumbar interbody fusion
A November 2021 study (2) explored the incidence and risk factors for adjacent segment disease in patients with lumbar degenerative diseases after a transforaminal lumbar interbody fusion (TLIF). The researchers found the incidence of adjacent segment disease after TLIF in patients with lumbar degenerative disease is approximately 5.2%. High BMI Body Mass Index and preoperative adjacent segment disc degeneration are more significant risk factors. “Encouraging patients to lose weight and trying to avoid lumbar fusion surgery at the vertebrae adjacent to a degenerated intervertebral disc may reduce the occurrence of adjacent segment disc degeneration.”
Spinal instability
An October 2021 paper (3) connected spinal instability, whether caused by spinal degeneration or spinal fusion, to adjacent segment disease.
Adjacent segment disease is a controversial process after spine stabilization (fusion surgery). In this study doctors compared what happens in the spine when vertebrae fuse as a result of birth abnormality or natural degenerative changes versus what happens in the spine following a fusion surgery. Why? To help doctors predict degenerative change following spinal fusion in the non-fused remaining segments. From the researchers:
“This article’s main purpose is to determine the degree of relationship of hypermobility and the aging process in the deterioration of the disks adjacent to fusion. In this study, the degenerative process developed by hypermobility in the adjacent segment due to incidental segmental fusion was evaluated. . . Damage to the adjacent segment disks in cases with incidental (non-surgical developmental of degenerative fusion caused by spinal hypermobility or spinal instability) fusion can still be seen at any age, with fusion, indicating that the hypermobility effect plays a more prominent role. The evidence of hypermobility without aging is that the segments adjacent to fusion undergo more degeneration than the distant disks.
Conclusion: Adjacent segment disease is under the influence of many factors. Our findings suggest that its incidence is increasing with the pathological processes initiated by hypermobility. It seems that, at least, it carries equal importance as compared to age. Fusion surgeries damage the adjacent segments under the influence of the passage of time beyond the physiological aging of the patient.”
Fusion takes away the natural curvature of the lumbar spine
Recently surgeons noted that fusion, by taking away the natural curve of the lumbar spine, increased the risk of adjacent segment deterioration. This was noted in a paper published in June 2021 (4) which suggested: “Lumbar lordosis is a critical feature of spinal morphology which correlates with the risk of developing Adjacent segment disease. The concept of maintenance of lumbar lordosis following fusion as a protective factor to the risk of developing adjacent segment stress and instability was described by several (studies). A recent study published in 2018 was the first to analyze the influence of Lumbar lordosis on the biomechanical characteristics of the adjacent segment after L4-L5 Transforaminal lumbar interbody fusion TLIF. The results showed that as Lumbar lordosis decreases, the stress of the adjacent disc increases. In conclusion, hypolordosis appears to increase the risk of adjacent segment deterioration.”
Which surgeries demonstrate better outcomes?
A December 2023 paper (5) compared the rate of post-surgical disc herniation following decompression of lumbar spinal stenosis. The authors cited previously published research that suggested “lumbar decompression techniques, associated with relative segmental instability especially in the presence of degenerated disc in older patients, are more likely to result in disc herniation compared to minimally invasive techniques.” In this study the researchers compared two surgical techniques, mini-open and minimally invasive decompression of lumbar spinal stenosis. In assessing patients following surgery, they found: “The incidence of postoperative disc herniation following spinal decompression for symptomatic lumbar stenosis was 5.8% following mini-open bilateral partial laminectomy compared to only 0.8% after minimally invasive laminotomy.”
The “Topping Off” technique to prevent adjacent segment disease
Let’s review the suggestions of a 2017 study (6) in describing the “topping off” or hybrid fusion technique to help prevent adjacent segment disease.
This “topping-off” technique refers to application of hybrid dynamic pedicle screw construct or interspinous process device above the fused segments. This technique provides a transitional zone between the fixed vertebrae and the mobile/unfused segments, which may decrease the incidence of adjacent segment disease. The rationale of this technique is that the semirigid zone provides a gradual transition from the rigid to mobile segments to lessen stress concentration at the adjacent level.
Does this new transition from rigid spine to flexible spine help prevent adjacent segment disease?
Again from the 2017 study: “Although the evidence is weak, the “topping-off” technique with hybrid stabilization device or interspinous process devices might decrease the incidence of proximal adjacent segment disease both radiographically and symptomatically as compared to the fusion group. . . In conclusion, the “topping-off” technique might be considered as a possible solution for postfusion adjacent segment disease , but further research is needed prior to wide application.”
To update this research, an August 2023 paper (7) found possible problems at the sacroiliac joint. In this study, researchers investigated the biomechanical effects of topping-off instrumentation on the sacroiliac joint after lumbosacral fusion. They found: “Motion, stress, and ligament strain at the sacroiliac joint increase when supplementing lumbosacral fusion with topping-off devices, suggesting that topping-off surgery may be associated with higher risks of sacroiliac joint degeneration and pain than fusion alone.”
Treatment options
When someone comes into our office with adjacent segment disease, we have to realistically assess the patient’s situation and offer the patient practical treatment options. In some people these treatment options will provide great relief as treatments may restore stability to the spine by addressing spinal ligament or other soft-tissue connective structure damage. PRP injections may help if there is a situation of ligament damage. Sometimes the case is very complicated and our treatments may not be able to offer any help.
Does PRP treatments help a spinal fusion fuse?
A March 2022 paper (8) found PRP as a biological agent in augmenting spinal fusion is limited. Current evidence does not support the use of PRP as an adjuvant to enhance spinal fusion.
References
1 Pinto EM, Teixeira A, Frada R, Atilano P, Miranda A. SURGICAL RISK FACTORS ASSOCIATED WITH THE DEVELOPMENT OF ADJACENT SEGMENT PATHOLOGY IN THE LUMBAR SPINE. EFORT Open Reviews. 2021 Oct;6(10):966-72.
2 Ye J, Yang S, Wei Z, Cai C, Zhang Y, Qiu H, Chu T. Incidence and Risk Factors for Adjacent Segment Disease After Transforaminal Lumbar Interbody Fusion in Patients with Lumbar Degenerative Diseases. Int J Gen Med. 2021 Nov 15;14:8185-8192. doi: 10.2147/IJGM.S337298. PMID: 34815692; PMCID: PMC8604649.
3 Hekimoğlu M, Başak A, Yılmaz A, Yıldırım H, Aydın AL, Karadag K, Özer AF. Adjacent segment disease (ASD) in incidental segmental fused vertebra and comparison with the effect of stabilization systems on ASD. Cureus. 2021 Oct;13(10).
4 Pinto EM, Teixeria A, Frada R, Oliveira F, Atilano P, Veigas T, Miranda A. Patient-related risk factors for the development of lumbar spine adjacent segment pathology. Orthopedic Reviews. 2021;13(2).
5 Uri O, Alfandari L, Folman Y, Keren A, Smith W, Paz I, Behrbalk E. Acute disc herniation following surgical decompression of lumbar spinal stenosis: a retrospective comparison of mini-open and minimally invasive techniques. J Orthop Surg Res. 2023 Dec 18;18(1):974. doi: 10.1186/s13018-023-04457-2. PMID: 38111077.
6 Chou PH, Lin HH, An HS, Liu KY, Su WR, Lin CL. Could the topping-off technique be the preventive strategy against adjacent segment disease after pedicle screw-based fusion in lumbar degenerative diseases? A systematic review. BioMed research international. 2017 Feb 22;2017.
7 Fan W, Zhang C, Wang QD, Guo LX, Zhang M. The effects of topping-off instrumentation on biomechanics of sacroiliac joint after lumbosacral fusion. Computers in Biology and Medicine. 2023 Aug 13:107357.
8 Muthu S, Jeyaraman M, Ganie PA, Khanna M. Is platelet-rich plasma effective in enhancing spinal fusion? Systematic overview of overlapping meta-analyses. Global spine journal. 2022 Mar;12(2):333-42.
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