Answer to the Letter to the Editor of Yi Shen et al. concerning “Risk factors for adjacent segment pathology requiring additional surgery after single-level spinal fusion: impact of pre-existing spinal stenosis demonstrated by preoperative myelography” by I. Yugué et al. (2015) Eur Spine J Aug 14 doi:10.1007/s00586-015-4291-5

Abstract Background Interspinous spacer (ISPs) was a promising treatment method for adjacent segment degeneration (ASD) after spinal fusion. Coflex, one of ISPs, has been deceived to prevent or decelerate ASD after spinal fusion, while the proof of the effectiveness of such device is still very limited. The purpose of this study was further to investigate the protection role of Coflex in vivo after spinal fusion, when implanted in adjacent segment and middle segment. Methods Three groups of beagles were allocated as follows (n=6): (1)L4-5 lumbar interbody fusion(IF). (2) L4-5 lumbar interbody fusion +L5-6 interspinous Coflex implantation(Cof1).(3) L4-5 and L6-7 interbody fusion+ L5-6 interspinous Coflex implantation (Cof2). In all animals, L5-6 discs were punctured to generate degeneration, and the intact L2–3 disc served as a noninjuries control (Con group). The effectiveness of Coflex on the prevention or deceleration of the progression of ASD was determined by magnetic resonance imaging, gross anatomical observation, histological and immunohistochemically analysis, and Real-time PCR analysis of gene expression. Results The objective disc in every group showed degeneration, however, the degeneration was more significant in IF group than Cof1 and Cof2 groups. MRI and histologic assay demonstrated that the discs of Cof1 and Cof2 groups maintained a relatively well-preserved structure as compared to the discs of IF group. Furthermore, immunohistochemistry analysis and real-time PCR demonstrated that the indicators of disc degeneration, TIMP1, BMP2, Col I, were up-regulated and disc matrix gene, Col II was down-regulated in IF group significantly Conclusions Coflex could decelerate the progression of ASD after spinal fusion, and it holds the same value not only at adjacent segment after single level spinal fusion, but also dose at the middle segment after “skipped” level (nonconsecutive) fusion

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Letter to the Editor regarding, “The necessity and risk factors of subsequent fusion after decompression alone for lumbar spinal stenosis with lumbar spondylolisthesis: 5 years follow-up in two different large populations”

The Spine Journal ◽

10.1016/j.spinee.2020.12.008 ◽

2021 ◽

Vol 21 (4) ◽

pp. 724

Author(s):

Tadhg J. O'Gara

Keyword(s):

Risk Factors ◽

Spinal Stenosis ◽

Lumbar Spinal Stenosis ◽

Letter To The Editor ◽

Large Populations ◽

Lumbar Spinal ◽

Lumbar Spondylolisthesis

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Risk Factors of Adjacent Segment Disease Requiring Surgery After Lumbar Spinal Fusion

Spine ◽

10.1097/brs.0000000000000164 ◽

2014 ◽

Vol 39 (5) ◽

pp. E339-E345 ◽

Cited By ~ 72

Author(s):

Jae Chul Lee ◽

Yongdai Kim ◽

Jae-Wan Soh ◽

Byung-Joon Shin

Keyword(s):

Risk Factors ◽

Spinal Fusion ◽

Adjacent Segment Disease ◽

Adjacent Segment ◽

Lumbar Spinal Fusion ◽

Lumbar Spinal

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Adjacent-level biomechanics after single versus multilevel cervical spine fusion

Journal of Neurosurgery Spine ◽

10.3171/2011.10.spine11116 ◽

2012 ◽

Vol 16 (2) ◽

pp. 172-177 ◽

Cited By ~ 46

Author(s):

Mark L. Prasarn ◽

Dinah Baria ◽

Edward Milne ◽

Loren Latta ◽

William Sukovich

Keyword(s):

Cervical Spine ◽

Maximum Load ◽

Spine Fusion ◽

Adjacent Segment ◽

Segmental Motion ◽

Single Level ◽

Additional Surgery ◽

Increased Risk ◽

Level Versus ◽

Cervical Spine Fusion

Object Previous studies have demonstrated that patients with spinal fusion are at greater risk for adjacent-segment disease and require additional surgery. It has been postulated that excessive motion of a given motion segment unit (MSU) leads to an increased risk of disc degeneration. It is the authors' hypothesis that a greater increase in adjacent-segment motion will be observed following a 2-level versus a single-level anterior cervical discectomy and instrumented fusion (ACDF). Therefore, they undertook this study to determine the effect of single-level versus 2-level ACDF on the biomechanics of adjacent MSUs. Methods Ten fresh-frozen human cervical spines were used in this study. The specimens were potted at C-4 and T-1 and tested in flexion and extension. Range of motion (ROM) was 30° of flexion and 15° of extension at a maximum load of 50 N. The specimens were tested intact and then were randomized into 2 groups of 5 specimens each. Group 1 underwent a single-level ACDF at the C5–6 level first, and Group 2 underwent the procedure at the C6–7 level. After testing, both groups had the fusion extended to include the C5–7 levels, and the testing was repeated. Changes in overall ROM, stiffness, and segmental motion were calculated and statistically analyzed using a paired Student t-test. Results An increase in sagittal ROM of 31.30% above (p = 0.012) and 33.88% below (p = 0.066) the fused MSU was found comparing a 2-level with a 1-level ACDF. The overall stiffness of the entire spinal construct increased 37.34% (p = 0.051) in extension and 30.59% (p = 0.013) in flexion as the second fusion level was added. As expected, the overall sagittal ROM of the entire spinal construct decreased by 13.68% (p = 0.0014) with a 2-level compared with a 1-level fusion. Conclusions This study has shown that the biomechanics at adjacent levels to a cervical spine fusion are altered and that there is increased adjacent-segment motion at the levels above and below, after a 2-level compared with a 1-level ACDF.

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