scholarly journals Effect of lordosis on adjacent levels after lumbar interbody fusion, before and after removal of the spinal fixator: a finite element analysis

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Fon-Yih Tsuang ◽  
Jui-Chang Tsai ◽  
Dar-Ming Lai

Abstract Background Literature indicates that adjacent-segment diseases after posterior lumbar interbody fusion with pedicle screw fixation accelerate degenerative changes at unfused adjacent segments due to the increased motion and intervertebral stress. Sagittal alignment of the spine is an important consideration as achieving proper lordosis could improve the outcome of spinal fusion and avoid the risk of adjacent segment diseases. Therefore, restoration of adequate lumbar lordosis is considered as a major factor in the long-term success of lumbar fusion. This study hypothesized that the removal of internal fixation devices in segments that have already fused together could reduce stress at the disc at adjacent segments, particularly in patients with inadequate lordosis. The purpose of this study was to analyze the biomechanical characteristics of a single fusion model (posterior lumbar interbody fusion with internal fixation) with different lordosis angles before and after removal of the internal fixation device. Methods Five finite element models were constructed for analysis; 1) Intact lumbar spine without any implants (INT), 2) Lumbar spine implanted with a spinal fixator and lordotic intervertebral cage at L4-L5 (FUS-f-5c), 3) Lumbar spine after removal of the spinal fixator (FUS-5c), 4) Lumbar spine implanted with a spinal fixator and non-lordotic intervertebral cage at L4-L5 (FUS-f-0c), and 5) Lumbar spine after removal of the spinal fixator from the FUS-f-0c model (FUS-0c). Results The ROM of adjacent segments in the FUS-f-0c model was found to be greater than in the FUS-f-5c model. After removing the fixator, the adjacent segments in the FUS-5c and FUS-0c models had a ROM that was similar to the intact spine under all loading conditions. Removing the fixator also reduced the contact forces on adjacent facet joints and reduced the peak stresses on the discs at adjacent levels. The greatest increase in stress on the discs was found in the FUS-f-0c model (at both L2/L3 and L3/L4), with intervertebral stress at L3/L4 increasing by 83% when placed in flexion. Conclusions This study demonstrated how removing the spinal fixation construct after bone fusion could reduce intradiscal pressure and facet contact forces at adjacent segments, while retaining a suitable level of lumbar lordosis.

2013 ◽  
Vol 19 (1) ◽  
pp. 90-94 ◽  
Author(s):  
Hironobu Sakaura ◽  
Tomoya Yamashita ◽  
Toshitada Miwa ◽  
Kenji Ohzono ◽  
Tetsuo Ohwada

Object A systematic review concerning surgical management of lumbar degenerative spondylolisthesis (DS) showed that a satisfactory clinical outcome was significantly more likely with adjunctive spinal fusion than with decompression alone. However, the role of adjunctive fusion and the optimal type of fusion remain controversial. Therefore, operative management for multilevel DS raises more complicated issues. The purpose of this retrospective study was to elucidate clinical and radiological outcomes after 2-level PLIF for 2-level DS with the least bias in determination of operative procedure. Methods Since 2005, all patients surgically treated for lumbar DS at the authors' hospital have been treated using posterior lumbar interbody fusion (PLIF) with pedicle screws, irrespective of severity of slippage, patient age, or bone quality. The authors conducted a retrospective review of 20 consecutive cases involving patients who underwent 2-level PLIF for 2-level DS and had been followed up for 2 years or longer (2-level PLIF group). They also analyzed data from 92 consecutive cases involving patients who underwent single-level PLIF for single-level DS during the same time period and had been followed for at least 2 years (1-level PLIF group). This second group served as a control. Clinical status was assessed using the Japanese Orthopaedic Association (JOA) score. Fusion status and sagittal alignment of the lumbar spine were assessed by comparing serial plain radiographs. Surgery-related complications and the need for additional surgery were evaluated. Results The mean JOA score improved significantly from 12.8 points before surgery to 20.4 points at the latest follow-up in the 2-level PLIF group (mean recovery rate 51.8%), and from 14.2 points preoperatively to 22.5 points at the latest follow-up in the single-level PLIF group (mean recovery rate 55.3%). At the final follow-up, 95.0% of patients in the 2-level PLIF group and 96.7% of those in the 1-level PLIF group had achieved solid spinal fusion, and the mean sagittal alignment of the lumbar spine was more lordotic than before surgery in both groups. Early surgery-related complications, including transient neurological complications, occurred in 6 patients in the 2-level PLIF group (30.0%) and 11 patients in the 1-level PLIF group (12.0%). Symptomatic adjacent-segment disease was found in 4 patients in the 2-level PLIF group (20.0%) and 10 patients in the 1-level PLIF group (10.9%). Conclusions The clinical outcome of 2-level PLIF for 2-level lumbar DS was satisfactory, although surgery-related complications including symptomatic adjacent-segment disease were not negligible.


2020 ◽  
pp. 219256822091937
Author(s):  
Hironobu Sakaura ◽  
Daisuke Ikegami ◽  
Takahito Fujimori ◽  
Tsuyoshi Sugiura ◽  
Yoshihiro Mukai ◽  
...  

Study Design: Retrospective study. Objective: To examine whether atherosclerosis has negative impacts on early adjacent segment degeneration (ASD) after posterior lumbar interbody fusion using traditional trajectory pedicle screw fixation (TT-PLIF). Methods: The subjects were 77 patients who underwent single-level TT-PLIF for degenerative lumbar spondylolisthesis. Using dynamic lateral radiographs of the lumbar spine before surgery and at 3 years postoperatively, early radiological ASD (R-ASD) was examined. Early symptomatic ASD (S-ASD) was diagnosed when neurologic symptoms deteriorated during postoperative 3-year follow-up and the responsible lesions adjacent to the fused segment were also confirmed on magnetic resonance imaging. According to the scoring system by Kauppila et al, the abdominal aortic calcification score (AAC score: a surrogate marker of systemic atherosclerosis) was assessed using preoperative lateral radiographs of the lumbar spine. Results: The incidence of early R-ASD was 41.6% at the suprajacent segment and 8.3% at the subjacent segment, respectively. Patients with R-ASD had significantly higher AAC score than those without R-ASD. The incidence of early S-ASD was 3.9% at the suprajacent segment and 1.4% at the subjacent segment, respectively. Patients with S-ASD had higher AAC score than those without S-ASD, although there was no significant difference. Conclusions: At 3 years after surgery, the advanced AAC had significantly negative impacts on early R-ASD after TT-PLIF. This result indicates that impaired blood flow due to atherosclerosis can aggravate degenerative changes at the adjacent segments of the lumbar spine after PLIF.


2014 ◽  
Vol 20 (5) ◽  
pp. 538-541 ◽  
Author(s):  
Shinya Okuda ◽  
Takenori Oda ◽  
Ryoji Yamasaki ◽  
Takafumi Maeno ◽  
Motoki Iwasaki

One of the most important sequelae affecting long-term results is adjacent-segment degeneration (ASD) after posterior lumbar interbody fusion (PLIF). Although several reports have described the incidence rate, there have been no reports of repeated ASD. The purpose of this report was to describe 1 case of repeated ASD after PLIF. A 62-year-old woman with L-4 degenerative spondylolisthesis underwent PLIF at L4–5. At the second operation, L3–4 PLIF was performed for L-3 degenerative spondylolisthesis 6 years after the primary operation. At the third operation, L2–3 PLIF was performed for L-2 degenerative spondylolisthesis 1.5 years after the primary operation. Vertebral collapse of L-1 was detected 1 year after the third operation, and the collapse had progressed. At the fourth operation, 3 years after the third operation, vertebral column resection of L-1 and replacement of titanium mesh cages with pedicle screw fixation between T-4 and L-5 was performed. Although the patient's symptoms resolved after each operation, the time between surgeries shortened. The sacral slope decreased gradually although each PLIF achieved local lordosis at the fused segment.


2019 ◽  
Vol 124 ◽  
pp. 470-471
Author(s):  
Yukitaka Nagamoto ◽  
Shinya Okuda ◽  
Tomiya Matsumoto ◽  
Tsuyoshi Sugiura ◽  
Yoshifumi Takahashi ◽  
...  

2011 ◽  
Vol 20 (S1) ◽  
pp. 41-45 ◽  
Author(s):  
C. A. Logroscino ◽  
L. Proietti ◽  
E. Pola ◽  
L. Scaramuzzo ◽  
F. C. Tamburrelli

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