Correlation between sagittal plane changes and adjacent segment degeneration following lumbar spine fusion

Adjacent segment degeneration following lumbar spine fusion remains a widely acknowledged problem, but there is insufficient knowledge regarding the factors that contribute to its occurrence. The aim of this study is to analyse the relationship between abnormal sagittal plane configuration of the lumbar spine and the development of adjacent segment degeneration. Eighty-three consecutive patients who underwent lumbar fusion for degenerative disc disease were reviewed retrospectively. Patients with spondylolytic spondylolisthesis and degenerative scoliosis were not included in this study. Mean follow-up period was 5 years. Results were analysed to determine the association between abnormal sagittal configuration and post operative adjacent segment degeneration. Thirty-one out of 83 patients (36.1%) showed radiographic evidence of adjacent segment degeneration. Patients with normal C7 plumb line and normal sacral inclination in the immediate post operative radiographs had the lowest incidence of adjacent level change compared with patients who had abnormality in one or both of these parameters. The difference was statistically significant (P<0.02). There was no statistically significant difference in the incidence of adjacent level degeneration between male and female patients; between posterior fusion alone and combined posterolateral and posterior interbody fusions; and between fusions extending down to the sacrum and fusions stopping short of the sacrum. It was concluded was that normality of sacral inclination is an important parameter for minimizing the incidence of adjacent level degeneration. Retrolisthesis was the most common type of adjacent segment change. Patients with post operative sagittal plane abnormalities should preferably be followed-up for at least 5 years to detect adjacent level changes.     

腰椎内固定融合术后邻近节段退变的影响因素

目的探讨腰椎内固定融合术后邻近节段退变的影响因素。方法对1998年3月至2002年5月33例行腰椎内固定融合术的病例进行随访研究,观察其术后邻近节段退变的发生率、发生年龄、部位、影像学特点以及临床表现,对是否“悬浮固定”、内固定融合范围、不同邻近节段退变的风险进行对比。结果33例患者随访34～82个月,平均4年7个月。发现影像学上有退变表现10例（占30．3％）,10例中有9例退变发生在头侧节段。发生邻近节段退变以60岁以上患者为主。是否进行“悬浮固定”对内固定融合术后邻近节段退变的影响无统计学差异。多节段融合术后较单节段融合术后邻近节段退变有增多的趋势。L2／L3作为邻近节段时退变风险较高,而L5／L1,作为邻近节段退变风险较低。结论头侧邻近节段较尾侧节段更容易发生退变。如果L2／L3可能作为邻近节段,术前有退变表现,术中需将其进行固定融合,而如果L5／S1在术前没有明显退变证据,则不需要将其进行固定融合。腰椎内固定融合时,尽量避免长节段固定融合。     

类风湿关节炎合并腰椎退行性疾病患者腰椎椎间融合术后邻近节段退行性变的相关因素

目的探讨类风湿关节炎(RA)合并腰椎退行性疾病患者腰椎椎间融合术后发生邻近节段退行性变(ASD的危险因素。方法回顾性分析2008年1月—2016年12月收治的55例RA合并腰椎退行性疾病患者的临床资料,其中29例采用减压并椎间融合术(融合组)治疗,26例采用单纯减压术(非融合组)治疗。记录手术前后红细胞沉降率(ESR)、C反应蛋白(CRP)、基质金属蛋白酶-3(MMP-3)等指标,采用28个关节疾病活动度评分联合CRP水平(DAS28-CRP)评估RA活动度;采用日本骨科学会(JOA)评分评估患者神经功能;测量X线片上腰椎邻近节段头端椎间隙狭窄及椎体滑脱程度以评估ASD情况。运用多因素logistic回归分析检验术后继发ASD的危险因素。结果所有手术顺利完成,术后随访1.5～6.0年,平均3.2年。2组术后JOA评分较术前均明显改善,且融合组显著高于非融合组,差异均有统计学意义(P 0.05)。融合组手术翻修率、影像学ASD及症状性ASD发生率显著高于非融合组,差异均有统计学意义(P 0.05)。多因素logistic回归分析显示,DAS28-CRP评分 4.7分、术前血清MMP-3含量升高是术后继发ASD的独立危险因素。结论 RA合并腰椎退行性疾病患者采用腰椎减压并椎间融合术治疗后出现ASD和需行翻修手术的风险高于采用单纯减压术治疗的患者,术前血清MMP-3含量和DAS28-CRP评分升高可能与腰椎椎间融合术后ASD的发生相关。     

Does Wallis implant reduce adjacent segment degeneration above lumbosacral instrumented fusion?

Delayed complications following lumbar spine fusion may occur amongst which is adjacent segment degeneration (ASD). Although interspinous implants have been successfully used in spinal stenosis to authors’ knowledge such implants have not been previously used to reduce ASD in instrumented lumbar fusion. This prospective controlled study was designed to investigate if the implantation of an interspinous implant cephalad to short lumbar and lumbosacral instrumented fusion could eliminate the incidence of ASD and subsequently the related re-operation rate. Groups W and C enrolled initially each 25 consecutive selected patients. Group W included patients, who received the Wallis interspinous implant in the unfused vertebral segment cephalad to instrumentation and the group C selected age-, diagnosis-, level-, and instrumentation-matched to W group patients without interspinous implant (controls). The inclusion criterion for Wallis implantation was UCLA arthritic grade <II, while the exclusion criteria were previous lumbar surgery, severe osteoporosis or degeneration >UCLA grade II in the adjacent two segments cephalad to instrumentation. All patients suffered from symptomatic spinal stenosis and underwent decompression and 2–4 levels stabilization with rigid pedicle screw fixation and posterolateral fusion by a single surgeon. Lumbar lordosis, disc height (DH), segmental range of motion (ROM), and percent olisthesis in the adjacent two cephalad to instrumentation segments were measured preoperatively, and postoperatively until the final evaluation. VAS, SF-36, and Oswestry Disability Index (ODI) were used. One patient of group W developed pseudarthrosis: two patients of group C deep infection and one patient of group C ASD in the segment below instrumentation and were excluded from the final evaluation. Thus, 24 patients of group W and 21 in group C aged 65+ 13 and 64+ 11 years, respectively were included in the final analysis. The follow-up averaged 60 ± 6 months. The instrumented levels averaged 2.5 + 1 vertebra for both groups. All 45 spines showed radiological fusion 8–12 months postoperatively. Lumbar lordosis did not change postoperatively. Postoperatively at the first cephalad adjacent segment: DH increased in the group W (P = 0.042); ROM significantly increased only in group C (ANOVA, P < 0.02); olisthesis decreased both in flexion (P = 0.0024) and extension (P = 0.012) in group W. The degeneration or deterioration of already existed ASD in the two cephalad segments was shown in 1 (4.1%) and 6 (28.6%) spines in W and C groups, respectively. Physical function (SF-36) and ODI improved postoperatively (P < 0.001), but in favour of the patients of group W (P < 0.05) at the final evaluation. Symptomatic ASD required surgical intervention was in 3 (14%) patients of group C and none in group W. ASD remains a significant problem and accounts for a big portion of revision surgery following instrumented lumbar fusion. In this series, the Wallis interspinous implant changed the natural history of ASD and saved the two cephalad adjacent unfused vertebra from fusion, while it lowered the radiographic ASD incidence until to 5 years postoperatively. Longer prospective randomized studies are necessary to prove the beneficial effect of the interspinous implant cephalad and caudal to instrumented fusion. We recommend Wallis device for UCLA degeneration I and II.     

Arthrodesis to L5 versus S1 in long instrumentation and fusion for degenerative lumbar scoliosis

There is a debate regarding the distal fusion level for degenerative lumbar scoliosis. Whether a healthy L5-S1 motion segment should be included or not in the fusion remains controversial. The purpose of this study was to determine the optimal indication for the fusion to the sacrum, and to compare the results of distal fusion to L5 versus the sacrum in the long instrumented fusion for degenerative lumbar scoliosis. A total of 45 patients who had undergone long instrumentation and fusion for degenerative lumbar scoliosis were evaluated with a minimum 2 year follow-up. Twenty-four patients (mean age 63.6) underwent fusion to L5 and 21 patients (mean age 65.6) underwent fusion to the sacrum. Supplemental interbody fusion was performed in 12 patients in the L5 group and eleven patients in the sacrum group. The number of levels fused was 6.08 segments (range 4–8) in the L5 group and 6.09 (range 4–9) in the sacrum group. Intraoperative blood loss (2,754 ml versus 2,938 ml) and operative time (220 min versus 229 min) were similar in both groups. The Cobb angle changed from 24.7° before surgery to 6.8° after surgery in the L5 group, and from 22.8° to 7.7° in the sacrum group without statistical difference. Correction of lumbar lordosis was statistically better in the sacrum group (P = 0.03). Less correction of lumbar lordosis in the L5 group seemed to be associated with subsequent advanced L5-S1 disc degeneration. The change of coronal and sagittal imbalance was not different in both groups. Subsequent advanced L5-S1 disc degeneration occurred in 58% of the patients in the L5 group. Symptomatic adjacent segment disease at L5-S1 developed in five patients. Interestingly, the development of adjacent segment disease was not related to the preoperative grade of disc degeneration, which proved minimal degeneration in the five patients. In the L5 group, there were nine patients of complications at L5-S1 segment, including adjacent segment disease at L5-S1 and loosening of L5 screws. Seven of the nine patients showed preoperative sagittal imbalance and/or lumbar hypolordosis, which might be risk factors of complications at L5-S1. For the patients with sagittal imbalance and lumbar hypolordosis, L5-S1 should be included in the fusion even if L5-S1 disc was minimal degeneration.     

Risk factors for adjacent segment degeneration after surgical correction of degenerative lumbar scoliosis

Background:

Degenerative lumbar scoliosis surgery can lead to development of adjacent segment degeneration (ASD) after lumbar or thoracolumbar fusion. Its incidence, risk factors, morbidity and correlation between radiological and clinical symptoms of ASD have no consensus. We evaluated the correlation between the occurrence of radiologic adjacent segment disease and certain imperative parameters.

Materials and Methods:

98 patients who had undergone surgical correction and lumbar/thoracolumbar fusion with pedicle screw instrumentation for degenerative lumbar scoliosis with a minimum 5 year followup were included in the study. We evaluated the correlation between the occurrence of radiologic adjacent segment disease and imperative patient parameters like age at operation, sex, body mass index (BMI), medical comorbidities and bone mineral density (BMD). The radiological parameters taken into consideration were Cobb''s angle, angle type, lumbar lordosis, pelvic incidence, intercristal line, preoperative existence of an ASD on plain radiograph and magnetic resonance imaging (MRI) and surgical parameters were number of the fusion level, decompression level, floating OP (interlumbar fusion excluding L5-S1 level) and posterolateral lumbar interbody fusion (PLIF). Clinical outcomes were assessed with the Visual Analogue Score (VAS) and Oswestry Disability Index (ODI).

Results:

ASD was present in 44 (44.9%) patients at an average period of 48.0 months (range 6-98 months). Factors related to occurrence of ASD were preoperative existence of disc degeneration (as revealed by MRI) and age at operation (P = 0.0001, 0.0364). There were no statistically significant differences between radiological adjacent segment degeneration and clinical results (VAS, P = 0.446; ODI, P = 0.531).

Conclusions:

Patients over the age of 65 years and with preoperative disc degeneration (as revealed by plain radiograph and MRI) were at a higher risk of developing ASD.     

Sublaminar wiring stabilization to prevent adjacent segment degeneration after lumbar spinal fusion

Introduction  Adjacent segment degeneration (ASD) is a complication of lumbar spinal fusion. There are some reports on the cause of this degeneration but none concerning its prevention. We performed sublaminar wiring stabilization to prevent ASD after posterolateral lumbar spinal fusion with instrumentation. The purpose of this study was to prospectively evaluate the efficacy of this procedure. Patients and methods  Between 2003 and 2004, 54 consecutive patients with lumbar spinal canal stenosis and multilevel instability of the lumbar spine underwent posterior decompression and posterolateral fusion with instrumentation. The mean age at the time of surgery was 66.7 ± 1.3 years, and the mean follow-up period was 40.0 ± 1.1 months, with a minimum of 29 months. Twenty-seven of the patients underwent conventional sublaminar wiring stabilization at the cephalad segment adjacent to the site of fusion to prevent ASD (group A), and the other 27 patients did not (group B). Some items were assessed, including clinical outcome using Japanese Orthopaedic Association (JOA) score, sagittal global lumbar alignment, and segmental motion in flexion–extension radiographs of the cephalad vertebral body adjacent to the site of fusion. Results  There were no significant differences in JOA scores between two groups, but 2 patients in group B underwent subsequent surgery due to ASD. Sagittal lumbar alignment did not change in group A but was significantly decreased in group B. With respect to segmental motion in flexion–extension radiographs, group A showed a significant decrease from 6.9° before surgery to 3.4° after surgery, on the other hand group B showed a significant increase from 5.6° before surgery to 8.4° after surgery. Conclusions  In this study, it was suggested that sublaminar wiring stabilization significantly reduces the range of motion of the adjacent segment and preserves sagittal lumbar alignment, which lead to prevention of ASD. The clinical outcome of the subsequent surgeries is relatively poor, so it is important to prevent ASD by any prevention such as sublaminar wiring stabilization.     

Can formetric 4D measurements predict the development of adjacent segment degeneration after single-segment PLIF?: Relative rotation angle as a sensitive predictor

BackgroundAdjacent segment degeneration (ASD) is a major issue after posterior lumbar interbody fusion (PLIF). The postoperative dynamic change of adjacent segments remains unknown. Hence, this study using the formetric 4D system (DIERS, International GmbH of Schlangenbad, Germany) to determine the impact of PLIF on ASD, and to compare the effectiveness with traditional radiography for the predication of ASD.MethodsEighty-five consecutive patients who underwent PLIF of a single-segment were included. The formetric 4D system was used to calculate the relative rotation angle between the fusion segment and the upper and lower adjacent vertebrae before and at 6, 12 and 24 months after surgery. The range of motion (ROM) and disc height (DH) of adjacent segments were measured using radiography before surgery and 24 months postoperatively. At the final follow-up, the visual analogue scale (VAS) and Oswestry disability index were used to evaluate the surgical outcome. The patients were divided into two groups according to the occurrence of radiographic ASD: the ASD group with progression of degeneration and the N-ASD group without progression of degeneration.ResultsThe index fusion segments included L2-3 to L5-S1. Preoperatively, the relative rotation angles formed by the fusion segment with the upper and lower adjacent vertebrae were 5.1° ± 2.2° and 3.3° ± 2.0°, respectively, and both angles increased significantly at all time points after surgery (p < 0.05). The angles changed most significantly during L2-3 fusion. Radiographic ASD developed in 13 of 85 patients (15.3%) at 24 months. And the relative rotation angle with the upper adjacent vertebra was larger in the ASD group than in the N-ASD group (p < 0.05).ConclusionThe relative rotation angle with adjacent vertebra increased significantly after lumbar fusion surgery. It may be a more sensitive predictor than the flexion-extension ROM and DH for the development of radiographic ASD.     

Risk factors for early-onset radiographical adjacent segment disease in patients with spondylolytic spondylolisthesis after single-level posterior lumbar interbody fusion

BACKGROUND CONTEXTThe risk factors for radiographical adjacent segment disease (ASD) in patients with degenerative spondylolisthesis have been previously reported. However, there are only few reports on patients with spondylolytic spondylolisthesis who underwent single-level posterior lumbar interbody fusion (PLIF).PURPOSEThe study aimed to investigate the risk factors for radiographical ASD in patients with L5–S1 spondylolytic spondylolisthesis who underwent single-level PLIF.STUDY DESIGN/SETTINGA retrospective studyPATIENT SAMPLEThis study retrospectively reviewed 135 consecutive patients (91 men and 44 women) with symptomatic L5–S1 spondylolytic spondylolisthesis who underwent single-level PLIF.OUTCOME MEASURESThe pre- and postoperative (at the final follow-up) spinopelvic parameters, % slip, sacral slope, lumbar lordosis (LL), pelvic tilt, pelvic incidence (PI), PI minus LL (PI ? LL), lumbosacral angle, C7 sagittal vertical axis, and thoracic kyphosis were measured using standing radiographs.METHODSRadiographical ASD was defined as disc height loss (>3 mm), increase of posterior angulation (>5°), or progression of spondylolisthesis (>3 mm) between the pre- and postoperative radiographs. Pfirrmann's classification was used to evaluate disc degeneration. The radiographical parameters and changes between the pre- and postoperative values were evaluated and compared for the non-ASD and ASD groups. Binary logistic regression analysis was performed to evaluate the adjusted associations between each potential explanatory variable and ASD development.RESULTSThe radiographical ASD incidence was 11%. Additionally, 60% of the patients with ASD had radiographical ASD at 1 year and all cases of radiographical ASD in this follow-up period occurred within 3 years after the initial surgery. The mean period of ASD occurrence after initial surgery was 21.7 ± 12.6 months. No patients required reoperation for radiographical ASD. Multivariate analysis revealed that a preoperative (odds ratio [OR], 5.9; 95% confidence interval [CI], 1.2–28.9; p=.03) and a postoperative (OR, 6.5; 95% CI, 1.2–34.5; p=.03) PI ? LL of ≥15° were risk factors for radiographical ASD.CONCLUSIONSPre- and postoperative PI ? LL value mismatch was identified as significant independent risk factors for radiographical ASD in patients with L5–S1 spondylolytic spondylolisthesis. Obtaining larger lordosis at L5–S1 may be the key to preventing radiographical ASD.     

颈椎前路融合术后相邻节段退变的临床观察与分析

[目的]研究颈椎前路融合术是否必然导致邻近节段退变(adjacent segment degeneration,ASD).[方法]1986～1999年,共346例采用“环锯法前路扩大脊髓减压+椎体间植骨内固定术”治疗颈椎退变性疾病,其中,1个间隙55例,2个间隙223例,3个间隙68例.分别评定融合节段头、尾侧相邻间隙及间隔间隙的影像学表现,对结果分组进行统计学检验.[结果]术后随访13.5 (4.1 ～18)年,发生邻近节段明显退变的156例(45.1％),间隔节段明显退变的23例(6.6％).间隔节段退变明显少于邻近节段退变,两者比较差异有统计学意义(P＜0.05).单纯头侧邻近节段发生ASD 84例,单纯尾侧邻近节段发生ASD 27例,头、尾侧邻近节段均发生的45例.头侧邻近节段ASD发生率明显高于尾侧邻近节段,两者比较差异有统计学意义(P＜0.05).按照融合间隙数不同分为单间隙组、2间隙组和3间隙组,单间隙术后ASD 25例(45.5％),其中8例(14.5％)需2次手术.2间隙术后ASD 101例(45.3％),其中37例(16.6％)需2次手术.3间隙术后ASD 30例(44.1％),其中12例(17.6％)需2次手术.各组间ASD发生率比较无显著性差异(P＞0.05).[结论]颈椎前路融合术加速了ASD的发生,并且多见于头侧相邻节段.单节段或多节段融合术后ASD的发生率无显著性差异.     

腰椎经后路椎体间融合后单边或双边固定对邻近节段退变的影响

背景：在行后路椎体融合内固定术中,椎弓根钉置入不可避免会损伤邻近关节突关节。目前一致认为单边固定因保留一侧关节突关节可明显降低邻近节段退变的发生率,但仍缺乏对邻近节段退变的影响因素及不同节段退变发生率的长期随访研究。目的：对比经后路椎体间融合术（posterior lumbar interbody fusion,PLIF）后单边或双边椎弓根螺钉固定对邻近节段退变的影响。方法：2006年2月至2007年12月,101例行PLIF手术的L4-L5椎间盘突出症患者纳入本研究。采用单边固定42例,双边固定59例。所有患者术后随访时间均超过5年。邻近节段分为三个节段：第1个近端邻近节段、第2个近端邻近节段及远端邻近节段。依据末次随访的影像学资料评估邻近节段退变的情况,并记录末次随访时的ODI评分评价腰椎功能。结果：单边固定组第1个近端邻近节段、第2个近端邻近节段及远端邻近节段退变的发生率分别为57.1%（24/42）、45.2%（19/42）、38.1%（16/42）;双边固定组第1个近端邻近节段、第2个近端邻近节段及远端邻近节段退变的发生率分别为72.9%（43/59）、68.0%（40/59）、50.8%（30/59）。两组第1个近端邻近节段和远端邻近节段退变发生率无统计学差异,而第2个近端邻近节段退变发生率具有统计学差异。末次随访时单边固定组和双边固定组的ODI评分分别为25.6±5.9、28.4±5.2,两组具有显著统计学差异（t=-2.503,P=0.014）。结论：对于行腰椎后路减压融合术的单节段腰椎间盘突出症患者,单边固定者邻近节段退变发生率低于双边固定者,尤其对于第2个近端邻近退变节段的患者。     

Does anterior lumbar interbody fusion promote adjacent degeneration in degenerative disc disease? A finite element study

Background  

The increase in the number of anterior lumbar interbody fusions being performed carries with it the potential for the long-term complication of adjacent segmental degeneration. While its exact mechanism remains uncertain, adjacent segment degeneration has become much more widespread. Using a nonlinear, three-dimensional finite element model to analyze and compare the biomechanical influence of anterior lumbar interbody fusion and lumbar disc degeneration on the superior adjacent intervertebral disc, we attempt to determine if anterior lumbar interbody fusion aggravates adjacent segment degeneration.     

Pre-existing adjacent level foraminal stenosis does not affect the outcome of a single level lumbar interbody fusion

BackgroundThe aim of this study was to investigate whether or not pre-existing asymptomatic neuroforaminal stenosis adjacent to the fusion level develops adjacent segment disease (ASD) after single-level lumbar interbody fusion.Summary and background dataRisk factors of ASD after spinal fusion have been well investigated, but there have been few studies focused on the relationship between ASD and pre-existing asymptomatic neuroforaminal stenosis.MethodsA total of 302 patients who had undergone a single-level lumbar interbody fusion were reviewed at a minimum of 2 year follow-up. They were 109 men and 193 women with a mean age of 68.8 years. Follow-up periods was averaged 53.5 months. ASD was defined as neurological deterioration related to adjacent segment pathologies which required an additional surgery. Based on the pathologies, patients were divided into three categories: ASD due to foraminal stenosis (ASD-FS), ASD due to central stenosis (ASD-CS), and ASD due to herniated disc (ASD-HD). Measured variables were age, gender, diagnosis, BMI, decompression procedures at adjacent segments, preoperative anterior/posterior slip, asymptomatic neuroforaminal stenosis, facet tropism, and postoperative spinopelvic parameters.ResultsThirty-eight patients (12.6%) developed ASD. There were 15 patients with ASD-FS, 18 patients with ASD-CS, and five patients with ASD-HD. Lumbar lordosis (LL) and sacral slope (SS) were significantly smaller and pelvic tilt (PT) was significantly larger in ASD-FS. Asymptomatic neuroforaminal stenosis was detected preoperatively in 33.3% of the ASD-FS group, and 18.6% of non-ASD group; the incidence was not significantly different.ConclusionsAdjacent-level neuroforaminal stenosis was not a significant risk of ASD after single-level lumbar interbody fusion, and might not need to be fused if asymptomatic.     

后路腰椎椎间融合术对邻近节段退变的影响

目的 腰椎融合术改变了腰椎的生物力学环境,使邻近节段应力集中,本研究就后路腰椎椎间融合术(posterior lumbar interbody fusion,PLIF)对邻近节段退变(adjacent segment degeneration,ASD)的影响进行探讨.方法 2002～2006年,采用PLIF治疗腰椎退...     

Comparison of adjacent segment degeneration after successful posterolateral fusion with unilateral or bilateral pedicle screw instrumentation: a minimum 10-year follow-up

Background context

In the instrumented fusion, adjacent segment facet joint violation or impingement by pedicle screws is unavoidable especially in cephalad segment, despite taking specific intraoperative precautions in terms of surgical approach. In such circumstances, unlike its original purpose, unilateral pedicle screw instrumentation can contribute to reduce the degeneration of cephalad adjacent segment by preventing contralateral cephalad adjacent facet joint from the unavoidable injury by pedicle screw insertion. However, to our knowledge, no long-term follow-up study has compared adjacent segment degeneration (ASD) between unilateral and bilateral pedicle screw instrumented fusion.

Purpose

To compare ASD after successful posterolateral fusion using either unilateral or bilateral pedicle screw instrumentation for patients with lumbar spinal stenosis and/or Grade 1 spondylolisthesis.

Study design

Retrospective case-control study.

Patient sample

One hundred forty-seven patients who had undergone one- or two-level posterolateral fusion with unilateral or bilateral pedicle screw instrumentation for lumbar spinal stenosis with or without low-grade spondylolisthesis and achieved successful fusion, with a minimum 10-year follow-up.

Outcome measure

The occurrence of radiologic ASD, Oswestry disability index (ODI) scores, and revision rates.

Methods

A total of 194 consecutive patients were contacted and encouraged to visit our hospital and to participate in our study. Radiologic ASD was evaluated at three motion segments: cephalad adjacent segment (first cephalad adjacent segment), one cephalad to cephalad adjacent segment (second cephalad adjacent segment), and caudal adjacent segment. Clinical outcomes were compared by ODI scores and revision rates.

Results

In total, 147 of 194 (75.8%) patients were available for at least 10 years of radiologic and clinical follow-up. Adjacent segment degeneration (in first cephalad or caudal adjacent segment) was noted in 55.9% (33 of 59 patients) of the unilateral group and 72.7% (64 of 88 patients) of the bilateral group (p=.035). The occurrence of ASD in each first cephalad and caudal adjacent segment was not significantly different between groups but that in second cephalad adjacent segment was significantly different between groups (p=.004). Clinical outcomes according to ODI showed significant difference between groups (p=.016), especially when ODI scores were compared in patients with ASD (p=.004).

Conclusions

In a minimum 10-year follow-up retrospective study of posterolateral fusion for lumbar spinal stenosis and/or Grade 1 spondylolisthesis, unilateral pedicle screw instrumentation showed a lower rate of radiologic ASD, especially in second cephalad adjacent segment, and a better clinical outcome by ODI.     

腰椎融合辅以邻近节段动态固定治疗腰椎退行性疾病的早期临床疗效观察

目的 评价腰椎融合辅以邻近节段K-Rod动态固定治疗腰椎退行性疾病的临床疗效及对腰椎运动功能的影响,探讨K-Rod动态固定对邻近节段保护的优劣.方法 回顾性分析2010年4月~2011年9月采用椎间融合辅以邻近节段K-Rod 动态固定及单节段椎间植骨融合内固定术的51例患者.A组（K-Rod组）24例患者术前邻近节段存在退变,行单节段融合辅以邻近节段K-Rod动态固定;B组（单节段融合组）27例患者术前邻近节段无不稳或退变,行单节段椎间植骨融合内固定术.对比评价2组腰腿痛视觉模拟量表（visual analogue scale,VAS）评分、Oswestry 功能障碍指数（ Oswestry disability Index,ODI） 、椎间隙高度、腰椎总活动度（range of motion,ROM）及头侧邻近第一节段活动度（ROM1）、头侧邻近第二节段或尾侧第一邻近节段活动度（ROM2）、保护节段及邻近节段退变（adjacent segment degeneration,ASD）发生率.结果随访 24~37个月.2组患者术后VAS评分及ODI均显著改善,且2组间差异无统计学意义.2组间腰椎总ROM术前及末次随访之间均无差异.A组保护节段末次随访时椎间隙高度与术前无差异.2组ROM1及ROM2术前术后相比差异均有显著统计学意义,2组间相比差异无统计学意义.A组末次随访时8例患者出现11（11/138,8%）枚螺钉松动;B组无螺钉松动.结论 腰椎融合辅以邻近节段动态固定具有较好的临床疗效,增加的动态固定保护了术前已存在退变的节段,避免了多节段融合,降低了单节段融合邻椎病的风险,因此适应证选择合适,具有较好的临床应用价值.     

The clinical characteristics and risk factors for the adjacent segment degeneration in instrumented lumbar fusion

STUDY DESIGN: A retrospective study. OBJECTIVE: The aims of this study were to evaluate the clinical significance of, characteristics of, and risk factors for adjacent segment degeneration (ASD) in patients who have undergone instrumented lumbar fusion. SUMMARY OF BACKGROUND DATA: ASD has been considered a potential long-term complication of spinal arthrodesis. However, the exact mechanisms and risk factors related to ASD are not completely understood. METHODS: A total of 48 patients who underwent instrumented lumbar fusion at L4-5 and had minimal ASD preoperatively were evaluated. The patients were divided into 2 groups at follow-up according to the development of ASD defined by radiologic criteria. Through review of their medical records and the radiologic files, the following variables were evaluated in the 2 groups: basic demographic data, body weight, body height, body mass index, bone mineral density, types of surgical approaches, preoperative and postoperative segmental and lumbar lordosis, and clinical outcomes. RESULTS: ASD was found in 30 (62.5%) patients. The variables that showed statistical intergroup differences were the mean age at surgery, the mean difference in the degree of preoperative from postoperative lumbar lordosis, and the proportion of patients who underwent anterior lumbar interbody fusion. However, there were no statistically significant intergroup differences in the Japanese Orthopedic Association score at 1-year postoperatively or at the final follow-up, or in the recovery rate, success rate, and complication rate. CONCLUSIONS: Radiographic ASD is relatively common long-term finding associated with instrumented lumbar fusion. However, radiographic evidence of ASD does not necessarily correlate with a poor outcome. Our results suggest that advanced age, anterior lumbar interbody fusion, and the restoration of the preoperative standing lumbar lordosis may have a protective effect against the development of ASD.     

腰椎后外侧融合术对已存在退变的相邻节段的中远期影响

目的评估腰椎后外侧融合对已经存在退变但未纳入融合范围的相邻节段的中远期影响。方法对本院2004年1月—2005年12月因腰椎退行性疾患接受后路椎板切除减压、经椎弓根内固定、后外侧植骨融合的158例患者进行随访,采用影像学方法对其相邻节段的转归进行分析,比较相邻节段术前无退变和已存在退变的椎间盘的远期进一步退变情况及相应的临床功能。结果 102例病例获得完整随访,平均随访65.2个月(54~71个月),其中26例(25.5%)出现了相邻节段的影像学退变。在相邻上位节段中,术前无退变和已存在退变的椎间盘随访时出现进一步退变的发生率分别为13.5%(10/74)和35.7%(10/28),差异有统计学意义(P0.05)。在相邻下位节段中,术前没有退变和已存在退变的椎间盘随访时出现进一步退变的发生率分别为12.5%(6/48)和22.2%(4/18),差异无统计学意义。临床评价显示无论术前相邻节段有无退变,Oswestry功能障碍指数(ODI)在术后6个月时均较术前明显改善(P0.05),并在最终随访时得到保持,但术前相邻节段存在退变组随访时ODI明显高于无退变组(P0.05)。结论与术前无退变的相邻节段椎间盘相比,术前已存在退变的相邻椎间盘融合术后更容易出现进一步退变,而且会影响其远期的临床疗效。