The Contrast Investigation Of Lumbar Semi-rigid Versus Rigid Internal Fixation On The Adjacent Segment Degeneration

Background:Posterior lumbar intervertebral fusion (PLIF) which has been regarded as a gold standard to treat lumbar degenerative disc disease, but it is indeed not a perfect method, though it has obtained a high fusion rate with the development of technology. One of its drawbacks is adjacent segment degeneration (ASD) which was regarded as one of the risk factors which will induce low back and/or sciatic nerve pain recurrence, even some case need revision surgery. To date, most published literatures have investigated the mechanisms of ASD, and the most popular viewpoint is that the abnormal increased range of motion and stress of the adjacent segment after fusion maybe the major reason for ASD. To date, we have not identified the risk factor, such as sex, age, fusion site, which affected the incidence of ASD. In order to avoid ASD, many technologies have been introducing by surgeons. The most noteworthy one is lumbar dynamic fixation which was regarded can reduce the incidence of ASD by avoiding the biomechanical change on the adjacent segment. However, we have no ideal whether dynamic fixation can prevent ASD or not. Though Isobar TTL, a new semi-rigid dynamic fixation, which has been introduced to clinic more than 10 years, few published literatures have reported its validity.Part 1 To contrast the clinical outcome of rigid versus semi-rigid lumbar internal fixationObjectives:To estimate the clinical outcome of lumbar rigid and semi-rigid internal fixation, respectively, then to contrast whether there is significant difference or not.Methods:1. Collection dataThe subjects were patients with degenerative lumbar disease. Inclusion criterias: (1) the course is more than half a year; (2) patients suffering from lumbar disc herniation, spondylolisthesis, lumbar spinal stenosis; (3) operation time (2002.1-2007.7); (4) Adjacent segment has been degenerative at preoperation (UCLA≤Ⅱ); (5) Adjacent segment does not get operation in the pre and postoperation; (6) PLIF and Isobar TTL; (7) the operation was performed by the same surgeon. We gained their imaging data and other information by the ID and MRI number.2. Match standard:Selecte the patients with the adjacent segment degeneration from PLIF group to compare with semi-rigid fixation group.3. Evaluation index:Oswestry disability index(ODI) and visual analogue scale(VAS) are introduced to analyse the subjective sensation of patients. The period when the ODI and VAS descend down to minimum value was named optimal recovery period 4. Imaging data:we evaluate degeneration situation of the lumbar by MRI and X-ray.5. Following-up:We had obtained the present imaging data and another information by the follow-up of out-patient clinic, telephone contact and home visits.6. Significant analysisThe methods which calculate the data are paired-samples T test and analysis of covariance in SPSS13.0 software, P<0.05 is regared as that there is significant difference.Results:1. In the rigid fixation group, there are 215 cases meet the Inclusion criterias, and147 cases (male 63, female 84) was followed up, average age is 49±9ys (18-72ys). The span of follow-up is 30.3±10.5 months (18-84months), lumbar disc herniation(33cases), lumbar spinal stenosis(39cases) and lumbar spondylolisthesis(75cases). In the semi-rigid fixation group, there are 47case meet the Inclusion criterias, and 29 cases (male 12, female 17) was followed up, average age is 52±12ys (33-65ys). The span of follow-up is 22.4±3.3 months (18-42months) lumbar disc herniation(17cases), lumbar spinal stenosis(4cases) and lumbar spondylolisthesis(8cases).2. ODI and VAS2.1 The situation of all of the rigid fixation cases:the ODI and VAS was (49.43±16.65)% and 5.02±2.16 in preoperation, (5.31±3.90)% and 0.20±0.45 in optimum condition, (10.53±8.00)% and 0.84±1.04 in the last follow-up respectively. There are statistic difference between different Periods about ODI and VAS, respectively (P<0.001). excellent 118 case(80.27%), good 20case(13.6%), fair 8 case(5.44%), bad 1 case(0.68%). The rate of satisfaction is 93.88%.2.2 The situation of all of the semi-rigid fixation cases:the ODI and VAS was (46.9±15.21)% and 5.48±2.01 in preoperation, (4.00±3.89)% and 0.34±0.55 in optimum condition, (12.69±12.23)% and 1.41±1.70 in the last follow-up respectively. There are statistic difference between different Periods about ODI and VAS, respectively (P<0.001). Excellent 20 cases(68.96%), good 5 cases(17.24%), fair3 cases (10.34%), bad 1 cases(3.45%). The rate of satisfaction is 86.21%.2.2 The situation of the cases compared with semi-rigid fixation:72 cases were evaluated, average age is 49.8±10.8ys (20-81ys), he span of follow-up period is 28.9±10.6months (18-84) the ODI and VAS was (53.22±18.62)% and 5.42±2.32 in preoperation, (7.42±4.73)% and0.76±0.81 in optimum condition, (11.25±7.00)%and 1.54±1.54 in the last follow-up respectively. There are statistic difference between different Periods about ODI and VAS, respectively (P<0.001). Excellent 52cases (72.22%), good 12 cases (16.67%), fair 7 cases (9.72%), bad 1 cases(1.39%). The rate of satisfaction is 88.89%.2.3 Comparison resultThere is no significant difference on follow-up period and age when they received the lumbar operation between control group and experiment group(tage=1.024, Page=0.308; tfollow-up=0.785, Pfollow-up=0.434). No significant difference was found on ODI and VAS in the time point of preoperation between the two groups, respectively(tODI=3.033, PODI=0.085; tVAS=-0.134, PVAS=0.894). Conversely, there are significant difference on ODI and VAS between the two groups in the optimal recovery period, respectively(FODI=6.846, PODI=0.002; FVAS=6.573, PVAS=0.012). Reversely, we do not find significant difference on ODI and VAS between two groups in the last follow-up period, respectively (FODI=0.286, PODI=0.752; FVAS=0.165, PVAS=0.686). Satisfaction rate has no significant difference (P=0.739).Conclusion: Both of rigid fixation and semi-rigid fixation moduses can get a good mid-term clinical outcome, and there is no significant difference (P>0.05)Part 2 The situation of ASD after rigid fixationObjectives:1. To observe the incidence of ASD after rigid fixation2. To evaluate the risk factors affecting incidence of ASDMethods:1. Data getting from the same rigid fixaton group as Part 1.2. Imaging evaluation:University of California at Los Angeles (UCLA) Grading Scale is used to evaluate ASD, and lumbar MRI is used to evaluate the degeneration of disc(pearce and the method recommended by prof. Hu Yougu).3. Factors which maybe affect the incidence of ASDSex, range of fusion, site of fusion, whether adjacent segment's disc has been degenerative.4. Significant analysisThe methods which calculate the data are 2test and Linear Regression in SPSS13.0 software, testing the standard of 0.05.Results:In the follow-up period,20 cases (13.6%) suffered from ASD, what is more, all of ASD appear on the cephalad adjacent segment. We discover that adjacent segment's disc which have been degenerative preoperation will significantly give rise to ASD (χ2=6.272, P=0.012). Logistic regression show that characteristic of adjacent disc is a significantly significant risk factor about ASD (P=0.046), but other factors are not.Conclusion:The incidence of ASD will be significantly raised by the situation that the intervertebral disc of adjacent segment has been degenerative before operation (P<0.05). Sex, range of fusion and site of fusion have no relationship with ASD (P>0.05).Part 3 The contrast investigation of semi-rigid lumbar internal fixation versus rigid lumbar internal fixation on the adjacent segment degenerationObjectives:1. To analyse whether semi-rigid fixation can prevent ASD or not.2. To analyse whether semi-rigid fixation can protect the segment adjacent to the fusion one.Methods:1.Data:Cases of semi-rigid group and cases compared with semi-rigid group in the rigid fixation group.2. Imaging evaluation is identical with Part 2.3. Significant analysis The methods which calculate the data areχ2 test, One-Way ANOVA and independent-samples T test in SPSS13.0 software, testing the standard of 0.05.Results:1. There is no significant difference on follow-up period and age when they received the lumbar operation between control group and experiment group (Page=0.308; Pfollow-up=0.434).2. There are 15 cases (20.83%) suffer from ASD in the rigid group. In the semi-rigid group,1 case (3.45%) suffers from ASD. There is significant difference between the two operation style on ASD (P=0.035).Conclusion:The semi-rigid fixation can protect the segment adjacent to the fusion segment, and prevent ASD (P<0.05).