Lumbar Stiffness Research Articles

Pregnancy Outcomes After Spinal Fusion with Instrumentation: Radiation Exposure Effects and Lumbar Stiffness Issues

Pregnancy Outcomes After Spinal Fusion with Instrumentation: Radiation Exposure Effects and Lumbar Stiffness Issues

Comparison of Non-radiographic Axial Spondyloarthritis and Ankylosing Spondyltis from a Single Rheumatology Hospital in Morocco.

According to the new classification criteria developed by The Assessment of SpondyloArthritis International Society, patients with axial spondyloarthritis (axSpA) can be classified in 2 subgroups: Patients with radiographic axial spondyloarthritis: ankylosing spondylitis patients (AS) and those with non-radiographic axial spondyloarthritis (nr-axSpA). The aim of the present study is to describe and discuss the differences and similarities between the two subgroups. A cross-sectional study was conducted in a single rheumatology hospital in Morocco. These included patients diagnosed as having axial spondyloarthritis according to ASAS criteria 2010, during a period of 6 years. The AS and the nr-axSpA subgroups were compared for the various axSpA-related variables. Of the 277 patients with a diagnosis of axial SpA who were included in this study, 160 had AS and 117 had nr-axSpA. AS and nr-ax-SpA shared a similar age at diagnosis, similar prevalence of low back pain, lumbar stiffness, extra-articular manifestations, BASDAI and BASFI. In the multivariate analysis, AS patients were mainly male with cervical stiffness, enthesitis, coxitis and high level of ESR (erythrocyte sedimentation rate). The females generally had a family history of SpA and arthritis and were associated to the nr-axSpA form in the univariate analysis. This was the first study to characterise patients with AS and nr-axSpA in Morocco. Consistent with other studies published, this study showed that patients with nr-axSpA and patients with AS shared a comparable degree of disease burden.

Maintaining Lumbar Spine Stability: A Study of the Specific and Combined Effects of Abdominal Activation and Lumbosacral Orthosis on Lumbar Intrinsic Stiffness

Two potential interventions for enhancing lumbar stability are to actively increase abdominal muscle activity, either through the abdominal drawing-in maneuver (ADIM) or bracing, and passively increase lumbar stiffness using a lumbosacral orthosis (LSO). To compare the increase in lumbar stiffness after 2 active interventions (ADIM versus bracing) and 1 passive intervention (LSO), and to evaluate the combined effect of active (abdominal bracing) and passive interventions. In this experimental and comparative study, lumbar stiffness, a surrogate measure of lumbar stability, was estimated in 25 healthy individuals during 7 trunk perturbation conditions: (1) control, (2) ADIM, (3) bracing at 5% of right external oblique maximal voluntary activation (5% bracing), (4) bracing at 10% of right external oblique maximal voluntary activation (10% bracing), (5) LSO, (6) LSO plus 5% bracing, and (7) LSO plus 10% bracing. Electromyographic biofeedback of the external oblique was provided on a monitor, while ultrasound was used for the ADIM to ensure a sustained contraction of the transversus abdominis. The ADIM, 5% bracing, and 10% bracing active interventions generated comparable lumbar stiffness. However, considering that bracing can range from 10% to 20%, it may be superior to hollowing, as further estimated with a mixed-effect statistical model. Combining bracing and an LSO resulted in an additive effect on lumbar stiffness. Bracing and ADIM produced comparable lumbar stiffness, as they were performed at the same overall abdominal activation levels (5% and 10% maximal voluntary activation). The independent effects of bracing and LSO raises the possibility of combining these interventions in some circumstances. J Orthop Sports Phys Ther 2019;49(4):262-271. Epub 18 Jan 2019. doi:10.2519/jospt.2019.8565.

Correlations Between Individuals’ Characteristics and Spinal Stiffness in Individuals With and Without Back Pain: A Combined Analysis of Multiple Data Sets

ObjectiveThe purpose of this study was to describe the correlations between individual characteristics and spinal stiffness as measured with different spinal stiffness measurement devices in individuals with and without back pain. MethodsA secondary analysis of 3 adult data sets obtained using 3 different devices, in 2 spinal regions, from a total of 5 separate cross-sectional studies was conducted. Differences in spinal stiffness between men and women and in the strength of correlations among spinal stiffness and age and anthropometric characteristics were evaluated using either the t test for independent samples, Pearson’s correlation coefficient, or Kendall’s τ rank correlation coefficient. ResultsAs expected, results varied between data sets; however, few factors had consistent correlations. Specifically, spinal stiffness was significantly lower in women than men in all 3 data sets. Height was positively correlated with spinal stiffness across all data sets. Although weight was correlated with thoracic stiffness, its correlation with lumbar stiffness varied. In 2 data sets, body mass index was inversely associated with lumbar spinal stiffness, whereas results from the thoracic spine region revealed a positive correlation. The results for 1 data set suggest that physiological measurement evaluating body weight distribution may also affect spinal stiffness; however, the specific correlation remains unclear. ConclusionDespite data set differences, significant correlations were observed, indicating that participants’ characteristics appear to affect spinal stiffness measurement.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P88. Medical complications and risk factors after long level spinal fusion for adult degeneration scoliosis

BACKGROUND CONTEXT Adult degenerative scoliosis (ADS) treated with long level internal fixation surgery is known for its high incidence of complications. PURPOSE The propose of this study was to determine current medical complication rates and the predictors of each individual medical complication in surgical ASD patients. STUDY DESIGN/SETTING A retrospective review comparative database was used to evaluate long level internal fixation surgery for adult degenerative scoliosis (ADS) patients. PATIENT SAMPLE One hundred and fifty-three ADS patients who underwent long level spinal fusion were included. The total medical complication incidence was 26.1%, which included infection (13.1%), neurological (12.4%), cardiopulmonary (10.5%), gastrointestinal (5.2%), and renal (1.3%) complications. OUTCOME MEASURES The radiological measurements included Cobb angle, PI-LL, lumbar lordosis (LL), spondylolisthesis, C7 sagittal vertical axis (C7SVA), the proximal junctional kyphosis (PJK), and pseudarthrosis. Clinical outcomes were collected preoperatively and last follow-up after surgery. Clinical outcomes include metrics of the Oswestry Disability Index (ODI), Japanese Orthopaedic Association (JOA) score, Visual Analog Scale (VAS), and Lumbar Stiffness Disability Index (LSDI). METHODS The patient- and surgical-related risk factors for each individual medical complication were identified by using univariate testing. Patients were separated into groups of with and without medical complication, into groups of with and without infection, into groups with and without neurological complications, and into groups with and without cardiopulmonary complications, retrospectively. Potential risk factors were identified using univariate testing. Multivariate Logistic regression was used to evaluate independent predictors of medical complications. RESULTS Patient-related independent risk factors for development of medical complications included diabetes (OR 2.87, P=.038), smoking (OR 4.44, P=.001); for infection were diabetes (OR 4.74, P=.006) and smoking (OR 3.17, P=.033); for neurological complications were BMI (OR 1.16, P=.010) and diabetes (OR 4.12, P=.014); for cardiopulmonary complications were hypertension (OR 4.35, P=.039), smoking (OR 4.23, P=.035) and cardiac comorbidity (OR 6.14, P=.015). Fusion level (OR 2.79 P=.000), length of hospital stay (OR 1.88 P=.016) and symptom duration (OR 2.57, P=.001). Surgical-related independent risk factors for development of medical complications were fusion level (OR 3.57, P=.000), operative time (OR 0.99, P=.041), osteotomy (OR 9.33, P=.004), blood transfusion (OR 4.37, P=.043) and LOS (OR 1.68, P=.001); for infection were fusion level (OR 2.55, P=.006), blood transfusion (OR 23.06, P=.001) and LOS (OR 1.36, P=.010); for neurological complication were fusion level (OR 2.54, P=.009), osteotomy (OR 9.35, P=.012) and blood transfusion (OR 6.90, P=.033); for cardiopulmonary complication were fusion level (OR 2.17, P=.001). CONCLUSIONS Diabetes and smoking were the most common patient-related independent risk factors increase the development of each individual medical complication. On the other hand, factors fusion levels and blood transfusion were the most common surgical-related independent risk factors increase the development of each individual medical complication. Prevention of these risk factors can reduce the incidence of complications in Chinese patients with ADS surgery.

Functional Limitations Due to Stiffness After Long-Level Spinal Instrumented Fusion Surgery to Correct Lumbar Degenerative Flat Back.

A retrospective analysis of functional limitations due to stiffness after long-level spinal instrumented fusion surgery to correct lumbar degenerative flat back was performed. To analysis the functional limitations in patients treated surgically for adult lumbar degenerative flat back (ALDFB) with long-level instrumented fusion to the sacrum or pelvis. Long-level instrumented fusion for ALDFB decreases back pain and spinal deformity. On the contrary, this surgery considerably eliminates spinal range of motion. This may have the potential to impair function and ability to perform activities of daily living (ADLs). Consecutive 44 patients who underwent long-level instrumented fusion to the sacrum or pelvis for ALDFB were retrospectively included in this study. All patients were followed up for a minimum of 13 months. The Lumbar Stiffness Disability Index for Korean Lifestyle and Oswestry Disability Index were administered and analyzed to assess the impact of spinal stiffness on daily living. Cohorts were defined based on the upper instrumented vertebrae (above T10 [group 1] or below L1 [group 2]) and lower instrumented vertebrae (S1 pedicle screw [group S] or iliac bolt screw [group I]). All patients showed deteriorated postoperative ADLs compared to preoperative values. Group 1 showed deterioration postoperatively compared to group 2. Group 1 showed deteriorated postoperative ADLs compared to preoperative values. In group 2, question 5 and 7 showed deterioration postoperatively compared to preoperative values, and question 2 and 10 showed improvement postoperatively compared to preoperative values. Group I showed deterioration postoperatively compared to group S. This study will hopefully allow surgeons to provide patients with ALDFB with a more informed explanation of expected surgery effects on specific ADLs. 3.

Radiographic Fusion Grade Does Not Impact Health-Related Quality of Life in the Absence of Instrumentation Failure for Patients Undergoing Posterior Instrumented Fusion for Adult Spinal Deformity

Pseudarthrosis and rod fracture (RF) remain significant concerns after fusion for adult spinal deformity (ASD). Although a radiographic system of fusion grade has been proposed, the correlation between fusion grade and health-related quality of life measures (HRQoL) is not known. In a retrospective review of a prospectively collected clinical database, patients that underwent ≥5-level posterior instrumented arthrodesis for ASD were evaluated. Fusion grade was determined on plain films using the Lenke criteria. Patients were grouped as 1) complete fusion (grade I or II at all levels), 2) incomplete fusion (grade 3 or 4 at any level), 3) rod fracture without revision (RF), and 4) rod fracture with revision (RFR). Outcome measures were the Oswestry Disability Index, Medical Outcomes Study 36-Item Short-Form Health Survey Physical and Mental Component Summaries, Scoliosis Research Society-22r total, and Lumbar Stiffness and Disability Index. There were 205 (85%) patients who achieved the minimum 2-year follow-up and were included. Complete fusion was achieved in 115 patients (56.1%), 55% patients (26.8%) had incomplete fusion, and 35% patients (17.1%) had RF. Of the 35 patients with RF, 19 (17.1%; 19/205) underwent revision while 16 (7.8%; 16/205) had RF without revision. HRQoL measures were significantly worse in the RFR group, whereas no significant differences were found between groups 1, 2, and3. Radiographic fusion grade after ASD surgery did not significantly impact HRQoL in the absence of RF. RFR was associated with significantly worse clinical outcomes. Fusion grade may be less predictive of clinical outcomes than the occurrence of RF.

Lumbar stiffness and femoroacetabular impingement -A case control study

Lumbar stiffness and femoroacetabular impingement -A case control study

Renal amyloidosis in ankylosing spondylitis: A monocentric study and review of literature.

Secondary renal amyloidosis (RA) is the most common type of renal involvement in ankylosing spondylitis (AS). We assessed the epidemiologic and clinico-biological profile of AS patients with RA, to analyze treatment modalities and prognostic aspects, and to determine predictive factors of RA during AS. This was a retrospective study including 13 cases of RA among 212 cases who presented with AS, during the period from 1978 to 2006. The median age of the patients at the time of diagnosing AS was 47 years (range: 19-67). There were 11 males and two females. RA onset was diagnosed after a mean follow-up of 144.6 months (range: 10-505) from the AS diagnosis. We noted erosive peripheral arthritis, lumbar stiffness with bamboo spine, and coxitis in 23.1%, 76.9%, and 30.8% of cases, respectively. Nephrotic syndrome was found in eight patients (61.5%). At the time of diagnosing RA, six patients had renal failure. Amyloid deposits were histologically proven by salivary gland biopsy in six cases (46.1%) and by renal biopsy in seven cases (53.8%). Four patients received a long-course treatment with colchicine but with a good outcome only in two cases. In our series, AS was more severe among patients with RA. Four predictive factors of RA were identified: smoking (P = 0.04), erosive peripheral arthritis (P = 0.002), bamboo spine (P = 0.001), and biologic indicators of inflammation (P = 0.0001). High erythrocyte sedimentation rate was identified as the only independent risk factor of RA during AS (P = 0.0001). Renal function as well as urinalysis should be monitored at regular intervals to detect early renal involvement during AS.

Biomechanics of Lumbar Motion-Segments in Dynamic Compression.

Recent epidemiology studies have reported increase in lumbar spine injuries in frontal crashes. Whole human body finite element models (FEHBM) are frequently used to delineate mechanisms of such injuries. However, the accuracy of these models in mimicking the response of human spine relies on the characterization data of the spine model. The current study set out to generate characterization data that can be input to FEHBM lumbar spine, to obtain biofidelic responses from the models. Twenty-five lumbar functional spinal units were tested under compressive loading. A hydraulic testing machine was used to load the superior ends of the specimens. A 75N load was placed on the superior PMMA to remove the laxity in the joint and mimic the physiological load. There were three loading sequences, namely, preconditioning, 0.5 m/s (non-injurious) and 1.0 m/s (failure). Forces and displacements were collected using six-axis load cell and VICON targets. In addition, acoustic signals were collected to identify the times of failures. Finally, response corridors were generated for the two speeds. To demonstrate the corridors, GHBMC FE model was simulated in frontal impact condition with the default and updated lumbar stiffness. Bi-linear trend was observed in the force versus displacement plots. In the 0.5 m/s tests, mean toe- and linear-region stiffnesses were 0.96±0.37 and 2.44±0.92 kN/mm. In 1.0 m/s tests, the toe and linear-region stiffnesses were 1.13±0.56 and 4.6±2.5 kN/mm. Lumbar joints demonstrated 2.5 times higher stiffness in the linear-region when the loading rate was increased by 0.5 m/s.

Stiffness After Pan-Lumbar Arthrodesis for Adult Spinal Deformity Does Not Significantly Impact Patient Functional Status or Satisfaction Irrespective of Proximal Endpoint.

Prospective, multicenter. To determine if stiffness significantly affects function or satisfaction after pan-lumbar arthrodesis. The Lumbar Stiffness Disability Index (LSDI) is a validated measure of the effect of lumbar stiffness on functional activities. Data suggests that patients undergoing fusion of the entire lumbar spine are at greatest risk of functional limitations from stiffness. The LSDI, Short Form 36, Scoliosis Research Society-22, and Oswestry Disability Index were administered preoperatively and at 2-year minimum follow-up to 103 spinal deformity patients from 11 centers. Patients were separated according to the proximal arthrodesis level; upper thoracic (T2-5) to pelvis (UT-Pelvis) or thoraco-lumbar (T10-T12) to pelvis (TL-Pelvis). Outcome scores were compared using Student t test or Tukey-Kramer Honest Significant Difference Analysis of Variance. Regression analysis of final LSDI scores versus Scoliosis Research Society-22 Satisfaction scores was performed. Mean ages, baseline values, and final scores of all outcome parameters were statistically equivalent in the two groups. Final LSDI scores did not change significantly from baseline in the UT-Pelvis (P = 0.478) or TL-Pelvis (P = 0.301) groups. In contrast, highly significant improvements (P ≤ 0.0001) from baseline were seen in both groups for other health-related QoL measures. The 2-year Satisfaction scores were statistically equivalent in the two groups, and the correlation between final LSDI and Satisfaction scores in the entire cohort was not significant (R = 0.013, P = 0.146). Patients undergoing pan-lumbar arthrodesis for adult spinal deformity did not experience substantial increases in disability due to stiffness of the low back, although they did report significant improvements in other health-related QoL measures. Further, LSDI scores did not correlate with patient satisfaction. There were no significant differences in perceived stiffness effects whether arthrodesis stopped in the thoracolumbar or upper thoracic regions. We hope these results will be useful to spine surgeons and patients during preoperative planning and discussions. 2.

Effects of different pelvic incidence minus lumbar lordosis mismatch after long posterior instrumentation and fusion for adult degenerative scoliosis

Objective: To evaluate the influence of PI-LL (pelvic incidence minus lumbar lordosis mismatch) on scoliosis correction, living quality and internal fixation related complications for adult degenerative scoliosis (ASD) after long posterior instrumentation and fusion. Methods: A total of 79 patients with ADS underwent long posterior instrumentation and fusion in the Department of Orthopedics at Beijing Chao Yang Hospital from January 2010 to January 2014 were retrospectively reviewed.There were 21 males and 58 females aging from 55 to 72 years with the mean age (63.4±4.8)years. The patients were divided into three groups according to immediately postoperative PI-LL: PI-LL<10°, 10°≤PI-LL≤20°, PI-LL>20°.Compare the Cobb's angles, PI-LL, Japanese Orthopaedic Association (JOA) score, Oswestry Disability Index (ODI), Visual Analog Scale (VAS) and Lumbar Stiffness Disability Index (LSDI). Measurement data were compared via t test and ANOVA, enumeration data were compared via Kruskal-Wallis test, noncontiguous data was performed by χ(2) test. Univariate linear regression equation was performed to investigate the relative influences of postoperative PI-LL on postoperative radiographic parameters and clinical outcome. Results: All the operations were successful without intraoperative complications. The operation time was 145-310 minutes (235.3±42.0) minutes, the intraoperative blood loss was 300-5 300 ml (1 021±787) ml, the duration of hospital was 12-18 d (14.5±1.3) d. A total of 4 to 10 (7.0±1.1) vertebra levels were fused. Compared to preoperative, the Cobb's angle of scoliosis ((4.2±1.8)° vs. (20.1±2.7)°), PI-LL ((16.1±8.6)° vs. (36.0±4.3)°), JOA (3.0±1.3 vs. 5.5±1.2), ODI (24.4±8.1 vs. 62.9±2.7), VAS (3.0±1.0 vs. 6.8±1.3) were significantly decreased postoperative (t=18.539~53.826, P<0.01). Compared to preoperative, postoperative Cobb's angle of scoliosis ((4.1±2.7)° vs. (19.5±2.7)°, (4.0±1.4)° vs. (20.2±2.4)°, (4.7±0.9)° vs. (20.6±3.0)°) (t=21.148-45.355, P<0.01) and PI-LL ((5.2±2.8)° vs. (35.8±4.9)°, (17.9±2.9)° vs. (37.2±3.9)°, (25.8±2.7)° vs. (34.5±4.0)°) (t=7.227-38.250, P<0.01) were significantly reduced postoperative in PI-LL<10° group, 10°≤PI-LL≤20° group and PI-LL>20° group. Compared to preoperative, ODI (27.7±4.9 vs. 63.3±2.6, 17.7±5.9 vs. 63.1±2.8, 30.6±6.5 vs. 62.3±2.5) (t=21.218~50.858, P<0.01), JOA (2.8±1.2 vs. 5.2±1.2, 3.3±1.1 vs. 5.7±1.1, 2.8±1.7 vs. 5.7±1.2) (t=9.042-16.025, P<0.01) and VAS (2.9±1.2 vs.7.0±1.3, 3.3±0.9 vs.7.0±1.4, 2.9±0.8 vs. 6.3±1.2) (t=16.073-22.214, P<0.01) were all significantly reduced at last follow-up. There were statistic differences in ODI and LSDI (F=38.477, P<0.01; F=37.063, P<0.01) at the last follow-up among the three groups. There was a negative correlation in PI-LL and LSDI according to linear regression (B=-5.838, P<0.01) in the last follow-up. All the patients were followed up, the follow-up duration were 2 to 5 years with the mean (3.1±0.7) years. The internal fixation failure related complications in 3 years included proximal junctional kyphosis (PJK) in 19 cases, internal fixation loosening in 6 cases. Eight patients received reoperation for severe local pain and low extremity symptoms. PJK occurrences were significantly different among PI-LL<10° group, 10°≤PI-LL≤20° group and PI-LL>20° group. Conclusions: The PI-LL between 10° and 20° may be the best choice in ADS patients after long posterior instrumentation and fusion for its better clinical outcome and less proximal junctional kyphosis (PJK). The overcorrection of LL may lead to more serious postoperative lumbar stiffness.

Optimum pelvic incidence minus lumbar lordosis value after operation for patients with adult degenerative scoliosis

Background ContextSchwab classification for adult degenerative scoliosis (ADS) concluded that health-related quality of life was closely related to curve type and three sagittal modifiers. It was suggested that pelvic incidence minus lumbar lordosis value (PI-LL) should be corrected within −10°~+10°. However, recent studies also indicated that ideal clinical outcomes could also be achieved in patients without the ideal PI-LL mentioned above. PurposeThis study evaluated the relation between the clinical outcomes and the PI-LL of Chinese patients with ADS who received long posterior internal fixation and fusion. Study DesignThis was a single-center retrospective comparative study of patients treated by long posterior internal fixation and fusion in our hospital between 2010 and 2014. Patient SampleInclusion criteria were age >45 years at the time of surgery, Cobb angle of lumbar curves ≥10°, long posterior internal fixation and fusion ≥least 3 motion segments, follow-up ≥2 years, complete preoperative and postoperative radiographic data, and functional evaluation results. Exclusion criteria were history of previous lumbar spine surgery, other kinds of scoliosis, history of severe spinal trauma, spinal tumor, ankylosing spondylitis, and spinal tuberculosis. Seventy-four patients were enrolled in this study. Outcome MeasuresOperative parameters included intraoperative blood loss, duration of surgery, length of hospital stay, number of fusion levels, and decompression. The radiological measurements included Cobb angle of the curves and PI-LL. Clinical outcomes were evaluated by the Japanese Orthopaedic Association score, Oswestry Disability Index (ODI), visual analog scale, and Lumbar Stiffness Disability Index (LSDI). In addition, the complications of surgery were also collected. One-way analysis of variance, Student t test, Kruskal-Wallis test, Pearson chi-square test, and curve estimation were calculated for variables. MethodsAll the patients were divided into Group 1 (long instrumentation and fusion to L5) and Group 2 (long instrumentation and fusion to S1). Operative parameters, radiological measurements, clinical outcomes, and complications of surgery were compared between two groups to confirm whether distal fusion level could influence therapeutic effect. Then patients were divided into PI-LL<10° (Group A), 10°≤PI-LL≤20° (Group B), PI-LL>20° (Group C). Operative parameters, radiological measurements, clinical outcomes, and complications of surgery were compared between each of the two groups. Curve estimation was performed to evaluate the relationship between postoperative PI-LL and clinical outcomes. ResultsNo difference was found between Group 1 and Group 2 in all postoperative parameters (p>.05). There were significant differences in final ODI (p<.001) and final LSDI (p<.001) among Group A, Group B, and Group C. Cubic curve model fitted the relationship between PI-LL and final ODI better than other models (R2=0.379, p<.001). Cubic curve model fitted the relationship between PI-LL and final LSDI better than other models (R2=0.691, p<.001). There was a significant difference in proximal junctional kyphosis (PJK) among groups (p=.038). No significant difference was found in other parameters. ConclusionsOptimal PI-LL value may be achieved between 10° and 20° in Chinese patients with ADS after long posterior instrumentation and fusion surgery with excellent clinical outcomes and a lower PJK occurrence.

Selecting caudal fusion levels: 2year functional and stiffness outcomes with matched pairs analysis in multilevel fusion to L5 versus S1.

Controversy persists as to whether to end multilevel thoracolumbar fusions caudally at L5 or S1. Some argue that stopping at L5 may preserve greater function, but there are few data comparing functional limitations due to lumbar stiffness in patients with fusion to L5 versus S1. The aim of this study was to evaluate whether patients undergoing multilevel thoracolumbar fusions with an L5 caudal endpoint have a better lumbosacral function than patients with an S1 caudal endpoint. Patients undergoing successful thoracolumbar fusion of 5 or more levels to L5 or S1, with solid fusion at 2year follow-up, were examined from a single European center in addition to a multi-center North American database of 237 patients. In total, 40 patients with a distal stopping point of L5 were matched with a subset of 40 patients with a distal endpoint of S1±pelvic fixation. The L5 and S1 groups were matched for the final Oswestry Disability Index (ODI), Sagittal Vertical Axis (SVA C7-S1), number of fusion levels, and age. Impacts of lumbar stiffness on function as measured by the Lumbar Stiffness Disability Index (LSDI) were compared using the conditional logistic regression. After matching, there was no significant difference between the S1 and L5 groups for the final ODI (29.22±21.6 for S1 versus 29.21±21.7 for L5; p=0.98), SVA (29.5±40.3mm for S1 versus 33.7±37.1mm for L5; p=0.97), mean age (61.6±11.0years for S1 versus 58.3±12.6years for L5; p=0.23), and number of fusion levels (9.7±3.3 levels for S1 versus 9.0±3 levels for L5; p=0.34). The final 2-year postoperative LSDI scores were not significantly different between the S1 group (28.08±21.47) and L5 group(29.21±21.66) (hazard ratio 0.99, 95% CI 0.97-1.03, p=0.81). The analysis of patients with multilevel thoracolumbar fusions demonstrated that after minimum 2year follow-up, self-reported functional impacts of lumbar stiffness were not significantly different between the patients with distal endpoints of L5 versus S1. The choice of distal fusion level of L5 does not appear to retain sufficient spinal flexibility to substantially affect postoperative function. Level III.

Effects of Lumbar Stiffness After Lumbar Fusion Surgery on Activities of Daily Living.

A retrospective cohort study. The aim of this study was to assess the effects of lumbar stiffness after lumbar fusion surgery on functional limitations, health-related quality of life, and activities of daily living (ADL). Postoperative outcomes after fusion surgery are usually assessed using patient-reported instruments to describe disability related to pain and health status. There are few studies on the effects of lumbar stiffness on ADL after lumbar fusion surgery. This study included 93 patients who underwent lumbar fusion surgery for degenerative lumbar disease. Their mean age was 69 years (range 51-79), and the mean follow-up was 34 months (24-46). The patients were categorized into 5 groups according to the number of segments involved: 0 level (decompression), 1 level, 2 levels, 3 levels, and 4 levels. They completed a 21-item questionnaire about their ADL and the Short Form Health Survey 36 (SF-36) to evaluate the effects of lumbar stiffness on ADL after surgery. There was a linear trend toward a decreased rating in all items in our questionnaire and in the physical component summary in the SF-36 related to postoperative lumbar stiffness. These trends were significantly related to the number of fused segments (P < 0.05 and P < 0.001, respectively). Patient satisfaction did not differ between the groups (P = 0.381). Patients who received a 1- or 2-level fusion reported no serious limitations in most ADL. Patients who received a 3- or 4-level fusion, especially 4-level fusion, reported more limitations because of postoperative lumbar stiffness. This study investigated in detail the effects of lumbar stiffness after fusion surgery on ADL. Spine surgeons should consider the patient's occupation and lifestyle in preoperative planning. These results will help the surgeon explain the possible outcomes to patients planning to undergo fusion surgery. 2.

Restoring lumbar spine stiffness using an interspinous implant in an ovine model of instability

BackgroundThe objective of this study was to determine the effect of an interspinous implant on lumbar spine stability and stiffness during dorsoventral loading. MethodsTwelve Merino lambs were mechanically tested in vivo. Oscillatory (2Hz) loads were applied to L2 under load control while displacements were monitored. Tri-axial accelerometers further quantified adjacent L3–L4 accelerations. Dorsoventral lumbar spine stiffness and L3 and L4 dorsoventral and axial displacements were determined over six trials of 20cycles of loading. Four conditions were examined: 1) initial intact, 2) following destabilization at L3–L4, 3) following the insertion of an InSwing® interspinous device at L3–L4, and 4) with the implant secured with a tension band. Comparisons were performed using a one-way ANOVA with repeated measures and post-hoc Bonferroni correction. FindingsCompared to the intact condition, destabilization significantly decreased lumbar stiffness by 4.5% (P=.001) which was only recovered by the interspinous device with tension band. The interspinous device caused a significant 9.75% (P=.001) increase in dorsoventral stiffness from destabilization that increased 14% with the tension band added (P=.001). The tension band was responsible for decreased displacements from the intact (P=.038), instability (P=.001), and interspinous device (P=.005) conditions. Dorsoventral L3–L4 motion significantly improved with the interspinous device (P=.01) and the addition of the tension band (P=.001). No significant differences in L3–L4 intersegmental stability were noted for axial motion in the sagittal plane. InterpretationThis ovine model provided objective in vivo biomechanical evidence of lumbar instability and its restoration by means of an interspinous implant during dorsoventral spinal loading.

Posterior percutaneous pedicle screw fixation for acute thoracolumbar vertebral fractures with simple anterior spinal column injury: study protocol for a retrospective, self-controlled trial

Background: Posterior pedicle screw fixation is commonly used for thoracolumbar fracture. However, associated disadvantages include severe trauma, extensive bleeding, long rehabilitation time, and long postoperative duration of intractable lumbar stiffness and low back pain. Percutaneous pedicle screw external fixation can reduce injury caused by screw insertion into the paraspinal muscles; particularly in acute thoracolumbar vertebral compression fracture with simple anterior spinal column injury. We hypothesized that minimally invasive posterior percutaneous pedicle screw fixation for acute thoracolumbar vertebral fractures with simple anterior spinal column injury would exhibit good curative effects. Methods/Design: This retrospective, single-center, self-controlled trial was performed in the PLA 153 Central Hospital, Zhengzhou, Henan Province, China. Thirty-two patients with acute thoracolumbar vertebral fracture with simple anterior spinal column injury (22 males and 10 females, average age 24.7 years, range 25-47 years) were included. All patients underwent minimally invasive posterior percutaneous pedicle screw internal fixation and were followed up for 3 months. The primary outcome measure was the Cobb angle of the injured vertebral body before, immediately after, and 3 months after internal fixation, which was used to investigate the change in the thoracolumbar spine curvature. The secondary outcome measures included: the anterior height of the injured vertebral body and radiographic findings before and immediately after internal fixation and at the last follow-up (to evaluate the recovery of thoracolumbar vertebral fracture), operation time, intraoperative blood loss, and duration of hospitalization. Other outcome measure was the incidence of adverse events 3 months after internal fixation. Discussion: This study aims to validate the curative effects of minimally invasive posterior percutaneous pedicle screw fixation in acute thoracolumbar vertebral fractures with simple anterior spinal column injury, and provide objective long-term follow-up data for future studies. Trial registration: ClinicalTrials.gov identifier: NCT02963571. Ethics: The study protocol had been approved by the Ethics Committee of PLA 153 Central Hospital, China and was performed in strict accordance with the Declaration of Helsinki developed by the World Medical Association. Informed consent: Written informed consent regarding study protocol and treatments had been obtained from each patient.

Functional Limitations Due to Lumbar Stiffness in Adults With and Without Spinal Deformity.

Cross-sectional analysis. To compare Lumbar Stiffness Disability Index (LSDI) scores between asymptomatic adults and patients with spinal deformity. The LSDI was designed and validated as a tool to assess functional impacts of lumbar spine stiffness and diminished spinal flexibility. Baseline disability levels of patients with adult spinal deformity (ASD) are high as measured by multiple validated outcome tools. Baseline lumbar stiffness-related disability has not been assessed in adults with and without spinal deformity. The LSDI and Scoliosis Research Society-22r (SRS-22r) were submitted to a group of asymptomatic adult volunteers. Additionally, a multicenter cross-sectional cohort analysis of patients with ASD from 10 centers was conducted. Baseline LSDI and SRS-22r were completed for both operatively and nonoperatively treated patients with deformity. The LSDI was completed by 176 asymptomatic volunteers and 693 patients with ASD. Mean LSDI score for asymptomatic volunteers was 3.4 +/- 6.3 out of a maximum score of 100, with significant correlation between increasing age and higher (worse) LSDI score (r = 0.30, P = 0.0001). Of the patients with spinal deformity undergoing analysis, 301 subsequently underwent surgery and 392 were subsequently treated nonoperatively. Operative patients had significantly higher preoperative LSDI scores than both nonoperative patients and asymptomatic volunteers (29.9 vs. 17.3 vs. 3.4, P < 0.0001 for both). For patients with ASD, significant correlations were found between LSDI and SRS-22 Pain and Function subscales (r = -0.75 and -0.76, respectively; P < 0.0001 for both). LSDI scores are low among asymptomatic volunteers, although stiffness-related disability increases with increasing age. Patients with ASD report substantial stiffness-related disability even prior to surgical fusion. Stiffness-related disability correlates with pain- and function-related disability measures among patients with spinal deformity.

Identification of intrinsic and reflexive contributions to low-back stiffness: medium-term reliability and construct validity

This study aimed at testing the reliability and construct validity of a trunk perturbation protocol (TPP) that estimates the intrinsic and reflexive contributions to low-back stiffness. The TPP consists of a series of pseudorandom position-controlled trunk perturbations in an apparatus measuring forces and displacements at the harness surrounding the thorax. Intrinsic and reflexive contributions to low-back stiffness were estimated using a system identification procedure, leading to 12 parameters. Study 1 methods (reliability): 30 subjects performed five 75-s trials, on each of two separate days (eight weeks apart). Reliability was assessed using the generalizability theory, which allowed computing indexes of dependability (ϕ, analogous to intraclass correlation coefficient) and standard errors of measurement (SEM). Study 2 methods (validity): 20 healthy subjects performed three 75-s trials for each of five experimental conditions assumed to provide different lumbar stiffness; testing the construct validity of the TPP using four conditions with different lumbar belt designs and one control condition without. Study 1 results (reliability): Learning was seen between the first and following trials. Consequently, reliability analyses were performed without the first trial. Simulations showed that averaging the scores of three trials can lead to acceptable reliability results for some TPP parameters. Study 2 results (validity): All lumbar belt designs increased low-back intrinsic stiffness, while only some of them decreased reflex stiffness, which support the construct validity of the TPP. Overall, these findings support the use of the TPP to test the effect of rehabilitation or between-groups differences with regards to trunk stiffness.

Functional limitations due to stiffness as a collateral impact of instrumented arthrodesis of the lumbar spine.

Prospective cohort study. To understand whether patients actually perceive increased limitations as compared with their preoperative state due to stiffness after lumbar arthrodesis. Lumbar arthrodesis by intention eliminates spinal motion in an attempt to decrease pain, deformity, and instability. Independent of pain, loss of mobility can impact ability to perform certain activities of daily living. The lumbar stiffness disability index (LSDI) is a validated measure of the effect of lumbar stiffness on functional activities. To date, no prospective evaluations of stiffness impacts on patient function after lumbar arthrodesis have been reported. The LSDI, 36-Item Short Form Health Survey, and Oswestry Disability Index were administered preoperatively and at 2-year minimum follow-up to 62 adult patients undergoing lumbar fusion for degenerative disease or spinal deformity. Patients also completed a satisfaction questionnaire at 2 years. Patients were separated according to the number of lumbar arthrodesis levels. Pre- and postoperative LSDI, 36-Item Short Form Health Survey physical composite score, and Oswestry Disability Index scores were compared using paired t tests. Significant improvements in Oswestry Disability Index were observed across all arthrodesis levels, and significant improvements in physical composite score were observed at level 1 and at 5 or more levels. Patients undergoing 1-level arthrodesis demonstrated statistically significant decreases in LSDI scores, indicating less impact from stiffness than at baseline. Patients with 3 or 4 levels and 5 or more levels of arthrodesis showed increases in LSDI scores, although none reached significance with the numbers available. Forty-six percent of patients reported that low back stiffness created significant limitations in activities of daily living, although 97% indicated that they would undergo the same procedure again and 91% reported that any increase in stiffness was an acceptable trade-off for their functional improvements from lumbar arthrodesis. Patients undergoing elective lumbar arthrodesis reported relatively limited functional deficit due to stiffness at 2-year follow-up. Paradoxically, patients undergoing 1-level arthrodesis actually reported significantly less limitation due to stiffness postoperatively. Although the effects of stiffness did trend toward greater impacts among patients undergoing longer fusions, 91% of patients were satisfied with trade-offs of function and pain relief in exchange for perceived increases in lumbar stiffness.