Search

Divi SN, Kepler CK, Hilibrand AS, et al. Patient Outcomes Following Short-segment Lumbar Fusion Are Not Affected by PI-LL Mismatch. Clin Spine Surg. Mar 1 2021;34(2):73-77., Visual AbstractThis is a visual representation of the abstract.

Study Design: Retrospective single-center study. Objective: Investigate the effect of posterior instrumentation on the relationship between lordosis and kyphosis. Methods: Surgically treated patients with a minimum of 6 months of follow-up were analyzed. Asymptomatic volunteers served to show the normal anatomical relationship between thoracic and lumbar curves. Patients were stratified based on postoperative instrumentation: “Thoracic Fusion” = complete fusion of thoracic spine; “Lumbar Fusion” = complete fusion of lumbar spine; and “Complete Fusion” = fusion from sacrum to at least T5. Bivariate correlations and regression analysis were used to evaluate the relationship between change in thoracic kyphosis (ΔTK) and change in spinopelvic mismatch (ΔPI-LL; pelvic incidence-lumbar lordosis) before and after fusion. Analyses were repeated in “Lumbar Fusion” patients with flexible preoperative thoracic spines. Results: For asymptomatic volunteers, the natural anatomical relationship between TK and LL was found to be TK = 41% of LL ( r = 0.425, P < .001). A total of 153 of 167 adult spinal deformity patients were included (62 years old, 26.7 kg/m2, 78% female). Mean follow-up was 11.5 ± 6.8 months. “Thoracic Fusion” group showed no alteration in the natural relationship between TK and LL (ΔTK = 39% ΔPI-LL), whereas “Lumbar Fusion” group had a reduction in reciprocal change (ΔTK = 34% ΔPI-LL) although a subanalysis of patients in the “Lumbar Fusion” group with flexible thoracic spines showed a marked compensation in reciprocal change with (ΔTK = 58% ΔPI-LL). Conclusion: The relationship between ΔTK and ΔPI-LL is dependent on level instrumented. “Thoracic Fusion” drives change in LL while this relationship is affected by TK’s natural stiffness in “Lumbar Fusion” patients.

Study Design: Retrospective study. Objectives: To investigate the effect of paraspinal muscle degeneration on the maintenance of local and global alignment among degenerative lumbar scoliosis (DLS) patients after corrective surgery. Methods: 98 DLS patients with a mean follow-up period of 38.3 months after corrective surgery were included. The T1 pelvic angle (TPA), lumbar lordosis (LL), pelvic incidence were measured preoperatively, immediate postoperatively and at last follow-up. All patients were divided into LL maintenance group (n = 21) and LL loss group (n = 77). For patients with well-aligned correction (immediate postoperative TPA ≤ 20°, n = 73), they were divided into TPA maintenance group (last follow-up TPA ≤ 20°) and TPA loss group (last follow-up TPA > 20°). The relative gross cross-sectional area (rGCSA) and fat infiltration (FI) of multifidus (MF) and erector spinae (ES), and the relative functional CSA (rFCSA) of psoas major (PS) were measured at L3, L4 and L5 on preoperative magnetic resonance imaging. Results: MF rGCSA were significantly smaller in LL loss group than in LL maintenance group. Both MF rGCSA and PS rFCSA were significantly smaller and MF FI was significantly higher in TPA loss group than in TPA maintenance group. Binary logistic regression revealed that the MF rGCSA was an independent factor of LL loss; Large immediate postoperative TPA was an independent risk factor of TPA loss, but not the parameters of paraspinal muscles. Conclusion: The effect of paraspinal muscles in lower lumbar segments might be mainly focused on the maintenance of local alignment rather than the global alignment.

Study Design: Cross sectional database study. Objective: To develop a fully automated artificial intelligence and computer vision pipeline for assisted evaluation of lumbar lordosis. Methods: Lateral lumbar radiographs were used to develop a segmentation neural network (n = 629). After synthetic augmentation, 70% of these radiographs were used for network training, while the remaining 30% were used for hyperparameter optimization. A computer vision algorithm was deployed on the segmented radiographs to calculate lumbar lordosis angles. A test set of radiographs was used to evaluate the validity of the entire pipeline (n = 151). Results: The U-Net segmentation achieved a test dataset dice score of 0.821, an area under the receiver operating curve of 0.914, and an accuracy of 0.862. The computer vision algorithm identified the L1 and S1 vertebrae on 84.1% of the test set with an average speed of 0.14 seconds/radiograph. From the 151 test set radiographs, 50 were randomly chosen for surgeon measurement. When compared with those measurements, our algorithm achieved a mean absolute error of 8.055° and a median absolute error of 6.965° (not statistically significant, P > .05). Conclusion: This study is the first to use artificial intelligence and computer vision in a combined pipeline to rapidly measure a sagittal spinopelvic parameter without prior manual surgeon input. The pipeline measures angles with no statistically significant differences from manual measurements by surgeons. This pipeline offers clinical utility in an assistive capacity, and future work should focus on improving segmentation network performance.

Study Design: A retrospective study of prospectively collected radiographic and clinical data. Objective: This study aims to investigate the relationship between endplate morphology parameters and the incidence of cage subsidence in patients with mini-open single-level oblique lateral lumbar interbody fusion (OLIF). Methods: We included 119 inpatients who underwent OLIF from February 2015 to December 2017. A total of 119 patients with single treatment level of OLIF were included. Plain anteroposterior and lateral radiograph were taken preoperatively, postoperatively, and during follow-up. The correlation between disc height, endplate concave angle/depth, cage position and cage subsidence were investigated. Functional rating index (Visual Analogue Scale for pain, and Roland Morris Disability Questionnaire) were employed to assess clinical outcomes. Results: Cage subsidence was more commonly seen at the superior endplates (42/119, 35.29%) than at the inferior endplates (6/119, 5.04%) (p < 0.01). More importantly, cage subsidence was significantly less in patients with superior endplates that were without concave angle (3/20, 15%) than with concave angle (37/99, 37.37%) (p < 0.05). Cage subsidence correlated negatively with preoperative anterior disc height (r = −0.21, p < 0.05), but positively with disc distraction rate (r = 0.27, p < 0.01). Lastly, the distance of cage to the anterior edges of the vertebral body showed a positive correlation (r = 0.26, p < 0.01). Conclusions: This study for the first time demonstrated that endplate morphology correlates with cage subsidence after OLIF. Since relatively flat endplates with smaller concave angle significantly diminish the incidence of subsidence, the morphology of cage surface should be taken into consideration when designing the next generation of cage. In addition, precise measurement of the disc height to avoid over-distraction, and more anteriorly placement of the cage is suggested to reduce subsidence.

Study Design: Prospective lumbar radiograph analysis. Objective: To compare changes in lumbar lordosis in standing flexion versus seated lateral radiographs. Methods: Standing lateral, standing flexion, and seated lateral X-rays of the lumbar spine were obtained in patients presenting with low back pain. Trauma, tumor, and revision cases were excluded. Changes in global lumbar as well as segmental lordosis were measured in each position. Results: Seventy adult patients were reviewed. Overall, the greatest changes in lordosis were seen at L4-S1 in both the seated and flexion X-rays (12.5° and 6.3°, respectively). Greater kyphosis was seen in seated versus flexion X-rays (21.6° vs 15.8°); changes in lordosis from L1-L3 were similar in both positions, with little change seen at these levels (approximately 5° to 7°). On subgroup analysis, these differences were magnified in analyzing only patients that moved at least 20° globally, and there were no significant differences between sitting and flexion in “stiff” patients that moved less than 20° globally. Conclusion: Greater lumbar kyphosis was seen in the seated position compared to standing flexion, especially from L4-S1. Given these results we suggest the use of seated lateral X-rays to dynamically assess the lumbar spine. These findings may also guide future research into the mechanism and clinical relevance of a stiff versus mobile lumbar spine, as well as into the sensitivity of seated X-rays in detecting instability.

Study Design: Review of the literature. Objectives: Anterior column realignment (ACR) is a powerful but relatively new minimally invasive technique for deformity correction. The purpose of this study is to provide a literature review of the ACR surgical technique, reported outcomes, and future directions. Methods: A review of the literature was performed regarding the ACR technique. A review of patients at our single center who underwent ACR was performed, with illustrative cases selected to demonstrate basic and nuanced aspects of the technique. Results: Clinical and cadaveric studies report increases in segmental lordosis in the lumbar spine by 73%, approximately 10° to 33°, depending on the degree of posterior osteotomy and lordosis of the hyperlordosis interbody spacer. These corrections have been found to be associated with a similar risk profile compared with traditional surgical options, including a 30% to 43% risk of proximal junctional kyphosis in early studies. Conclusions: ACR represents a powerful technique in the minimally invasive spinal surgeon’s toolbox for treatment of complex adult spinal deformity. The technique is capable of significant sagittal plane correction; however, future research is necessary to ascertain the safety profile and long-term durability of ACR.

Study Design: Meta-analysis. Objective: Proximal junctional kyphosis (PJK) is a complication of surgical management for adult spinal deformity with a multifactorial etiology. Many risk factors are controversial and their relative importance are not fully understood. We aimed to identify the surgical, radiographic, and patient-related risk factors associated with PJK and proximal junctional failure (PJF). Methods: A systematic literature search was performed using PubMed, Cochrane Database of Systematic Reviews, and EMBASE. The inclusion criteria included prospective randomized control trials and prospective/retrospective cohort studies of adult patients with radiographic evidence of PJK, which was defined as a proximal junctional sagittal Cobb angle ≥10° and at least 10° greater than the preoperative measurement. Studies required a minimum of 10 patients and 12 months of follow-up. Results: A total of 14 unique studies, including 1908 patients were included. The pooled analysis showed significant differences between the PJK and non-PJK groups in age (weighted mean difference [WMD] −3.80; P = .03), prevalence of osteopenia/osteoporosis (odds ratio [OR] 1.99; P = .0004), preoperative sagittal vertical axis (SVA) (WMD −17.52; P = .02), preoperative lumbar lordosis (LL) (WMD −1.22; P = .002), pedicle screw instrumentation at the upper instrumented vertebra (UIV) (OR 1.67; P = .02), change in SVA (WMD −11.87; P = .01), fusion to sacrum/pelvis/ilium (OR 2.14; P < .00 001), change in LL (WMD −5.61; P = .01), and postoperative SVA (WMD −7.79; P = .008). Conclusions: Our meta-analysis suggests that age, osteopenia/osteoporosis, high preoperative SVA, high postoperative SVA, low preoperative LL, use of pedicle screws at the UIV, SVA change/correction, LL change/correction, and fusion to sacrum/pelvis/iliac region are risk factors for PJK.

Study Design: Retrospective case series. Objective: To investigate which sagittal parameters contribute to a normal sagittal vertical axis (SVA) when there is a pelvic incidence-lumbar lordosis (PI-LL) mismatch >10° following adult spinal deformity (ASD) correction. Methods: We performed a retrospective review of ASD patients with >5 levels fused. Sagittal measurements between cohorts of postoperative PI-LL >10° and PI-LLResults: We analyzed 52 patients with a mean age of 59 ± 16 years. In patients with a postoperative SVA 10° than when PI-LL10° than when PI-LL 2 = 0.51) than with PI-LL alone ( R2 = 0.33). Lastly, there was no significant correlation between change in pre- to postoperative SVA with change in TK for all cases ( P = .73), but in cases where change in PI-LL was Conclusion: Our results demonstrate that PT and TK, and not just PI-LL, play an important role in maintaining sagittal balance when there is a PI-LL mismatch >10°.

Study Design Retrospective case series. Objective StaXx XD (Spine Wave, Inc., Shelton, CT, United States) is an expandable polyaryl-ether-ether-ketone (PEEK) wafer implant utilized in the treatment of lumbar degenerative disease. PEEK implants have been successfully used as interbody devices. Few studies have focused on expandable PEEK devices. The aim of the current study is to determine the radiographic and clinical outcome of expandable PEEK cages utilized for transforaminal lumbar interbody fusion in patients with lumbar degenerative diseases. Methods Forty-nine patients who underwent lumbar interbody fusion with implantation of expandable PEEK cages and posterior instrumentation were included. The clinical outcome was evaluated using the visual analog scale (VAS) and the Oswestry Disability Index (ODI). Radiographic parameters including disk height, foraminal height, listhesis, local disk angle of the index level/levels, regional lumbar lordosis, and graft subsidence were measured preoperatively, postoperatively, and at latest follow-up. Results At an average follow-up of 19.3 months, the minimum clinically important difference for the ODI and VAS back, buttock, and leg were achieved in 64, 52, 58, and 52% of the patients, respectively. There was statistically significant improvement in VAS back (6.42 versus 3.11, p Conclusions Midterm results indicate that expandable PEEK spacers can effectively and durably restore disk and foraminal height and improve the outcome without significant subsidence.

Study Design: Retrospective cohort study. Objective: The S2-alar-iliac (S2AI) technique has been described as an alternative method for pelvic fixation in place of iliac screws (ISs) in spinal deformity surgery. The objective of this study was to analyze the impact of S2AI screws on radiographical outcomes, including spinopelvic parameters. Methods: A retrospective review of 17 patients receiving ISs and 46 patients receiving S2AI screws for correction of adult spinal deformity between 2010 and 2015 with minimum 1-year follow-up was conducted. Patient data on postoperative complications, including reoperation rates and proximal junctional kyphosis (PJK), and radiographical parameters was collected and statistically analyzed. Results: With mean follow-up of 21.1 months, the overall reoperation rate was significantly lower in the S2AI group than in the IS group (21.7% vs 58.8%, P = .01), but the incidence of PJK was similar (32.6% vs 35.3%, P > .99). Moreover, the time to reoperation in the IS group was significantly shorter than in the S2AI group (P = .001), and the S2AI group trended toward a longer time to reoperation due to PJK (P = .08). There was a significantly higher change in pelvic incidence (PI) in the S2AI group (−6.0°) compared with the IS group (P = .001). Conclusions: Compared with the IS technique, the S2AI technique demonstrated a lower rate of overall reoperation, a similar rate of PJK, longer time to reoperation, and possible reduction in PI. Future studies may be warranted to clarify the mechanism of these results and how they can be translated into improved patient care.

Study Design This is a retrospective study. Objective The objective of this study was to assess the sagittal stable vertebra (SSV) versus the first lordotic vertebra (FLV) as the inferior fusion level in patients undergoing spinal surgery for thoracic hyperkyphosis. The main outcome of interest was the development of distal junctional kyphosis (DJK). Summary of Background Data Prior research has pointed to selection of the FLV for the distal instrumentation level in fusion for thoracic hyperkyphosis. In 2009, Cho et al introduced the concept of the SSV after recognizing the development of DJK despite fusion to the FLV. Methods Patients were reviewed who had undergone spinal fusion for thoracic hyperkyphosis. Preoperative radiographs were reviewed to assess thoracic kyphosis, lumbar lordosis, SSV, and FLV. Postoperative radiographs were reviewed to assess curve correction and whether patients developed DJK or implant failure. Results We reviewed 22 patients with a mean age at surgery of 18 (range 14 to 22). Mean preoperative kyphosis was 85 ± 14 degrees, and mean postoperative kyphosis at final follow-up was 59 ± 12 degrees for a mean correction of 26 ± 12 degrees. Eleven patients developed DJK and four patients experienced hardware failure. In 12 patients, the SSV was inferior to the FLV. Rates of DJK when the instrumentation included the SSV or FLV were 13 and 38%, respectively. Conclusions Fusion to the SSV is superior at preventing DJK when compared with fusion to the FLV.

Study Design Cross-sectional study. Objective Sacropelvic parameters in various spine and hip disorders have been published in various studies. We aimed to study the normal sacropelvic parameters and curvatures of the spine and their correlation in asymptomatic Indian adults in relation to variations in sex and age. Methods The study included 101 asymptomatic adults (50 men and 51 women with an average age of 47.16 and 48.59 years, respectively). For each subject, the thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS) were measured from standing lateral radiographs. After stratification of the group by sex and age with a cutoff of 50 years, descriptive, correlation, and regression analysis were performed using SPSS software. Results The average PI, SS, PT, LL, and TK values were 55.48 (±5.31), 35.99 (±7.53), 17.97 (±7.16), 48.84 (±9.82), and 32.55 (±10.92), respectively. No statistically significant difference was observed in these values with regards to sex and age 50 years but the pelvic incidence was found to be higher in women. A positive correlation between the PI and SS and a negative correlation between the SS and PT was observed. A positive correlation between the TK and LL was found in subjects > 50 years. Simple and multiple regression analyses were also performed for different groups. Conclusion The current study is the first of asymptomatic Indian adults and provides invaluable information to the clinicians about the normal range of sacropelvic and spinopelvic parameters, which is useful to plan spinal deformity corrections and to evaluate pathologic conditions associated with abnormal angular values.

IntroductionRestoration of sagittal balance is paramount in any type of spinal reconstructive surgery. Recent work has demonstrated that the failure to maintain lumbar lordosis following fusion not...

IntroductionResearch of degenerative diseases of the spine it is recommended performing radiographs and magnetic resonance imaging (MRI). Physiological curvature of the lumbar spine varies from 35 ...

AimTo investigate the effect of a primary single level TLIF on the lumbar sagittal profile (segmental lordosis and total lumbar lordosis) comparing pre-operative, intra-operative and post-operative...

IntroductionSpino-pelvic parameters are crucial to address the spinal sagittal balance; such measurements require standardized lateral x-ray views that include the spine as well as the hips, which ...

IntroductionRadiological outcome of Lumbar Lordosis restored following Extreme Lateral Interbody Fusion (XLIF) plus Pedicle Screw Insertion (PSI). Improving sagittal alignment in the lumbosacral sp...

Introduction In the past 10 years, the importance of the sagittal shape of human pelvis has been pointed out by the orthopedists. However, most studies were defined in Western and Korean populations. It is unclear whether these characteristics of Chinese spinopelvic sagittal alignment differ from those of western and Korean populations. In addition, the predictive equation of lumbar lordosis remains unclear. This study described normal types of spinopelvic sagittal alignment in Chinese asymptomatic subjects, and investigated a prediction equation of lumbar lordosis from selective spinal and pelvic sagittal parameters. Material and Methods This was a prospective radiological analysis using full-spine standing lateral radiographs of Chinese volunteers. A total of 171 volunteers (94 males and 77 females; mean age, 23 years [range, 18–28 years]) participated. Pelvic and spinal parameters were measured according to geometric characteristics. The Pearson correlation test was calculated, regression analysis was running with the lumbar lordosis (predicted variable), and the other spinal and pelvic parameters (predictor variables), to determine the best sets of predictors to include in the model. Results Mean pelvic incidence was 44.6 ± 9.5 degrees, significantly less than that reported in Western subjects. The volunteers were classified into four types according to the location of their apex of total lumbar lordosis. As the apex of total lumbar lordosis moved cranially, lordosis tilt decreased, whereas lower lumbar lordosis, pelvic incidence, sacral slope, and the number of vertebral bodies included in the lower lumbar lordosis increased. On the basis of the pelvic incidence, total lumbar lordosis predictive equation was 0.639 PI + 20.593 degrees. Preliminary prediction of lower lumbar lordosis was PI-10 degrees. Conclusion The sagittal alignment of Chinese population could be classified into four types, and was different from that of Caucasian. Lower lumbar lordosis comprised most of total lumbar lordosis, the role of pelvic incidence in determining the sagittal curve was mainly through the adjustment of lower lumbar lordosis. Using regression analysis, total lumbar lordosis could be precisely predicted in asymptomatic subjects. To optimally plan surgery for spinal deformity, the prediction of postoperative lower lumbar lordosis curvature was equally important as that of total lumbar lordosis.

Introduction Maintaining both lumbar lordosis and paraspinal muscle function is important for prevention of sagittal imbalance. We previously reported that the cross-sectional area of the paraspinal muscles tends to decrease with age. To quantify the depth of the groove between the paraspinal muscles, we have developed our own parameter, the T-back value, which indicates the length of the bulge of muscle on the attachment of the spinous process. The T-back value is strongly correlated with the CSA of the paraspinal muscles. The occurrence of T-back value of 0 or less shows a marked increase in individuals aged 60 years or older. The CSA of the paraspinal and psoas muscles shows a similar decreasing trend with age, but fat infiltration of the paraspinal muscles is far more prominent than that of the psoas muscles in the elderly. The aims of this study are to investigate the CSA and fat infiltration of the psoas muscles in patients with paraspinal muscle atrophy, and to compare the findings with those in patients having a T-back value above 0. Methods Among 704 patients who underwent MRI of the lumbar spine at our hospital during 2010, 141 patients had a T-back value of 0 or less. Of these 141 patients, there were 120 patients, 40 men and 80 women, aged 60 years or older. We defined these as T-back − group. The control group included 120 age- and sex-matched individuals with a T-back value above0. We defined them as T-back + group. We compared their data from the two groups. The body mass index (BMI) of participants was calculated. Lumbar lordosis was measured on sagittal T2-weighted MR images. Axial T2-weighted MR images and a digital image analysis technique were used to measure the cross-sectional area and the percentage of fat infiltration of the paraspinal and psoas muscles at the intervertebral disc levels from L1/2 to L4/5 bilaterally. Then the mean values of both sides were used as CSA and the percentage of fat respectively Results The T-back − group had a significantly lower BMI than the T-back + group. Lumbar lordosis was significantly smaller in the T-back − group than in the T-back + group. In addition, the CSA of the paraspinal muscles was significantly smaller in the T-back − group than the T-back + group. The %Fat of the paraspinal muscles was significantly higher in the T-back − group than the T-back + group. When the CSA of the psoas muscles was compared across all spinal levels, there was no significant difference between the two groups. The %Fat of the psoas muscles also showed no significant difference between the two groups. Conclusion The patients in this study were divided into two groups according to the T-back value. The T-back − group had a smaller BMI, less lumbar lordosis, and the advanced atrophy of the paraspinal muscles than the T-back + group. However, MRI features of the psoas muscles were similar in the two groups. This study demonstrates that the psoas muscles are less susceptible to atrophy than the paraspinal muscles.