Cellular behavior and extracellular matrix turnover in bovine annulus fibrosus cells under hydrostatic pressure and deviatoric strain

Intervertebral disc herniation is a common spinal disorder that is often treated with discectomy when conservative measures fail. To devise therapeutic strategies for tears in the annulus fibrosus (AF), the regenerative capability of AF cells under spinal loading needs to be addressed. We hypothesized that the compressive loading associated with deformation in AF cells reduces synthetic and degradative activities in extracellular matrix and cell proliferation. We evaluated expression of key matrix molecules and cell proliferation by RT-PCR and immunohistochemistry by inner and outer bovine AF cells incubated under hydrostatic pressure (HP), arc-bending strain (Strain), and combined HP and Strain (HP/Strain) mimicking spinal loading. Inner AF cells showed significantly increased levels of aggrecan core protein, chondroitin sulfate N-acetylgalactosaminyltransferase-1, and tissue inhibitor of metalloproteinases-2 by 6 days under HP (p < 0.05), with a tendency toward increased matrix metalloproteinase-13. Outer AF cells demonstrated a significant decline in collagen type-2 under Strain and HP/Strain (p < 0.05) and a tendency toward suppression of collagen type-1 and elastin expression compared to HP and unloaded control. On the other hand, proliferating cell nucleus antigen increased significantly under Strain and HP/Strain in inner AF and declined under unloaded and HP in outer AF (p < 0.05). Immunohistology findings supported reductions in gene expressions of matrix molecules. Thus, changes in HP/Strain in AF appear to diminish synthetic and degradative activities while increasing cell proliferation. To promote regeneration, continuous overloading should be avoided, as it converts the synthetic activity to a state in which tissue repair is limited.

Long-term efficacy of microendoscopic laminotomy for lumbar spinal stenosis in advanced degenerative spondylolisthesis with or without dynamic spinal instability: a propensity score-matching analysis

OBJECTIVE

In this study, the authors aimed to determine the mid- to long-term outcomes of microendoscopic laminotomy (MEL) for lumbar spinal stenosis (LSS) with degenerative spondylolisthesis (DS) and identify preoperative predictors of poor mid- to long-term outcomes.

METHODS

The authors retrospectively reviewed the medical records of 274 patients who underwent spinal MEL for symptomatic LSS. The minimum postoperative follow-up duration was 5 years. Patients were classified into two groups according to DS: those with DS (the DS+ group) and those without DS (the DS- group). The patients were subjected to propensity score matching based on sex, age, BMI, surgical segments, and preoperative leg pain visual analog scale scores. Clinical outcomes were evaluated 1 year and > 5 years after surgery.

RESULTS

Surgical outcomes of MEL for LSS were not significantly different between the DS+ and DS- groups at the final follow-up (mean 7.8 years) in terms of Oswestry Disability Index (p = 0.498), satisfaction (p = 0.913), and reoperation rate (p = 0.154). In the multivariate analysis, female sex (standard β -0.260), patients with slip angle > 5° in the forward bending position (standard β -0.313), and those with dynamic progression of Meyerding grade (standard β -0.325) were at a high risk of poor long-term outcomes.

CONCLUSIONS

MEL may have good long-term results in patients with DS without dynamic instability. Women with dynamic instability may require additional fusion surgery in approximately 25% of cases for a period of ≥ 5 years.

Outcomes and Vertebral Osteophytes and Bulging Intervertebral Discs Occupancy as a Decision-Making Tool for Surgical Success in Patients Undergoing Microendoscopic Foraminotomy for Lumbar Foraminal Stenosis

OBJECTIVE

The objective of this study was to determine the long-term outcomes of microendoscopic foraminotomy in treating lumbar foraminal stenosis and identify the optimal extent of decompression that yields improved results and fewer complications.

METHODS

A retrospective cohort study reviewed the medical records of 95 consecutive patients who underwent microendoscopic foraminotomy for lumbar foraminal stenosis. Clinical outcomes were assessed using the Japanese Orthopaedic Association scoring system and visual analog scale for low back and leg pain. Surgical success was determined by meeting significant improvement thresholds for back and leg pain at 2 years postoperatively. Multiple regression analysis identified factors associated with improved pain scores. Receiver operating characteristic curve analysis determined the cut-off values for successful surgeries.

RESULTS

Significant improvements were observed in Japanese Orthopaedic Association and visual analog scale scores for back and leg pain 2 years postoperatively compared with preoperative scores (P < 0.0001) and sustained over a ≥5-year follow-up period. Reoperation rates were low and did not significantly increase over time. Multiple regression analysis identified occupancy of the vertebral osteophytes and bulging intervertebral discs (O/D complex) as surgical success predictors. A 45.0% O/D complex occupancy cutoff value was determined, displaying high sensitivity and specificity for predicting surgical success.

CONCLUSIONS

This study provides evidence supporting the long-term efficacy of microendoscopic foraminotomy for lumbar foraminal stenosis and predicting surgical success. The 45.0% O/D complex occupancy cut-off value can guide patient selection and outcome prediction. These insights contribute to informed surgical decision-making and underscore the importance of evaluating the O/D complex in preoperative planning and predicting outcomes.

Risk factors of postoperative coronal malalignment following long-segment spinal fusion surgery in which multilevel lateral lumbar interbody fusion was used for degenerative lumbar kyphoscoliosis

OBJECTIVE

In patients with adult spinal deformity, especially degenerative lumbar kyphoscoliosis (DLKS), preoperative sagittal malalignment and coronal malalignment (CM) often coexist. Lateral lumbar interbody fusion (LLIF) has recently been widely chosen for DLKS treatment due to its minimal invasiveness and excellent sagittal alignment correction. However, postoperative CM may remain or occur due to an oblique takeoff phenomenon following multilevel LLIF, resulting in poor clinical outcomes. The authors investigated the risk factors for postoperative CM after long-segment fusion corrective surgery in which multilevel LLIF was used in patients with DLKS.

METHODS

Fifty-four consecutive patients with DLKS, main Cobb angle ≥ 20°, and lumbar lordosis ≤ 20° who underwent corrective spinal fusion surgery, including extreme lateral interbody fusion at ≥ 3 segments, were included at the authors' institute between April 2014 and October 2019. Patients who underwent suitable 3-column osteotomy, classified as grade 3-6 per the Scoliosis Research Society-Schwab criteria, were excluded. Patients were divided into CM and non-CM groups based on postoperative CM evaluated using standard standing-position radiographs obtained 2 years postoperatively. CM was defined as an absolute C7-CSVL (deviation of C7 plumb line off central sacral vertical line; calculated by defining the convex side of the CSVL as positive numerical values) value of ≥ 3.0 cm. Patient demographics and preoperative sagittal alignment parameters were evaluated. The following variables were measured to assess coronal alignment: main Cobb angle; preoperative C7-CSVL; amount of lateral listhesis; L4, L5, and sacral coronal tilt angles; coronal vertebral deformity angles; and coronal spine rigidity.

RESULTS

Regarding risk factors for postoperative CM, patient characteristics, preoperative sagittal parameters, and coronal parameters did not significantly differ between the 2 groups, except for preoperative C7-CSVL (p = 0.016). Multivariate logistic regression analysis revealed that preoperative C7-CSVL (+1 cm; OR 1.23, 95% CI 1.05-1.50; p = 0.007) was a significant predictor of postoperative CM. Receiver operating characteristic curve analysis demonstrated that the cutoff value for preoperative C7-CSVL was +0.3 cm, the sensitivity was 85.7%, the specificity was 60.6%, and the area under the curve was 0.70.

CONCLUSIONS

In corrective fusion surgery for DLKS in which multilevel LLIF was used, the occurrence of postoperative CM was associated with preoperative C7-CSVL. According to the C7-CSVL, which was evaluated by defining the convex side of the CSVL as positive numerical values and the concave side as negative numerical values, the CM group had a significantly higher value of preoperative C7-CSVL than did the non-CM group. Alternative corrective fusion methods, other than multiple LLIFs, may be considered in DLKS cases with a C7-CSVL of +0.3 cm or greater.

Clinical and radiographic characteristics of increased signal intensity of the spinal cord at the vertebral body level in patients with cervical myelopathy

BACKGROUND

Increased signal intensity (ISI) is usually recognized at the disc level of the responsible lesion in the patients with cervical myelopathy. However, it is occasionally seen at the vertebral body level, below the level of compression. We aimed to investigate the clinical significance and the radiographic characteristics of ISI at the vertebral body level.

METHODS

This retrospective study included 135 patients with cervical spondylotic myelopathy who underwent surgery and with local ISI. We measured the local and C2-7 angle at flexion, neutral, and extension. We also evaluated the local range of motion (ROM) and C2-7 ROM. The patients were classified into group D (ISI at disc level) and group B (ISI at vertebral body level).

RESULTS

The prevalence was 80.7% (109/135) and 19.3% (26/135) for groups D and B, respectively. Local angle at flexion and neutral were more kyphotic in group B than in group D. The local ROM was larger in group B than in group D. Moreover, C2-7 angle at flexion, neutral and extension were more kyphotic in group B than in group D. Two years later, local angle at flexion, neutral, and extension were also kyphotic in group B than group D; however, local and C2-7 ROM was not significantly different between the two groups. There was no significant difference of clinical outcomes 2 years postoperatively between both groups.

CONCLUSIONS

Group B was associated with the kyphotic alignment and local greater ROM, compared to group D. As the spinal cord is withdrawn in flexion, the ISI lesion at vertebral body might be displaced towards the disc level, which impacted by the anterior components of the vertebrae. ISI at the vertebral body level might be related to cord compression or stretching at flexion position. This should be different from the conventionally held pincer-mechanism concept.

Unique Characteristics of New Bone Formation Induced by Lateral Lumbar Interbody Fusion Procedure

Introduction

Despite the absence of bone grafting in the area outside the cage, lateral bridging callus outside cages (LBC) formation is often observed here following extreme lateral interbody fusion (XLIF) conversely to conventional methods of transforaminal lumbar interbody fusion and posterior lumbar interbody fusion. The LBC, which may increase stabilization and decrease nonunion rate in treated segments, has rarely been described. This study aimed to identify the incidence and associated factors of LBC following XLIF.

Methods

We enrolled 136 consecutive patients [56 males, 80 females; mean age 69.6 (42-85) years] who underwent lumbar fusion surgery using XLIF, including L4/5 level with posterior fixation at a single institution between February 2013 and February 2018. One year postoperatively, the treated L4/5 segments were divided into the LBC formation and non-formation groups. Potential influential factors, such as age, sex, body mass index, bone density, height of cages, cage material (titanium or polyetheretherketone [PEEK]), presence or absence of diffuse idiopathic skeletal hyperostosis (DISH), and radiological parameters, were evaluated. Multivariate logistic regression analysis was performed for factors significantly different from the univariate analysis.

Results

The incidence of LBC formation was 58.8%. Multivariate logistic regression analysis showed that the length of osteophytes [+1 mm; odds ratio, 1.29; 95% confidence interval, 1.17-1.45; p<0.0001] was significant LBC formation predictive factors. Receiver operating characteristic curve analysis demonstrated that the cut-off value for osteophyte length was 14 mm, the sensitivity was 58.8%, the specificity was 84.4%, and the area under the ROC curve for this model was 0.79.

Conclusions

The incidence of LBC formation was 58.8% in L4/5 levels one year after the XLIF procedure. We demonstrated that the length of the osteophyte was significantly associated with LBC formation.

Using Electrical Stimulation of the Ulnar Nerve Trunk to Predict Postoperative Improvement in Hand Clumsiness in Patients With Cervical Spondylotic Myelopathy

STUDY DESIGN

A prospective cohort study.

OBJECTIVE

To investigate whether the immediate and short-term effects of preoperative electrical peripheral nerve stimulation (ePNS) on performance of the 10-second test could predict the early postoperative outcomes of patients with cervical spondylotic myelopathy (CSM).

SUMMARY OF BACKGROUND DATA

Previous studies have shown that early clinical improvement in CSM patients may be because of reversal of spinal cord ischemia after spinal cord compression.

MATERIALS AND METHODS

We conducted a 10-second test before surgery, after ePNS, and at discharge (one week after surgery) in 44 patients with CSM who underwent C3-C7 laminoplasty and evaluated their correlations. The effects of the procedures (ePNS or operation) and sides (stimulated or nonstimulated side) for the 10-second test were analyzed using repeated measures analysis of variance. The Pearson correlation coefficient was used to measure the relationship between the 10-second test values according to the method (after ePNS vs. surgery). In addition, the Bland-Altman method was used to evaluate the degree of agreement between the 10-second test obtained after ePNS versus shortly after surgery.

RESULTS

The preoperative 10-second test showed the most improvement immediately after the administration of ePNS, with a gradual decrease for the first 30 minutes after completion. After the initial 30 minutes, performance decreased rapidly, and by 60 minutes performance essentially returned to baseline. The 10-second post-ePNS had a strong positive correlation with the 10-second test in the early postoperative period (at discharge=one week after surgery). These phenomena were observed with the left hand, the side stimulated with ePNS, as well as the right hand, the side not stimulated.

CONCLUSIONS

Early postoperative outcomes after CSM surgery may be predicted by the results of preoperative ePNS.

LEVEL OF EVIDENCE

Level 3.

Erratum for Lumbar Fusion including Sacroiliac Joint Fixation Increases the Stress and Angular Motion at the Hip Joint: A Finite Element Study

[This corrects the article DOI: 10.22603/ssrr.2021-0231.].

Importance of physiological age in determining indications for adult spinal deformity surgery in patients over 75 years of age: a propensity score matching analysis

PURPOSE

Physiologically, people age at different rates, which leads to a discrepancy between physiological and chronological age. Physiological age should be a priority when considering the indications for adult spinal deformity (ASD) surgery. The primary objective of this study was to determine the characteristics of the postoperative course, surgical outcomes, and complication rates to extend the healthy life expectancy of older ASD patients (≥ 75 years). The secondary objective was to clarify the importance of physiological age in the surgical treatment of older ASD patients, considering frailty.

METHODS

A retrospective review of 109 consecutive patients aged ≥ 65 years with symptomatic ASD who underwent a corrective long fusion with lateral interbody fusion from the lower thoracic spine to the pelvis from 2015 to 2019 was conducted. Patients were classified into two groups according to age (group Y [65-74 years], group O [≥ 75 years]) and further divided into four groups according to the ASD-frailty index score (Y-F, Y-NF, O-F, and O-NF groups). To account for potential risk factors for perioperative course characteristics, complication rates, and surgical outcomes, patients from the database were subjected to propensity score matching based on sex, BMI, and preoperative sagittal spinal alignment (C7 sagittal vertical axis, pelvic incidence-lumbar lordosis, and pelvic tilt). Clinical outcomes were evaluated 2 years postoperatively, using three patient-reported outcome measures of health-related quality of life: the Oswestry Disability Index, Scoliosis Research Society questionnaire (SRS-22), and Short Form 36 (SF-36). Additionally, the postoperative time-to-first ambulation, as well as minor, major, and mechanical complications, were evaluated.

RESULTS

In the comparison between Y and O groups, patients in group O were at a higher risk of minor complications (delirium and urinary tract infection). In contrast, other surgical outcomes of group O were comparable to those of group Y, except for SRS-22 (satisfaction) and time to ambulation after surgery, with better outcomes in Group O. Patients in the O-NF group had better postoperative outcomes (time to ambulation after surgery, SRS-22 (function, self-image, satisfaction), SF-36 [PCS]) than those in the Y-F group.

CONCLUSIONS

Older age warrants monitoring of minor complications in the postoperative management of patients. However, the outcomes of ASD surgery depended more on frailty than on chronological age. Older ASD patients without frailty might tolerate corrective surgery and have satisfactory outcomes when minimally invasive techniques are used. Physiological age is more important than chronological age when determining the indications for surgery in older patients with ASD.

S2 alar-iliac screw loosening as a preventive factor for hip joint osteoarthritis after adult spinal deformity surgery: a case-control study

PURPOSE

This study aimed to evaluate the progression of hip pathology and risk factors after ASD surgery.

METHODS

This case-control study enrolled 123 patients (246 hips); seven hips underwent hip arthroplasty were excluded. We measured the center-edge (CE) angle, joint space width (JSW), and Kellgren-Lawrence (KL) grade. We defined a CE angle˂25° as developmental dysplasia of the hip (DDH). We evaluated S2 alar-iliac (AI) screw loosening at final follow-up.

RESULTS

The annual decrease in the JSW was 0.31 mm up to 1 year, and 0.13 mm after 1 year (p = 0.001). KL grade progression occurred in 24 hips (10.0%; group P), while no progression occurred in 215 (90.0%; group N) hips. Nonparametric analysis between groups P and N revealed that significant differences were observed in sex, DDH, KL grade, ratio of S2AI screw fixation at baseline, and ratio of S2AI screw loosening at final follow-up. Multiple logistic regression analysis revealed that DDH (p = 0.018, odds ratio (OR) = 3.0, 95%CI = 1.2-7.3), baseline KL grade (p < 0.0001, OR = 37.7, 95%CI = 7.0-203.2), and S2AI screw fixation (p = 0.035, OR = 3.4, 95%CI = 1.1-10.4) were significant factors. We performed sub-analysis to elucidate the relationship between screw loosening and hip osteoarthritis in 131 hips that underwent S2AI screw fixation. Non-loosening of the S2AI screw was a significant factor for KL grade progression (p < 0.0001, OR = 8.9, 95%CI = 3.0-26.4).

CONCLUSION

This study identified the prevalence and risk factors for the progression of hip osteoarthritis after ASD surgery. Physicians need to pay attention to the hip joint pathology after ASD surgery.

POS0848 HEALTHCARE RESOURCE UTILIZATION AND COST BURDEN OF DERMATOMYOSITIS

Background

Dermatomyositis (DM) is a rare chronic systemic autoimmune disease characterized by muscle weakness and skin rashes. DM is also frequently associated with other clinical manifestations including interstitial lung disease, calcinosis, dysphagia, cardiac involvement, and malignancy. With few approved treatment options, DM has high morbidity and mortality. Limited information is available on the economic impact imposed by DM on the healthcare system.

Objectives

To estimate the economic burden associated with DM in a prevalence cohort, including healthcare resource utilization and costs from both the health insurance plan and patient perspectives.

Methods

A retrospective cohort study was conducted using a large, integrated administrative database of employer-sponsored commercial and public health plans in the United States (PharMetrics Plus, Jan 2014 - June 2020). Patients (age ≥18 years) were selected if they were diagnosed with dermatomyositis (≥1 inpatient claim or ≥2 outpatient claims ≥30 days apart with International Classification of Diseases, 10th Revision, Clinical Modification: M33.0x, M33.1x, or M33.9x) and continuously enrolled in the health plan during the 6 months before (baseline) and 1 year after (follow-up) a randomly selected DM diagnosis date (index date). Patients were matched 1:3 to a control group without DM or related myositis conditions based on birth year, gender, census region, insurance plan type, and index year. Healthcare resource use (HCRU) and costs over the 1-year follow-up period were compared between patients with DM versus matched controls to assess the incremental economic burden of DM. Statistical comparisons were conducted using generalized estimating equation models with binomial, negative binomial, or Tweedie distributions for binary, count, and cost outcomes, respectively. The models used robustly clustered standard errors to account for correlation between the matched samples.

Results

Patients with DM (N=3,207) and matched controls (N=9,621) were 49.4 years old on average and 76.8% were female. HCRU was significantly higher among patients with DM than controls in terms of outpatient, inpatient, emergency room, and other medical visits (all p<0.001; Table 1). Medical service and pharmacy costs to the plan were also significantly higher for patients with DM (p<0.001 vs. controls for all cost categories; Figure 1). Total annual costs to the healthcare plan were 5.4-fold higher among patients with DM (mean ± standard deviation: $39,508 ± 83,093) relative to controls without DM ($7,349 ± 32,816) (Δ=$32,159; p<0.001). Outpatient visit costs ($28,131) comprised 71.2% of the total for patients with DM; costs of outpatient-administered DM-related treatments ($15,855) accounted for the majority of outpatient visit costs. Patients with DM incurred 2-fold higher out-of-pocket costs (coinsurance, copayments, or deductibles) than controls ($4,803 ± 13,181 vs. $2,456 ± 10,708; Δ=$2,346; p<0.001).

Table 1.

Annual resource use in patients with DM vs. controls

Patients with DM N = 3,207Controls N = 9,621IRR or OR95% confidence intervalP-valueInpatient admissions, mean ± SD0.2 ± 0.70.1 ± 0.43.1(2.6 - 3.7)< 0.001Any inpatient admission, %12.1%4.9%2.7(2.3 - 3.1)< 0.001Outpatient visits, mean ± SD27.7 ± 31.710.8 ± 18.92.6(2.4 - 2.7)< 0.001Emergency room visits, mean ± SD0.7 ± 1.60.4 ± 1.21.8(1.6 - 2.0)< 0.001Any emergency room visit, %30.4%20.7%1.7(1.5 - 1.8)< 0.001Other visits, mean ± SD0.3 ± 0.80.2 ± 0.71.8(1.6 - 2.1)< 0.001Any other visit, %20.0%11.2%2.0(1.8 - 2.2)< 0.001

IRR: incidence rate ratio; OP, outpatient; OR: odds ratio, SD: standard deviation.

Notes: IRRs are reported for count outcomes; ORs are reported for binary outcomes. Other visits include durable medical equipment and dental or vision care.

Conclusion

DM is associated with substantial HCRU and costs per patient, with average incremental costs of $32,159 to the health plan and $2,346 to the patient annually as compared to controls. This study is among the first to document the clinical burden leading to high economic impacts of DM.

Acknowledgements

Funding for this study was provided by Pfizer Inc.

Disclosure of Interests

Arielle Bensimon Consultant of: Pfizer, as an employee of Analysis Group, Kristina Chen Employee of: Pfizer, Ahmed Noman Consultant of: Pfizer, as an employee of Analysis Group, Riley Taiji Consultant of: Pfizer, as an employee of Analysis Group at the time that this study was conducted, Erica Yim Consultant of: Pfizer, as an employee of Analysis Group, Vanja Sikirica Shareholder of: Pfizer, which manufactures medications approved for use in Rheumatology., Employee of: Pfizer at the time of this work and a current employee of Moderna., Rohit Aggarwal Consultant of: Abbvie, Alexion, AstraZeneca, Pfizer, Octapharma, Csl Behring, BMS, Argenx, Corbus, EMD, Janssen, Kezar, Kyverna, Roivant, Q32, Corbus, EMD Serono, Jubliant, Scipher, Boehringer Ingelheim and Mallinckrodt, Grant/research support from: Pfizer, BMS, Q32, EMD Serono, Mallinckrodt, Genentech, and Boehringer Ingelheim

A novel technique using ultrasonography in upper airway management after anterior cervical decompression and fusion

Background

Airway complications are the most serious complications after anterior cervical decompression and fusion (ACDF) and can have devastating consequences if their detection and intervention are delayed. Plain radiography is useful for predicting the risk of dyspnea by permitting the comparison of the prevertebral soft tissue (PST) thickness before and after surgery. However, it entails frequent radiation exposure and is inconvenient. Therefore, we aimed to overcome these problems by using ultrasonography to evaluate the PST and upper airway after ACDF and investigate the compatibility between X-ray and ultrasonography for PST evaluation.

Methods

We included 11 radiculopathy/myelopathy patients who underwent ACDF involving C5/6, C6/7, or both segments. The condition of the PST and upper airway was evaluated over 14 days. The Bland–Altman method was used to evaluate the degree of agreement between the PST values obtained using radiography versus ultrasonography. The Pearson correlation coefficient was used to determine the relationship between the PST measurement methods. Single-level and double-level ACDF were performed in 8 and 3 cases, respectively.

Results

PST and upper airway thickness peaked on postoperative day 3, with no airway complications. The Bland–Altman bias was within the prespecified clinically nonsignificant range: 0.13 ± 0.36 mm (95% confidence interval 0.04–0.22 mm). Ultrasonography effectively captured post-ACDF changes in the PST and upper airway thickness and detected airway edema.

Conclusions

Ultrasonography can help in the continuous assessment of the PST and the upper airway as it is simple and has no risk of radiation exposure risk. Therefore, ultrasonography is more clinically useful to evaluate the PST than radiography from the viewpoint of invasiveness and convenience.

Lumbar Fusion including Sacroiliac Joint Fixation Increases the Stress and Angular Motion at the Hip Joint: A Finite Element Study

Introduction

Adult spinal fusion surgery improves lumbar alignment and patient satisfaction. Adult spinal deformity surgery improves saggital balance not only lumbar lesion, but also at hip joint coverage. It was expected that hip joint coverage rate was improved and joint stress decreased. However, it was reported that adjacent joint disease at hip joint was induced by adult spinal fusion surgery including sacroiliac joint fixation on an X-ray study. The mechanism is still unclear. We aimed to investigate the association between lumbosacral fusion including sacroiliac joint fixation and contact stress of the hip joint.

Methods

A 40-year-old woman with intact lumbar vertebrae underwent computed tomography. A three-dimensional nonlinear finite element model was constructed from the L4 vertebra to the femoral bone with triangular shell elements (thickness, 2 mm; size, 3 mm) for the cortical bone's outer surface and 2-mm (lumbar spine) or 3-mm (femoral bone) tetrahedral solid elements for the remaining bone. We constructed the following four models: a non-fusion model (NF), a L4-5 fusion model (L5F), a L4-S1 fusion model (S1F), and a L4-S2 alar iliac screw fixation model (S2F). A compressive load of 400 N was applied vertically to the L4 vertebra and a 10-Nm bending moment was additionally applied to the L4 vertebra to stimulate flexion, extension, left lateral bending, and axial rotation. Each model's hip joint's von Mises stress and angular motion were analyzed.

Results

The hip joint's angular motion in NF, L5F, S1F, and S2F gradually increased; the S2F model presented the greatest angular motion.

Conclusions

The average and maximum contact stress of the hip joint was the highest in the S2F model. Thus, lumbosacral fusion surgery with sacroiliac joint fixation placed added stress on the hip joint. We propose that this was a consequence of adjacent joint spinopelvic fixation. Lumbar-to-pelvic fixation increases the angular motion and stress at the hip joint.

Lateral interbody release for fused vertebrae via transpsoas approach in adult spinal deformity surgery: a preliminary report of radiographic and clinical outcomes

BACKGROUND

Lateral interbody release (LIR) via a transpsoas lateral approach is a surgical strategy to address degenerative lumbar scoliosis (DLS) patients with anterior autofusion of vertebral segments. This study aimed to characterize the clinical and radiographic outcomes of this lumbar reconstruction strategy using LIR to achieve anterior column correction.

METHODS

Data for 21 fused vertebrae in 17 consecutive patients who underwent LIR between January 2014 and March 2020 were reviewed. Demographic and intraoperative data were recorded. Radiographic parameters were assessed preoperatively and at final follow-up, including segmental lordotic angle (SLA), segmental coronal angle (SCA), bone union rate, pelvic incidence (PI), lumbar lordosis (LL), pelvic tilt, sacral slope, PI-LL mismatch, sagittal vertical axis, Cobb angle, and deviation of the C7 plumb line from the central sacral vertical line. Clinical outcomes were evaluated using Oswestry Disability Index (ODI), visual analog scale (VAS) scores for low back and leg pain, and the short form 36 health survey questionnaire (SF-36) postoperatively and at final follow-up. Complications were also assessed.

RESULTS

Mean patient age was 70.3 ± 4.8 years and all patients were female. Average follow-up period was 28.4 ± 15.3 months. Average procedural time to perform LIR was 21.3 ± 9.7 min and was not significantly different from traditional lateral interbody fusion at other levels. Blood loss per single segment during LIR was 38.7 ± 53.2 mL. Fusion rate was 100.0% in this cohort. SLA improved significantly from - 7.6 ± 9.2 degrees preoperatively to 7.0 ± 8.8 degrees at final observation and SCA improved significantly from 19.1 ± 7.8 degrees preoperatively to 8.7 ± 5.9 degrees at final observation (P < 0.0001, and < 0.0001, respectively). All spinopelvic and coronal parameters, as well as ODI and VAS, improved significantly. Incidence of peri- and postoperative complications such as iliopsoas muscle weakness and leg numbness in patients who underwent LIR was as much as XLIF. Incidence of postoperative mechanical failure following LIR was also similar to XLIF. Reoperation rate was 11.8%. However, there were no reoperations associated with LIR segments.

CONCLUSIONS

The LIR technique for anterior column realignment of fused vertebrae in the context of severe ASD may be an option of a safe and effective surgical strategy.

Long-term Clinical Outcomes of Microendoscopic Laminotomy for Cervical Spondylotic Myelopathy: A 5-Year Follow-up Study Compared With Conventional Laminoplasty

STUDY DESIGN

This was a retrospective cohort study.

OBJECTIVE

The objective of this study was to characterize the long-term clinical and radiographic results of articular segmental decompression surgery using endoscopy [cervical microendoscopic laminotomy (CMEL)] for cervical spondylotic myelopathy (CSM) and to compare outcomes to conventional expansive laminoplasty (ELAP).

SUMMARY OF BACKGROUND DATA

The spinal cord compression in CSM consists of a pincer mechanism due to bulging disk and a hypertrophied ligamentum flavum. The long-term clinical benefits of segmental decompression surgery, which removes the dorsal compressive elements of articular segment in CSM patients, have not yet been elucidated.

MATERIALS AND METHODS

Consecutive patients with CSM who required surgical treatment were enrolled. All enrolled patients (n=81) underwent CMEL or ELAP. All patients were followed postoperatively for >5 years. The preoperative and 5-year follow-up evaluation included neurological assessment [Japanese Orthopaedic Association (JOA) score], JOA recovery rates, axial neck pain (visual analog scale), and cervical sagittal alignment (C2-C7 subaxial cervical angle).

RESULTS

Sixty-four patients (CMEL group: 33, ELAP group: 31) were included for analysis. The preoperative JOA score was 10.1 points in the CMEL group and 11.1 points in the ELAP group (P=0.15). The JOA recovery rates were similar, 58.6% in the CMEL group and 55.2% in the ELAP group (P=0.55). The axial neck pain in the CMEL group was significantly lower than that in the ELAP group (P<0.01). At 5-year follow-up, cervical alignment was more favorable in the CMEL group, with an average 2.9 degrees gain in lordosis [vs. 2.3 degrees loss of lordosis in the ELAP group (P<0.05)] and lower incidence of postoperative kyphosis.

CONCLUSIONS

CMEL is a novel, less invasive, technique that allows for multilevel posterior cervical decompression for treatment of CSM. Our 5-year follow-up data demonstrates that patients after CMEL have similar neurological outcomes to conventional laminoplasty, with significantly less postoperative axial pain and improved subaxial cervical lordosis when compared with their traditional laminoplasty counterparts.

Anti-allodynic and promotive effect on inhibitory synaptic transmission of riluzole in rat spinal dorsal horn

Riluzole (2-amino-6-(trifluoromethoxy)benzothiazole) is a drug known for its inhibitory effect on glutamatergic transmission and its anti-nociceptive and anti-allodynic effects in neuropathic pain rat models. Riluzole also has an enhancing effect on GABAergic synaptic transmission. However, the effect on the spinal dorsal horn, which plays an important role in modulating nociceptive transmission, remains unknown. We investigated the ameliorating effect of riluzole on mechanical allodynia using the von Frey test in a rat model of neuropathic pain and analyzed the synaptic action of riluzole on inhibitory synaptic transmission in substantia gelatinosa (SG) neurons using whole-cell patch clamp recordings. We found that single-dose intraperitoneal riluzole (4 mg/kg) administration effectively attenuated mechanical allodynia in the short term in a rat model of neuropathic pain. Moreover, 300 μM riluzole induced an outward current in rat SG neurons. The outward current induced by riluzole was not suppressed in the presence of tetrodotoxin. Furthermore, we found that the outward current was suppressed by simultaneous bicuculline and strychnine application, but not by strychnine alone. Altogether, these results suggest that riluzole enhances inhibitory synaptic transmission monosynaptically by potentiating GABAergic synaptic transmission in the rat spinal dorsal horn.

Impact of an intraoperative coronal spinal alignment measurement technique using a navigational tool for a 3D spinal rod bending system in adult spinal deformity cases

OBJECTIVE

In corrective spinal surgery for adult spinal deformity (ASD), the focus has been on achieving optimal spinopelvic alignment. However, the correction of coronal spinal alignment is equally important. The conventional intraoperative measurement methods currently used for coronal alignment are not ideal. Here, the authors have developed a new intraoperative coronal alignment measurement technique using a navigational tool for a 3D spinal rod bending system (CAMNBS). The purpose of this study was to test the feasibility of using the CAMNBS for coronal spinal alignment and to evaluate its usefulness in corrective spinal surgery for ASD.

METHODS

In this retrospective cohort study, patients with degenerative lumbar kyphoscoliosis, a Cobb angle ≥ 20°, and lumbar lordosis ≤ 20° who had undergone corrective surgery (n = 67) were included. The pelvic teardrops on both sides, the S1 spinous process, the central point of the apex, a point on the 30-mm cranial (or caudal) side of the apex, and the central point of the upper instrumented vertebra (UIV) and C7 vertebra were registered using the CAMNBS. The positional information of all registered points was displayed as 2D figures on a monitor. Deviation of the UIV plumb line from the central sacral vertical line (UIV-CSVL) and deviation of the C7 plumb line from the CSVL (C7-CSVL) were measured using the 2D figures. Nineteen patients evaluated using the CAMNBS (BS group) were compared with 48 patients evaluated using conventional intraoperative radiography (XR group). The UIV-CSVL measured intraoperatively using the CAMNBS was compared with that measured using postoperative radiography. The prevalence of postoperative coronal malalignment (CM) and the absolute value of postoperative C7-CSVL were compared between the groups on radiographs obtained in the standing position within 4 weeks after surgery. Postoperative CM was defined as the absolute value of C7-CSVL ≥ 30 mm. Further, the measurement time and amount of radiation exposure were measured.

RESULTS

No significant differences in demographic, sagittal, and coronal parameters were observed between the two groups. UIV-CSVL was 2.3 ± 9.5 mm with the CAMNBS and 1.8 ± 16.6 mm with the radiographs, showing no significant difference between the two methods (p = 0.92). The prevalence of CM was 2/19 (10.5%) in the BS group and 18/48 (37.5%) in the XR group, and absolute values of C7-CSVL were 15.2 ± 13.1 mm in the BS group and 25.0 ± 18.0 mm in the XR group, showing statistically significant differences in both comparisons (p = 0.04 and 0.03, respectively). The CAMNBS method required 3.5 ± 0.9 minutes, while the conventional radiograph method required 13.3 ± 1.5 minutes; radiation exposure was 2.1 ± 1.1 mGy in the BS group and 2.9 ± 0.6 mGy in the XR group. Statistically significant differences were demonstrated in both comparisons (p = 0.0002 and 0.03, respectively).

CONCLUSIONS

From this study, it was evident that the CAMNBS did not increase postoperative CM compared with that seen using the conventional radiographic method, and hence can be used in clinical practice.

Does prophylactic use of topical gelatin-thrombin matrix sealant affect postoperative drainage volume and hematoma formation following microendoscopic spine surgery? A randomized controlled trial

BACKGROUND CONTEXT

Microendoscopic spinal surgery has demonstrated efficacy and is increasingly utilized as a minimally invasive approach to neural decompression, but there is a theoretical concern that bleeding and postoperative epidural hematoma (PEH) may occur with increased frequency in a contained small surgical field. Hemostatic agents, such as topical gelatin-thrombin matrix sealant (TGTMS), are routinely used in spine surgery procedures, yet there has been no data on whether PEH is suppressed by these agents when administered in microendoscopic spine surgery.

PURPOSE

The purpose of this study was to investigate the effect of TGTMS on bleeding and PEH formation in lumbar micoroendoscopic surgery.

STUDY DESIGN

This is a randomized controlled trial (RCT) with additional prospective observational cohort.

PATIENT SAMPLE

Patients were registered from July 2017 to September 2018 and a hundred and three patients undergoing microendoscopic laminectomy for lumbar spinal stenosis at a single institution were enrolled in this study.

OUTCOME MEASURES

The primary outcome was the drainage volume within 48 hours after surgery. Secondary outcomes were the numerical rating scale (NRS) of leg pain on the second (NRS2) and seventh day (NRS7) after surgery and the hematoma area ratio (HAR) in horizontal images on magnetic resonance image (MRI).

METHODS

In the RCT, 41 cases that received TGTMS (F group) were compared with 41 control group cases (C group) that did not receive TGTMS at the end of the procedure. Drainage volume, NRS2, NRS7, and HAR on MRI were evaluated. Nineteen cases were excluded from the RCT (I group) due to difficulty of hemostasis during surgery and the intentional use of TGTMS for hemostasis. I group was compared with C group in the drainage volume and NRS of leg pain as a prospective observational study.

RESULTS

The RCT demonstrated no statistically significant difference in drainage volume between those receiving TGTMS (117.0±71.7; mean±standard deviation) and controls (125.0±127.0; p=.345). The NRS2 and NRS7 was 3.5±2.6 and 2.8±2.5 in the F group, respectively, and 3.1±2.6 and 2.1±2.3 in the C group, respectively. The HAR on MRI was 0.19±0.19 in the F group and 0.17±0.13 in the C group. There was no significant difference in postoperative leg pain and HAR (p=.644 for NRS2, p=.129 for NRS7, and p=.705 for HAR). In the secondary observational cohort, the drainage volume in the I group was 118.3±151.4, and NRS2 and NRS7 was 3.5±2.0 and 2.6±2.6, respectively. There were no statistically significant differences in drainage volume (p=.386) or postoperative NRS of leg pain between these two groups (p=.981 and .477 for NRS2 and NRS7, respectively).

CONCLUSIONS

The prophylactic use of TGTMS in patients undergoing microendoscopic laminotomy for lumbar spinal stenosis did not demonstrate any difference in postoperative bleeding or PEH. Nonetheless, for patients that had active bleeding that required the use of TGTMS, there was no evidence of difference in postoperative clinical outcomes relative to controls.

Lateral lumbar interbody fusion after reduction using the percutaneous pedicle screw system in the lateral position for Meyerding grade II spondylolisthesis: a preliminary report of a new lumbar reconstruction strategy

BACKGROUND

Utilization of a cage with a large footprint in lateral lumbar interbody fusion (LLIF) for the treatment of spondylolisthesis leads to a high fusion rate and neurological improvement owing to the indirect decompression effect and excellent alignment correction. However, if an interbody space is too narrow for insertion of an LLIF cage for cases of spondylolisthesis of Meyerding grade II or higher, LLIF cannot be used. Therefore, we developed a novel strategy, LLIF after reduction by the percutaneous pedicle screw (PPS) insertion system in the lateral position (LIFARL), for surgeons to perform accurate and safe LLIF with PPS in patients with such pathology. This study aimed to introduce the new surgical strategy and to present preliminary clinical and radiological results of patients with spondylolisthesis of Meyerding grade II.

METHODS

Six consecutive patients (four men and two women; mean age, 72.7 years-old; mean follow-up period, 15.3 months) with L4 spondylolisthesis of Meyerding grade II were included. Regarding the surgical procedure, first, PPSs were inserted into the L4 and L5 vertebrae fluoroscopically, and both rods were placed in the lateral position. The L5 set screws were fixed tightly, and the L4 side of the rod was floated. Second, the L4 vertebra was reduced by fastening the L4 set screws so that they expanded the anteroposterior width of the interbody space. At that time, the L4 set screws were not fully tightened to the rods to prevent the endplate injury. Finally, the LLIF procedure was started. After inserting the cage, a compression force was added to the PPSs, and the L4 set screws were completely fastened.

RESULTS

The mean operative time was 183 min, and the mean blood loss was 90.8 mL. All cages were positioned properly. Visual analog scale score and Oswestry disability index improved postoperatively. Bone union was observed using computed tomography 12 months after surgery.

CONCLUSION

For cases with difficulty in LLIF cage insertion for Meyerding grade II spondylolisthesis due to the narrow anteroposterior width of interbody space, LIFARL is an option to achieve LLIF combined with posterior PPS accurately and safely.

TRIAL REGISTRATION

UMIN-Clinical Trials Registry, UMIN000040268, Registered 29 April 2020, https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000045938.

Adjacent segment disease on hip joint as a complication of spinal fusion surgery including sacroiliac joint fixation

PURPOSE

Recently, the number of adult spinal deformity surgeries including sacroiliac joint fixation (SIJF) by using an S2 alar iliac screw or iliac screw has increased to avoid the distal junctional failure. However, we occasionally experienced patients who suffered from hip pain after a long instrumented spinal fusion. We hypothesized that long spinal fusion surgery including SIJF influenced the hip joint as an adjacent joint. The aim of this paper was to evaluate the association between spinal deformity surgery including SIJF and radiographic progression of hip osteoarthritis (OA).

METHODS

This study was retrospective cohort study. In total, 118 patients who underwent spinal fusion surgery at single center from January 2013 to August 2018 were included. We measured joint space width (JSW) at central space of the hip joint. We defined reduction of more than 0.5 mm/year in JSW as hip OA progression. The patients were divided into two groups depending on either a progression of hip osteoarthritis (Group P), or no progression (Group N).

RESULTS

The number of patients in Group P and Group N was 47 and 71, respectively. Factor that was statistically significant for hip OA was SIJF (p = 0.0065, odds ratio = 7.1, 95% confidence interval = 1.6-31.6). There were no other significant differences by the multiple logistic regression analysis.

CONCLUSION

This study identified spinal fixation surgery that includes SIJF as a predictor for radiographic progression of hip OA over 12 months. We should pay attention to hip joint lesions after adult spinal deformity surgery, including SIJF.

A short-segment fusion strategy using a wide-foot-plate expandable cage for vertebral pseudarthrosis after an osteoporotic vertebral fracture

OBJECTIVE

Various surgical treatments have been reported for vertebral pseudarthrosis after osteoporotic vertebral fracture (OVF). However, the outcomes are not always good. The authors now have some experience with combined anterior-posterior short-segment spinal fusion (1 level above and 1 level below the fracture) using a wide-foot-plate expandable cage. Here, they report their surgical outcomes with this procedure.

METHODS

Between June 2016 and August 2018, 16 consecutive patients (4 male and 12 female; mean age 75.1 years) underwent short-segment spinal fusion for vertebral pseudarthrosis or delayed collapse after OVF. The mean observation period was 20.1 months. The level of the fractured vertebra was T12 in 4 patients, L1 in 3, L2 in 4, L3 in 3, and L4 in 2. Clinical outcomes were assessed using the lumbar Japanese Orthopaedic Association (JOA) scale and 100-mm visual analog scale for low-back pain. Local kyphotic angle, intervertebral height, bone union rate, and instrumentation-related adverse events were investigated as imaging outcomes. The data were analyzed using the Wilcoxon signed-rank test.

RESULTS

The mean operating time was 334.3 minutes (range 256-517 minutes), and the mean blood loss was 424.9 ml (range 30-1320 ml). The only perioperative complication was a superficial infection of the posterior wound that was cured by irrigation. The lumbar JOA score and visual analog scale value improved from 11.2 and 58.8 mm preoperatively to 20.6 and 18.6 mm postoperatively, respectively. The mean local kyphotic angle and mean intervertebral height were 22.6° and 28.0 mm, respectively, before surgery, -1.5° and 40.5 mm immediately after surgery, and 7.0° and 37.1 mm at the final observation. Significant improvement was observed in both parameters immediately after surgery and at the final observation when compared with the preoperative values. Intraoperative endplate injury occurred in 8 cases, and progression of cage subsidence of 5 mm or more was observed in 2 of these cases. Proximal junctional kyphosis was observed in 2 cases. There were no cases of screw loosening. No cases required reoperation due to instrument-related adverse events. Bone union was observed in all 14 cases that had CT evaluation.

CONCLUSIONS

This short-segment fusion procedure is relatively minimally invasive, and local reconstruction and bone fusion have been achieved. This procedure is considered to be attempted for the surgical treatment of osteoporotic vertebral pseudarthrosis after OVF.