Published papers

Ossification of the posterior longitudinal ligament (OPLL) is a progressive disease. The bridging of ossified lesions to the vertebral body gradually increases, thereby decreasing the mobility of the cervical spine; thus, cervical spine function may decrease over time. However, cervical spine function in patients with cervical OPLL has not been evaluated in large prospective studies. Therefore, we conducted a prospective multicenter study to clarify whether ossification spread can influence cervical spine function and quality of life (QOL) in patients with cervical OPLL. In total, 238 patients (162 men, 76 women; mean age, 63.9 years) were enrolled from 16 institutions. Each patient underwent whole spine computed tomography and was evaluated for cervical spine function and QOL using the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ). In the multivariate regression analysis, a higher neck VAS score and a larger number of bridge formations of OPLL in the whole spine were significant predictors of adverse outcomes related to cervical spine function. This is the first prospective multicenter study to reveal the impact of ossification spread on cervical spine function. These findings are important to understand the natural course of OPLL and can serve as controls when evaluating postoperative cervical spine function.

STUDY DESIGN: A longitudinal, 20-year comparative study of patients with whiplash-associated disorders (WAD). OBJECTIVE: The aim of this study was to clarify the long-term impact of WAD on patient symptoms and on magnetic resonance imaging (MRI) findings of the cervical spine, in comparison with asymptomatic volunteers. SUMMARY OF BACKGROUND DATA: The long-term impact of WAD has not been fully elucidated. METHODS: Between 1993 and 1996, we conducted a cross-sectional comparative study of 508 acute WAD patients and 497 asymptomatic volunteers, all of whom underwent MRI on cervical spine and physical examinations. For this 20-year follow-up comparative study, 75 WAD patients and 181 control subjects aged <60 years were recruited from the original cohort. The MRI findings, including discs' signal intensities, posterior disc protrusions, anterior dural compressions, spinal cord disc space narrowing, and foraminal stenoses, were evaluated using two to four numerical grades. The results of the WAD patients and control subjects were compared. RESULTS: In this follow-up, the prevalence of shoulder stiffness (72.0% vs. 45.9%), headache (24.0% vs. 12.2%), and arm pain (13.3% vs. 3.9%) were significantly greater in WAD patients than in control subjects. The multiregression analysis revealed that a history of WAD was associated with shoulder stiffness (odds ratio [OR]: 3.36), headache (OR: 2.39), and arm pain (OR: 3.82). Although MRI findings in WAD patients were more degenerated than in control subjects in the initial study, all MRI findings were similar at the 20-year follow-up. There were no significant correlations between clinical cervical symptoms and progression in each MR finding in either group. CONCLUSION: After 20 years, whiplash injuries significantly impacted the residual symptoms of shoulder stiffness, headache, and arm pain when compared with initially asymptomatic volunteers. The progression of degenerative changes in the cervical intervertebral discs after 20 years revealed no association with existing whiplash injuries, neither did the residual cervical-related symptoms.Level of Evidence: 3.

Mechanical failure (MF) following adult spinal deformity (ASD) surgery is a severe complication and often requires revision surgery. Predicting a patient’s risk of MF is difficult, despite several potential risk factors that have been reported. The purpose of this study was to establish risk stratification model for predicting the MF based on demographic, and radiographic data. This is a multicenter retrospective review of the risk stratification for MF and included 321 surgically treated ASD patients (55 ± 19 yr, female: 91%). The analyzed variables were recorded for at least 2 yr and included age, gender, BMI, BMD, smoking status, frailty, fusion level, revision surgery, PSO, LIF, previous surgery, spinal alignment, GAP score, Schwab-SRS type, and rod materials. Multivariate logistic regression analyses were performed to identify the independent risk factors for MF. Each risk factor was assigned a value based on its regression coefficient, and the values of all risk factors were summed to obtain the PRISM score (range 0–12). We used an 8:2 ratio to split the data into a training and a testing cohort to establish and validate the model. MF developed in 41% (n = 104) of the training subjects. Multivariate analysis revealed that BMI, BMD, PT, and frailty were independent risk factors for MF (BMI: OR 1.7 [1.0–2.9], BMD: OR 3.8 [1.9–7.7], PT: OR 2.6 [1.8–3.9], frailty: OR 1.9 [1.1–3.2]). The MF rate increased with and correlated well with the risk grade as shown by ROC curve (AUC of 0.81 [95% CI 0.76–0.86]). The discriminative ability of the score in the testing cohort was also good (AUC of 0.86 ([95% CI 0.77–0.95]). We successfully developed an MF-predicting model from individual baseline parameters. This model can predict a patient’s risk of MF and will help surgeons adjust treatment strategies to mitigate the risk of MF.

Introduction: Osteoporotic vertebral fracture (OVF) is the most common osteoporotic fracture, and some patients require surgical intervention to improve their impaired activities of daily living with neurological deficits. However, many previous reports have focused on OVF around the thoracolumbar junction, and the surgical outcomes of lumbar OVF have not been thoroughly discussed. We aimed to investigate the surgical outcomes for lumbar OVF with a neurological deficit. Methods: Patients who underwent fusion surgery for thoracolumbar OVF with a neurological deficit were enrolled at 28 institutions. Clinical information, comorbidities, perioperative complications, Japanese Orthopaedic Association scores, visual analog scale scores, and radiographic parameters were compared between patients with lower lumbar fracture (L3-5) and those with thoracolumbar junction fracture (T10-L2). Each patient with lower lumbar fracture (L group) was matched with to patients with thoracolumbar junction fracture (T group). Results: A total 403 patients (89 males and 314 females, mean age: 73.8 ± 7.8 years, mean follow-up: 3.9 ± 1.7 years) were included in this study. Lower lumbar OVF was frequently found in patients with lower bone mineral density. After matching, mechanical failure was more frequent in the L group (L group: 64%, T group: 39%; p < 0.001). There was no difference between groups in the clinical and radiographical outcomes, although the rates of complication and revision surgery were still high in both groups. Conclusions: The surgical intervention for OVF is effective in patients with myelopathy or radiculopathy regardless of the surgical level, although further study is required to improve clinical and radiographical outcomes.

Introduction: Intramedullary lesions and tumors are generally accessed by a posterior approach. However, if the lesion is located on the ventral side of the spinal cord, a posterior resection with myelotomy poses technical difficulties. We report two cases of complete resection of a cervical ventral intramedullary cavernous hemangioma using an anterior approach. Case Report: Two cases of intramedullary cavernous hemangioma located on the ventral side of the spinal cord were successfully treated by total resection with anterior cervical corpectomy followed by anterior spinal fusion with an autologous bone strut from the iliac crest. In both cases, the postoperative course was uneventful, and there was no neurological deficit. Bony fusion was achieved, and there was no recurrence or complication during a follow-up period of at least two years. Conclusions: Here, we describe an anterior approach for total resection of cavernous hemangiomas on the ventral side of the cervical spinal cord. Outcomes were stable two years after the operations. Although the method should be assessed with more patients and a longer follow-up time, this anterior approach may be useful for the radical resection of a vascular malformation or tumor.

Study Design.A retrospective multicenter database review of 240 consecutive patients at least 21 years of age (mean 58±17, range 22-79) who underwent surgery for adult spinal deformity (ASD) and were followed at least 2 years.Objective.To investigate how treatment for frailty affects complications in surgery for ASD.Summary of Background Data.Several recent studies have focused on associations between frailty and surgical complications. However, it is not clear whether treating frailty affects complication rates in surgery for ASD.Methods.Patients were categorized as robust (R group), prefrail, or frail based on the modified frailty index (mFI); prefrail and frail patients were divided by good control of frailty (G group), defined as treatment following the appropriate guidelines for each mFI factor, or poorly controlled frailty (PC group). We compared clinical outcomes and perioperative and 2-year complications between the three groups.Results.Of the 240 patients, 142 (59%) were robust, 81 (34%) were prefrail, and 17 (7%) were frail. Among the frail and prefrail patients, 71 (72%) were classified as G and 27 (28%) as PC. The perioperative complication rate was similar in the G and PC groups (32% vs. 37%) but was significantly lower in the R group (15%, P<0.01). The age-and sex-Adjusted odds ratio for 2-year complications was not different in the P group when the G group was referenced (odds ratio 1.3 [0.5-3.2], P=0.63). In the G and PC groups, which had similar 2-year outcomes, the Scoliosis Research Society-22 function and total scores were significantly lower than in the R group (function: R 3.9±0.7, G 3.5±0.7, P 3.3±0.6; total: R 3.9±0.6, 3.7±0.7, 3.4±0.6; P<0.01).Conclusion.Regardless of its treatment status, frailty increases the risk of complications and inferior clinical outcomes in ASD surgery. Surgeons should routinely evaluate frailty and inform patients of frailty-related risks when considering surgery for ASD.Level of Evidence: 4.

Study Design: Retrospective single-center study. Objective: We investigated the risk factors of postoperative shoulder imbalance (PSI) in patients with Lenke type 2 adolescent idiopathic scoliosis (AIS) including the position of preoperative upper end vertebra (UEV). Methods: Seventy-five patients with Lenke type 2 AIS who underwent posterior correction and fusion surgeries from 2008 to 2018 were included. We included only patients whose upper instrumented vertebrae were at T2. The patients were divided into 2 groups based on radiographic shoulder height (RSH) at final follow-up, namely PSI group and non-PSI group, and PSI was defined as RSH > 10 mm. UEV, RSH, Cobb angle, curve flexibility, T1 and T2 tilt, correction rate, Risser grade, Scoliosis Research Society-22 scores, and demographic data were compared between the groups using independent t-tests or chi-square tests. Variables with P value < 0.20 in univariate analysis were assessed in logistic regression analysis. Results: Thirty-four patients in the PSI group and 37 patients in the non-PSI group were analyzed. Univariate analysis revealed that there were more patients with UEV at T1 (PSI: 85%, non-PSI: 54%, P < 0.01) and Risser grade ≥ 3 (PSI: 88%, non-PSI: 62%; P < 0.05) in the PSI group than in the non-PSI group. Logistic regression analysis revealed that UEV at T1 (odds ratio [OR] = 4.1 [1.2–14.4], P < 0.05) and Risser grade ≥ 3 (OR = 3.9 [1.1–14.5], P < 0.05) are significantly associated with PSI. Conclusions: UEV at T1 and Risser grade ≥ 3 at the time of surgery are significant risk factors of PSI.

© 2018 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals, Inc. Background: Congenital scoliosis (CS) is defined as a lateral curvature of the spine due to the vertebral malformations and has an incidence of 0.5–1/1,000 births. We previously examined TBX6 in Japanese CS patients and revealed that approximately 10% of CS was caused by TBX6 mutations. However, the genetic cause of remaining CS is unknown. Methods: We recruited 78 CS patients without TBX6 mutations and major comorbidities, and investigated the genes previously reported to be associated with CS and congenital vertebral malformations by whole-exome sequencing. Results: We identified the compound heterozygous missense variants in LFNG in one patient. No likely disease-causing variants were identified in other patients, however. LFNG encodes a GlcNAc-transferase. The LFNG variants showed loss of their enzyme function. Conclusions: A LFNG mutation is reported in a case of spondylocostal dysostosis (SCD), a skeletal dysplasia with severe malformations of vertebra and rib. The CS patient with LFNG mutations had multiple vertebral malformations including hemivertebrae, butterfly vertebrae, and block vertebrae, and rib malformations. LFNG mutations may cause a spectrum of phenotypes including CS and SCD. The current list of known disease genes could explain only a small fraction of genetic cause of CS.

© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. Purpose: To clarify the effect of posterior correction and fusion surgery on the trunk–pelvic kinematics during gait in adolescent idiopathic scoliosis (AIS) patients with single thoracic major curve. Methods: Among preoperative AIS patients who planned correction surgery, 18 patients with Lenke type 1A or B were selected for this study. All patients were female. The patients’ trunk and pelvic kinematics during gait were measured three-dimensionally and dynamically using reflective markers, optoelectronic motion capture system. The gait analysis was performed before and 1–2 years after surgery. The trunk and pelvic symmetry during gait was evaluated at coronal, sagittal, and transverse planes between concave and convex sides. Results: The trunk and pelvic angles in sagittal and coronal planes were equivalent between concave and convex sides before and after surgery. Preoperatively, transverse trunk rotation angles were significantly deviated toward the concave (left) side during both static standing (4.3 ± 2.0°) and gait (8.8 ± 0.6°, p < 0.01). Preoperative transverse pelvic rotation angles were significantly deviated toward the convex side during static standing (4.0 ± 3.8°). However, pelvis displayed with symmetric rotational kinematics during gait. Postoperatively, the deviated transverse trunk rotation angle significantly decreased (1.6 ± 0.3°), and the transverse rotational kinematics of both trunk and pelvis improved to symmetric. Conclusions: Posterior correction and fusion surgery have improved preoperative asymmetric global rotational kinematics of trunk and pelvis in transverse plane to symmetric postoperatively in AIS patients with thoracic single major curve. Graphical abstract: These slides can be retrieved under Electronic Supplementary Material.[Figure not available: see fulltext.].

© 2018 Elsevier Inc. BACKGROUND CONTEXT: Spinal epidural lipomatosis (SEL) is a condition in which excess lumbar epidural fat (EF) deposition often leads to compression of the cauda equina or nerve root. Although SEL is often observed in obese adults, no systematic research investigating the potential association between SEL and metabolic syndrome has been conducted. PURPOSE: To elucidate potential association between SEL and metabolic syndrome. STUDY DESIGN: An observational study used data of a medical checkup. PATIENT SAMPLE: We retrospectively reviewed data from consecutive subjects undergoing medical checkups. A total of 324 subjects (174 men and 150 women) were enrolled in this study. OUTCOME MEASURES: The correlation of EF accumulation with demographic data and metabolic-related factors was evaluated. METHODS: The degree of EF accumulation was evaluated based on the axial views of lumbar magnetic resonance imaging. Visceral and subcutaneous fat areas were measured at the navel level using abdominal computed tomography. Metabolic syndrome was diagnosed according to the criteria of the Japanese Society of Internal Medicine. The correlation of SEL with metabolic syndrome and metabolic-related conditions was statistically evaluated. RESULTS: The degree of EF accumulation demonstrated a significant correlation to body mass index, abdominal circumference, and visceral fat area. However, age, body fat percentage, and subcutaneous fat area showed no correlation with the degree of EF accumulation. Logistic regression analysis revealed that metabolic syndrome (odds ratio [OR]=3.8, 95% confidence interval [CI]=1.5–9.6) was significantly associated with SEL. Among the diagnostic criteria for metabolic syndrome, visceral fat area ≥100 cm 2 (OR=4.8, 95% CI=1.5–15.3) and hypertension (OR=3.5, 95% CI=1.1–11.8) were observed to be independently associated with SEL. CONCLUSION: This is the first study to demonstrate that metabolic syndrome is associated with SEL in a relatively large, unbiased population. Our data suggest that metabolic-related conditions are potentially related to EF deposition and that SEL could be a previously unrecognized manifestation of metabolic syndrome.

© 2018 The Japanese Orthopaedic Association Background: Diffuse idiopathic skeletal hyperostosis (DISH) makes the spine prone to unstable fractures with neurological deterioration. This study was conducted to assess clinical and radiographic features of spinal fractures in DISH by the level of spinal injury, and to evaluate the optimal treatment for each level. Methods: A multicenter retrospective study over a 5-year period, including 46 patients (35 males; 11 females) with a mean age of 77.2 ± 9.7 years at the time of injury. By fracture level, there were 7 cervical (15.2%), 25 thoracic (54.3%), and 14 lumbar (30.4%) fractures. We recorded the cause of injury, whether diagnosis was delayed, and neurological status by Frankel grade. Ossification and fracture patterns were assessed by CT-multi-planar reconstruction (MPR). Results: Neurological status immediately after the cervical-spine injury was C (28.6%) or E (71.4%); after thoracic injury, C (12.0%) or E (88.0%); and after lumbar injury, D (21.4%) or E (78.6%). Inability to walk at admission was more frequent in patients with a spinal-cord injury above the lumbar level (P = .033). Vertebral-body fractures were observed in 14.3% of the cervical injuries, 80.0% of the thoracic injuries, and 50.0% of the lumbar injuries (P = .004). Most patients with a cervical fracture had a disc-level fracture (85.7%). Posterior-column ankylosis was observed in 14.3% of the cervical-fracture group, 72.0% of the thoracic-fracture group, and 78.6% of the lumbar-fracture group (P = .008). Conclusion: Ossification and fracture patterns in patients with DISH varied distinctly by the level of spinal injury. Intervertebral-disc fractures were frequently observed in the cervical spine. Delayed diagnosis, vertebral-body fracture, and posterior-column ankylosis were observed in the thoracolumbar spine. This study recommends 3 above and 3 below fusion, to avoid instrumentation failure in the fixation of spinal fracture in patients with DISH.

© 2019 Background: Short stride length is one of clinical symptoms associated with lumbar spinal stenosis (LSS). Short stride is a risk factor for falls; therefore, identification of factors associated with short stride is critical for fall prevention in LSS patients. Although the Two-Step test can conveniently assess maximal stride length, it has not become widely used; therefore, its data are limited. We identified the potential factors associated with short stride of elderly LSS patients using Two-Step test. Methods: Clinical data of patients aged >65 years who planned to undergo surgery for LSS were prospectively collected at multiple institutions. Patients were assessed with the Two-Step test and Timed Up-and-Go Test prior to surgery; 357 consecutive patients were enrolled. We determined the cut-off value of the Two-Step test score for short stride, referring to the Timed Up-and-Go Test score of 13.5 s, used to indicate high risk of falls in elderly individuals. Logistic regression model was constructed to identify factors associated with short stride. Results: The Two-Step test score showed moderate-to-strong inverse correlation with that of Timed Up-and-Go Test (r = −0.65, p < 0.001). Using the tentative Two-Step test cut-off value (0.93) for short stride, multivariable analysis showed that age ≥80 years (OR = 2.3, 95% CI:1.1–4.8), a score of <60 for lumbar function in Japanese Orthopedic Association Back Pain Evaluation Questionnaire (OR = 2.7, 95% CI:1.5–4.7), motor deficit (OR = 2.7, 95% CI:1.2–6.1), and sagittal vertical axis ≥50 mm (OR = 2.1, 95% CI:1.2–3.5) were factors significantly associated with short stride in elderly patients with LSS. Conclusions: Using the Two-Step test, we found that 80 years old and over, lumbar dysfunction, motor deficit of the lower extremities, and forward-bent posture were associated with short stride in LSS patients. Therefore, elderly LSS patients with these conditions may have a higher risk for falls.

STUDY DESIGN: A multicenter retrospective case series of patients treated surgically for adult spinal deformity (ASD). OBJECTIVE: The aim of this study was to compare clinical outcomes between propensity score matched ASD patients with or without drop body syndrome (DBS). SUMMARY OF BACKGROUND DATA: DBS is an extreme primary sagittal-plane deformity often seen in Asian countries. Although the importance of sagittal alignment is widely recognized, surgical outcomes for deformities purely in the sagittal plane are poorly understood. METHODS: This study included 243 consecutive patients (age 66 ± 17 years; range 22-78) who were treated surgically for ASD and were followed at least 2 years (mean follow-up 3.7 ± 2.3 years). DBS was defined as a primary lumbar kyphosis with PI-LL >40°, Cobb angle <30°, and multifidus cross-sectional area <300 mm. DBS patients were matched with non-DBS patients by propensity scores for age, gender, lowest instrumented vertebra (LIV) level, and number of levels fused. Demographics, radiographic findings, and clinical outcomes were compared between DBS and non-DBS patients. RESULTS: Of 243 patients with ASD, 34 had DBS (14%); 28 of these were propensity-matched with ASD patients without DBS. Baseline bone mineral density (BMD), body mass index (BMI), and frailty were similar in DBS and non-DBS patients. Baseline sagittal alignment was worse in DBS than in non-DBS patients [C7SVA 14 ± 5 vs. 8 ± 5 cm; pelvic incidence (PI) - lumbar lordosis (LL) 60 ± 14 vs. 36 ± 20°], and scoliosis research society (SRS)22 scores were also worse for DBS patients (2.5 ± 0.6 vs. 2.9 ± 0.8). Although DBS patients had more complications (20 DBS vs. 16 non-DBS), the clinical outcomes were similarly improved in both groups after surgery. At the 2-year follow-up, the spinopelvic malalignment was worse in DBS than non-DBS patients (PI-LL 17 ± 16° vs. 8 ± 13°, P < 0.05). CONCLUSION: DBS affected 14% of 234 ASD patients. Although DBS patients had inferior baseline SRS22 scores than non-DBS patients, ASD surgery resulted in similar clinical improvement in both groups. Future studies should examine the influence of lifestyle and genetics on clinical outcomes after surgery for DBS.3.

OBJECTIVE The Scoliosis Research Society-22r questionnaire (SRS-22r) has been shown to be reliable, valid, and responsive to change in patients with adult spinal deformity (ASD) undergoing surgery. The minimal clinically important difference (MCID) is the smallest difference in a health-related quality of life score that is considered to be worthwhile or clinically important to the individual. The authors hypothesized that the proportion of patients with ASD achieving an MCID in the SRS-22r score would be different between two culturally different cohorts. The purpose of this study was to compare the proportion of patients with ASD achieving MCID for the SRS-22r domains in North American (NA) and Japanese cohorts. METHODS A total of 137 patients from North America (123 women, mean age 60.0 years) and 60 patients from Japan (56 women, mean age 65.5 years) with at least 2 years of follow-up after corrective spine surgery for ASD were included. Except for self-image, published Japanese MCID values of SRS-22r for ASD were higher (function = 0.90, pain = 0.85, self-image = 1.05, subtotal = 1.05) than the published NA MCID values (function = 0.60, pain = 0.40, self-image = 1.23, subtotal = 0.43). RESULTS There was a statistically significant improvement in all SRS-22r domain scores at 2 years compared to baseline in both cohorts. Except for mental health (NA = 0.32, Japanese = 0.72, p = 0.005), the mean improvement from baseline to 2 years was similar between the NA and Japanese cohorts. The proportion of patients achieving MCID was higher in North America for function (NA = 51%, Japanese = 30%, p = 0.006), pain (NA = 80%, Japanese = 47%, p < 0.001), and subtotal (NA = 72%, Japanese = 35%, p < 0.001), while there was no significant difference for self-image (NA = 53%, Japanese = 58%, p = 0.454). CONCLUSIONS Despite similar improvements in SRS-22r domain scores from baseline to 2 years postoperatively, the proportion of patients reaching SRS-22r MCID for function, pain, and subtotal after ASD surgery was higher in the NA cohort than in the Japanese cohort. This may imply that patients in North America and Japan may value observed changes in clinical status differently.

Introduction: Gliofibroma is a rare tumor that develops in the brain and spinal cord. Due to the rarity of its nature, its pathophysiology and appropriate treatment remain elusive. We report a case of intramedullary spinal cord gliofibroma that was surgically treated multiple times. This report is of great significance because this is the first case of recurrence of this tumor. Case presentation: A 32-year-old woman complained of gait disturbance and was referred to our institution. At the age of 13 years, she was diagnosed with intramedullary gliofibroma and underwent gross total resection (GTR) in another hospital. Based on imaging findings, tumor recurrence was suspected at the level of cervical spinal cord, and surgery was performed. However, the resection volume was limited to 50% because the boundary between the tumor and spinal cord tissue was unclear and intraoperative neuromonitoring alerted paralysis. At 1 year postoperatively, the second surgery was performed to try to resect the residual tumor, but subtotal resection was achieved at most. At 2 years after the final surgery, no tumor recurrence was observed, and neurologic function was maintained to gait with cane. Discussion: Although complete resection is desirable for this rare tumor at the initial surgery, there is a possibility to recur even after GTR with long-term follow-up. During surgical treatment for tumor recurrence, fair adhesion to the spinal cord is expected, and reoperation and/or adjuvant therapy might be considered in the future if the tumor regrows and triggers neurological deterioration.

Purpose: To elucidate the influence of spinal deformity in adolescent idiopathic scoliosis (AIS) on lumbar intervertebral disc (IVD) degeneration in adulthood using magnetic resonance imaging (MRI). Methods: A total of 102 patients (8 men, 94 women; mean age, 31.4 years) who had developed idiopathic scoliosis at the age of 10–18 years and underwent preoperative lumbar spine MRI at the age of ≥ 20 were included in the study. Twenty volunteers (3 men, 17 women; mean age, 33.6 years) without scoliosis were assessed as controls. We divided the adult scoliosis patients into two groups: Group A consisted of patients with lumbar modifier A, and Group BC consisted of those with modifiers B and C. IVD degeneration from L1/2 to L5/S1 was assessed by MRI. The Scoliosis Research Society-22 (SRS-22) patient questionnaire was used in the patients’ clinical assessment. Results: There were 40 patients in the Group A and 62 in the Group BC. Compared to the control groups, significant IVD degeneration was observed at L2/3 and L3/4 in Group A, and at all levels except for L5/S1 in Group BC. The proportion of degenerated IVDs patients (Grades 1c and 2) was significantly higher in Group BC than those in Group A at L3/L4 and L4/L5. Furthermore, the severity of IVD degeneration was significantly greater in the group BC than in the group A at all levels, except for L5/S1, especially in patients aged > 30 years. The mean scores of all subdomains in the SRS-22 questionnaire were comparable between the two groups. Conclusion: Our study showed that the residual lumbar curvature from AIS may have accelerated IVD degeneration in adulthood, especially in patients aged > 30 years. Level of evidence: III.

Background: Patients with DISH are susceptible to spinal fractures and subsequent neurological impairment, including after minor trauma. However, DISH is often asymptomatic and fractures may have minimal symptoms, which may lead to delayed diagnosis. The purpose of this study was to identify risk factors for delayed diagnosis of spinal fractures in patients with diffuse idiopathic skeletal hyperostosis (DISH). Methods: The subjects were 285 patients with DISH surgically treated at 18 medical centers from 2005 to 2015. Cause of injury, imaging findings, neurological status at the times of injury and first hospital examination, and the time from injury to diagnosis were recorded. A delayed diagnosis was defined as that made >24 h after injury. Results: Main causes of injury were minor trauma due to a fall from a standing or sitting position (51%) and high-energy trauma due to a fall from a high place (29%) or a traffic accident (12%). Delayed diagnosis occurred in 115 patients (40%; 35 females, 80 males; mean age 76.0 ± 10.4 years), while 170 (60%; 29 females, 141 males; mean age 74.6 ± 12.8 years) had early diagnosis. Delayed group had a significantly higher rate of minor trauma (n = 73, 63% vs. n = 73, 43%), significantly more Frankel grade E (intact neurological status) cases at the time of injury (n = 79, 69% vs. n = 73, 43%), and greater deterioration of Frankel grade from injury to diagnosis (34% vs. 8%, p < 0.01). In multivariate analysis, a minor trauma fall (OR 2.08; P < 0.05) and Frankel grade E at the time of injury (OR 2.29; P < 0.01) were significantly associated with delayed diagnosis. Conclusion: In patients with DISH, it is important to keep in mind the possibility of spinal fracture, even in a situation in which patient sustained only minor trauma and shows no neurological deficit. This is because delayed diagnosis of spinal fracture can cause subsequent neurological deterioration.

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

Background:Distal adding-on (DA) in adolescent idiopathic scoliosis is a radiographic complication that can negatively affect clinical results. However, the risk factors for DA and the influences of DA on the residual lumbar curves have not been fully elucidated in Lenke type 1B and 1C curves. The objective of this study was to investigate risk factors for postoperative DA in Lenke type 1B and 1C curves, and the influence of DA on residual lumbar curves.Methods:We retrospectively evaluated 46 adolescent idiopathic scoliosis patients with Lenke type 1B or 1C curves who underwent posterior correction and fusion surgery with selective thoracic fusion. Patients were grouped according to the presence or absence of DA on radiographs at the 2-year follow-up. We compared coronal radiographic parameters between the 2 groups, including the Cobb angle, L4 tilt angle, apical translation, and relative positions of the end vertebra (EV), stable vertebra (SV), neutral vertebra (NV), and last touching vertebra (LTV) to the lower instrumented vertebra (LIV).Results:DA was present in 11 patients (24%) at the 2-year follow-up, and the mean LIV-EV, LIV-NV, LIV-SV, and LIV-LTV relative positions were significantly smaller in the DA than in the non-DA group. Preoperative radiographic parameters were similar between the 2 groups, including the mean L4 tilt angle (non-DA,-8±4 degrees; DA,-7±4 degrees). At the 2-year follow-up, the mean apical translation of the lumbar curve was smaller in the DA group (non-DA,-16±8 mm; DA,-7±11 mm) and the mean L4 tilt angle was significantly more horizontalized (non-DA,-8±4 degrees; DA,-1±5 degrees). Multivariate analysis showed that the number of levels between the LIV and LTV (LIV-LTV) was significantly associated with DA.Conclusions:A LIV at or cranial to the LTV was a significant risk factor for postoperative DA in Lenke type 1B and 1C curves. Spontaneous correction of the residual lumbar curve was superior in patients with DA.

Introduction: Approximately 3% of osteoporotic vertebral fractures develop osteoporotic vertebral collapse (OVC) with neurological deficits, and such patients are recommended to be treated surgically. However, a proximal junctional fracture (PJFr) following surgery for OVC can be a serious concern. Therefore, the aim of this study is to identify the incidence and risk factors of PJFr following fusion surgery for OVC. Methods: This study retrospectively analyzed registry data collected from facilities belonging to the Japan Association of Spine Surgeons with Ambition (JASA) in 2016. We retrospectively analyzed 403 patients who suffered neurological deficits due to OVC below T10 and underwent corrective surgery; only those followed up for !2 years were included. Potential risk factors related to the PJFr and their cut-off values were calculated using multivariate logistic regression analysis and receiver operating characteristic (ROC) analysis. Results: Sixty-three patients (15.6%) suffered PJFr during the follow-up (mean 45.7 months). In multivariate analysis, the grade of osteoporosis (grade 2, 3: adjusted odds ratio (aOR) 2.92; p=0.001) and lower instrumented vertebra (LIV) level (sacrum: aOR 6.75; p=0.003) were independent factors. ROC analysis demonstrated that lumbar bone mineral density (BMD) was a predictive factor (area under curve: 0.72, p=0.035) with optimal cut-off value of 0.61 g/cm2 (sensitivity, 76.5%; specificity, 58.3%), but that of the hip was not (p=0.228). Conclusions: PJFr was found in 16% cases within 4 years after surgery; independent risk factors were severe osteoporosis and extended fusion to the sacrum. The lumbar BMD with cut-off value 0.61 g/cm2 may potentially predict PJFr. Our findings can help surgeons select perioperative adjuvant therapy, as well as a surgical strategy to prevent PJFr following surgery.