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Background and Objectives: This study is a retrospective analysis aimed at understanding the incidence and risk factors of proximal junctional kyphosis (PJK) following long-instrumented spinal fusion from L1 to the sacrum in patients with mild to moderate sagittal imbalance. Materials and Methods: It recruited consecutive patients undergoing instrumented fusion from L1 to the sacrum for degenerative lumbar disease between June 2006 and November 2019 in a single institution. The patients' preoperative clinical data, muscle status at T12-L1 on magnetic resonance images, and sagittal spinopelvic parameters were analyzed. Univariate analysis was used to compare clinical and radiographic data between PJK and non-PJK patients. Logistic regression analysis was used to investigate the independent risk factors for PJK. Results: A total of 56 patients were included in this study. The mean age at surgery was 67.3 years and mean follow-up period was 37.3 months. In total, 10 were male and 46 were female. PJK developed in 23 (41.1%) out of 56; of these patients, 20 (87.0%) developed PJK within 1 year postoperatively. In the univariate analysis between PJK and non-PJK patients, the PJK group showed more frequent osteoporosis, lower body mass index, smaller cross-sectional area (CSA) and more fat infiltration (FI) in erector spinae muscle at T12-L1 and larger preoperative TLK and PT with statistical significance ( p < 0.05). In the logistic regression analysis, severe (>50%) FI in erector spinae muscle (OR = 43.60, CI 4.10-463.06, R 2 N = 0.730, p = 0.002) and osteoporosis (OR = 20.49, CI 1.58-264.99, R 2 N = 0.730, p = 0.021) were statistically significant. Conclusions: Preexisting severe (>50%) fat infiltration in the erector spinae muscle and osteoporosis were independent risk factors associated with PJK following instrumented fusion from L1 to the sacrum, but age was not a risk factor.

Objective: To analyze the characteristics of "severe" dynamic sagittal imbalance (DSI) in patients with adult spinal deformity (ASD) and establish criteria for them., Methods: We retrospectively analyzed 102 patients with ASD presenting four cardinal signs of lumbar degenerative kyphosis. All patients underwent deformity corrective surgery and were divided into three groups according to the diagnostic criteria based on the Oswestry disability index and dynamic features (△Time walk : time until C7 sagittal vertical axis [C7SVA] reaches ≥ 20 cm after the start of walking) of sagittal imbalance. The paravertebral back muscles were analyzed and compared using T2-weighted axial imaging. We performed a statistically time-dependent spinopelvic sagittal parameter analysis of full standing lateral lumbar radiographs. Lumbar flexibility was analyzed using dynamic lateral lumbar radiography., Results: The patients were classified into the mild (△Time walk  ≥ 180 s, 35 patients), moderate (180 s > △Time walk  ≥ 30 s, 38 patients), and severe (△Time walk  < 30 s, 29 patients) groups. The back muscles in the severe group exhibited a significantly higher signal intensity (533.4 ± 237.5, p < 0.05) and larger area of fat infiltration (35.2 ± 5.4, p < 0.05) than those in the mild (223.8 ± 67.6/22.9 ± 11.9) and moderate groups (294.4 ± 214.7/21.6 ± 10.6). The analysis of lumbar flexibility revealed significantly lower values in the severe group (5.8° ± 2.5°, p < 0.05) than in the mild and moderate groups (14.2° ± 12.4° and 11.4° ± 8.7°, respectively). The severe group had significantly lower lumbar lordosis (LL, 25.1° ± 22.7°, p < 0.05) and Pelvic incidence-LL mismatch (PI-LL, 81.5° ± 26.6°, p < 0.001) than those of the mild (8.2° ± 16.3°/58.7° ± 18.8°) and moderate (14.3° ± 28.6°/66.8° ± 13.4°) groups. On receiver operating characteristic curve analysis, PI-LL was statistically significant, with an area under the curve of 0.810 (95% confidence interval) when the baseline was set at 75.3°. The severe group had more postoperative complications than the other groups., Conclusions: Our results suggest the following criteria for severe DSI: C7SVA > 20 cm within 30 s of walking or standing, a rigid lumbar curve < 10° on dynamic lateral radiographs, and a PI-LL mismatch > 75.3°., (© 2024. The Author(s).)

Objective: Junctional failures after long fusion stopping at L5 can present at both proximal and distal ends. The purpose of this study was to investigate incidences and risk factors of proximal junctional failure (PJF) and distal junctional failure (DJF) after long lumbar instrumented fusion stopping at L5 for adult spinal deformity., Methods: Sixty-three patients who underwent long fusion surgery stopping at L5 with a minimum follow-up of 3 years were reviewed retrospectively. PJF and DJF were defined as newly developed back pain and/or radiculopathy with corresponding radiographic failures. The incidence and risk factors of each junctional failure were analyzed using a log-rank test and Cox proportional hazards model., Results: Twelve men and 51 women were included in our study. Their mean age was 68.5 ± 7.0 years and the mean follow-up period was 84.5 ± 45.3 months. PJF and DJF occurred in 17 (27%) and 16 patients (25.4%), respectively. PJF and DJF developed at median durations of 32.1 months and 13.3 months, respectively, showing no significant difference between the two. Three patients presented with both PJF and DJF. Risk factors for PJF included lower body mass index, higher preoperative lumbar lordosis, and higher postoperative sagittal vertical axis (SVA) (hazard ratio, 0.570, 1.055, and 1.040, respectively). For DJF, higher preoperative SVA was an independent risk factor (hazard ratio, 1.010)., Conclusions: After long fusion surgery stopping at L5, PJF and DJF occurred at similar rates. Lower body mass index, higher preoperative lumbar lordosis, and higher postoperative SVA were risk factors for PJF. Higher preoperative SVA was an independent risk factor for DJF., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objective: The aim of this study was to investigate time-dependent rates and indications of unplanned reoperation and to evaluate the most common indication depending on the time interval after pedicle subtraction osteotomy (PSO) for correction of thoracolumbar kyphosis in patients with ankylosing spondylitis (AS)., Methods: A total of 321 consecutive patients with AS (284 men; mean age 43.8 years) with thoracolumbar kyphosis who underwent PSO were included. Patients who underwent reoperation after the index surgery were divided according to the duration of the follow-up period., Results: A total of 51 patients (15.9%) underwent unplanned reoperations. The reoperation groups had greater preoperative and postoperative C7 sagittal vertical axis (SVA), and less lordotic postoperative osteotomy angle (-4.3° ± 18.6° vs -15.0° ± 13.7°, p < 0.001). The perioperative change in SVA was not significantly different between groups (-10.0 ± 7.1 cm vs -10.0 ± 5.1 cm, p = 0.970), while that in the osteotomy angle was significantly different (-22.4° ± 21.3° vs -30.0° ± 11.5°, p = 0.014). Most reoperations (45.1%; 23/51) were performed within 2 weeks of the initial operation. Within 2 weeks, the most common cause of reoperation was neurological deficit in 10 patients, with a cumulative reoperation rate of 3.2%. After 3 years, the most common complications were mechanical complications in 8 patients, accounting for 15.7% (8/51) of patients. Overall, the most common indications for reoperation were mechanical complications (17 patients; 5.3%), followed by neurological deficits (12 patients; 3.7%)., Conclusions: PSO may be the most effective surgical procedure for the correction of thoracolumbar kyphosis in patients with AS. However, 51 patients (15.9%) required an unplanned reoperation.

Objective: We investigated the characteristics and revision rate of junctional failure after surgical correction for thoracolumbar kyphosis in patients with ankylosing spondylitis., Methods: A total of 230 patients had undergone surgical correction for thoracolumbar kyphosis from 2010 to 2019. The state of ankylosis between the uppermost instrumented vertebra (UIV) and UIV+1 and between the lowermost instrumented vertebra (LIV) and LIV-1 was analyzed using a modified Stoke ankylosing spondylitis spine score. Proximal junctional failure (PJF) and distal junctional failure (DJF) were defined as any type of symptomatic junctional failure., Results: Of the 230 patients, 23 (10.0%) had developed junctional failure. Of these 23 patients, 16 had had partial ankylosis and 7 had had complete ankylosis. PJF had developed in 10 patients and DJF in 13. The most common type of junctional failure was a junctional fracture, which developed in 12 patients. PJF had developed by UIV fracture in 4 patients, UIV+1 fracture in 1 patient, and UIV+2 in 1 patient. DJF had developed by LIV fracture in 6 patients, metallic failure in 5, and progression of DJF in 2 patients. The average time to the development of PJF and DJF was 13 months and 12.4 months, respectively. All 10 patients with PJF and 7 of 13 patients with DJF (53.8%) had required reoperation. Of the 12 patients with junctional fracture, 11 (91.7%) had undergone reoperation., Conclusions: Of the 23 patients with junctional failure, 16 had had immature ossification of the anterior longitudinal ligament. Therefore, to prevent junctional failure, the state of ankylosis seems to be important for selecting the fusion level after osteotomy. Once junctional failure has developed, however, reoperation should be considered owing to the stress concentration at the UIV or LIV., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Study Design: A retrospective study., Objective: The aim of this study was to investigate proximal junctional kyphosis (PJK) after lumbosacral long fusion according to preoperative Roussouly and lumbar degenerative kyphosis (LDK) types., Summary of Background Data: Although previous studies have suggested some risk factors for PJK, the effects of preoperative grade of sagittal imbalance and paraspinal muscles degeneration on PJK remain unclear., Methods: Eighty-seven patients who had undergone lumbosacral fusion more than five levels with available clinical and radiological data were enrolled. The presence of PJK defined as sagittal Cobb angle ≥20° between the uppermost instrumented vertebra (UIV) and two supra-adjacent vertebrae at postoperative 2-year radiographs was recorded. Its occurrence was compared according to preoperative Roussouly and LDK types (Takemistu type) and the degree of paraspinal muscle degeneration at the upper level of UIV. Other sagittal radiographic parameters were also measured., Results: In this series, 28 patients (group I, 32.2%) showed radiological PJK, whereas 59 patients did not show radiological PJK (non-PJK patients, group II, 67.8%) at postoperative 2 years. PJK presented more prevalence in type III and type IV of LDK types (26/27, 96.3%). However, Roussouly types did not show any significant difference in PJK prevalence. In radiological parameters, a larger preoperative SVA (P = 0.018) and PI-LL (P = 0.015) were associated with PJK. Also, smaller quantity and lower quality of paraspinal muscles at T12-L1 level showed significant (P < 0.001) relationship with PJK. On multivariate logistic regression, higher LDK type (odds ratio [OR]: 2.11, 95% confidence interval [CI]: 1.24-3.56), smaller quantity (OR: 1.03, 95% CI: 1.00-1.07), and higher degree of paraspinal muscle degeneration (OR: 1.46, 95% CI: 0.92-2.31) were independent predictors of postoperative PJK., Conclusion: Although various factors are related to PJK following long segment fusion, preoperative conditions such as LDK types and degree of paraspinal muscle degeneration might be related to the development of PJK.Level of Evidence: 3., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose: Authors assumed that the stability of iliac screw (IS) fixation could affect the development of proximal junctional kyphosis (PJK). The purpose of this study was to analyze the relationship between IS loosening and PJK after long fusion surgery for adult spinal deformity (ASD)., Methods: Sixty-eight ASD patients (6 males, 62 females; mean age, 68.1 years) who underwent long fusion surgery with IS fixation were reviewed. The incidence and risk factors of IS loosening were investigated. The relationship between IS loosening and PJK was also analyzed., Results: IS loosening and PJK appeared in 33 and 19 patients, respectively. The median time for IS loosening and PJK to develop was 6.0 months (range 1.3-59.2) and 9.1 months (range 1.3-73.2), respectively. PJK developed in patients without IS loosening more frequently than in patients with IS loosening. PJK did not develop in 28 patients who presented with IS loosening first. IS loosening developed 5 months postoperatively in those 28 patients, whereas IS loosening was present 11 months postoperatively in 4 patients who presented with PJK first. Preoperative PT (OR = 1.091) and IS loosening (OR = 0.343) were significantly related with the development of PJK. IS loosening was significantly associated with postoperative PI-LL > 10° (OR = 0.957), postoperative SVA (OR = 1.023), and postoperative PT (OR = 1.072)., Conclusion: Postoperative sagittal malalignment should be avoided to prevent IS loosening and PJK. IS loosening occurred earlier than PJK and seemed to affect the development of PJK. This relationship supports the hypothesis that distal stability of long constructs may increase proximal junctional stress., Level of Evidence: III. These slides can be retrieved under Electronic Supplementary Material.

Objective: To identify clinical and radiographic features of subtypes of acute proximal junctional failures (PJFs) following correction surgery for degenerative sagittal imbalance., Methods: The study included 157 patients with mean age 68.0 ± 6.3 years who underwent correction surgery for degenerative sagittal imbalance. Acute PJFs were categorized into 4 subtypes: fracture at uppermost instrumented vertebra (UIV), fracture at vertebra just proximal to UIV (UIV+1), fixation failure at UIV, and junctional subluxation. Demographic, clinical, and radiographic data were analyzed retrospectively., Results: There were 18 patients with acute PJFs. PJF group had significantly lower T-score (-3.3 ± 1.1 vs. -1.9 ± 1.5) on bone densitometry and lower body mass index (BMI) (23.0 ± 3.9 kg/m 2 vs. 25.6 ± 3.7 kg/m 2 ) than non-PJF group. Radiographic parameters exhibited no significant differences. UIV fracture, UIV+1 fracture, UIV fixation failure, and junctional subluxation were observed in 5, 6, 4, and 3 patients. Fixation failure developed the earliest (median 1.3 months), followed by UIV fracture (1.5 months). UIV fracture occurred earlier than UIV+1 fracture (36 months). Patients with UIV or UIV+1 fracture had significantly lower T-scores than others. Although BMI and T-score were significant risk factors for all PJFs (P = 0.043 and P = 0.021, respectively), different risk factors for each subtype of PJFs were identified on separate risk factor analysis., Conclusions: Patients with acute PJFs had lower T-score and BMI. Each subtype of PJFs had different clinical and radiographic features. Although BMI and T-score were associated with all PJFs, each subtype may have different risk factors. Identifying risk factors for each subtype of acute PJFs may help avoid it., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Purpose: To predict spinal canal compromise, the assessment of plain radiography with magnetic resonance imaging (MRI) can aid the detection of vertebral body collapse and prevent the development of neurological deficits., Methods: Patients who suffered osteoporotic vertebral fractures (OVFs) between January 2012 and December 2014 underwent consecutive radiological assessments, including measurements of anterior height loss (AHL), posterior height loss (PHL), and the kyphotic angle (KA). The fracture morphology was classified by AOSpine thoracolumbar spine injury classification system. MRI was performed at the initial assessment and the extent of canal encroachment (CE) was calculated in all patients. Follow-up computed tomography (CT) or MRI was performed in patients exhibiting significant height loss in follow-up radiography. The fracture patterns in T1- and T2-weighted MRI were also assessed., Results: A total of 485 patients visited our institute for treatment of OVFs and 97 were enrolled; 15 were male and 82 were female. The mean age at initial visit was 70.3±14.6years. The initial spinal CE was correlated with the initial PHL and the initial AHL. The follow-up CE was correlated with age, the initial PHL, and the difference between the initial and last PHL (ΔPHL (initial-last) ). OVFs with both endplate fractures have a greater tendency of posterior wall collapse than those with single endplate fracture. On initial T1-weighted sagittal MRI, a diffuse low signal change pattern of the fractured vertebra was correlated with PHL. Delayed neurological deficits developed in four patients. These patients underwent surgical intervention., Conclusions: In patients with simple compression fractures, attention should be paid to the posterior vertebral body and both endplates as well as the T1-weighted MRI findings to allow early detection of spinal canal compromise, which can have devastating consequences., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Purpose: To analyze pre- and postoperative spinopelvic parameters and sagittal profiles in lumbar degenerative kyphoscoliosis (LDK) patients who underwent surgery using iliac screw (IS) and the incidence and risk factor of radiological adjacent segment degeneration (ASD)., Methods: A total of 32 patients, who had undergone surgical correction and lumbar/thoracolumbar fusion with pedicle screws and IS instrumentation for LDK with a minimum 2-year follow-up, were included. Ten cases with ASD (group 1) and 22 cases without ASD (group 2) were compared to see pre- and postoperative change in sagittal view of spine and adjacent segment. Parameters of both groups were analyzed before and after surgery with each parameters being tested on correlativity. All deformity types of patients were classified using Scoliosis Research Society (SRS)-Schwab classification. Risk factors of ASD were evaluated using variables of SRS-Schwab classification., Results: Group 1, rather than group 2, showed significant increment in pelvic incidence (PI). Curve types, classified using SRS-Schwab classification, were all corrected using IS; and after correction, coronal curve type was N curve and PI minus lumbar lordosis (LL) and pelvic tilt showed tendency to decrease. Cases with preoperative sagittal vertical axis (SVA) more than 10 cm and with postoperative PI minus LL more than 20° were at higher risk of developing ASD., Conclusion: For those with high PI, it might be a risk to cause ASD. Maintaining normal thoracic and lumbar angle, correction of SVA less than 4 cm, and PI minus LL below 20° are proper ways to avoid ASD after surgery.

The etiology of congenital scoliosis and its development remains unclear and has not yet been fully identified, even there are theories that congenital scoliosis could be derived from the failure of formation or failure of segmentation, which are etiologically heterogeneous with genetic, epigenetic, and environmental factors contributing to their occurrence. We reported a case of long-term follow-up after posterior vertebral column resection (PVCR) in both identical twins with similar congenital kyphoscoliosis at thoracolumbar levels. Twin I had been noticed by his parents to have asymmetry of his back at age 5 years, but no treatment was given. Twin II was first noticed to have a spinal problem at 11 years of age by his parents. Overtime, spine of both twins became further deviated to the left with kyphosis and was referred to our hospital. Both monozygotic twins were treated by PVCR and satisfactory results were demonstrated at 10-year follow-up.This case is the first report on the surgical treatment with PVCR, almost simultaneously, in both identical twins who had similar congenital vertebral anomalies causing kyphoscoliosis. Both identical twins with congenital kyphoscoliosis had undergone surgical correction by PVCR, anterior support with a mesh cage and posterior fusion using pedicle screws at the age of 14 years and achieved a satisfactory correction and a stable spine without curve progression with 10-year follow-up., Competing Interests: The authors have no funding and conflicts of interest to disclose. Institutional Review Board approval of Inje University Sanggye Paik Hospital (IRB No. 2015-02-019) was obtained before data collection and analysis.

Purpose: To investigate the causes of late-onset, progressive neurological deficits in patients with severe angular kyphosis caused by spondylitis secondary to tuberculosis (TB spondylitis)., Methods: From 2000 to 2011, 36 patients with severe angular kyphosis secondary to TB spondylitis (TB kyphosis) were enrolled in the study. All patients had late-onset, progressive neurological deficits. The causes of these deficits were classified with respect to the level of the causative lesion. Group A (n = 25, 69.4%) comprised patients whose neurological deficits resulted from the kyphosis itself. Patients in group B (n = 11, 30.6%) had developed neurological symptoms related to a lesion cephalad or caudal from the kyphosis. Surgical intervention was performed in 23 patients; 13 patients were treated conservatively. Clinical outcomes were evaluated using the American Spinal Injury Association (ASIA) impairment scale., Results: The late onset of neurological deficits was attributed to cord compression, pure cord distraction, stenosis, and instability above or below the level of the angular kyphosis. An improvement of the neurological symptoms at the cord level after surgical intervention, as indicated by a change from a non-ambulatory (ASIA impairment scale A/C) to an ambulatory (ASIA D/E) status, occurred in four of nine (44.4%) surgically treated patients. However, only 2 of 10 (20.0%) patients treated conservatively showed cord level improvement, as assessed using the ASIA impairment scale., Conclusions: In their evaluation of paraplegic patients, spine surgeons should consider the many potential causes of late-onset neurological deficits in TB spondylitis to avoid performing unnecessary surgery. A simpler procedure may yield equivalent results.

Background Text: Thoracic ossification of the ligamentum flavum (TOLF) is an uncommon pathology, but it may sometimes grow and cause serious neurologic manifestations. Little has been demonstrated yet about the epidemiology and etiology of TOLF.Purpose: This study aimed to estimate the prevalence and clinical characteristics of TOLF.Design: A cross-sectional study was carried out.Patient Sample: All individuals who had undergone chest computed tomography (CT) for the evaluation of pulmonary disease or for medical examination for 1 year at our institute comprised the patient sample.Outcome Measures: Presence of TOLF and the association of these findings with thoracic kyphosis (TK), ossification of posterior longitudinal ligament (OPLL), space available for cord (SAC), age, gender, body mass index (BMI), and diabetes were the outcome measures.Methods: Prevalence and distribution of TOLF, TK, and concurrent OPLL were analyzed on CT scans. Through reviews of their medical records, clinical characteristics including age, gender, BMI, and diabetes were investigated. Logistic regression analysis was performed to determine the risk factors of TOLF.Results: A total of 4,999 individuals (2,929 men and 2,070 women) were included for the analysis. Thoracic ossification of the ligamentum flavum was found in 1,090 individuals (674 men and 416 women. A single TOLF lesion was noted in 592 individuals and multiple lesions were noted in 498 individuals. The most commonly involved level was T10-T11. Distribution of TOLF showed two peaks: and the highest peak was at the lower thoracic spine (T10-12) and the second highest peak was at T3-T5. Thoracic kyphosis was 31.5°±9.5° in the TOLF group and 29.7°±8.9° in the non-TOLF group (p<.001). Space available for cord/anteroposterior canal diameter ratio in TOLF level was 0.882. Logistic regression analysis showed that gender and TK were significantly associated with TOLF.Conclusions: Incidental TOLF was found in 21.8% of the study cohort. Gender and TK were related to TOLF. [ABSTRACT FROM AUTHOR]

Study Design: A retrospective study.Objective: The aim of this study was to investigate proximal junctional kyphosis (PJK) after lumbosacral long fusion according to preoperative Roussouly and lumbar degenerative kyphosis (LDK) types.Summary Of Background Data: Although previous studies have suggested some risk factors for PJK, the effects of preoperative grade of sagittal imbalance and paraspinal muscles degeneration on PJK remain unclear.Methods: Eighty-seven patients who had undergone lumbosacral fusion more than five levels with available clinical and radiological data were enrolled. The presence of PJK defined as sagittal Cobb angle ≥20° between the uppermost instrumented vertebra (UIV) and two supra-adjacent vertebrae at postoperative 2-year radiographs was recorded. Its occurrence was compared according to preoperative Roussouly and LDK types (Takemistu type) and the degree of paraspinal muscle degeneration at the upper level of UIV. Other sagittal radiographic parameters were also measured.Results: In this series, 28 patients (group I, 32.2%) showed radiological PJK, whereas 59 patients did not show radiological PJK (non-PJK patients, group II, 67.8%) at postoperative 2 years. PJK presented more prevalence in type III and type IV of LDK types (26/27, 96.3%). However, Roussouly types did not show any significant difference in PJK prevalence. In radiological parameters, a larger preoperative SVA (P = 0.018) and PI-LL (P = 0.015) were associated with PJK. Also, smaller quantity and lower quality of paraspinal muscles at T12-L1 level showed significant (P < 0.001) relationship with PJK. On multivariate logistic regression, higher LDK type (odds ratio [OR]: 2.11, 95% confidence interval [CI]: 1.24-3.56), smaller quantity (OR: 1.03, 95% CI: 1.00-1.07), and higher degree of paraspinal muscle degeneration (OR: 1.46, 95% CI: 0.92-2.31) were independent predictors of postoperative PJK.Conclusion: Although various factors are related to PJK following long segment fusion, preoperative conditions such as LDK types and degree of paraspinal muscle degeneration might be related to the development of PJK.Level of Evidence: 3. [ABSTRACT FROM AUTHOR]