Curve evolution during bracing in children with scoliosis secondary to early-onset neurofibromatosis type 1: indicators of rapid curve progression.

BACKGROUND: Scoliosis secondary to neurofibromatosis type 1 (NF1) in children aged <10 years is an important etiology of early-onset scoliosis (EOS). This study was performed to investigate the curve evolution of patients with EOS secondary to NF1 undergoing bracing treatment and to analyze high-risk indicators of rapid curve progression. METHODS: Children with EOS due to NF1 who underwent bracing treatment from 2010 to 2017 were retrospectively reviewed. The angle velocity (AV) at each visit was calculated, and patients with rapid curve progression (AV of >10°/year) were identified. The age at modulation and the AV before and after modulation were obtained. Patients with (n = 18) and without rapid curve progression (n = 10) were statistically compared. RESULTS: Twenty-eight patients with a mean age of 6.5 ±â€Š1.9 years at the initial visit were reviewed. The mean Cobb angle of the main curve was 41.7°â€Š±â€Š2.4° at the initial visit and increased to 67.1°â€Š±â€Š8.6° during a mean follow-up of 44.1 ±â€Š8.5 months. The overall AV was 6.6°â€Š±â€Š2.4°/year for all patients. At the last follow-up, all patients presented curve progression of >5°, and 20 (71%) patients had progressed by >20°. Rapid curve progression was observed in 18 (64%) patients and was associated with younger age at the initial visit and a higher incidence of modulation change during follow-up (t = 2.868, P = 0.008 and <0.001, respectively). The mean AV was 4.4°â€Š±â€Š1.2°/year before modulation and 11.8°â€Š±â€Š2.7°/year after modulation (t = 11.477, P < 0.010). CONCLUSIONS: Curve progression of >10°/year is associated with younger age at the initial visit, and modulation change indicated the occurrence of the rapid curve progression phase.

Both structural damage and inflammation of the lumbar spine contribute to the sagittal imbalance in ankylosing spondylitis patients with thoracolumbar kyphosis.

BACKGROUND: The relationship between structural damage and inflammation of the spine and the sagittal imbalance in ankylosing spondylitis (AS) is not well understood. The present study aimed to investigate the correlation between structural damage and inflammation of the lumbar spine and the sagittal imbalance in AS patients with thoracolumbar kyphosis. METHODS: Forty-five AS patients with thoracolumbar kyphosis were retrospectively reviewed. Six sagittal spinal parameters, including the C7 tilt (C7T), spino-sacral angle (SSA), global kyphosis (GK), the sagittal vertical axis (SVA), thoracic kyphosis (TK), and lumbar lordosis (LL), were measured. Structural damage of the lumbar spine was assessed by the modified Stoke AS Spine Score (mSASSS) on radiographs. Lumbar spinal inflammation was evaluated by the AS spinal magnetic resonance imaging (MRI) activity (ASspiMRI-a) on MRI. Correlation analysis was performed using the paired sample t-test. Multivariable linear regression models were constructed to analyze the contributions of mSASSS and ASspiMRI-a to the sagittal parameters. RESULTS: The average values of the sagittal parameters C7T, SSA, GK, SVA, TK, and LL were 68.1°, 80.1°, 77.3°, 168.7 mm, 47.7°, and -0.7°, respectively. The average mSASSS and ASspiMRI-a scores were 9.8 and 10.8, respectively. Correlation analysis showed that the mSASSS and ASspiMRI-a were correlated with C7T, SSA, SVA, and LL (the Spearman correlation coefficients were -0.439, -0.390, 0.424, and 0.530 for mSASSS; -0.406, -0.402, 0.378, and 0.486 for ASspiMRI-a; P<0.05). The C7T, SSA, and SVA were significantly correlated with LL (r=-0.696, -0.779, and 0.633, respectively; P<0.05). There was a weak correlation between the mSASSS and ASspiMRI-a (ß=0.299, P=0.046). The multivariable regression models indicated that the sagittal imbalance was determined to a greater extent by the mSASSS than ASspiMRI-a (the ß values were -1.550 vs. -0.649 for C7T, -1.865 vs. -1.231 for SSA, 9.161 vs. 3.823 for SVA, and 3.128 vs. 1.717 for LL). CONCLUSIONS: Both structural damage and inflammation of the lumbar spine contributed to the sagittal imbalance in AS patients with thoracolumbar kyphosis. In the late stages of AS, the sagittal imbalance was more attributable to the structural damage than the inflammation of the lumbar spine.

Does relocation of the apex after osteotomy affect surgical and clinical outcomes in patients with ankylosing spondylitis and thoracolumbar kyphosis?

OBJECTIVE: Relocation of the apex is often found in patients with ankylosing spondylitis (AS)-associated thoracolumbar/lumbar kyphosis after corrective surgery. This study evaluates the influence of different postoperative apex locations on surgical and clinical outcomes of osteotomy for patients with AS and thoracolumbar kyphosis. METHODS: Sixty-two patients with a mean age of 34.6 ± 9.7 years (range 17-59 years) and a minimum of 2 years of follow-up, who underwent 1-level lumbar pedicle subtraction osteotomy for AS-related thoracolumbar kyphosis, were enrolled in the study, as well as 62 age-matched healthy individuals. Patients were divided into 2 groups according to the postoperative location of the apex (group 1, T8 or above; group 2, T9 or below). Demographic data, radiographic measurements (including 3 postoperative apex-related parameters), and clinical outcomes were compared between the 2 groups preoperatively, postoperatively, and at the last follow-up. Furthermore, a subgroup analysis was performed among patients with a postoperative apex located at T6-11 and postoperatively the entire AS cohort was compared with normal controls regarding the apex location of the thoracic spine. RESULTS: In the majority of the enrolled patients, the apex location changed from T12-L2 preoperatively to T6-9 postoperatively. The sagittal vertical axis (SVA) differed significantly both postoperatively (25.7 vs 59.0 mm, p = 0.001) and at the last follow-up (34.6 vs 59.9 mm, p = 0.003) between the 2 groups, and the patients in group 1 had significantly smaller horizontal distance between the C7-vertical line and the apex (DCA) than the patients in group 2 (67.5 vs 103.7 mm, p = 0.001). Subgroup analysis demonstrated similar results, showing that the patients with a postoperative apex located at T8 or above had an average SVA < 47 mm. Notably, a significant correlation was found between postoperative SVA and DCA (r = 0.642, p = 0.001). Patients who underwent an osteotomy at L3 had limited apex relocation but larger SVA correction than those at L1 or L2. However, no significant difference was found in health-related quality of life between the 2 groups. CONCLUSIONS: AS patients with an apex located at T8 or above after surgery tended to have better SVA correction (within 47 mm) than those who had a more caudally located apical vertebra. For ideal postoperative apex relocation, a higher (closer to or at the preoperative apex) level of osteotomy is more likely to obtain the surgical goal.

Radiologic and Pathological Investigation of Pseudarthrosis in Ankylosing Spondylitis: Distinguishing Between Inflammatory and Traumatic Etiology.

OBJECTIVE: To investigate the pathogenesis of pseudarthrosis in ankylosing spondylitis (AS) based on the pathological analysis of specimens harvested during surgery. METHODS: Radiographic and clinical data for 17 consecutive AS patients with pseudarthrosis were retrospectively analyzed. Meanwhile, the pathological analysis of specimens obtained during surgery was also performed. RESULTS: In total, 18 extensive Andersson lesions were included. Pseudarthrosis located at the apical region were noted in 12 patients. Complete ossified anterior longitudinal ligaments above or below pseudarthrosis and fracture through posterior elements or facet joints were observed in 7 and 6 lesions, respectively. The most definitive pathological characteristic in all cases was proliferating hypovascular edematous fibrous tissue involving disc, bone-disc border, and vertebral body. Fibrinoid necrosis, necrotic bone fragments, hemosiderin deposits, and active subchondral osteogenesis were found, indicating trauma process. Mild perivascular collections of inflammatory cells were detected in only 2 cases. CONCLUSION: AS-related pseudarthrosis is more likely to originate from mechanical trauma than inflammation. The above-mentioned radiological and histological findings showed that multiple mechanisms lead to the formation of pseudarthrosis. These mechanisms include excessive stress, insufficiency fracture, and an acute fracture involving a 3-column structure.

Complications of spinal osteotomy for thoracolumbar kyphosis secondary to ankylosing spondylitis in 342 patients: incidence and risk factors.

OBJECTIVETo describe the incidence of complications in spinal osteotomy for thoracolumbar kyphosis caused by ankylosing spondylitis (AS) and to investigate the risk factors for these complications.METHODSFrom April 2000 to July 2017, 342 consecutive AS patients with a mean age (± SD) of 35.4 ± 9.8 years (range 17-71 years) undergoing spinal osteotomy were enrolled. Patients with complications within the 1st postoperative year were identified. Demographic, radiological, and surgical data were compared between patients with and without complications. The complications were classified into intraoperative and postoperative complications.RESULTSA total of 310 consecutive pedicle subtraction osteotomy (PSO) and 37 multiple Smith-Petersen osteotomy (SPO) procedures were performed in 342 patients. Overall, 47 complications were identified in 47 patients (13.7%), including 31 intraoperative complications and 16 postoperative complications. Patients with complications were older than those without (p = 0.006). A significant difference was observed in preoperative global kyphosis (GK), lumbar lordosis (LL), sagittal vertical axis (SVA), and the correction of these radiographic parameters between patients with and without complications (p < 0.05). Two-level PSO (p = 0.022) and an increased number of instrumented vertebrae (p = 0.019) were significantly associated with an increased risk of complications.CONCLUSIONSThe overall incidence of complications was 13.7%. Age; preoperative GK, LL, and SVA; the correction of GK, LL, and SVA; 2-level PSO; and number of instrumented vertebrae were risk factors. Therefore, the potential risk of extensive surgeries with large correction and long fusion in older AS patients with severe GK should be seriously considered in surgical decision-making.

Accuracy of Freehand Pedicle Screw Placement in Surgical Correction of Thoracolumbar Kyphosis Secondary to Ankylosing Spondylitis: A Computed Tomography Investigation of 2314 Consecutive Screws.

OBJECTIVE: To evaluate the accuracy and safety of freehand pedicle screw placement in surgical correction for thoracolumbar kyphosis caused by ankylosing spondylitis (AS). METHODS: We retrospectively reviewed 266 consecutive patients with AS who underwent osteotomy for kyphosis correction with freehand screw insertion from January 1998 to April 2015 at our institution. A total of 2314 pedicle screws in 158 patients with AS with postoperative computed tomography scans were included in the study. Postoperative computed tomography was performed to classify accuracy of screws, using the established Gertbein classification (grade 0: no perforation, grade 1: perforation <2 mm, grade 2: perforation between 2 and 4 mm, and grade 3: perforation >4 mm). Patients were divided into 2 groups according to coronal Cobb angle: group A (n = 21, Cobb angle ≥10°), group B (n = 137, Cobb angle <10°). RESULTS: Among the 2314 pedicle screws, 2168 pedicle screw placements were categorized as grade 0, 71 were grade 1, 51 were grade 2, and 24 were grade 3. Breaches occurred more frequently in L1-S1 than the thoracic spine (7.1% and 5.4%, respectively). T5 (25.0%) and S1 (17.7%) experienced the greatest breach rate, whereas T8, L1, and L3 had the lowest breach rate. The breach rate of group A was greater than that of group B (7.9% vs. 6.1%). None of the breaches resulted in either neurologic deficits or vascular complications. CONCLUSIONS: Freehand pedicle screw placement can be performed safely with acceptable breach rate in patients with AS and thoracolumbar kyphosis.

The clinical relevance of the presence of bridging syndesmophytes on kyphosis correction and maintenance following pedicle subtraction osteotomy for thoracolumbar kyphotic deformity in ankylosing spondylitis: a comparative cohort study.

BACKGROUND: The presence of bridging syndesmophytes (BS) in spinal osteotomy region serves traditionally as one critical determinant for selection of osteotomy techniques. While nowadays the proportion of kyphotic ankylosing spondylitis (AS) patients receiving pedicle subtraction osteotomy (PSO) with yet mobile neighboring disc has seen a substantial increase. Literatures investigating the clinical relevance of the presence of BS on kyphosis correction and maintenance following PSO are scarce. METHODS: A total of 71 thoracolumbar kyphotic AS patients treated with single-level PSO at our hospital between September 2010 and August 2014 were retrospectively reviewed, 32 of whom were stratified into the BS group (BG). The operative corrections of multiple spino-pelvic sagittal parameters were assessed. Comparison of the contribution of adjacent disc wedging to total correction per PSO segment was made between the BS and non-BS groups (NBG). The correction loss were also evaluated and compared with a minimum 2-year follow-up. RESULTS: A significantly younger age (30.97 ± 8.28 vs. 40.31 ± 8.44 yrs., p < 0.001), smaller pelvic incidence (PI) (43.03 ± 10.60 vs. 49.36 ± 9.75°, p = 0.011), greater wedging index of osteotomized vertebra (1.17 ± 0.16 vs. 1.09 ± 0.08, p = 0.011) and larger local kyphosis (19.59 ± 10.84 vs. 13.56 ± 8.50°, p = 0.013) was observed in NBG preoperatively. Patients in BG and NBG accomplished comparable amount of kyphosis correction per PSO segment (40.22 ± 7.09 vs. 43.85 ± 8.71°, p = 0.062). However, the contribution of adjacent disc wedging to total correction per PSO was significantly larger in NBG [8.10 ± 6.19 (18.5%) vs. 1.09 ± 2.88° (2.7%), p < 0.001]. By ultimate follow-up, the global kyphosis (18.26 ± 10.97 vs. 21.51 ± 10.89°, p < 0.05) and thoracic kyphosis (37.95 ± 11.87 vs. 42.87 ± 11.56°, p < 0.05) deteriorated significantly in the NBG but not BG, so was further pelvic retroversion as represented by increased pelvic tilt (19.46 ± 8.13 vs. 23.44 ± 8.19°, p < 0.05) and decreased sacral slope (23.02 ± 9.12 vs. 18.62 ± 10.10°, p < 0.05). Loss of corrections concerning contribution of adjacent disc wedging was also larger in NBG (1.41 ± 3.27 vs. 0.22 ± 1.49°, p < 0.05). CONCLUSIONS: Our study might suggest that the evaluation and treatment methods of kyphotic AS patients needed to be fine-tuned with appropriate subgrouping by the presence of syndesmophytes with bamboo sign as they were potentially distinct groups with different PI, contributor of lordosing capability and prognosis that might require separate analysis.

Does postoperative PI-LL mismatching affect surgical outcomes in thoracolumbar kyphosis associated with ankylosing spondylitis patients?

OBJECTIVE: To investigate if pelvic incidence (PI) and lumbar lordosis (LL) mismatching affects surgical outcomes for ankylosing spondylitis (AS) related kyphosis following 1-level lumbar pedicle subtraction osteotomy (PSO). PATIENTS AND METHODS: AS patients with thoracolumbar kyphosis, who underwent 1-level lumbar PSO from March 2006 and February 2014 in our institution, were retrospectively reviewed. The radiographic measurements and health-related quality of life (HRQoL) scores, including Oswestry Disability Index (ODI) and Visual Analogue Scale (VAS) for pain, were recorded at baseline and the last follow-up. Patients were divided into 2 groups according to PI-LL matching or not postoperatively (Match Group, Mismatch Group), and comparison of the aforementioned parameters between the two groups was performed. RESULTS: Seventy patients were enrolled with a mean age of 34.60 ±â€¯9.45 years (range, 17 yrs.-59 yrs.). Among them, 44 were included in the Match Group and 26 in the Mismatch Group. At baseline, patients in the Match Group had larger LL (p = 0.014) and smaller pelvic tilt (PT, p < 0.001) than patients in the Mismatch Group. At the last follow-up, along with larger LL (p = 0.004) and smaller PT (p = 0.001), Match Group patients also had significantly smaller sagittal vertical axis (SVA, 3.31 cm vs 6.27 cm, p = 0.001) than those in the Mismatch Group. Seventy-five percent (33/44) of the patients in the Match Group had a SVA < 5 cm at the last follow-up, while in the Mismatch Group, only 35% (9/26) of the patients did. However, no significant difference was found between the two groups regarding HRQoL scores. CONCLUSION: Patients with postoperative PI-LL matching were more likely to have a better correction of SVA; they also tended to have a smaller preoperative PT. However, PI-LL mismatching didn't affect HRQoL scores at the last follow-up, which was different from the results of previous studies in the settings of ASD.

Association between braced curve behavior by pubertal growth peak and bracing effectiveness in female idiopathic scoliosis: a longitudinal cohort study.

BACKGROUND: Pre-pubertal idiopathic scoliosis (IS) is associated with high risk of bracing ineffectiveness. Integrated multidimensional maturity assessments are useful but complex to predict the high-risk occurrence of curve progression. This study is designed to provide a simple screening method for brace effectiveness by determining whether or not the braced curve behavior at growth spurt, being defined as variations in Cobb angle velocity (AV) at peak height velocity (PHV), can be a new factor predictive of brace outcome prescribed before PHV. METHODS: This is a retrospective study of a series of 35 IS girls with simplified skeletal maturity score no more than 3 at initiation of bracing treatment and followed up through the growth spurt until brace weaning or surgery. Serial Cobb angle and maturity indicators involving height velocity, Risser sign, triradiate cartilage, simplified skeletal maturity score and distal radius and ulna classification were assessed and patients were stratified into either a positive or negative category based on a positive or negative value of AV at PHV. Comparisons were made between the positive and negative AV groups, as well as the failed and successful bracing groups, using independent sample T test and crosstab analysis. Logistic regression analysis was used to identify the predictive factors of failed brace treatment. RESULTS: Brace treatment prescribed before PHV was found to have an overall failure rate of 57.1% and a surgical rate of 45.7%. Negative AV at PHV accounting for 54.3% of the recruited patients were associated with lower brace failure rate (36.8% vs. 81.2%, p = 0.016) and surgical rate (21.1% vs. 75.0%, p = 0.002). Patients in the failed bracing group showed higher ratio of thoracic curve (80.0% vs. 26.7%,p = 0.002) and higher AV at growth peak (2.3 ± 9.1 vs. -6.5 ± 11.4°/yrs., p = 0.016). The logistic regression analysis revealed that positive AV at PHV (OR = 9.268, 95% CI = 1.279-67.137, p = 0.028) and thoracic curve type (OR = 13.391, 95% CI = 2.006-89.412, p = 0.007) were strong predictive factors of ineffective brace treatment initiated before PHV. CONCLUSIONS: Sustained curve correction following bracing despite early onset and rapid pubertal growth was strongly predictive of effective brace control of scoliosis.

Quantitative evaluation of the relationship between COMP promoter methylation and the susceptibility and curve progression of adolescent idiopathic scoliosis.

PURPOSE: The cartilage oligomeric matrix protein (COMP) was reported to be down-regulated in adolescent idiopathic scoliosis (AIS). The purposes of the study were to evaluate the roles of COMP promoter methylation on the abnormal gene expression and the epigenetic phenotype in AIS. METHODS: DNA samples of 50 AIS patients and 50 healthy controls were analyzed. Five CpG sites of COMP gene were amplified and sequenced using the polymerase chain reaction (PCR) and the pyrophosphate sequencing technology, while the COMP gene expression was evaluated using real-time PCR. Comparisons were analyzed with the Chi-square test and independent t test. Pearson coefficients of correlation were used to evaluate the association between gene methylation and clinical phenotypes. RESULTS: The average COMP gene promoter methylation of the AIS and control groups was 12.26 ± 2.36 and 8.76 ± 1.94 (p < 0.0001), and correspondingly the relative expression of COMP gene expression was 0.52 ± 0.12 and 1.16 ± 0.52 (p < 0.001), respectively. The correlation analysis showed significantly negative correlation between methylation level and gene expression (p < 0.0001). The comparison analysis between AIS patients with positive and negative methylation showed significant difference in chronological age (p < 0.001) and Cobb angle of main curve (p = 0.011). The methylation level of the COMP promoters was significantly correlated with Cobb angle of main curve and age (p < 0.0001) among the five CpG sites. CONCLUSIONS: AIS patients had significantly high COMP promoter methylation and low gene expression. Positive and high COMP promoter methylation was correlated with young age and high Cobb angle of main curve. Therefore, COMP gene promoter methylation may provide significant prognostic information in predicting the susceptibility and curve progression of AIS.

Radiological morphology variances of osteotomized vertebra-disc complex following pedicle subtraction osteotomy for ankylosing spondylitis with thoracolumbar kyphosis: the incidence, mechanisms, and prognosis.

BACKGROUND CONTEXT: Inaccurate osteotomy cut along with incomplete or even subluxated bone-on-bone closure of osteotomy gap following pedicle subtraction osteotomy (PSO) may be disastrous, hampering the lordosing effect and increasing the likelihood of complications. The inelastic yet osteoporotic spine in ankylosing spondylitis (AS) is specially predisposed to such suboptimal osteotomy, while the relevant data concerning this issue are scarce. PURPOSE: This study aimed to analyze the incidence of radiological morphology variances (RMV) of osteotomized vertebra-disc complex (OVDC) following PSO in patients with kyphotic AS, conceptualize the mechanisms of the deviated morphology, and investigate the prognosis. STUDY DESIGN: This is a retrospective radiological data analysis. PATIENT SAMPLE: The sample being screened comprises 71 patients with thoracolumbar kyphotic AS who underwent single-level PSO at our hospital between March 2006 and February 2014. They were stratified by the presence of bridging syndesmophytes (BS) locating within the OVDC. OUTCOME MEASURES: Any irregular radiological configuration of OVDC other than the wedge morphology would be considered as RMV and were studied with care to fully describe and classify the spectrum of deviated morphologic features. Multiple spinopelvic sagittal parameters were measured to assess both the regional lordosing effect and the global realignment of sagittal spinal profile. METHODS: For each selected patient with confirmed RMV, the radiological morphology was assessed, defined, and categorized. The prognosis involving surgical corrections and maintenance of spinopelvic sagittal parameters, as well as the remodeling in disordered osteotomized vertebral shape over time, were also investigated. RESULTS: The incidence of RMV was 21.9% in positive BS group (PG) and 30.8% in negative BS group (NG). Inappropriate angle and range of osteotomy accounted for the largest share (1 pts for PG and 10 pts for NG, 57.9%) of mechanisms responsible for RMV, followed by vertebral subluxation (VS) (5 pts for PG and 2 pts for NG, 36.8%) and failed osteotomy gap closure (1 pts for PG, 5.3%). For these patients, the mean bony lordosing effect per PSO segment was 36.0°±8.9° postoperatively, and decreased to 34.7°±8.7° by a mean follow-up of 3 years (p=.076). The magnitude of neighboring disc opening was significantly higher in NG (10.2°±6.5° vs. 2.4°±3.2°, p=.009). The global kyphosis and sagittal vertical axis were significantly corrected (77.0°±21.2° vs. 24.4°±18.8°; 160.6°±72.4° vs. 48.2°±38.6 mm, all p<.001) and remained stable by the ultimate follow-up (p>.05). No devastating neurologic deficits were noticed. Patients with VS and failed osteotomy gap closure exclusively showed solid bone healing and adaptive remodeling without rod breakage at final follow-up. CONCLUSIONS: Radiological morphology variances of OVDC were a high occurrence following PSO in AS, being mainly attributed to inaccurate osteotomy cut and VS. Neighboring disc opening and rotational or translational subluxation were major available remedial mechanisms strengthening the lordosing effect when that of vertebral wedging was impaired and insufficient. The bone fusion and remodeling concerning the subluxated or dislocated osteotomized vertebra was utterly favorable, maintaining the kyphosis correction and preventing instrumentation failure.

The patterns of loss of correction after posterior wedge osteotomy in ankylosing spondylitis-related thoracolumbar kyphosis: a minimum of five-year follow-up.

BACKGROUND: Short-term studies have demonstrated good surgical outcomes after pedicle subtraction osteotomy (PSO) in ankylosing spondylitis (AS) patients, but there is a paucity of literature focused on middle-term results, especially regarding patterns of loss of correction. The objective of this study is to assess the durability of surgical outcomes and the patterns of loss of correction in thoracolumbar kyphosis secondary to AS following lumbar PSO with over 5-year follow-up. METHODS: We performed a retrospective review of 155 consecutive AS patients undergoing lumbar PSO from January 2001 to December 2011. Twenty-four patients were included with an average follow-up of 6.9 years (range, 5-15 years). Radiographical evaluations included global kyphosis (GK), lumbar lordosis (LL), sagittal vertical axis, spinal-sacral angle, kyphosis of proximal non-fused segments (KPNS), angle of fused segments (AFS), osteotomized vertebra angle (OVA), distal intervertebral disc wedging (DIDW) and proximal junctional angle. Meanwhile, clinical outcomes were assessed by the Oswestry disability index (ODI) and Numerical rating scale (NRS). RESULTS: The average correction per PSO segment was 34.9°. Significant improvement in sagittal parameters were found postoperatively, and no obvious deterioration was noticed during the follow-up. Mild loss of correction in GK (2.82°) and LL (3.77°) were observed at the final follow-up (P < 0.05). The KPNS and DIDW increased from 26° and -5.0° postoperatively to 30° and -2.2° at the final follow-up (P < 0.05), respectively. In contrast, no significant diminishment was identified in OVA and AFS (P > 0.05). The ODI and NRS improved significantly from 20.6 and 6.6 preoperatively to 5.9 and 2.3 at the final follow-up (P < 0.05). CONCLUSIONS: PSO is an effective procedure for treating AS-related thoracolumbar kyphosis and can maintain sustained surgical outcomes during the middle-term follow-up. The loss of correction was mainly attributable to non-instrumented segments without fully ossified bridging syndesmophyte in the thoracolumbar region instead of instrumented levels.

Mechanisms, Predisposing Factors, and Prognosis of Intraoperative Vertebral Subluxation During Pedicle Subtraction Osteotomy in Surgical Correction of Thoracolumbar Kyphosis Secondary to Ankylosing Spondylitis.

STUDY DESIGN: A retrospective study. OBJECTIVE: To analyze the mechanisms, predisposing factors, and prognosis of the intraoperative vertebral subluxation (VS) during pedicle subtraction osteotomy (PSO) for thoracolumbar kyphosis secondary to ankylosing spondylitis (AS). SUMMARY OF BACKGROUND DATA: VS is one of the most daunting challenges that surgeons encounter during PSO closure, especially in patients with AS with ankylosed and mostly osteoporotic spine. Unfortunately, there is a paucity of research designed to conceptualize the mechanisms, predisposing factors, and discuss the complication-avoidance strategies and prognosis. METHODS: A retrospective single-center review was performed for a consecutive series of 153 patients with AS with rigid thoracolumbar kyphosis who underwent one-level PSO from April 2000 to December 2013. The incidence of the VS at the level of PSO during correction was analyzed and the potential causative factors were investigated. RESULTS: VS occurred in six patients with the incidence being 3.9% in this patient cohort. The predisposing factors were (1) early fracture of the anterior cortex of the osteotomized vertebra (OV); (2) excessive decancellation from vertebral body causing parallel collapse of the vertebral column with significant loss of the ability to create local lordosis; (3) improper manual osteoclasis due to insufficient decancellation of the OV; and (4) inappropriate application of cantilever technique and concomitant long instrumentation. The early surgical complication involved one patient with cerebrospinal fluid leakage at the osteotomized site, but no devastating neurological deficits. During follow-up, bone healing and adaptive vertebral remodeling with no rod breakage were observed for all these six patients. CONCLUSION: Intraoperative VS was a rare occurrence associated with inappropriate manual manipulation of osteotomy, gap closure, and rod insertion. Neurological complication was a potential risk, but could be well prevented with extensive laminectomy and emergency actions favoring partial subluxation reduction. Moreover, adaptive bone remodeling and fusion at the level of VS ensured the maintenance of kyphosis correction and avoidance of instrumentation failure. LEVEL OF EVIDENCE: 4.

[Anatomical feature of lumbar and S1 pedicle in patients with thoracolumbar kyphosis secondary to ankylosing spondylitis].

OBJECTIVE: To measure the correlative parameters of vertebral pedicles from L1 to S1 by CT scan in the patients with thoracolumbar kyphosis secondary to ankylosing spondylitis(AS) and disc degenerative disease(DDD), and analyze their anatomical difference in order to provide the selection and placement of pedicle screw during operation. METHODS: The clinical data of 30 male AS patients (AS group) with the mean age of(35.7±9.5) years (ranged, 23 to 51) and 30 male DDD patients (DDD group) with the mean age of(52.4±8.9) years(ranged, 39 to 64) underwent surgery in our institution from March 2012 to November 2014 were analyzed. The CT scans of lumbar and sacrum were performed before surgery. The parameters of vertebral pedicle from L1 to S1 were measured and compared, including pedicle width (PW), pedicle screw path length (PL), pedicle height (PH), pedicle transverse angle (EA), and pedicle inclined angle (FA). Paired sample t-test was used to detect the divergence in the above-mentioned data between left and right sides. In addition, results between two groups were compared using independent sample t-test. RESULTS: The study showed that a gradual increase in the average pedicle width both AS group and DDD group from L1 to S1. The average PW of AS group was bigger than DDD group in L5 and S1(P<0.05), it was(16.47±2.66) mm and (21.76±2.97)mm vs. (14.51±2.11)mm and (18.87±2.14) mm respectively;the average PL of DDD group was smaller than AS group from L1 to S1(P<0.05); the both maximum of PL were in L3 segment; the average EA of AS group was smaller than DDD group from L1 to S1; the average FA of AS group was significantly smaller than DDD group from L3 to S1, (P<0.05), was(-2.88±10.24)°, (-7.88±10.22)°, (-7.70±10.40)°, (-5.15±10.25)° vs. (4.05±2.21)°, (7.79±4.38)°, (7.07±3.21)°, (12.62±3.21)°, respectively. CONCLUSIONS: Increasing the strength of internal fixation is feasible to insert the larger and bigger pedicle screws in low lumbar and S1 among AS patients, while the EA should be decreased properly and the direction on the sagittal plane should be adjusted.

Does the Traversing Length of the Aorta Change After Closing Wedge Osteotomy for Ankylosing Spondylitis Patients With Thoracolumbar Kyphosis?: A Magnetic Resonance Imaging Investigation.

STUDY DESIGN: A prospective magnetic resonance imaging (MRI) study. OBJECTIVE: To investigate the change in aortic traversing length in patients with thoracolumbar kyphosis secondary to ankylosing spondylitis (AS) after closing wedge osteotomy (CWO). SUMMARY OF BACKGROUND DATA: The CWO has been widely adopted for the correction of thoracolumbar kyphosis caused by AS. During this procedure, the aorta may be elongated in the instrumented area, which implies a potential risk of the aortic injury. To date, no reports have been specifically published using MRI to investigate the alteration in aortic traversing length in patients with AS undergoing CWO. METHODS: From June 2013 to July 2015, 24 patients with AS with thoracolumbar kyphosis with a mean age of 38.1 years were recruited in the present study. All patients underwent single-level CWO. MRI examinations were performed before and 2 weeks after surgery. For each subject, the aortic diameter and length were measured on the MRI. Radiographic measurements included the global kyphosis, thoracic kyphosis, lumbar lordosis, local kyhosis, angle of fusion levels, and anterior height of the osteotomized vertebra. The height of these patients was also recorded. RESULTS: The aortic traversing length significantly increased by an average of 2.0 cm after surgery. Significant changes in height, global kyphosis, lumbar lordosis, local kyphosis, and angle of fusion levels were observed (P < 0.01), whereas the anterior height of the osteotomized vertebra was comparable before and after surgery (P > 0.05). In addition, the correlation analysis revealed a significant correlation between the aortic traversing length and changes in global kyphosis, lumbar lordosis, local kyphosis, angle of fusion levels, and height (P < 0.01). CONCLUSION: The stretch of the aorta after CWO for the correction of thoracolumbar kyphosis was quantitatively verified by MRI investigation in the present study. Spine surgeons should be aware of the potential vulnerability of aortic injury in patients with AS undergoing CWO. LEVEL OF EVIDENCE: 4.

Can acetabular orientation be restored by lumbar pedicle subtraction osteotomy in ankylosing spondylitis patients with thoracolumbar kyphosis?

PURPOSE: To evaluate whether acetabular orientation (abduction and anteversion) can be restored by lumbar pedicle subtraction osteotomy (PSO) in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis. MATERIALS AND METHODS: A total of 33 consecutive AS patients with thoracolumbar kyphosis undergoing one-level lumbar PSO were retrospectively reviewed. Radiographical measurements included sagittal vertical axis, global kyphosis, thoracic kyphosis, local kyphosis, lumbar lordosis, pelvic incidence, sacral slope, and pelvic tilt. Acetabular abduction and anteversion were measured on CT scans of the pelvis before and after lumbar PSO. The preoperative and postoperative parameters were compared by the paired samples t test. Pearson's correlation analysis was conducted to determine the correlations between the changes in acetabular abduction and anteversion and the changes in sagittal spinopelvic parameters. RESULTS: After lumbar PSO, sagittal vertical axis, global kyphosis, and pelvic tilt were corrected from 15.7 ± 6.7 cm, 66.8° ± 17.5°, and 38.6° ± 9.0° to 2.9 ± 4.9 cm, 21.3° ± 8.2°, and 23.2° ± 8.2°, respectively (p < 0.001). Of note, acetabular abduction and anteversion decreased from 59.6° ± 4.6° to 31.4° ± 6.5° before surgery to 51.4° ± 6.5° and 20.2° ± 4.4° after surgery, respectively (p < 0.001). Moreover, the changes in acetabular abduction and anteversion were observed significantly correlated with the change in pelvic tilt (r = 0.527, p = 0.002; r = 0.586, p < 0.001). CONCLUSION: Abnormal acetabular abduction and anteversion could be corrected by lumbar PSO in AS patients with thoracolumbar kyphosis. Consequently, a relatively normal acetabular orientation could be achieved after lumbar PSO, which might decrease the potential risk of dislocation in AS patients with spine and hip deformities requiring subsequent THR surgery.

Sagittal Vertical Axias, Spinosacral Angle, Spinopelvic Angle, and T1 Pelvic Angle: Which Parameters May Effectively Predict the Quality of Life in Ankylosing Spondylitis Patients With Thoracolumbar Kyphosis?

STUDY DESIGN: This is a retrospective study. OBJECTIVE: To identify the relationship between global sagittal alignment and health-related quality of life (HRQoL) in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis. SUMMARY OF BACKGROUND DATA: Little data are available on correlation between global sagittal alignment and HRQoL in AS. MATERIALS AND METHODS: A total of 107 AS patients were included in this study. The radiographic parameters were measured on lateral radiographs of the whole spine, including sagittal vertical axias (SVA), spinosacral angle (SSA), spinopelvic angle (SPA), and T1 pelvic angle (TPA). HRQoL was assessed using the oswestry disability index questionnaire, the bath ankylosing spondylitis disease activity index, the bath ankylosing spondylitis functional index, and short form-36 questionnaire. The patients were divided into 2 groups: group A (n=76, global kyphosis≤70 degrees), group B (n=31, global kyphosis>70 degrees). Statistical analysis was performed to identify significant differences between these 2 groups. In addition, correlation analysis and multiple regression analysis between radiologic parameters and clinical questionnaires were conducted. RESULTS: With respect to SVA, SSA, SPA, TPA, and HRQoL scores, significant differences were observed between 2 groups (P<0.05). Also, SVA, SSA, SPA, and TPA were significantly related to HRQoL. Multiple regression analysis revealed that SVA, SSA, SPA, and TPA were significant parameters in the prediction of HRQoL in AS patients with thoracolumbar kyphosis. Of note, HRQoL related much more to SSA and SPA than SVA and TPA. CONCLUSIONS: AS patients with moderate and severe deformity were demonstrated to be significantly different in terms of SVA, SSA, SPA, TPA, and HRQoL. Moreover, SVA, SSA, SPA, and TPA correlated with HRQoL significantly. In particular, SSA and SPA could better predict HRQoL than SVA and TPA in AS patients with thoracolumbar kyphosis.

Morphometric analysis of iatrogenic breast asymmetry secondary to operative breast shape changes in thoracic adolescent idiopathic scoliosis.

PURPOSE: Spontaneous surgical alterations of the distorted surface shape of thoracic cage in adolescent idiopathic scoliosis (AIS) may relocate and remodel the bilateral breast mounds. The purpose of this study was to analyze the influence of scoliosis correction surgery on female breast morphology and to identify the risk factors for iatrogenic breast asymmetry secondary to operative breast shape changes in AIS. METHODS: Thoracic AIS girls undergoing correction surgery were reviewed. Ten parameters concerning morphometric and CT evaluations of breast profile and symmetry were measured. The degree of asymmetry was determined and comparisons were made for evaluation of operative breast shape changes. The morphologically aggravated breast asymmetry would be considered if the concave and convex difference of either sternal notch-nipple length or sternal notch-nipple tilt angle increased post-operatively. Potential risk factors for iatrogenic breast asymmetry were identified. RESULTS: Sixty-eight AIS girls were reviewed. The concave breasts showed significantly more linear and less angular changes in morphological parameters post-operatively (p < 0.05). The concave and convex difference was significantly increased in morphological parameters and yet decreased in radiographic parameters. Ratio of aggravated morphological breast asymmetry was 61.2 %, and this patient group trended to have a minor pre-operative breast asymmetry though the difference was not statistically significant (p > 0.05). Moreover, patients with apex located at or above T7 showed greater changes in both morphological and radiographic dimensions as compared with those with apex beneath T7 (p < 0.05). CONCLUSION: The incidence of aggravated post-operative breast asymmetry is notable. Those with higher thoracic apex level, combined with minor pre-operative breast asymmetry, were at relatively higher risk of iatrogenic breast asymmetry aggravation post-operatively. Moreover, discrepancy existed between the morphometric and radiographic parameters concerning the surgical influence on breast asymmetry.

Is There any Correlation Between Pathological Profile of Facet Joints and Clinical Feature in Patients With Thoracolumbar Kyphosis Secondary to Ankylosing Spondylitis?: An Immunohistochemical Investigation.

STUDY DESIGN: An immunohistochemical analysis. OBJECTIVE: The aim of this study was to systematically and extensively evaluate the immunopathology of the facet joints in patients with thoracolumbar kyphosis secondary to ankylosing spondylitis (AS). SUMMARY OF BACKGROUND DATA: The facet joints may be predominantly involved in the process of spinal inflammation in AS. Thus, a detailed investigation of the immunopathology at sites of facet joints is of crucial importance in understanding the pathogenesis of AS. METHODS: The facet joints were obtained from 30 AS patients and 23 age- and gender-matched controls (patients with fresh thoracolumbar fracture). The facet joints were assessed immunohistochemically by analyzing the number of infiltrating T cells (CD3, CD4, CD8), B cells (CD20), microvessel density (CD34), osteoblasts (CD56), bone marrow macrophages (CD68), and osteoclasts (CD68) per high-power field (hpf). According to the presence or absence of persistent inflammation, AS patients were divided into 2 groups: A (patients with persistent inflammation) and B (patients without persistent inflammation). Lumbar spinal mobility was assessed using the modified Schober index (MSI). RESULTS: Two or more CD3+ T cell aggregates were found in the facet joints from 18 of 30 AS patients, whereas 1 CD3+ T cell aggregate was noted in 5 of 23 patients with thoracolumbar fracture. The levels of T cells (CD4+ and CD8+), CD20+B cells, CD56+ osteoblasts, and CD34+ microvessel density were significantly higher in AS patients than in the controls (all P < 0.01). Notably, the MSI score in group A was significantly higher than that in group B (P < 0.01). CONCLUSION: Active spinal inflammation is frequently observed in AS patients with thoracolumbar kyphosis. In addition, persistent inflammation in facet joints may further contribute to the loss of spinal mobility in the later stages of AS. These findings indicate that careful monitoring of disease activity is mandatory for AS patients in its advanced stage. LEVEL OF EVIDENCE: 4.

Change in Abdominal Morphology After Surgical Correction of Thoracolumbar Kyphosis Secondary to Ankylosing Spondylitis: A Computed Tomographic Study.

STUDY DESIGN: A computed tomographic study. OBJECTIVE: To investigate the change in abdominal morphology in surgically treated patients with ankylosing spondylitis (AS) and thoracolumbar kyphosis. SUMMARY OF BACKGROUND DATA: Severe thoracolumbar kyphosis in patients with AS exerts pressure on the abdominal cavity and subsequently causes intra-abdominal complications. Several spinal osteotomy techniques have been widely used to correct AS-related thoracolumbar kyphosis. To date, the changed abdominal morphology in patients with AS undergoing surgical correction of thoracolumbar kyphosis has not been addressed. METHODS: A total of 29 patients with AS undergoing lumbar pedicle subtraction osteotomy for correction of thoracolumbar kyphosis were retrospectively reviewed. Computed tomographic scans of the spine were used to measure the longitudinal, transverse, and anterior-posterior diameters of the abdominal cavity. Furthermore, the abdominal cavity was considered as an ellipsoid structure, thereby allowing calculation of its volume. Radiographical evaluations included global kyphosis (GK), thoracic kyphosis, lumbar lordosis (LL), and angle of fusion levels (AFL). RESULTS: The longitudinal diameter of abdominal cavity significantly increased (P < 0.01), whereas the transverse and anterior-posterior diameters of the abdominal cavity did not change, postoperatively (P > 0.05). Significant changes in GK, LL, and AFL were observed (P < 0.01). The abdominal cavity volume (ACV) increased by an average of 652  mL. The change in ACV was significantly correlated with the changes in GK (r = 0.453, P = 0.014), LL (r = 0.42, P = 0.023), and AFL (r = 0.388, P = 0.037). CONCLUSION: The increased ACV after correction of thoracolumbar kyphosis was quantitatively confirmed by this study. Thus, the improvement in digestive function after correction of thoracolumbar kyphosis secondary to AS, which has been previously documented, may be because of an increase in ACV. Moreover, spine surgeons should be aware of the potential risk for the development of abdominal complications caused by the lengthening of longitudinal diameter of the abdominal cavity. LEVEL OF EVIDENCE: 3.