Strategies to avoid internal carotid artery injury in "sandwich" atlantoaxial dislocation patients during surgery.

PURPOSE: To elucidate the anatomic relationship between the internal carotid artery (ICA) and the bony structures of the craniovertebral junction among "sandwich" atlantoaxial dislocation (AAD) patients, and to analyze the risks of injury during surgical procedures. METHODS: The distance from the medial wall of ICA to the midsagittal plane (D1), the shortest distance between the ICA wall and the anterior cortex of the lateral mass of atlas (LMA) (D2) on the most caudal and cranial levels of LMA and the angle (A) between the sagittal plane passing through the screw entry point of C1 lateral mass(C1LM) screw and the medial tangent line of the vessel passing through the entry point were measured. Besides, the location of ICA in front of the atlantoaxial vertebra was divided into 4 categories (Z1-Z4). RESULTS: There was a statistically difference between the male and female patients regarding D1, and the difference between D2 at level a and level b as well as angle A between the left and right sides were statistically different (p < 0.05). Ninety-two ICAs (57.5%) were anteriorly located in Z3, 50 (31.3%) were located in Z4, 17 were located in Z2, and only one ICA was located in Z1 in all 80 patients. CONCLUSIONS: In "sandwich" AAD patients, particular attention should be paid to excessively medialized ICA to avoid ICA injury during trans-oral procedures, and the risk of injuring the ICA with more cranially and medially angulated C1LM screw placement was relatively less during posterior fixation procedures. A novel classification of ICA location was used to describe the relationship between ICA and LMA.

A novel 3D-printed locking cage for anterior atlantoaxial fixation and fusion: case report and in vitro biomechanical evaluation.

BACKGROUND: Treatment of atlantoaxial dislocation is aimed at reduction and stabilization of the atlantoaxial joint. 3D printing refers to a process where additive manufacturing is achieved under precise computer control. Literature on its utilization in anterior atlantoaxial fixation and fusion is rare. This study is the first report on a 3D-printed locking cage used in the anterior procedure for atlantoaxial dislocation. METHODS: A middle-aged male in his 40s presented with weakness and numbness of his extremities for 3 years and could only walk slowly with assistance. Imaging studies revealed severe anterior migration of C1, irreducible atlantoaxial dislocation, and severe cervical-medullary compression. A preoperative plan consisting of trans-oral soft tissue release and fixation using tailor-designed 3D-printed cages was devised. Following fluoroscopic confirmation of reduction of the atlantoaxial joints, two customized 3D-printed cages made of titanium alloy were inserted into the bilateral facet joints, which were then locked by six screws into the lateral masses of C1 and C2. The microstructure of the inserted cages was optimized for improved biomechanical stability and enhanced osseo-integration, without the need for bone grafting. In addition, a biomechanical test was performed on seven human cadaveric specimens comparing the novel implant with the conventional C1 lateral mass-C2 pedicle screw construct in three modes of motion (flexion-extension, lateral bending, axial rotation). RESULTS: Improvement of neurologic function in the patient was evident immediately after surgery. He was able to walk independently 1 month post-operatively. At the 12-month follow-up, coronal reconstruction of CT demonstrated properly-positioned 3D-printed cages, evidence of osseo-integration at the bone-implant interface, and no subsidence or displacement of the implant. Eighteen months out of surgery, the mJOA score improved to 15, and lateral X-ray confirmed reduction of atlanto-axial dislocation. Additionally, the new construct provided strong fixation comparable to that conferred by conventional constructs as there was no significant difference observed between the two groups in all three directions of motion. CONCLUSIONS: The novel implant represents a new option in the treatment of irreducible atlantoaxial dislocation. It can provide strong anterior support for solid fixation and fusion with a low profile and a microstructure that obviates the need for bone grafting.

Reliability and validity of simplified Chinese version of the Italian spine youth quality of life questionnaire in adolescents with idiopathic scoliosis.

BACKGROUND: The Italian Spine Youth Quality of Life (ISYQOL) questionnaire is used to evaluate health-related quality of life in adolescents with Idiopathic Scoliosis. The study aimed to undertake the process of cultural adaptation of the ISYQOL questionnaire into Simplified Chinese. METHODS: Translate from Italian into Simplified Chinese. It involved 138 adolescents whose Cobb angle ranged between 20 and 40 degrees, 50 wearing the brace and 88 not wearing the brace. Statistical analysis calculated the reliability, floor effects, and ceiling effects of the ISYQOL. After that, construct validity was measured by analyzing the ISYQOL relationship Scoliosis Research Society-22 patient Questionnaire (SRS-22). RESULTS: There were no floor or ceiling effects in the ISYQOL questionnaire. Cronbach's alpha coefficient evaluated for Internal consistency was 0.75 in the no-treated group and 0.88 in the brace-treated group. Intraclass correlation coefficients assessed with the use of the test-retest method were 0.72 in the no-treated group and 0.80 in the brace-treated group. A strong relationship exists between the ISYQOL measure and SRS-22 scores (rho = 0.62; p < 0.01), reflecting the high validity of the questionnaires. Both ISYQOL and SRS-22 scores showed no statistical difference between groups wearing and not wearing the brace (p > 0.05). CONCLUSIONS: Trans-cultural validation in Chinses language showed the reliability and validity of the ISYQOL.

The value of dynamic MRI in the treatment of cervical spondylotic myelopathy: a protocol for a prospective randomized clinical trial.

BACKGROUND: Cervical spondylotic myelopathy (CSM) is the most severe type of cervical spondylosis and the most common cause of spinal cord dysfunction among adults over 55 years old. MRI plays an important role in the diagnosis and evaluation of CSM, which can directly demonstrate the correlation between disc, spinal cord, posterior structures and abnormal signal in spinal cord. Static MRI can only show the static and neutral position of spinal cord, which is not enough to understand the pathogenesis of CSM. Dynamic MRI demonstrating the extension and flexion position of spinal cord can be a better tool for the treatment of CSM, especially the surgical decision making. METHOD: A total of 180 CSM patients who have indications for surgery will be recruited in outpatient of Peking University Third Hospital and assigned to three groups (Group A, B and C) based on their static MRI after consent. Group A (incomplete dura compression) means the signal of cerebral spinal fluid (CSF) is still visible. Group B (complete dura compression) means no CSF signal and no shape change of spinal cord. Group C (spinal cord compression) means shape change of spinal cord. Two surgical plans will be made for each participant by one professional surgeon according to the static MRI and dynamic MRI respectively and we will randomly choose one to perform via a random number system. Follow-up will be maintained at 3, 6, and 12 months after surgery through outpatient or telephone interview, including mJOA score, 10-s G&R (grip and release) and 10-s step test, SF-36 score, radiographic examination and complications. Finally, data collection and statistical analysis will be finished by researchers who are blinded to recruitment and treatment. DISCUSSION: This study will help us to explore the indication of dynamic MRI and the value of dynamic MRI in the treatment of CSM, especially the surgical decision making. Dynamic MRI can be a useful tool in the treatment of CSM patients. TRIAL REGISTRATION: ChiCTR1900023014. Registered on May 7th, 2019.

Atlantoaxial dislocation with congenital "sandwich fusion" in the craniovertebral junction: a retrospective case series of 70 patients.

BACKGROUND: In the setting of congenital C1 occipitalization and C2-3 fusion, significant strain is placed on the atlantoaxial joint. Vertebral fusion both above and below the atlantoaxial joint (i.e., a "sandwich") creates substantial instability. We retrospectively report on a case series of "sandwich fusion" atlantoaxial dislocation (AAD), describing the associated clinical characteristics and detailing surgical treatment. To the best of our knowledge, the present study is the largest investigation to date of this congenital subgroup of AAD. METHODS: Seventy consecutive patients with sandwich fusion AAD, from one senior surgeon, were retrospectively reviewed. The clinical features and the surgical treatment results were assessed using descriptive statistics. No funding sources or potential conflict of interest-associated biases exist. RESULTS: The mean patient age was 42.2 years (range: 5-77 years); 36 patients were male, and 34 were female. Fifty-eight patients (82.9%) had myelopathy, with Japanese Orthopaedic Association (JOA) scores ranging 4-16 (mean: 12.9). Cranial neuropathy was involved in 10 cases (14.3%). The most common presentation age group was 31 to 40 years (24 cases, 34.3%). Radiological findings revealed brainstem and/or cervical-medullar compression (58 cases, 82.9%), syringomyelia (16 cases, 22.9%), Chiari malformation (12 cases, 17.1%), cervical spinal stenosis (10 cases, 14.3%), high scapula deformity (1 case, 1.4%), os odontoideum (1 case, 1.4%), and dysplasia of the atlas (1 case, 1.4%). Computed tomography angiography was performed in 27 cases, and vertebral artery (VA) anomalies were identified in 14 cases (51.9%). All 70 patients underwent surgical treatment, without spinal cord or VA injury. Four patients (5.7%) suffered complications, including 1 wound infection, 1 screw loosening, and 2 cases of bulbar paralysis. In the 58 patients with myelopathy, the mean JOA score increased from 12.9 to 14.5. The average follow-up time was 50.5 months (range: 24-120 months). All 70 cases achieved solid atlantoaxial fusion at the final follow-up. CONCLUSIONS: Sandwich fusion AAD, a unique subgroup of AAD, has distinctive clinical features and associated malformations such as cervical-medullar compression, syringomyelia, and VA anomalies. Surgical treatment of AAD was associated with myelopathy improvement and minimal complication occurrence.

The use of CT Hounsfield unit values to identify the undiagnosed spinal osteoporosis in patients with lumbar degenerative diseases.

PURPOSES: Our purpose was to use computed tomography (CT) Hounsfield unit (HU) values to identify the undiagnosed spinal osteoporosis in patients with lumbar degenerative diseases. METHODS: A total of 334 patients with lumbar degenerative diseases were retrospectively reviewed and divided into two groups according to the degree of lumbar degenerative changes in preoperative lumbar CT images. Patients who had at least three vertebrae with severe degeneration at L1-L4 were placed in the degenerative group, and others were placed in the control group. HU value of trabecular bone in middle axial CT image of vertebral body, T-score and bone mineral density (BMD) at L1-L4 and hips were measured. CT HU thresholds for osteoporosis were obtained from control group and then applied to identify undiagnosed spinal osteoporosis. RESULTS: There were 182 patients in the degenerative group and 152 patients in the control group. CT HU value had a positive correlation with T-score and BMD of lumbar spine in both groups (P < 0.001), while the correlation coefficients at L1-L4 were higher in the control group (> 0.7) than in the degenerative group (< 0.7). T-score and BMD of lumbar spine were higher in the degenerative group (P < 0.05), while CT HU value, T-score and BMD of hips had no significant difference between two groups. According to the linear regression equations of vertebral T-score and CT HU value in the control group, the thresholds matching T-score of - 2.5 were 110, 100, 85 and 80HU for L1, L2, L3 and L4, respectively. Defining CT osteoporosis as L1 ≤ 110HU or L2 ≤ 100HU or L3 ≤ 85HU or L4 ≤ 80HU was 88.5% (69/78) specific and 60.8% (45/74) sensitive for distinguishing DXA osteoporosis of lumbar spine in the control group. The rate of undiagnosed spinal osteoporosis was higher in the degenerative group than in the control group according to CT HU thresholds (38.7% vs. 11.5%, P < 0.05). CONCLUSIONS: Degenerative changes in the lumbar spine can increase BMD and T-score provided by lumbar DXA, leading to an underestimation of vertebral osteoporosis. Thresholds for osteoporosis based on CT HU values can be used as a complementary method to identify undiagnosed spinal osteoporosis in patients with lumbar degenerative diseases. These slides can be retrieved under Electronic Supplementary Material.

Post-Operative Pain Assessment and Management in Cerebral Palsy (CP): A Two-Pronged Comparative Study on the Experience of Surgical Patients.

INTRODUCTION: This study compares the current practice patterns of pain assessment and management between children with and without CP following either posterior spinal instrumentation and fusion (PSIF) or hip osteotomy (HO). METHODS: Two cohorts of CP patients were retrospectively identified and matched with non-CP patients based on age, surgical procedure, and approach to post-operative pain management. Sixteen CP patients undergoing PSIF and twenty-two undergoing HO were respectively matched with the same numbers of non-CP patients receiving the same procedures. The frequency of assessments conducted, highest pain scores recorded on each post-operative day (POD), and the amount of adjuvant analgesics administered were collected for POD 0-4. RESULTS: Patients with CP were significantly more frequently evaluated for pain post-operatively, tended to have lower pain scores as measured by current scales, and received slightly fewer analgesics. Patients with CP differed from their non-CP counterparts in both frequency and method of post-operative pain assessment. CONCLUSIONS: The purpose of this study is to elucidate the current state of post-operative pain assessment and management in children with CP undergoing major orthopaedic surgeries, to improve CP patient/caregiver understanding and expectation of the post-operative experience regarding pain, and to provide recommendations for improving the post-operative care for these patients.

Multiple Silver Nanoparticles Anchored Hollow Mesoporous Silica Nanospheres by Polyacrylic Acid Aggregate Templating Approach for Catalytic Reduction of p-Nitrophenol.

Anchoring metal cores inside porous shells can endow metal catalyst with high selectivity and stability. Herein, multiple silver nanoparticles were successfully anchored in hollow mesoporous silica nanospheres (Ag@HMSNs) through a facile one-pot method. Polyacrylic acid aggregates self-assembled in water/ethanol solvent were used as core templates and Ag nanoparticles captors, and hexadecyl trimethoxysilane (C16TMS) was used as the pore-making agent. The hollow cavity, encapsulated multiple Ag nanoparticles, and mesoporous silica shell of the Ag@HMSNs were confirmed by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and nitrogen sorption analysis. Just as expected, Ag nanoparticles (2-5 nm) were encapsulated in the cavity of hollow mesoporous silica nanospheres with the size of about 200 nm. The fabricated Ag@HMSNs showed excellent performance for catalytic reduction of p-nitrophenol (4-NP). Also, catalytic activity of the Ag@HMSNs for 4-NP reduction was increased with the addition amount of the pore-making agents and surface areas. The superior catalytic performance was attributed to the unique structural features of Ag@HMSNs architecture, in which the mesoporous shell provided readily accessible pathway for fast transport of reactants to the encapsulated Ag nanoparticles.

3D Printing in Spine Surgery.

In the past 5 years, the application of 3D printing technology in the field of spine surgery had obtained enormous and substantial progress. Among which, vertebral skeleton model (including lesion model) printing has been widely used in clinical application due to its relatively simple technology and low cost. It shows practical value and becomes popular as the reference of clinical education, auxiliary diagnosis, communication between doctor and patient, and the planning of surgical approaches as well as the reference of more accurate operation in surgery. On the basis of vertebral skeleton model printing, it can be used to design and make navigation template to guide internal fixation screw, which also obtains some remarkable clinical effects. However, 3D printing technology has a more profound influence on spine surgery. The part with full expectation is undoubtedly the clinical application of 3D printing microporous metal implant and personalized implant as well as the clinical application of 3D printing biological materials in the future.

A systematic review of complications in thoracic spine surgery for ossification of the posterior longitudinal ligament.

PURPOSE: To answer two questions: (1) what are the common complications associated with surgery for thoracic myelopathy caused by ossification of the posterior longitudinal ligament, and (2) which surgical approach is safer with regard to the incidence of post-operative complications. METHODS: Relevant literature searches were performed using the Cochrane Central Register of Controlled Trials, PubMed, EMBASE, the Chinese Biomedical Literature Database, the China National Knowledge Infrastructure, KoreaMed, and the Japan CentraRevuoMedicina. RESULTS: 15 studies met the inclusion criteria and were retrieved. They included a total of 595 patients, 39 % of whom were male and 61 % female. The mean patient age ranged from 52.6 to 60.9 years. The mean recovery rate from each individual study varied between 24.7 and 77.6 % and the pooled neurologic function recovery rate was 50.4 %. From these 15 studies, the mean complication rate was 39.4 %. By far, two complications were more common than the others: cerebrospinal fluid leakage (incidence rate 22.5 %) and post-operative neurologic deficit (incidence rate 13.9 %). 7.7 % of patients from the indirect decompression group experienced cerebrospinal fluid leakage, while it was reported in 25.6 % of those in the direct decompression group. Neurologic deficit was reported in 8.4 % of patients undergoing indirect decompression and 19.8 % of those undergoing direct decompression. CONCLUSIONS: Cerebrospinal fluid leakage and neurologic deficit were the two most common complications following surgical decompression of the thoracic spine with ossification of the posterior longitudinal ligament. Patients undergoing indirect decompression surgeries had significantly lower complication rates compared with those undergoing direct decompression surgeries.

The relationship between changes of cervical sagittal alignment after anterior cervical discectomy and fusion and spino-pelvic sagittal alignment under roussouly classification: a four-year follow-up study.

BACKGROUND: Anterior cervical discectomy and fusion (ACDF) is widely used in the treatment of cervical degenerative disease; however, the variation of cervical sagittal alignment changes after ACDF has been rarely explored. The purpose of this study is to determine the relationship between changes of cervical sagittal alignment after ACDF and spino-pelvic sagittal alignment under Roussouly classification. METHODS: A cohort of 133 Chinese cervical spondylotic patients who received ACDF from 2011 to 2012 was recruited. All patients were categorized with Roussouly Classification. Lateral X-ray images of global spine were obtained, and preoperative and postoperative parameters were measured and analyzed, including C2-C7 angles (C2-C7), C0-C7 angles (C0-C7), external auditory meatus (EAM) tilt, sacral slope (SS), thoracic kyphosis (TK), lumbar lordosis (LL), spinal sacral angles (SSA), Superior adjacent inter-vertebral angle (SAIV), inferior adjacent inter-vertebral angle (IAIV) and et al. The Wilcoxon signed-rank test was used for intragroup comparisons preoperatively and at postoperative 48 months. RESULTS: Among the parameters, C2-C7 and C0-C7 showed significant increase, while EAM TK, and IAIV decreased significantly. In type I, EAM and TK decreased significantly, however SS showed a significant increase; in type II, TK showed a significant decrease, but SSA showed a significant increase; in type III, a significant increase of C0-C7 was observed with a significant decrease in EAM, nevertheless, LL, SS and SSA showed significant decreases; and in type IV, C2-C7 showed a significant increase and EAM decreased significantly. The percentage of lordotic alignment in cervical spine increased, which was presenting in type I, III and IV. Nevertheless, the amount of patients with straight cervical alignment increased in type II. CONCLUSION: The backward movement of head occurs is the compensatory mechanism in cervical sagittal alignment modifications after ACDF. The compensatory alteration of spino-pelvic sagittal alignment varied in different Roussouly type.

Calcific discitis with giant thoracic disc herniations in adults.

PURPOSE: Calcific discitis is a self-limiting process most commonly seen in the cervical spine of children. Rare literature exists regarding the natural history and management of this condition in adults, especially when it presents as a giant thoracic disc herniation into the spinal canal. Giant herniations in the thoracic spine are typically surgically removed to reduce the chance of permanent neurologic deficit from spinal cord compression. However, when associated with calcific discitis, they may undergo spontaneous regression with the need for surgery obviated. METHODS: Medical records and radiographic studies of two adult patients with calcific discitis and myelopathy due to spinal cord compression by giant thoracic disc herniations were retrospectively reviewed. Search of the literature on calcific discitis in adults and spontaneous regression of calcified thoracic disc herniations was separately performed. RESULTS: Both patients were young male adults presenting with back pain and early signs of myelopathy. With restriction of activities and oral NSAIDs, their symptoms were relieved within 3 months. Four adult cases of calcific discitis (characteristic central calcification confined within the nucleus pulposus) and three instances of spontaneous regression of small- to medium-sized thoracic calcified disc herniations were identified from the literature. CONCLUSIONS: The demonstration of spontaneous resorption of giant calcified thoracic disc herniations in two adult patients with calcific discitis supplements the existing literature and provides the first evidence that giant calcified thoracic disc herniations may still undergo spontaneous remission and a "wait and watch" strategy may be justified at least in the initial management of these patients, even with the presence of mild myelopathy.

Genetic insights into the 'sandwich fusion' subtype of Klippel-Feil syndrome: novel FGFR2 mutations identified by 21 cases of whole-exome sequencing.

BACKGROUND: Klippel-Feil syndrome (KFS) is a rare congenital disorder characterized by the fusion of two or more cervical vertebrae during early prenatal development. This fusion results from a failure of segmentation during the first trimester. Although six genes have previously been associated with KFS, they account for only a small proportion of cases. Among the distinct subtypes of KFS, "sandwich fusion" involving concurrent fusion of C0-1 and C2-3 vertebrae is particularly noteworthy due to its heightened risk for atlantoaxial dislocation. In this study, we aimed to investigate novel candidate mutations in patients with "sandwich fusion." METHODS: We collected and analyzed clinical data from 21 patients diagnosed with "sandwich fusion." Whole-exome sequencing (WES) was performed, followed by rigorous bioinformatics analyses. Our focus was on the six known KFS-related genes (GDF3, GDF6, MEOX1, PAX1, RIPPLY2, and MYO18). Suspicious mutations were subsequently validated through in vitro experiments. RESULTS: Our investigation revealed two novel exonic mutations in the FGFR2 gene, which had not previously been associated with KFS. Notably, the c.1750A > G variant in Exon 13 of FGFR2 was situated within the tyrosine kinase domain of the protein, in close proximity to several established post-translational modification sites. In vitro experiments demonstrated that this certain mutation significantly impacted the function of FGFR2. Furthermore, we identified four heterozygous candidate variants in two genes (PAX1 and MYO18B) in two patients, with three of these variants predicted to have potential clinical significance directly linked to KFS. CONCLUSIONS: This study encompassed the largest cohort of patients with the unique "sandwich fusion" subtype of KFS and employed WES to explore candidate mutations associated with this condition. Our findings unveiled novel variants in PAX1, MYO18B, and FGFR2 as potential risk mutations specific to this subtype of KFS.

Patient-specific 3D-printed Brace for Adolescent Idiopathic Scoliosis: A Prospective Cohort Study.

OBJECTIVE: To evaluate the efficacy, safety of patient-tailored 3D printed brace in the treatment of adolescent idiopathic scoliosis (AIS), and to compare the health-related quality of life (HRQoL) of patients treated with two different types of brace. MATERIALS AND METHODS: From September 2017 to August 2020, 103 AIS patients requiring non-operative management were prospectively recruited in this study. All patients were followed up every 6 months, clinical and radiological examination were assessed at each follow-up time. Full-length anteroposterior X-ray of the spine in the standing position was performed obtained. At the last follow-up, each patient completed a standardized HRQoL questionnaire. Compliance is defined as that the patient insists on wearing the brace for ≥ 23h every day (full-time wearing) and follow-up every 6 months until bone maturity.The rate of major curve Cobb progression was defined that maximum Cobb Angle of major curve greater than 6° compared with that at the initial diagnosis, or aggravated to more than 45° so that orthopedic surgery was recommended during treatment, which was defined as the rate of conversion to surgery. The effects of these two types of braces on the rate of major curve Cobb progression and HRQoL were analyzed by independent sample t-test ad Chi-square test. RESULTS: The thickness was 4 mm for thoracolumbosacral orthosis (TLSO) and 3 mm for 3D-printed brace (3DPB). In addition, compared with the material used in TLSO, the weight (600-800 grams) of the 3DPB materials with the same area is reduced by about 25-30%. 55 patients (49.1%) and 48 patients (33.1%) were respectively included in the 3DPB cohort and the TLSO cohort.The maximum Cobb angle of major curve in the 3DPB cohort was significantly lower than those in the TLSO cohort at 6 months, 12 months and the last follow-up (p < 0.01). The thoracic kyphosis (TK) and lumbar lordosis (LL) of the two cohorts at the last follow-up were lower than those before brace treatment, in addition, there was a significant difference in TK (p = 0.001) and LL (p = 0.004) between the two cohorts at the follow-up. The scores of physical function, pain, self-image, mental health and treatment satisfaction in the Chinese version of SRS-22 in the 3DPB cohort were higher than those in the TLSO cohort (p < 0.01 and p < 0.05, respectively). The scores of the 3DPB cohort were significantly higher than those of the TLSO group in the four dimensions (p = 0.008, 0.013, 0.015, and 0.002, respectively) of the EuroQol-5D health description system except for mobility, and the overall health status of EuroQol-5D was higher for the 3DPB cohort (p < 0.001). At the last follow-up, One patient in the 3DPB cohort and ten patients in the TLSO cohort had major curve Cobb progression of greater than 6°, and the rate of major curve Cobb progression in 3DPB cohort was significantly lower than that in the TLSO cohort (OR 14.2, 95% CI 1.7∼115.8, p < 0.01). One patient in the 3DPB and seven patients in the TLSO cohorts received subsequent surgery or was recommended for surgery, and the rate of conversion to surgery was significantly lower than in the 3DPB cohort (OR 9.2, 95% CI 1.1∼77.9, p < 0.05). CONCLUSIONS: Patient-tailored 3D-printed brace is lighter, thinner, and more comfortable than conventional braces in the treatment of AIS. It can substantially improve the HRQoL of patients and can significantly reduce the progression of major curve Cobb progression and rate of conversion of surgery.

Preoperative radiological indicators for prediction of difficult laryngoscopy in patients with atlantoaxial dislocation.

Background: Difficult airway remains a great challenge in patients with atlantoaxial dislocation (AAD). Preoperative evaluation and reliable prediction are required to facilitate the airway management. We aimed to screen out reliable radiological indicators for prediction of difficult laryngoscopy in patients with AAD. Methods: A retrospective nested case-control study within a single center longitudinal AAD cohort was conducted to investigate the radiological indicators. All the patients with difficult laryngoscopy from 2010 to 2021 were enrolled as the difficult laryngoscopy group. Others in the cohort without difficult laryngoscopy were randomly selected as the non-difficult laryngoscopy group by individually matching with the same gender, same surgery year, and similar age (±5 years) at a ratio of 6:1. Radiological data on preoperative lateral X-ray images between the two groups were compared. Bivariate logistic regression model was applied to screen out the independent predictive indicators and calculate the odds ratios of indicators associated with difficult laryngoscopy. Receiver operating characteristic curve and area under the curve (AUC) were used to describe the discrimination ability of indicators. Results: A total of 154 patients were finally analyzed in this study. Twenty-two patients with difficult laryngoscopy and matched with 132 controls. Four radiological parameters showed significant difference between the two groups. Among which, ΔC1C2D (the difference of the distance between atlas and axis in the neutral and extension position), owned the largest AUC. Conclusions: ΔC1C2D could be a valuable radiologic predictor for difficult laryngoscopy in patients with AAD.

Overstrain on the longitudinal band of the cruciform ligament during flexion in the setting of sandwich deformity at the craniovertebral junction: a finite element analysis.

BACKGROUND CONTEXT: In the setting of "sandwich deformity" (concomitant C1 occipitalization and C2-3 nonsegmentation), the C1-2 joint becomes the only mobile joint in the craniovertebral junction. Atlantoaxial dislocation develops earlier with severer symptoms in sandwich deformity, which has been hypothesized to be due to the repetitive excessive tension in the ligaments between C1 and C2. PURPOSE: To elucidate whether and how the major ligaments of the C1-2 joint are affected in sandwich deformity, and to find out the ligament most responsible for the earlier development and severer symptoms of atlantoaxial dislocation in sandwich deformity. STUDY DESIGN: A finite element (FE) analysis study. METHODS: A three-dimensional FE model from occiput to C5 was established using anatomical data from a thin-slice CT scan of a healthy volunteer. Sandwich deformity was simulated by eliminating any C0-1 and C2-3 segmental motion respectively. Flexion torque was applied, and the range of motion of each segment and the tension sustained by the major ligaments of C1-2 (including the transverse and longitudinal bands of the cruciform ligament, the alar ligaments, and the apical ligament) were analyzed. RESULTS: Tension sustained by the longitudinal band of the cruciform ligament and the apical ligament during flexion is significantly larger in the FE model of sandwich deformity. In contrast, tension in the other ligaments is not significantly changed in the sandwich deformity model compared with the normal model. CONCLUSIONS: Considering the importance of the longitudinal band of the cruciform ligament to the stability of the C1-2 joint, our findings implicate that the early onset, severe dislocation, and unique clinical manifestations of atlantoaxial dislocation in patients with sandwich deformity are mainly due to the enlarged force loaded on the longitudinal band of the cruciform ligament. CLINICAL SIGNIFICANCE: The enlarged force loaded on the longitudinal band of the cruciform ligament can add to its laxity and thus reducing its ability to restrict the cranial migration of the odontoid process. This is in accordance with our clinical experience that dislocation of the atlantoaxial joint in patients with sandwich deformity is mainly craniocaudal, which means severer cranial neuropathy, Chiari deformity, and syringomyelia, and more difficult surgical treatment.

Clinical and Surgical Characteristics of Patients with Atlantoaxial Dislocation in the Setting of Sandwich Fusion: A Case-Control Analysis of Over 500 Patients with Mid-Term to Long-Term Follow-up.

BACKGROUND: Patients with "sandwich" fusion (concomitant C1 occipitalization and C2-C3 nonsegmentation), a subtype of Klippel-Feil syndrome, are at particular risk for developing atlantoaxial dislocation (AAD). However, the clinical and surgical characteristics of AAD in patients with sandwich fusion have not been clearly defined. METHODS: A retrospective case-control study with a large sample size and a minimum 2-year follow-up was performed. From 2000 to 2018, 253 patients with sandwich AAD underwent a surgical procedure; these patients constituted the case group, and a matching number of patients with non-sandwich AAD were randomly selected to form the control group. Clinical data from electronic medical records and various imaging studies were analyzed and compared. The Japanese Orthopaedic Association (JOA) scale was used to evaluate neurological function. RESULTS: Patients with sandwich AAD, compared with patients with non-sandwich AAD, had symptom onset at a younger age (34.8 compared with 42.8 years; p < 0.001) and had a higher likelihood for myelopathy (87.4% compared with 74.7%; p < 0.001). Patients with sandwich AAD had a higher incidence of lower cranial nerve palsy (7.9% compared with 0.0%; p < 0.001), a lower preoperative JOA score (13.4 compared with 14.2; p < 0.001), and higher incidences of accompanying Type-I Chiari malformation (20.9% compared with 1.2%; p < 0.001) and syringomyelia (21.3% compared with 1.6%; p < 0.001). Finally, patients with sandwich AAD had higher likelihoods of undergoing transoral release (28.5% compared with 5.1%; p < 0.001) and use of salvage fixation techniques (34.4% compared with 6.3%; p < 0.001), and had lower postoperative results for the JOA score (14.9 compared with 15.9; p < 0.001) and improvement rate (43.8% compared with 58.2%; p < 0.001). CONCLUSIONS: Patients with sandwich AAD demonstrated distinct clinical manifestations. Versatility involving the use of various internal fixation techniques and transoral release procedures was frequently required in the surgical management of these patients, and meticulous and personalized preoperative planning would be of paramount importance. LEVEL OF EVIDENCE: Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Chinese validation of the quality of life profile for spinal deformities (QLPSD).

We aimed to translate and validate the Quality of Life Profile for Spine Deformities (QLPSD), an age-specific tool assessing the individuals' health-related quality of life (HRQoL), into a Chinese version for adolescent individuals with adolescent idiopathic scoliosis (AIS). The Chinese version was translated from the original Spanish QLPSD following widely accepted guidelines and evaluated by both individuals with AIS and experts. 172 Chinese-speaking individuals between 9 and 18 years of age with Cobb angles between 20° and 40° were included. Internal consistency, test-retest reliability, and floor and ceiling effects were all analyzed. Convergent validity was evaluated by correlating the measures in the Chinese QLPSD with those in the 22-item Scoliosis Research Society Questionnaire (SRS-22). Known-groups construct validity was assessed by comparing the QLPSD scores of two groups of individuals divided by their Cobb angles. The internal consistency (total Cronbach's alpha = 0.917) and the test-retest reliability (total intra-class correlation coefficient = 0.896) were both satisfactory. The Chinese QLPSD correlated well with the SRS-22 in the total score and in relevant subscales (r = -0.572, p < 0.01). The questionnaire was able to differentiate between individuals with different Cobb angles. No floor or ceiling effects were shown in the total score, neither were there ceiling effects in the subscales, but floor effects were observed in four of the five subscales, between 20.0% and 45.7%. The Chinese version of the QLPSD shows adequate transcultural adaptation, reliability, and validity, and is useful as a clinical evaluation tool for the HRQoL of adolescent Chinese-speaking individuals with AIS.

MPF-net: An effective framework for automated cobb angle estimation.

In clinical practice, the Cobb angle is the gold standard for idiopathic scoliosis assessment, which can provide an important reference for clinicians to make surgical plan and give medical care to patients. Currently, the Cobb angle is measured manually on both anterior-posterior(AP) view X-rays and lateral(LAT) view X-rays. The clinicians first find four landmarks on each vertebra, and then they extend the line from landmarks and measure the Cobb angle by rules. The whole process is time-consuming and subjective, so that the automated Cobb angle estimation is required for efficient and reliable Cobb angle measurement. The noise in X-rays and the occlusion of vertebras are the main difficulties for automated Cobb angle estimation, and it is challenging to utilize the information between the multi-view X-rays of the same patient. Addressing these problems, in this paper, we propose an effective framework named MPF-net by using deep learning methods for automated Cobb angle estimation. We combine a vertebra detection branch and a landmark prediction branch based on the backbone convolutional neural network, which can provide the bounded area for landmark prediction. Then we propose a proposal correlation module to utilize the information between neighbor vertebras, so that we can find the vertebras hidden by ribcage and arms on LAT X-rays. We also design a feature fusion module to utilize the information in both AP and LAT X-rays for better performance. The experiment results on 2738 pair of X-rays show that our proposed MPF-net achieves precise vertebra detection and landmark prediction performance, and we get impressive 3.52 and 4.05 circular mean absolute errors on AP and LAT X-rays respectively, which is much better than previous methods. Therefore, we can provide clinicians with automated, efficient and reliable Cobb angle measurement.

Accuracy of post-operative recall by degenerative cervical myelopathy patients using the modified Japanese Orthopaedic Association scale.

Background and Aim: The modified Japanese Orthopaedic Association (mJOA) scale is one of the primary measures of neurological function used on patients with degenerative cervical myelopathy (DCM). Contrary to some reports, the mJOA is not based on patient-reported outcomes as it is an assessment conducted by physicians, allied health professionals, or trained staff. To date, the accuracy of post-operative recall by DCM patients of their pre-operative neurological function, as assessed by the mJOA scale, has not been examined. This study, therefore, aimed to evaluate recall accuracy in DCM patients using the mJOA scale. Methods: This study analyzed recall capacity of DCM patients who had undergone anterior cervical discectomy and fusion by a single surgeon at a large academic spine center between February 2012 and August 2017. Patient recall of neurological function pre-surgery was assessed at 3, 12, and 24 months post-surgery using the mJOA scale. Actual mJOA scores were also determined at each follow-up. Recall error (RE) was defined as the difference between recalled mJOA score at each post-operative visit and the actual baseline score. Age, gender, surgical segments, hospital length of stay, actual mJOA scores at follow-up, and actual rate of improvement in mJOA score were analyzed as predictors of recall accuracy. Descriptive statistics were collected to profile the characteristics of patients enrolled in the study cohort. All statistical computing and graphing were performed with R software and generalized estimating equation (GEE) model fitting was done using geepack package. Results: A total of 105 patients (56.2% of males and 43.8% of females) were enrolled in the study. The median ± SD (range) age at the pre-surgical baseline measurement was 50 ± 8 (25 - 78) years. The recalled mJOA scores at the three follow-up time points were lower than the actual mJOA scores. The recall accuracy gradually decreased over time. Estimated coefficients showed that all variables in the GEE model except for surgical fusion segments were significant (P < 0.05). The pre-operative actual baseline mJOA score was inversely associated with RE. An increasing actual mJOA score over time had a significant positive influence on RE. Greater RE was found in males compared to females. Unexpectedly, age was inversely associated with RE. Conclusions: The RE increases with the time interval between pre-surgical measurement and post-surgical follow-up and is more prominent in male DCMs patients following upper spine surgery. Relevance for Patients: It is necessary to select post-operative patients who need to pay attention according to the three factors of post-operative time, gender, and age, that is, patients with large RE should be given early or timely psychological counseling and treatment concerns, so as to reduce the occurrence of potential medical disputes and improve the level of medical safety.