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.

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.

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.

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.

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.

Facile Construction of Hybrid Hydrogels with High Strength and Biocompatibility for Cranial Bone Regeneration.

The significant efforts being made towards the utilization of artificial soft materials holds considerable promise for developing tissue engineering scaffolds for bone-related diseases in clinics. However, most of these biomaterials cannot simultaneously satisfy the multiple requirements of high mechanics, good compatibility, and biological osteogenesis. In this study, an osteogenic hybrid hydrogel between the amine-functionalized bioactive glass (ABG) and 4-armed poly(ethylene glycol) succinimidyl glutarate-gelatin network (SGgel) is introduced to flexibly adhere onto the defective tissue and to subsequently guide bone regeneration. Relying on the rapid ammonolysis reaction between amine groups (-NH2) of gelatin and ABG components and N-hydroxysuccinimide (NHS)-ester of tetra-PEG-SG polymer, the hydrogel networks were formed within seconds, offering a multifunctional performance, including easy injection, favorable biocompatibility, biological and mechanical properties (compressive strength: 4.2 MPa; storage modulus: 104 kPa; adhesive strength: 56 kPa), which could facilitate the stem cell viability, proliferation, migration and differentiation into osteocytes. In addition, the integration between the SGgel network and ABG moieties within a nano-scale level enabled the hybrid hydrogel to form adhesion to tissue, maintain the durable osteogenesis and accelerate bone regeneration. Therefore, a robust approach to the simultaneously satisfying tough adhesion onto the tissue defects and high efficiency for bone regeneration on a mouse skull was achieved, which may represent a promising strategy to design therapeutic scaffolds for tissue engineering in clinical applications.

Cross-cultural adaptation and validation of the Chinese version of the Spine Oncology Study Group Outcomes Questionnaire.

Background context: Patients with spinal metastases always have a poor health-related quality of life (HRQoL) and disease- and treatment-related adverse outcomes. The Spine Oncology Study Group Outcomes Questionnaire (SOSGOQ) has been verified and validated in English for patients with spinal metastases but not in Chinese. Purpose: This paper aimed to complete the cross-cultural adaptation of the Chinese version of the SOSGOQ, to verify its reliability and validity, and to report on the HRQoL of Chinese patients with spinal metastases. Study design/setting: This is a single-center, prospective, observational cross-sectional study. Patient sample: Seventy-six patients were enrolled in this study. Outcome measures: The SOSGOQ is made up of five HRQoL domains (physical function, neurological function, pain, mental health, social function) and post-therapy questions. The EQ-5D 3L questionnaire covers five items in mobility, self-care, usual activities, pain discomfort, and anxiety-depression, each with three answer options. The SF-36 comprises 36 items divided into eight domains. Methods: A single-center, prospective, observational cross-sectional study involving patients with spinal metastases who underwent surgery was conducted. HRQoL was evaluated using the Chinese version of the SOSGOQ, the Medical Outcomes Study Questionnaire Short Form 36 Health Survey (SF-36), and the EuroQol 5-Dimension questionnaire (EQ-5D). Demographic, tumor, symptom, and treatment data, as well as Eastern Cooperative Oncology Group (ECOG) information, were collected. Internal consistency reliability, convergent validity, concurrent validity, and clinical validity were used to evaluate reliability. A Spearman's correlation analysis was used to analyze the relationship between variables. Results: This study enrolled 76 patients, with a mean age of 55.8 years. The kidney was the most common primary tumor site, and the thoracic spine was the most affected. The internal consistency of the overall SOSQOQ (0.907) was higher than the EQ-5D (0.819), and all items of the SOSQOQ had a high convergent validity (>0.40). The SOSGOQ was significantly correlated with the EQ-5D in respective domains (p < 0.001) and overall score (p < 0.001), whereas the SF-36 was related to the overall SOSGOQ score and most domains. Total SOSGOG was significantly sensitive to changes in ECOG (p = 0.017), prior surgery (p = 0.001), and tumor type (p = 0.026). Conclusions: The SOSGOQ is a reliable and effective tool for evaluating HRQoL in patients with spinal metastases, with high sensitivity and specificity. Surgical treatment can significantly improve patients' HRQoL.

A sustained release of alendronate from an injectable tetra-PEG hydrogel for efficient bone repair.

Significant efforts on construction of smart drug delivery for developing minimally invasive gelling system to prolong local delivery of bisphosphonates are considered as promising perspectives for the bone-related diseases, which provide the hydrogels with unique bioactivities for bone repair in clinic. Herein, we have constructed an alendronate (ALN)-conjoined injectable tetra-PEG hydrogel with excellent biocompatibility, uniform network, and favorable mechanical properties in one-pot strategy. In views of the quick ammonolysis reaction between N-hydroxysuccinimide (NHS)-ester of tetra-PEG-SG and amine groups of tetra-PEG-NH2 polymer and ALN molecules, the uniform networks were formed within seconds along with the easy injection, favorable biocompatibility and mechanical properties for hydrogel scaffolds. On account of the simultaneous physical encapsulation and chemical linkage of the ALN within the hydrogels, the ALN-conjoined tetra-PEG hydrogel exhibited a sustained drug release delivery that could persistently and effectively facilitate viability, growth, proliferation, and osteogenesis differentiation of stem cells, thereby allowing the consequent adaptation of hydrogels into the bone defects with irregular shapes, which endowed the ALN-conjoined tetra-PEG hydrogel with depot formulation capacity for governing the on-demand release of ALN drugs. Consequently, the findings imply that these drug-based tetra-PEG hydrogels mediate optimal release of therapeutic cargoes and effective promotion of in situ bone regeneration, which will be broadly utilized as therapeutic scaffolds in tissue engineering and regenerative medicine.

Prospective study of preoperative autologous blood donation for patients with high risk of allogeneic blood transfusion in lumbar fusion surgery: a study protocol of a randomised controlled trial.

INTRODUCTION: Preoperative autologous blood donation (PABD) can be used to reduce the exposure of allogeneic blood transfusion in patients undergoing elective surgery. Better blood management to avoid anaemia and reduce allogeneic blood transfusion after spine surgery become increasingly important with development of enhanced recovery after surgery. We present here the design of a randomised controlled trial with three groups to verify the clinical effectiveness of PABD in patients at high risk of transfusion for lumbar fusion surgery and explore the optimal timing of autologous blood donation. METHOD AND ANALYSIS: Patients (age 18-70 years) who will receive lumbar fusion surgery for degenerative disease with haemoglobin over 110 g/L and 'high risk' of allogeneic blood transfusion are eligible, unless they refuse participation or are diagnosed with malignant metastases, infection, cardiovascular and cerebrovascular diseases, haematological disorders or relevant drug history and critical illnesses. A total of 1200 patients will be recruited and randomised into three groups. Patients in group A will not receive PABD and be regarded as control group. PABD will be performed for patients in groups B and C. Blood donation will be finished at 1 week (±3 day) before surgery in group B and 2 weeks (±3 day) before surgery in group C. Primary outcome measures will include haemoglobin decline, incidence and amount of allogeneic blood transfusion. Secondary outcome measures will include days of hospitalisation after surgery, haematocrit level and incidence of complications. This study is a single-centre and open-label randomised controlled trial. The sample size is calculated with reference to the retrospective data and previous studies. ETHICS AND DISSEMINATION: This trial has been approved by the Peking University Third Hospital Medical Science Research Ethic Committee (no: 2020-262-02). Results of the trial will be submitted for publication in a peer-reviewed journal and as conference presentations. TRIAL REGISTRATION NUMBER: ChiCTR2000039824, preresults.

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.

Medium to long term follow-up of survival and quality of life in patients with primary tumors of the cervical spine: Experience From a large single center.

Objectives: To evaluate the survival and medium to long term health-related quality of life (HRQoL) of patients with primary cervical spinal tumors in a cross-sectional study and to identify any significant associations with demographic or clinical characteristics. Methods: Patients diagnosed with primary cervical spinal tumors were retrospectively enrolled and their clinical, radiologic, and follow-up data (specifically the EQ-5D questionnaire) were collected. Univariate and multivariate Cox time-dependent regression analyses were performed to examine the significance of certain variables on overall survival. Univariate and multivariate logistic regression analyses were conducted to identify variables significant for overall HRQoL and each dimension of the EQ-5D. Results: A total of 341 patients were enrolled in the study with a mean follow-up of 70 months. The diagnosis was benign in 246 cases, malignant in 84, and unconfirmed in 11. The 5-year overall survival rate was 86% and the 10-year overall survival rate was 65%. Multivariate analysis suggested that surgical treatment (P = 0.002, hazard ratio [HR] = 0.431, 95% CI. [0.254, 0.729]), benign and malignant tumors [P < 0.001, HR = 2.788, 95% CI. (1.721, 4.516)], tumor and surrounding normal tissue boundary [P = 0.010, HR = 1.950, 95% CI. (1.171, 3.249)], and spinal instability [P = 0.031, HR = 1.731, 95% CI. (1.051, 2.851)] still had significant effects on survival. Conclusions: In this cross-sectional study, we evaluated the survival period and medium and long-term health-related quality of life of patients with primary tumors of the cervical spine, and analyzed the significant related factors of tumor clinical characteristics. Surgery, myelopathy, malignancy, spinal pain relieved by lying down or supine position, and tumor infiltration on MRI were significant predictors for overall survival. Enneking stage and age were significant predictors for HRQoL.

Spinous Process Screw Fixation: A Salvage Technique in Subaxial Cervical Spinal Instrumentation.

OBJECTIVE: We sought to evaluate the feasibility and efficacy of spinous process screws in subaxial cervical fixation. METHODS: A retrospective study was conducted on 7 patients receiving posterior cervical instrumentation for subaxial fracture dislocation or atlantoaxial dislocation from 2014 to 2015. In addition, a biomechanical test was performed on 7 fresh-frozen cadaveric spine samples (from the occiput to C7) from healthy human subjects with no history of spinal trauma. And lastly, the potential trajectories of cervical spinous process screws of 100 adults were measured through axial computed tomography in order to establish the general rule for applicability of this technique. RESULTS: Rigid fixation and solid fusion were achieved in all 7 patients included in the study. Biomechanical test results revealed no significant difference between bilateral lateral mass screw fixation and the hybrid lateral mass and spinous process screw fixation constructs. Measurement of the potential trajectory suggested that spinous process screw fixation was a viable technique in the subaxial cervical spine in the general population. CONCLUSIONS: The spinous process screw fixation technique in the subaxial cervical spine is a viable and effective salvage option for patients in whom conventional posterior fixations were not sufficient and salvage, supplementary techniques were required.

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.

Translation and validation of the Chinese version of Brace Questionnaire (BrQ).

BACKGROUND: The Brace Questionnaire (BrQ) is a tool developed to assess the health-related quality of life (HRQoL) among patients with adolescent idiopathic scoliosis (AIS) who receiving bracing as the primary treatment. It was initially developed and validated in Greek. The current study aimed to culturally adapt and psychometrically validate the BrQ in contemporary Chinese used in mainland China. METHODS: Translation of the BrQ from the original Greek into Chinese was performed. This study involved 70 Chinese adolescents between 10 and 18 years of age with a diagnosis of AIS and a Cobb angle measuring between 20 and 40 degrees. All patients received the same kind of brace for more than 4 months. Statistical analyses included internal consistency and the floor and ceiling effects of the BrQ. Subsequently, convergent validity was evaluated by correlating the measures in the BrQ with those in the Scoliosis Research Society-22 Questionnaire (SRS-22). RESULTS: There were no floor and ceiling effects observed with the Chinese version of BrQ. The intra-class correlation coefficient (ICC) was 0.967. Internal consistency as measured by Cronbach's alpha was 0.923. The global BrQ score correlated strongly with the SRS-22 total score (r=0.743, P<0.001). Most domain-level sub-scores from the BrQ correlated with the respective domain scores of SRS-22. CONCLUSIONS: Cross-cultural translation and validation demonstrated excellent reliability, high internal consistency and satisfactory concurrent validity of the Chinese version of BrQ.

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.

Vertebral Artery Variations at the Craniovertebral Junction in "Sandwich" Atlantoaxial Dislocation Patients.

OBJECTIVE: To summarize the vertebral artery (VA) pattern of 96 "sandwich" atlantoaxial dislocation (AAD) patients and to describe the strategies of reducing the injury of VA during surgery. METHODS: From 2009 to 2020, we retrospectively reviewed the 3-dimensional computed tomography angiography data of 96 AAD patients combined with atlas occipitalization and C2-3 fusion, which were diagnosed as "sandwich" AAD and 96 patients as control group patients who were without atlas occipitalization, C2-3 fusion and any other cervical bone deformity at our institution. The variations of each side of VA were described in 3 different parts (C0-1, C1-2, and C2-3) according to the characteristics of the 3-part pathological structures in "sandwich" subgroup. RESULTS: One hundred ninety-two sides of VAs in every group of patients were analyzed and every VA was described separately at 3 different level regions. There were different variations in these 3 different regions: 4 variations in the upper fusion region, 5 variations in the sandwiched region, and 6 variations in the lower fusion region in sandwich AAD patients. And the rate of VA deformity in sandwich AAD patients was much higher and more types of VA variations existed. CONCLUSION: In "sandwich" AAD patients, deformities of vertebral arteries in craniovertebral junction are more common, and the same VA may have deformities at different levels that severely affect surgical procedures. Therefore, preoperative imaging examination of VA for "sandwich" AAD patients is vital of guiding surgeons to avoid injury of VA during surgery.

New Classification Algorithm Guiding Surgical Decision-making for Posterior Longitudinal Ligament Ossification of the Thoracic Spine: A Study of 108 Patients With Mid-term to Long-term Follow-up.

STUDY DESIGN: This is a single-center, retrospective, cohort study. OBJECTIVE: The objective of this study was to propose a surgical classification algorithm guiding the choice of surgical approaches for ossification of the posterior longitudinal ligament (OPLL) in the thoracic spine based on the characteristics of each patient's specific pathology. SUMMARY OF BACKGROUND DATA: Surgical decision-making in this OPLL patient population requires balancing a more definitive decompression of the thoracic spinal cord through direct decompression against a higher risk of significant complications. MATERIALS AND METHODS: Patients with a primary diagnosis of thoracic OPLL who received surgical decompression in a tertiary spine center between May 2009 and June 2015 were included. Surgical planning was guided by our classification algorithm according to the location and the extent of OPLL in each patient. Patient demographics, neurological function using the 11-point Japanese Orthopaedic Association scale, length of procedure, estimated blood loss, the occurrence of major complications, etc., were extracted from the database of electronic medical record system. The Kruskal-Wallis test and Fisher exact test were used when data were not normally distributed. RESULTS: A total of 115 patients (33 men and 82 women) were included in this study, among whom 108 had a follow-up of at least 12 months (average: 51.7±22.2 mo, range: 12-100 mo). On the basis of our classification algorithm, 11 patients were type I, 26 were type II, 60 were type III, 11 were type IV, and the choice of surgical decompression techniques used in each patient followed that recommended by the algorithm in all cases. On average, the Japanese Orthopaedic Association score improved from 5.0±1.8 preoperatively to 8.7±1.7 postoperatively, with a Hirabayashi improvement rate of 63.6%. CONCLUSION: A new surgical classification algorithm guiding the choice of approach for decompression of OPLL in the thoracic spine was validated in a series of 108 patients through an analysis of their clinical outcomes and surgical complications. LEVEL OF EVIDENCE: Level III.