Publications by authors named "Kenny Yat Hong Kwan"

18 Publications

  • Page 1 of 1

Does Diabetes Affect the Surgical Outcomes in Cases With Cervical Ossification of the Posterior Longitudinal Ligament? A Multicenter Study From Asia Pacific Spine Study Group.

Global Spine J 2021 Mar 10:2192568221996300. Epub 2021 Mar 10.

Department of Orthopaedics and Traumatology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong.

Study Design: Retrospective multicenter study.

Objectives: To evaluate the surgical outcomes of cervical ossification of the posterior longitudinal ligament (OPLL) in diabetes mellitus (DM) patients.

Methods: Approximately 253 cervical OPLL patients who underwent surgical decompression with or without fixation were registered at 4 institutions in 3 Asian countries. They were followed up for at least 2 years. Demographics, imaging, and surgical information were collected, and cervical Japanese Orthopaedic Association (JOA) scores and the visual analog scale (VAS) for the neck were used for evaluation.

Results: Forty-seven patients had DM, showing higher hypertension and cardiovascular disease prevalence. Although they presented worse preoperative JOA scores than non-DM patients (10.5 ± 3.1 vs. 11.8 ± 3.2; = 0.01), the former showed comparable neurologic recovery at the final follow-up (13.9 ± 2.9 vs. 14.2 ± 2.6; = 0.41). No correlation was noted between the hemoglobin A1c level in the DM group and the pre- and postoperative JOA scores. No significant difference was noted in VAS scores between the groups at pre- and postsurgery. Regarding perioperative complications, DM patients presented a higher C5 palsy frequency (14.9% vs. 5.8%; = 0.04). A similar trend was observed when surgical procedure was limited to laminoplasty.

Conclusions: This is the first multicenter Asian study to evaluate the impact of DM on cervical OPLL patients. Surgical results were favorable even in DM cases, regardless of preoperative hemoglobin A1c levels or operative procedures. However, caution is warranted for the occurrence of C5 palsy after surgery.
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http://dx.doi.org/10.1177/2192568221996300DOI Listing
March 2021

Predictors of neurologic outcome after surgery for cervical ossification of the posterior longitudinal ligament differ based on myelopathy severity: a multicenter study.

J Neurosurg Spine 2021 Mar 12:1-10. Epub 2021 Mar 12.

2Department of Neurosurgery, Spine and Spinal Cord Institute, Severance Hospital, Yonsei University College of Medicine, Seoul.

Objective: The purpose of this retrospective multicenter study was to compare prognostic factors for neurological recovery in patients undergoing surgery for cervical ossification of the posterior longitudinal ligament (OPLL) based on their presenting mild, moderate, or severe myelopathy.

Methods: The study included 372 consecutive patients with OPLL who underwent surgery for cervical myelopathy between 2006 and 2016 in East Asian countries with a high OPLL prevalence. Baseline and postoperative clinical outcomes were assessed using the Japanese Orthopaedic Association (JOA) myelopathy score and recovery ratio. Radiographic assessment included occupying ratio, cervical range of motion, and sagittal alignment parameters. Patient myelopathy was classified as mild, moderate, or severe based on the preoperative JOA score. Linear and multivariate regression analyses were performed to identify patient and surgical factors associated with neurological recovery stratified by baseline myelopathy severity.

Results: The mean follow-up period was 45.4 months (range 25-140 months). The mean preoperative and postoperative JOA scores and recovery ratios for the total cohort were 11.7 ± 3.0, 14.5 ± 2.7, and 55.2% ± 39.3%, respectively. In patients with mild myelopathy, only age and diabetes correlated with recovery. In patients with moderate to severe myelopathy, older age and preoperative increased signal intensity on T2-weighted imaging were significantly correlated with a lower likelihood of recovery, while female sex and anterior decompression with fusion (ADF) were associated with better recovery.

Conclusions: Various patient and surgical factors are correlated with likelihood of neurological recovery after surgical treatment for cervical OPLL, depending on the severity of presenting myelopathy. Older age, male sex, intramedullary high signal intensity, and posterior decompression are associated with less myelopathy improvement in patients with worse baseline function. Therefore, myelopathy-specific preoperative counseling regarding prognosis for postoperative long-term neurological improvement should include consideration of these individual and surgical factors.
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http://dx.doi.org/10.3171/2020.8.SPINE20504DOI Listing
March 2021

Toward the Development of a Comprehensive Clinically Oriented Patient Profile: A Systematic Review of the Purpose, Characteristic, and Methodological Quality of Classification Systems of Adult Spinal Deformity.

Neurosurgery 2021 May;88(6):1065-1073

Department of Orthopaedic Surgery, Radboud University Medical Center, Nijmegen, The Netherlands.

Background: Existing adult spinal deformity (ASD) classification systems are based on radiological parameters but management of ASD patients requires a holistic approach. A comprehensive clinically oriented patient profile and classification of ASD that can guide decision-making and correlate with patient outcomes is lacking.

Objective: To perform a systematic review to determine the purpose, characteristic, and methodological quality of classification systems currently used in ASD.

Methods: A systematic literature search was conducted in MEDLINE, EMBASE, CINAHL, and Web of Science for literature published between January 2000 and October 2018. From the included studies, list of classification systems, their methodological measurement properties, and correlation with treatment outcomes were analyzed.

Results: Out of 4470 screened references, 163 were included, and 54 different classification systems for ASD were identified. The most commonly used was the Scoliosis Research Society-Schwab classification system. A total of 35 classifications were based on radiological parameters, and no correlation was found between any classification system levels with patient-related outcomes. Limited evidence of limited quality was available on methodological quality of the classification systems. For studies that reported the data, intraobserver and interobserver reliability were good (kappa = 0.8).

Conclusion: This systematic literature search revealed that current classification systems in clinical use neither include a comprehensive set of dimensions relevant to decision-making nor did they correlate with outcomes. A classification system comprising a core set of patient-related, radiological, and etiological characteristics relevant to the management of ASD is needed.
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http://dx.doi.org/10.1093/neuros/nyab023DOI Listing
May 2021

Are Higher Global Alignment and Proportion Scores Associated With Increased Risks of Mechanical Complications After Adult Spinal Deformity Surgery? An External Validation.

Clin Orthop Relat Res 2021 02;479(2):312-320

K. Y. H. Kwan, The University of Hong Kong, Pokfulam, Hong Kong.

Background: The Global Alignment and Proportion (GAP) score, based on pelvic incidence-based proportional parameters, was recently developed to predict mechanical complications after surgery for spinal deformities in adults. However, this score has not been validated in an independent external dataset.

Questions/purposes: After adult spinal deformity surgery, is a higher GAP score associated with (1) an increased risk of mechanical complications, defined as rod fractures, implant-related complications, proximal or distal junctional kyphosis or failure; (2) a higher likelihood of undergoing revision surgery to treat a mechanical complication; and (3) is a lower (more proportioned) GAP score category associated with better validated outcomes scores using the Oswestry Disability Index (ODI), Scoliosis Research Society-22 (SRS-22) and the Short Form-36 questionnaires?

Methods: A total of 272 patients who had undergone corrective surgeries for complex spinal deformities were enrolled in the Scoli-RISK-1 prospective trial. Patients were included in this secondary analysis if they fulfilled the original inclusion criteria by Yilgor et al. From the original 272 patients, 14% (39) did not satisfy the radiographic inclusion criteria, the GAP score could not be calculated in 14% (37), and 24% (64) did not have radiographic assessment at postoperative 2 years, leaving 59% (159) for analysis in this review of data from the original trial. A total of 159 patients were included in this study,with a mean age of 58 ± 14 years at the time of surgery. Most patients were female (72%, 115 of 159), the mean number of levels involved in surgery was 12 ± 4, and three-column osteotomy was performed in 76% (120 of 159) of patients. The GAP score was calculated using parameters from early postoperative radiographs (between 3 and 12 weeks) including pelvic incidence, sacral slope, lumbar lordosis, lower arc lordosis and global tilt, which were independently obtained from a computer software based on centralized patient radiographs. The GAP score was categorized as proportional (scores of 0 to 2), moderately disproportional (scores of 3 to 6), or severely disproportional (scores higher than 7 to 13). Receiver operating characteristic area under curve (AUC) was used to assess associations between GAP score and risk of mechanical complications and risk of revision surgery. An AUC of 0.5 to 0.7 was classified as "no or low associative power", 0.7 to 0.9 as "moderate" and greater than 0.9 as "high". We analyzed differences in validated outcome scores between the GAP categories using Wilcoxon rank sum test.

Results: At a minimum of 2 years' follow-up, a higher GAP score was not associated with increased risks of mechanical complications (AUC = 0.60 [95% CI 0.50 to 0.70]). A higher GAP score was not associated with a higher likelihood of undergoing a revision surgery to treat a mechanical complication (AUC = 0.66 [95% 0.53 to 0.78]). However, a moderately disproportioned GAP score category was associated with better SF-36 physical component summary score (36 ± 10 versus 40 ± 11; p = 0.047), better SF-36 mental component summary score (46 ± 13 versus 51 ± 12; p = 0.01), better SRS-22 total score (3.4 ± 0.8 versus 3.7 ± 0.7, p = 0.02) and better ODI score (35 ± 21 versus 25 ± 20; p = 0.003) than severely disproportioned GAP score category.

Conclusion: Based on the findings of this external validation study, we found that alignment targets based on the GAP score alone were not associated with increased risks of mechanical complications and mechanical revisions in patients with complex adult spinal disorders. Parameters not included in the original GAP score needed to be considered to reduce the likelihood of mechanical complications.

Level Of Evidence: Level III, diagnostic study.
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http://dx.doi.org/10.1097/CORR.0000000000001521DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7899533PMC
February 2021

Brace Effectiveness Is Related to 3-Dimensional Plane Parameters in Patients with Adolescent Idiopathic Scoliosis.

J Bone Joint Surg Am 2021 Jan;103(1):37-43

Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Pokfulam, Hong Kong.

Background: Although scoliosis is a 3-dimensional (3D) deformity, little research has been performed on the use of 3D imaging in brace curve correction. The purpose of the present study was to determine the effect of axial-plane parameters on the outcomes of bracing with a thoracolumbosacral orthosis for adolescent idiopathic scoliosis.

Methods: This prospective longitudinal cohort study included patients with adolescent idiopathic scoliosis who fulfilled the criteria for bracing according to the Scoliosis Research Society, and was conducted from the time the patient began wearing the brace through a minimum follow-up of 2 years or until a surgical procedure was performed. Radiographs made with use of an EOS Imaging System were used to reconstruct 3D images of the spine at the pre-brace, immediate in-brace, 1-year in-brace, and latest follow-up out-of-brace stages. Univariate and multiple linear regressions were performed to determine the association between axial rotation correction and curve progression at the time of the latest follow-up. Logistic regressions were performed to model the probability of risk of progression.

Results: Fifty-three patients were enrolled, and 46 patients were included in the analysis. At the time of the latest follow-up, 30 patients did not experience curve progression and 16 patients had curve progression. There was no difference in baseline demographic characteristics between groups. For the transverse-plane parameters, there was a significant difference between non-progression and progression groups in pre-brace apical vertebral rotation (4.5° ± 11.2° compared with -2.4° ± 9.8°, respectively; p = 0.044) and in 1-year in-brace apical vertebral rotation correction velocity (2.0° ± 5.0°/year compared with -1.7° ± 4.4°/year, respectively; p = 0.016). Logistic regression analysis showed that pre-brace apical vertebral rotation (odds ratio, 1.063; 95% confidence interval, 1.000 to 1.131; p = 0.049) and 1-year in-brace apical vertebral rotation correction velocity (odds ratio, 1.19; 95% confidence interval, 1.021 to 1.38; p = 0.026) were associated with an increased risk of curve progression. There was no difference in Scoliosis Research Society 22-Item scores between patients who experienced curve progression and those who did not.

Conclusions: In this prospective study, we demonstrated that axial-plane parameters and the correction of these parameters during bracing are related to the successful use of the brace.

Level Of Evidence: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.
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http://dx.doi.org/10.2106/JBJS.20.00267DOI Listing
January 2021

A review of the manufacturing process and infection rate of 3D-printed models and guides sterilized by hydrogen peroxide plasma and utilized intra-operatively.

3D Print Med 2020 Mar 30;6(1). Epub 2020 Mar 30.

Department of Orthopaedics and Traumatology, The University of Hong Kong, Hong Kong, Hong Kong.

3D printing in the context of medical application can allow for visualization of patient-specific anatomy to facilitate surgical planning and execution. Intra-operative usage of models and guides allows for real time feedback but ensuring sterility is essential to prevent infection. The additive manufacturing process restricts options for sterilisation owing to temperature sensitivity of thermoplastics utilised for fabrication. Here, we review one of the largest single cohorts of 3D models and guides constructed from Acrylonitrile butadiene styrene (ABS) and utilized intra-operatively, following terminal sterilization with hydrogen peroxide plasma. We describe our work flow from initial software rendering to printing, sterilization, and on-table application with the objective of demonstrating that our process is safe and can be implemented elsewhere. Overall, 7% (8/114 patients) of patients developed a surgical site infection, which was not elevated in comparison to related studies utilizing traditional surgical methods. Prolonged operation time with an associated increase in surgical complexity was identified to be a risk factor for infection. Low temperature plasma-based sterilization depends upon sufficient permeation and contact with surfaces which are a particular challenge when our 3D-printouts contain diffusion-restricted luminal spaces as well as hollows. Application of printouts as guides for power tools may further expose these regions to sterile bodily tissues and result in generation of debris. With each printout being a bespoke medical device, it is important that the multidisciplinary team involved in production and application understand potential pitfalls to ensuring sterility as to minimize infection risk.
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http://dx.doi.org/10.1186/s41205-020-00061-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7106677PMC
March 2020

Selection of Lowest Instrumented Vertebra Using Fulcrum Bending Radiographs Achieved Shorter Fusion Safely Compared With the Last "Substantially" Touching Vertebra in Lenke Type 1A and 2A Curves.

Spine (Phila Pa 1976) 2019 Dec;44(24):E1419-E1427

Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong.

Study Design: Retrospective study with prospective radiographic data collection.

Objective: To compare fusion level determination criteria using the fulcrum bending radiograph (FBR) and the last substantially touched vertebra (STV) as the lowest instrumented vertebra (LIV) in the radiographic outcomes of correction surgery for Lenke 1A and 2A scoliosis patients with a minimum of 2-year follow-up.

Summary Of Background Data: The STV has been proposed as the LIV in Lenke 1A and 2A curves to avoid postoperative distal adding-on. However, the influence of the inherent flexibility of the curves on selecting the LIV in relation to the STV is not known.

Methods: A total of 65 consecutive Lenke 1A and 2A patients who underwent posterior selective thoracic fusion were included in this study with a minimum of 2-year follow-up. LIV determination was compared with the FBR and STV methods. The curve correction, trunk shift, radiographic shoulder height, list, and the incidence of distal adding-on were documented.

Results: Mean preoperative, postoperative, and final follow-up standing coronal Cobb angles of primary curves were 59.37°, 15.58°, and 16.62° respectively. Using the FBR to determine the LIV, STV was selected in 16 patients (25%), STV-1 in 34 (52%), STV-2 in 11 (17%), and STV-3 in three (5%). Fusion level difference between using FBR and STV method was statistically significantly larger (P = 0.019) in patients with more than 70% fulcrum flexibility (mean: 1.18 levels, range: 0-3 levels) than those with less than or equal to 70% flexibility (mean: 0.70 level, range: -1 to 3 levels). Mean fulcrum flexibility was 73.9% in patients who achieved a shorter fusion by FBR method and 66.3% in patients who did not achieve a shorter fusion. Adding-on was observed in three patients (4.6%).

Conclusion: By considering the curve flexibility, LIV determination using FBR method achieved a shorter fusion than STV method in over 70% of Lenke 1A and 2A patients, while being safe and effective at 2-year follow-up.

Level Of Evidence: 3.
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http://dx.doi.org/10.1097/BRS.0000000000003182DOI Listing
December 2019

Impact of Thoracic Cage Dimension and Geometry on Cardiopulmonary Function in Patients With Congenital Scoliosis: A Prospective Study.

Spine (Phila Pa 1976) 2019 Oct;44(20):1441-1448

Department of Orthopedics and Traumatology, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong SAR, China.

Study Design: A prospective study of cardiopulmonary function in patients with congenital scoliosis (CS).

Objective: To investigate the relationship of thoracic cage deformity and exercise tolerance in CS patients.

Summary Of Background Data: Congenital thoracic scoliosis and chest deformity lead to restrictive pulmonary dysfunction and in some severe cases cause cardiopulmonary failure. However, it is still unknown the relationship between thoracic deformity and exercise performance.

Methods: Patients with congenital thoracic spinal deformity were included and had radiological assessment of thoracic cage, pulmonary function testing, and cardiopulmonary exercise testing. Thoracic dimension including height, width, and depth were measured and geometry parameters were calculated. Two-tailed Pearson and Spearman correlation test and linear regression analysis were performed to investigate correlation of radiographic parameters, pulmonary function, and physical capacity.

Results: Sixty patients (41 females and 19 males) were included, with an average age of 18.9 years. Patients with smaller thoracic height (P < 0.001) and width (P < 0.01) and larger depth (P < 0.05) had significantly worse static pulmonary function. In exercise testing, these patients showed significant tendency of ventilation insufficiency, including lower minute ventilation (P < 0.05), faster breathing frequency (P < 0.05), and smaller tidal volume (P < 0.01). Thoracic depth was negatively correlated to exercise capacity, reflected by work rate (P < 0.001), peak oxygen intake (P < 0.001), and heart rate (P = 0.043). Patients with abnormal thoracic geometry, especially a lower ratio of height to depth and a lower ratio of width to depth, have significantly worse static pulmonary function and exercise capacity (all P < 0.05).

Conclusion: Decreasing thoracic height and width results in restrictive pulmonary dysfunction. Distortion and asymmetry of the thoracic cage are associated with abnormal breathing pattern and reduction of exercise capacity.

Level Of Evidence: 3.
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http://dx.doi.org/10.1097/BRS.0000000000003178DOI Listing
October 2019

Cardiopulmonary Function in Patients with Congenital Scoliosis: An Observational Study.

J Bone Joint Surg Am 2019 Jun;101(12):1109-1118

Department of Orthopedics and Traumatology, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong SAR, China.

Background: Patients with congenital scoliosis often have restrictive pulmonary dysfunction on static pulmonary function testing (PFT). Although frequently asymptomatic during daily activities, these patients are generally assumed to have reduced exercise capacity. The aim of this study was to use dynamic cardiopulmonary exercise testing (CPET) to investigate exercise capacity and its association with spinal deformity in patients with congenital scoliosis.

Methods: Sixty patients with congenital scoliosis who underwent preoperative spinal radiography, PFT, and CPET were included from January 2014 to November 2017. The impact of thoracic spinal deformity and rib anomalies on pulmonary function and physical capacity was investigated.

Results: A significant deterioration in pulmonary function with increases in the severity of the major thoracic curve was demonstrated by the forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and total lung capacity (all p < 0.001). The ratio of FEV1 to FVC was similar regardless of thoracic curve severity. A smaller tidal volume during exercise testing reflected restrictive dysfunction in the patients with the most severe curves. CPET also revealed a significant trend of faster breathing by patients with a severe thoracic curve (p < 0.001). Exercise capacity indicators such as work rate (p = 0.019), heart rate (p = 0.015), and oxygen saturation (p = 0.006) were significantly reduced only in patients with a thoracic curve of >100°. Pulmonary dysfunction was the major contributor to exercise intolerance. Compared with mild pulmonary dysfunction, moderate and severe dysfunction was associated with an abnormal breathing pattern and lower work rate (p = 0.032) and peak oxygen intake (p = 0.042), indicating worse exercise tolerance.

Conclusions: Congenital scoliosis leads to restrictive pulmonary dysfunction, which reduces the tidal volume and forces patients to accelerate respiratory rates during exercise. Patients with a thoracic curve of >100° are unable to compensate and have significantly reduced exercise capacity.

Level Of Evidence: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.
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http://dx.doi.org/10.2106/JBJS.18.00935DOI Listing
June 2019

Minimum 2-Year Experience with Magnetically Controlled Growing Rods for the Treatment of Early-Onset Scoliosis: A Systematic Review.

Asian Spine J 2019 08 26;13(4):682-693. Epub 2019 Mar 26.

Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR.

Magnetically controlled growing rods have been used to treat early-onset scoliosis for the last 9 years; however, few studies have been published, with only short-term follow-up. The aim of the present study is to systematically review the outcomes of magnetically controlled growing rods in the treatment of early-onset scoliosis with a minimum of 2-year follow-up. Studies were included if patients with early-onset scoliosis (scoliosis diagnosed before 10 years of age) underwent implantation of magnetically controlled growing rods with a minimum of 2-year follow-up. The literature review and data extraction followed the established preferred reporting items for systematic review and meta-analysis guidelines. Data of distraction frequency, number of distractions, distracted length, Cobb angle, kyphosis, T1-T12 length, and T1-S1 length preoperatively, postoperatively, and at final follow-up were collected. Data regarding complications and unplanned reoperations were also extracted. The mean values of these parameters were calculated, or pooled meta-analysis was performed if available. Ten articles were included in this systematic review, with a total of 116 patients and a follow-up period between 23 and 61 months. The mean preoperative Cobb angle and kyphosis angle were 60.1° and 38.0°, respectively, and improved to 35.4° and 26.1° postoperatively. At final follow-up, the Cobb and kyphosis angles were maintained at 36.9° and 36.0°, respectively. The average preoperative T1-T12 and T1-S1 lengths were 180.6 mm and 293.6 mm, respectively, and increased to 198.3 mm and 320.3 mm postoperatively. T1-T12 and T1-S1 lengths were 212.3 mm and 339.3 mm at final follow-up, respectively. The overall rate of patients with complications was 48% (95% confidence interval [CI], 0.38-0.58) and unplanned reoperation 44% (95% CI, 0.33-0.55) after sensitivity analysis. The current evidence from different countries with a minimum of a 2-year follow-up suggests that magnetically controlled growing rods are an effective technique to treat pediatric scoliosis and promote spine growth. However, nearly half of patients still developed complications or required unplanned reoperations.
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http://dx.doi.org/10.31616/asj.2018.0272DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6680029PMC
August 2019

Non-neurologic adverse events after complex adult spinal deformity surgery: results from the prospective, multicenter Scoli-RISK-1 study.

Eur Spine J 2019 01 16;28(1):170-179. Epub 2018 Oct 16.

Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, 5/F Professorial Block, Queen Mary Hospital, 102 Pokfulam Road, Pokfulam, Hong Kong.

Purpose: Accurate information regarding the expected complications of complex adult spinal deformity (ASD) is important for shared decision making and informed consent. The purpose of the present study was to investigate the rate and types of non-neurologic adverse events after complex ASD surgeries, and to identify risk factors that affect their occurrence.

Methods: The details and occurrence of all non-neurologic adverse events were reviewed in a prospective cohort of 272 patients after complex ASD surgical correction in a mulitcentre database of the Scoli-RISK-1 study with a planned follow-up of 2 years. Logistic regression analyses were used to identify potential risk factors for non-neurologic adverse events.

Results: Of the 272 patients, 184 experienced a total of 515 non-neurologic adverse events for an incidence of 67.6%. 121 (44.5%) patients suffered from more than one adverse event. The most frequent non-neurologic adverse events were surgically related (27.6%), of which implant failure and dural tear were most common. In the unadjusted analyses, significant factors for non-neurologic adverse events were age, previous spine surgery performed, number of documented non-neurologic comorbidities and ASA grade. On multivariable logistic regression analysis, previous spine surgery was the only independent risk factor for non-neurologic adverse events.

Conclusions: The incidence of non-neurologic adverse events for patients undergoing corrective surgeries for ASD was 67.6%. Previous spinal surgery was the only independent risk factor predicting the occurrence of non-neurologic adverse events. These findings complement the earlier report of neurologic complications after ASD surgeries from the Scoli-RISK-1 study. These slides can be retrieved under Electronic Supplementary Material.
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http://dx.doi.org/10.1007/s00586-018-5790-yDOI Listing
January 2019

The prevalence and years lived with disability caused by low back pain in China, 1990 to 2016: findings from the global burden of disease study 2016.

Pain 2019 Jan;160(1):237-245

Department of Orthopaedics, Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.

The aim of this work was to quantify the prevalence and years lived with disability (YLDs) caused by low back pain (LBP) in China from 1990 to 2016. Data from the GBD 2016 (Global Burden of Diseases, Injuries, and Risk Factors Study 2016) were used. We analyzed the age-sex-province-specific prevalence and YLDs for LBP of 33 provinces/regions in China. Comparisons were made with the data retrieved from the 1990 GBD study. We estimated that 5.45 × 10 individuals had LBP in 1990, which rose to 6.73 × 10 in 2016. The age-standardized prevalence of LBP decreased from 5.6% (95% uncertainty interval [95% UI]: 4.9%-6.3%) in 1990 to 4.2% (95% UI: 3.8%-4.8%) in 2016. The YLDs for LBP increased from 6.2 million (95% UI: 4.3-8.3 million) in 1990 to 7.7 million (95% UI: 5.4-10.2) in 2016. Age-standardized YLD rate (per 100,000 person) decreased from 637.5 (95% UI: 449.9-848.8) in 1990 to 481.9 (95% UI: 338.6-637.0) in 2016. A female preponderance was observed for prevalence and YLDs. The prevalence and YLDs rate for LBP slightly decreased from 1990 to 2016 in China; however, the total individuals and YLDs increased. Low back pain still ranks as the second leading cause of YLD burden disease in China. Considerable attention should be paid for LBP, especially in the female population.
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http://dx.doi.org/10.1097/j.pain.0000000000001396DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6319591PMC
January 2019

3D-printing techniques in spine surgery: the future prospects and current challenges.

Expert Rev Med Devices 2018 Jun 5;15(6):399-401. Epub 2018 Jun 5.

c Department of Orthopaedics , Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai Key Laboratory of Orthopaedic Implants , Shanghai , China.

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http://dx.doi.org/10.1080/17434440.2018.1483234DOI Listing
June 2018

Mechanical and Clinical Evaluation of a Shape Memory Alloy and Conventional Struts in a Flexible Scoliotic Brace.

Ann Biomed Eng 2018 Aug 24;46(8):1194-1205. Epub 2018 Apr 24.

Centre for Orthopaedic Surgery, Central, Hong Kong SAR, China.

Smart materials have attracted considerable attention in the medical field. In particular, shape memory alloys (SMAs) are most commonly utilized for their superelasticity (SE) in orthopaedic treatment. In this study, the resin struts of a flexible brace for adolescent idiopathic scoliosis (AIS) are replaced with different conventional materials and an SMA. The corrective mechanism mainly depends on the compressive force applied by the brace at the desired location. Therefore, the mechanical properties of the materials used and the interface pressure are both critical factors that influence the treatment effectiveness. The results indicate that titanium is the most rigid among the five types of materials, whereas the brace with SMA struts presents the best recovery properties and the most stable interface pressure. A radiographic examination of two patients with AIS is then conducted to validate the results, which shows that the SMA struts can provide better correction of thoracic curvature. These findings suggest that SMAs can be applied in orthoses because their SE allows for continuous and controllable corrective forces.
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http://dx.doi.org/10.1007/s10439-018-2016-8DOI Listing
August 2018

Prediction of survival in patients with symptomatic spinal metastases: Comparison between the Tokuhashi score and expert oncologists.

Surg Oncol 2018 Mar 3;27(1):7-10. Epub 2017 Nov 3.

Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong.

Background: Existing scoring systems have suboptimal accuracy in prognosticating patients with spinal metastases. Currently, there is no superior method in predicting survival. This study aims to compare the accuracy of survival prediction by expert oncologists versus the revised Tokuhashi scores with actual survivals in a cohort of symptomatic spinal metastases patients.

Methods: All patients who underwent surgical treatment for metastatic spinal tumours in a tertiary hospital between January 2011 to December 2015 were reviewed. Each patient's data was reconstructed into an anonymised clinical scenario and presented independently to five blinded attending oncologists with at least three years' post fellowship experience. They were surveyed for survival prediction twice at no less than four weeks' interval apart; the test-retest reliability was examined. The agreement of their prognostication and modified Tokuhashi scores were compared with actual survivals.

Results: Fifty-five patients were included during the study period. The mean age at presentation was 61.1 years (range, 41 to 79), and mean actual survival was 21.6 months (range, 1 to 68). Cohen's kappa agreement with actual survival was higher by oncologists' estimation (0.52) than by revised Tokuhashi score prediction (0.31) (p = 0.018). Intra-class correlation showed high inter-reliability (0.71) between the five oncologists and a high test-retest reliability (0.69) between both rounds of the survey.

Conclusion: This study showed that expert oncologists provided more accurate survival prediction than revised Tokuhashi scores in patients with spinal metastases. Future studies are required to identify factors in their assessment that led to improved accuracy.
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http://dx.doi.org/10.1016/j.suronc.2017.11.001DOI Listing
March 2018

Effectiveness of Schroth exercises during bracing in adolescent idiopathic scoliosis: results from a preliminary study-SOSORT Award 2017 Winner.

Scoliosis Spinal Disord 2017 16;12:32. Epub 2017 Oct 16.

Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong.

Background: Bracing has been shown to decrease significantly the progression of high-risk curves to the threshold for surgery in patients with adolescent idiopathic scoliosis (AIS), but the treatment failure rate remains high. There is evidence to suggest that Schroth scoliosis-specific exercises can slow progression in mild scoliosis. The aim of this study was to evaluate the efficacy of Schroth exercises in AIS patients with high-risk curves during bracing.

Methods: A prospective, historical cohort-matched study was carried out. Patients diagnosed with AIS who fulfilled the Scoliosis Research Society (SRS) criteria for bracing were recruited to receive Schroth exercises during bracing. An outpatient-based Schroth program was given. Data for these patients were compared with a 1:1 matched historical control group who were treated with bracing alone. The assessor and statistician were blinded. Radiographic progression, truncal shift, and SRS-22r scores were compared between cases and controls.

Results: Twenty-four patients (5 males and 19 females, mean age 12.3 ± 1.4 years) were included in the exercise group, and 24 patients (mean age 11.8 ± 1.1 years) were matched in the control group. The mean follow-up period for the exercise group was 18.1 ± 6.2 months. In the exercise group, spinal deformity improved in 17% of patients (Cobb angle improvement of ≥ 6°), worsened in 21% (Cobb angle increases of ≥ 6°), and remained stable in 62%. In the control group, 4% improved, 50% worsened, and 46% remained stable. In the subgroup analysis, 31% of patients who were compliant (13 cases) improved, 69% remained static, and none had worsened, while in the non-compliant group (11 cases), none had improved, 46% worsened, and 46% remained stable. Analysis of the secondary outcomes showed improvement of the truncal shift, angle of trunk rotation, the SRS function domain, and total scores in favor of the exercise group.

Conclusion: This is the first study to investigate the effects of Schroth exercises on AIS patients during bracing. Our findings from this preliminary study showed that Schroth exercise during bracing was superior to bracing alone in improving Cobb angles, trunk rotation, and QOL scores. Furthermore, those who were compliant with the exercise program had a higher rate of Cobb angle improvement. The results of this study form the basis for a randomized controlled trial to evaluate the effect of Schroth exercises during bracing in AIS.

Trial Registration: HKUCTR-2226. Registered 22 June 2017 (retrospectively registered).
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http://dx.doi.org/10.1186/s13013-017-0139-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5641990PMC
October 2017

Unplanned Reoperations in Magnetically Controlled Growing Rod Surgery for Early Onset Scoliosis With a Minimum of Two-Year Follow-Up.

Spine (Phila Pa 1976) 2017 Dec;42(24):E1410-E1414

Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong.

Study Design: A retrospective review of prospectively collected clinical and radiologic data of patients with magnetically controlled growing rods (MCGRs) from a multi-centered study with a minimum of 2-year follow-up.

Objective: The aim of this study was to describe the incidence and causes of unplanned reoperations and to report the outcomes of patients treated with MCGR for early-onset scoliosis (EOS).

Summary Of Background Data: Published clinical studies have demonstrated that MCGR is safe and effective for curvature control of EOS, and can avoid repeated surgeries for distractions. However, there have been no reports on the unplanned reoperations and complications of MCGR for EOS with a large series of patients.

Methods: Between 2009 and 2012, 30 patients with EOS underwent MCGR implantation in six institutions. A retrospective review of prospectively collected clinical and radiologic data with a minimum of 2-year follow-up was conducted. Demographic data, radiologic measurements, unplanned reoperations, and other complications were noted. Risk factors for unplanned reoperations were analyzed.

Results: Patients underwent MCGR implantation at the mean age of 7.2 years. The mean follow-up period was 37 months. Fourteen patients (46.7%) underwent an unplanned reoperation within the follow-up period, with a mean time to reoperation of 23 months after initial surgery (range, 5-48 months). Causes of unplanned reoperation were failure of rod distractions, proximal foundation failure, rod breakage, and infection. More frequent distractions (between 1 week and 2 months) were associated with a higher rate of reoperation than distraction frequencies between 3 and 6 months (71% vs. 25%).

Conclusion: This is the largest series with the longest follow-up to date that examines the need for additional unplanned surgery after the initial procedure. It highlights that MCGR surgery can be associated with unplanned reoperations, and more frequent distractions may be a risk factor. Long-term comparative studies with traditional growing rod are required to evaluate the effectiveness of this implant.

Level Of Evidence: 4.
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http://dx.doi.org/10.1097/BRS.0000000000002297DOI Listing
December 2017

Ten year follow-up of Jarcho-Levin syndrome with thoracic insufficiency treated by VEPTR and MCGR VEPTR hybrid.

Eur Spine J 2018 07 12;27(Suppl 3):287-291. Epub 2017 Jun 12.

Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, Queen Mary Hospital, The University of Hong Kong, Pokfulam Road, Hong Kong, SAR, Hong Kong.

Purpose: Jarcho-Levin syndrome patients commonly suffer from repeated respiratory infections and become ventilator dependent due to an insufficient thoracic volume. Multiple congenital vertebral anomalies are associated with this genetic disorder and results in stunted spine growth. The purpose of this case report is to present the results of a hybrid vertical expandable prosthetic titanium rib (VEPTR) and magnetically controlled growing rod (MCGR) construct for the management of a patient with Jarcho-Levin syndrome.

Methods: A boy with Jarcho-Levin syndrome undergoes a hybrid VEPTR-MCGR construct to treat his thoracic insufficiency syndrome and spinal deformity.

Results: The patient could wean off ventilator and had reduced chest complications with the construct. He was also able to achieve some spine length gain with the distraction device. However, there were limitations in prolonged treatment as no spine height was gained once he reached 12 years old. Once no further growth can be achieved, the MCGR led to progressive kyphosis. Nevertheless, at latest follow-up after the removal of all implants, the patient could maintain satisfactory correction of both thoracic and spine deformities.

Conclusions: A hybrid construct is necessary for managing Jarcho-Levin syndrome as the VEPTR deals with the thoracic cage deformity while the MCGR deals with the spine deformity.
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http://dx.doi.org/10.1007/s00586-017-5164-xDOI Listing
July 2018