Prudence Wing Hang Cheung

Learning Curve in Monitoring Magnetically Controlled Growing Rod Distractions With Ultrasound

Study Design. Prospective study. Objective. To determine whether a learning curve exists for ultrasound measurement of magnetically controlled growing rod (MCGR) distractions. Summary of Background Data. For patients managed by MCGRs, close monitoring of interval distraction length gains is important to determine whether the distractions are translating into actual spine growth. Radiographs are the criterion standard for measuring length gains, but ultrasound has been shown to be effective in monitoring distraction lengths without radiation exposure. It is, however, an operator-dependent tool and thus the accuracy of ultrasound measurement of distracted length may improve with experience. Methods. This is a prospective correlation analysis of patients who underwent MCGR treatment for scoliosis. The study period was inclusive of 19th February 2013 to 31st March 2015. All subjects were consecutively recruited in a prospective manner. Data regarding date of the distraction visit, and the interval radiograph and ultrasound measurements of the distracted lengths were collected. Only those episodes with both radiograph and ultrasound performed were used for analysis. The mean differences in change of radiograph and ultrasound measurements were plotted to determine correlation differences and to observe for a learning curve. Results. A total of 379 distraction episodes were analyzed. The mean differences between ultrasound and radiograph measurements per distraction episode were −0.3 mm for the right rod and −0.1 mm for the left rod. For learning curve analysis, there were three distinct timepoints in which the difference of correlation became significantly better and were described as clusters. The correlation in the first cluster (19th February 2013 to 15th October 2013) was 0.612 (right rod) and 0.795 (left rod), the second cluster (16th October 2013 to 20th May 2014) was 0.879 (right rod) and 0.918 (left rod), and the third cluster (21st May 2014 to 31st March 2015) was 0.956 (right rod) and 0.932 (left rod). Thus, a plateau was observed at the second cluster, which translated to 97 to 146 rod measurements. Conclusion. Correlation between radiograph and ultrasound measurements is reasonable to begin with but improves with time. During initial use, successful distractions should correlate between the clinical feel and ultrasound confirmation. Although the absolute value may not be accurate and may require radiographs to confirm, with time and experience, ultrasound measurements can then be more reliable. Level of Evidence: 3

Reliability Analysis of the Distal Radius and Ulna Classification for Assessing Skeletal Maturity for Patients with Adolescent Idiopathic Scoliosis

Study Design Prospective radiographic study. Objective To test the reliability of the Distal Radius and Ulna Classification (DRU). Methods This single-center study included prospectively recruited subjects with adolescent idiopathic scoliosis managed with bracing. The left-hand radiographs were measured using the DRU classification by two examiners. Intra- and interobserver reliability analysis were performed using intraclass correlation (ICC) analysis. Results From these clinics, 161 patients (124 females and 37 males) with left-hand radiographs were included in the study. The mean age was 13.3 years (standard deviation: 1.5). There was excellent intra- (ICC: 0.93 to 0.95) and interobserver (ICC: 0.97) reliability. Conclusions The DRU classification scheme has been shown to be accurate in determining the peak growth phase and growth cessation. It has now been confirmed to be a reliable tool. Future prospective studies should be performed to investigate its application in deciding when to apply bracing or operative treatment.

Decompression without Fusion for Low-Grade Degenerative Spondylolisthesis.

Study Design Retrospective series. Purpose Assess results of decompression-only surgery for low-grade degenerative spondylolisthesis with consideration of instability. Overview of Literature There is no consensus on whether fusion or decompression-only surgery leads to better outcomes for patients with low-grade degenerative spondylolisthesis. Current trends support fusion but many studies are flawed due to over-generalization without consideration of radiological instability and their variable presentations and natural history. Methods Patients with surgically treated degenerative spondylolisthesis from 1990–2013 were included. Clinical and radiological instability measures were included. Any residual or recurrence of symptoms, revision surgery performed and functional outcome scores including the numerical global rate of change scale, visual analogue scale, and modified Barthel index were measured. Follow-up periods for patients were divided into short-term (<5 years), mid-term (5–10 years) and long-term (>10 years). Results A total of 64 patients were recruited. Mechanical low back pain was noted in 48 patients and most (85.4%) had relief of back pain postoperatively. Radiological instability was noted in 4 subjects by flexion-extension radiographs and 12 subjects with prone traction radiographs by increased disc height and reduction of olisthesis and slip angle. From the results of the short-term, mid-term and long-term follow-up, reoperation only occurred within the first 5-year follow-up period. All functional scores improved from preoperative to postoperative 1-year follow-up. Conclusions Decompression-only for low-grade degenerative spondylolisthesis has good long-term results despite instability. Further higher-level studies should be performed on this patient group with radiological instability to suggest the superior surgical option.

The distal radius and ulna classification in assessing skeletal maturity: a simplified scheme and reliability analysis.

The aim of this study is to simplify the distal radius and ulna classification for practical use and to test its reliability. This was a prospective single-center study of patients with juvenile and adolescent idiopathic scoliosis. Left-hand radiographs were retrieved for measurements by three examiners. Reliability analysis was carried out by intraclass correlation. 34 females and 16 males were recruited, mean age 12.7 years (±SD 1.7). The grades varied from R4–R11 to U1–U9. There was strong to near-perfect intraclass correlation. This study concludes that the simplified distal radius and ulna classification is a reliable tool for assessment of skeletal maturity.

Curve Progression in Adolescent Idiopathic Scoliosis Does Not Match Skeletal Growth

Background Determining the peak growth velocity of a patient with adolescent idiopathic scoliosis (AIS) is important for timely treatment to prevent curve progression. It is important to be able to predict when the curve-progression risk is greatest to maximize the benefits of any intervention for AIS. The distal radius and ulna (DRU) classification has been shown to accurately predict skeletal growth. However, its utility in predicting curve progression and the rate of progression in AIS is unknown. Questions/purposes (1) What is the relationship between radius and ulna grades to growth rate (body height and arm span) and curve progression rate? (2) When does peak curve progression occur in relation to peak growth rate as measured by months and by DRU grades? (3) How many months and how many DRU grades elapse between peak curve progression and plateau? Methods This was a retrospective analysis of a longitudinally maintained dataset of growth and Cobb angle data of patients with AIS who presented with Risser Stages 0 to 3 and were followed to maturity at Risser Stage 5 at a single institute with territory-wide school screening service. From June 2014 to March 2016, a total of 513 patients with AIS fulfilled study inclusion criteria. Of these, 195 were treated with bracing at the initial presentation and were excluded. A total of 318 patients with AIS (74% girls) with a mean age of 12 ± 1.5 years were studied. For analysis, only data from initial presentation to commencement of intervention were recorded. Data for patients during the period of bracing or after surgery were not used for analysis to eliminate potential interventional confounders. Of these 318 patients, 192 were observed, 119 were braced, and seven underwent surgery. Therefore 192 patients (60.4%) who were observed were followed up until skeletal maturity at Risser Stage 5; no patients were lost to followup. The mean curve magnitude at baseline was 21.6o ± 4.8o. Mean followup before commencing intervention or skeletal maturity was 4.3 ± 2.3 years. Standing body height, arm span, curve magnitude, Risser stage, and DRU classification were studied. A subgroup analysis of 83 patients inclusive of acceleration, peak, and deceleration progression phases for growth and curve progression was studied to determine any time lag between growth and curve progression. Results were described in mean ± SD. Results There was positive correlation between growth rate and curve progression rate for body height (r = 0.26; p < 0.001) and arm span (r = 0.26; p < 0.001). Peak growth for body height occurred at radius grade (R) 6 (0.56 ± 0.29 cm/month) and ulna grade (U) 4 (0.65 ± 0.31 cm/month); peak change in arm span occurred at R5 (0.67 ± 0.33 cm/month) and U3 (0.67 ± 0.22 cm/month); and peak curve progression matched with R7 (0.80 ± 0.89 cm/month) and U5 (0.84 ± 0.78 cm/month). Subgroup analysis confirmed that peak curve progression lagged behind peak growth rate by approximately 7 months or one DRU grade. The mean time elapsed between the peak curve progression rate and the plateau phase at R9 U7 was approximately 16 months, corresponding to two DRU grades. Conclusions By using a standard skeletal maturity parameter in the DRU classification, this study showed that the maximal curve progression occurs after the peak growth spurt, suggesting that the curve should be monitored closely even after peak growth. In addition, the period of potential curve continuing progression extends nearly 1.5 years beyond the peak growth phase until skeletal maturity. Future studies may evaluate whether by observing the trend of growth and curve progression rates, we can improve the outcomes of interventions like bracing for AIS. Level of Evidence Level II, prognostic study.

Mapping the SRS-22r questionnaire onto the EQ-5D-5L utility score in patients with adolescent idiopathic scoliosis

This is a prospective study to establish prediction models that map the refined Scoliosis Research Society 22-item (SRS-22r) onto EuroQoL-5 dimension 5-level (EQ-5D-5L) utility scores in adolescent idiopathic scoliosis (AIS) patients. Comparison of treatment outcomes in AIS can be determined by cost-utility analysis. However, the mainstay spine-specific health-related quality of life outcome measure, the SRS-22r questionnaire does not provide utility assessment. In this study, AIS patients were prospectively recruited to complete both the EQ-5D-5L and SRS-22r questionnaires by trained interviewers. Ordinary least squares regression was undertaken to develop mapping models, which the validity and robustness were assessed by using the 10-fold cross-validation procedure. EQ-5D-5L utility scores were regressed on demographics, Cobb angle, curve types, treatment modalities, and five domains of the SRS-22r questionnaire. Three models were developed using stepwise selection method. EQ-5D-5L scores were regressed on 1) main effects of SRS-22r subscale scores, 2) as per 1 plus squared and interaction terms, and 3) as per 2 plus demographic and clinical characteristics. Model goodness-of-fit was assessed using R-square, adjusted R-square, and information criteria; whereas the predictive performance was evaluated using root mean square error (RMSE), mean absolute error (MAE), and the proportion of absolute error within the threshold of 0.05 and 0.10. A total of 227 AIS patients with mean age of 15.6 years were recruited. The EQ-5D-5L scores were predicted by four domains of SRS-22r (main effects of ‘Function’, ‘Pain’, ‘Appearance’ and ‘Mental Health’, and squared term of ‘Function’ and ‘Pain’), and Cobb angle in Model 3 with the best goodness-of-fit (R-square/adjusted R-square: 62.1%/60.9%). Three models demonstrated an acceptance predictive performance in error analysis applying 10-fold cross-validation to three models where RMSE and MAE were between 0.063–0.065 and between 0.039–0.044, respectively. Model 3 was therefore recommended out of three mapping models established in this paper. To our knowledge, this is the first study to map a spine-specific health-related quality of life measure onto EQ-5D-5L for AIS patients. With the consideration and incorporation of demographic and clinical characteristics, over 60% variance explained by mapping model 3 enabled the satisfactory prediction of EQ-5D-5L utility scores from existing SRS-22r data for health economic appraisal of different treatment options.

Predictability of Supine Radiographs for Determining In-brace Correction for Adolescent Idiopathic Scoliosis

Study Design. Retrospective radiographic study. Objective. To assess whether flexibility as revealed by the supine radiograph, predicts in-brace curve correction. Summary of Background Data. Currently there is no consensus regarding a standard method to assess curve flexibility and immediate brace effectiveness in treating adolescent idiopathic scoliosis (AIS). Brace fabrication methods may be variable but ideally it should achieve maximal curve correction. Curve flexibility governs the degree of curve correction in-brace and hence dynamic radiographs are commonly performed prior to brace fitting. Methods. This was a radiographic analysis of AIS patients treated with underarm bracing. Correlation of pre-brace, supine, and immediate in-brace Cobb angles was performed. Relationship with possible contributing factors including age, sex, body height, weight, age at menarche and Risser staging was studied. Major and minor curves were compared independently for correlation but the regression model was constructed based on the major curve only. Results. From 105 patients with mean age of 12.2 ± 1.2 years at brace fitting, supine Cobb angle measurement has significant correlation with immediate in-brace Cobb angle (r = 0.740). Univariate analyses showed no significant relationship with age, weight, height, date of menarche, Risser stage or pre-brace Cobb angle. Our regression model (in-brace Cobb angle = 0.809 × supine Cobb angle) had good fit of the data. Conclusion. Supine radiograph predictably determines the flexibility of the scoliotic curve to brace treatment. It can be used as a guideline to determine the amount of correction achievable with brace-wear. The effectiveness of the brace is dependent on the inherent flexibility of the curve rather than its size or type. Level of Evidence: 3

Psychometric validation of the cross-culturally adapted traditional Chinese version of the Back Beliefs Questionnaire (BBQ) and Fear-Avoidance Beliefs Questionnaire (FABQ)

PurposeTo translate and cross-culturally adapt the Back Beliefs Questionnaire (BBQ) and Fear-Avoidance Beliefs Questionnaire (FABQ) into traditional Chinese for their use in patients experiencing low back pain (LBP).MethodsThis was a prospective questionnaire translation and psychometric validation of the BBQ and FABQ in Chinese patients with back pain. Patients also completed the Traditional Chinese (Hong Kong) versions of the Oswestry Disability Index (ODI), the Short Form-12 version 2 (SF-12v2) questionnaires and the visual analogue scale (VAS) for LBP. Construct validity was assessed using Spearman’s correlation test against the subscales and domains with similar constructs. Internal consistency was assessed by Cronbach’s alpha (α). Sensitivity was determined by known-group comparisons.ResultsA total of 100 patients were recruited. Both BBQ (α = 0.810) and FABQ (α = 0.859) demonstrated excellent overall internal consistency. BBQ scores significantly correlated with ODI scores, VAS-LBP and all domains of SF-12v2 (p < 0.01–0.05), whereas only FABQ Work subscale correlated with ODI scores (p < 0.01) and VAS-LBP (p < 0.05). Both FABQ subscales correlated with only specific domains of SF-12v2 (p < 0.01–0.05). FABQ-W was sensitive to difference between patients with acute versus chronic back pain.ConclusionsBoth the adapted BBQ and FABQ (Traditional Chinese-Hong Kong) were demonstrated to have satisfactory psychometric properties, with adequate internal consistencies, construct validity and sensitivity to certain clinical parameters. Our findings were based on a clinically relevant patient group and provides insight into patients’ own perception of back pain which may often be different from that of surgeons. This is a platform for future cross-cultural comparisons.Level of evidence2.Graphical abstractThese slides can be retrieved under Electronic Supplementary Material.

Psychometric Validation of the Adapted Traditional Chinese (Hong Kong) Version of the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ)

Study Design. A prospective questionnaire translation and validation. Objective. The aim of this study was to translate and cross-culturally adapt the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ) into Traditional Chinese (Hong Kong) and to assess its validity, reliability, and sensitivity for differentiating cervical myelopathy (CM) and presence of acute neck/shoulder pain. Summary of Background Data. CM frequently presents with various symptoms affecting patients’ quality of life. Hence, a patient-oriented instrument such as JOACMEQ is necessary to assess patient-perceived outcomes of CM treatment. Methods. The English version of JOACMEQ was translated and adapted using double forward and single backward translations. The translated JOACMEQ was administered to patients with suspected CM, followed by the Traditional Chinese (Hong Kong) version of the Neck Disability Index (NDI), EuroQol five-dimension five-level (EQ-5D-5L), and Short Form-12 version 2 (SF-12v2) questionnaires. Construct validity of the domains was assessed using Spearman correlation test against domains with similar constructs. Internal consistency was assessed by Cronbachs alpha. Sensitivity of the adapted JOACMEQ was determined by known group comparisons. Results. A total of 100 patients were recruited. Psychometric testing of the translated JOACMEQ demonstrated an excellent overall internal consistency with Cronbachs &agr; > 0.9, and good internal consistency of Lower Extremity Function (0.823) and Quality of Life (0.875) domains. Score of all domains of the translated JOACMEQ had significant correlations (P < 0.01–0.05) with nearly all domains of SF-12v2 and with both NDI and EQ-5D-5L scores. JOACMEQ was sensitive in detecting differences (P < 0.001) between subjects who had CM and those without, and also between those patients with/without CM experiencing current neck/shoulder pain. Conclusion. Our translated JOACMEQ has satisfactory psychometric properties, including adequate clinical and construct validity, and internal consistency in patients with suspected/diagnosed CM and can differentiate between those with/without pain. It is demonstrated as a sensitive outcome measure for CM and neck/shoulder pain. Level of Evidence: 2

Data-driven modeling for scoliosis prediction

Traditional medical therapies for scoliosis are mostly based on the experience and intuitions of doctors, which does not guarantee the effectiveness of the treatment. Scoliosis prediction is of great significance to reduce the uncertainty for doctors on deciding the optimum treatment for patients. The paper aims to develop a prediction model to help physicians to make right decisions for an appropriate treatment. The change of Cobb angle in a definite period, which reflects the progress of scoliosis, is commonly considered as indication of scoliosis severity. The present study proposed several prediction models of scoliosis progression based on time series analysis and general regression methods. Performances of different time series methods as well as different general regression models were compared by the root mean square error (RMSE), standard deviation (SD) and the mean absolute percentage error (MAPE) as well as the Pearson product-moment correlation coefficient (r). The results show that the exponential moving average method performs better than any of the chosen time series methods and the linear regression model has higher predictive capability than any of the general regression models being compared.