Displaying publications 1 - 20 of 42 in total

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  1. Chan CYW, Chung WH, Mihara Y, Lee SY, Ch'ng PY, Hasan MS, et al.
    J Orthop Surg (Hong Kong), 2020 8 9;28(3):2309499020936005.
    PMID: 32762498 DOI: 10.1177/2309499020936005
    PURPOSE: Various surgical strategies including combined approach and spinal osteotomies in severe rigid scoliosis had been reported with significant perioperative complication rates. The use of single-staged posterior spinal fusion (PSF) utilizing a dual attending surgeon strategy for severe rigid scoliosis has not been widely reported.

    METHODS: This was a retrospective study aimed to evaluate the perioperative outcome of single-staged PSF in severe rigid idiopathic scoliosis patients (Cobb angle ≥90° and ≤30% flexibility). Forty-one patients with severe rigid idiopathic scoliosis who underwent single-staged PSF were included. The perioperative outcome parameters were operation duration, intraoperative blood loss, intraoperative hemodynamic parameters, preoperative and postoperative hemoglobin, transfusion rate, patient-controlled anesthesia morphine usage, length of postoperative hospital stay, and perioperative complications. Radiological parameters included preoperative and postoperative Cobb angle, correction rate, side-bending flexibility, and side-bending correction index.

    RESULTS: The mean age was 16.9 ± 5.6 years. The mean preoperative Cobb angle was 110.8 ± 12.1° with mean flexibility of 23.1 ± 6.3%. The mean operation duration was 215.5 ± 45.2 min with mean blood loss of 1752.6 ± 830.5 mL. The allogeneic blood transfusion rate was 24.4%. The mean postoperative hospital stay was 76.9 ± 26.7 h. The mean postoperative Cobb angle and correction rate were 54.4 ± 12.8° and 50.9 ± 10.1%, respectively. The readmission rate in this cohort was 2.4%. Four perioperative complications were documented (9.8%), one somatosensory evoke potential signal loss, one superficial infection, one lung collapse, and one superior mesenteric artery syndrome.

    CONCLUSIONS: Severe rigid idiopathic scoliosis treated with single-staged PSF utilizing a dual attending surgeon strategy demonstrated an average correction rate of 50.9%, operation duration of 215.5 min, and postoperative hospital stay of 76.9 h with a 9.8% perioperative complication rate.

  2. Chan CYW, Chong JSL, Lee SY, Ch'ng PY, Chung WH, Chiu CK, et al.
    Spine (Phila Pa 1976), 2020 Dec 01;45(23):1661-1667.
    PMID: 32756286 DOI: 10.1097/BRS.0000000000003641
    STUDY DESIGN: Prospective study.

    OBJECTIVE: To determine the parents'/patients' perception on the informed consent process prior to posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS) patients.

    SUMMARY OF BACKGROUND DATA: Understanding parents/patients perspective on the process is important in order to achieve the goal of consent and prevent medico-legal implications.

    METHODS: Fifty AIS patients operated between August 2019 and November 2019 were prospectively recruited. Parents'/patients' perceptions on three sections were evaluated: the process of the informed consent, specific operative risk which they were most concerned with and the accountability of surgeons for the surgical risks. These data were ranked and scored using a 5-point Likert Scale. Preferences were reported in mean and standard deviation. Differences in terms of preferences were studied using One-way analysis of variance (ANOVA) analysis and deemed significant when P 

  3. Chan CYW, Chiu CK, Ch'ng PY, Lee SY, Chung WH, Hasan MS, et al.
    Spine J, 2021 07;21(7):1049-1058.
    PMID: 33610804 DOI: 10.1016/j.spinee.2021.02.009
    BACKGROUND CONTEXT: The implementation of a dual attending surgeon strategy had improved perioperative outcomes of idiopathic scoliosis (IS) patients. Nevertheless, the learning curve of a dual attending surgeon practice in single-staged posterior spinal fusion (PSF) surgery has not been established.

    OBJECTIVE: To evaluate the surgical learning curve of a dual attending surgeon strategy in IS patients.

    STUDY DESIGN: Retrospective study.

    PATIENT SAMPLE: 415 IS patients (Cobb angle <90°) who underwent PSF using a dual attending surgeon strategy OUTCOME MEASURES: Primary outcomes included operative time, total blood loss, allogenic blood transfusion requirement, length of hospital stay and perioperative complication rate.

    METHODS: Regression analysis using Locally Weighted Scatterplot Smoothing (LOWESS) method was applied to create the best-fit-curve between case number versus operative time and total blood loss in identifying cut-off points for the learning curve.

    RESULTS: The mean Cobb angle was 60.8±10.8°. Mean operative time was 134.4±32.1 minutes and mean total blood loss was 886.0±450.6 mL. The mean length of hospital stay was 3.0±1.6 days. The learning curves of a dual attending surgeon strategy in this study were established at the 115th case (operative time) and 196th case (total blood loss) respectively (p

  4. Chan CYW, Ch'ng PY, Lee SY, Chung WH, Chiu CK, Kwan MK
    Global Spine J, 2023 Mar;13(2):443-450.
    PMID: 33691529 DOI: 10.1177/2192568221998642
    STUDY DESIGN: Retrospective.

    PURPOSE: To evaluate the relationship between shoulder/ neck imbalance with distal adding-on phenomenon and to identify other risk factors in Lenke 1 and 2 (non-AR curves) adolescent idiopathic scoliosis (AIS) patients.

    METHODS: 100 Lenke 1 and 2 AIS patients with lowest instrumented vertebra (LIV) cephalad to or at L1 were recruited. Medial shoulder/ neck balance was represented by T1-tilt and cervical axis (CA). Lateral shoulder balance was represented by clavicle angle (Cla-A) and radiographic shoulder height (RSH). Distal adding-on phenomenon was diagnosed when there was disc wedging below LIV of >5o at final follow-up. Predictive factors and odds ratio were derived using univariate and multivariate logistic regression analysis.

    RESULTS: Mean age of this cohort was 15.9 ± 4.4 years. Mean follow-up duration was 30.9 ± 9.6 months. Distal adding-on phenomenon occurred in 19 patients (19.0%). Only Risser grade, preoperative CA and final follow-up lumbar Cobb angle were the independent factors. A positive preoperative CA deviation increased the odds of distal adding-on by 5.4 times (95% CI 1.34-21.51, P = 0.018). The mean immediate postoperative T1-tilt, CA, RSH and Cla-A were comparable between the group with distal adding-on and the group without.

    CONCLUSION: Distal adding-on phenomenon occurred in 19.0% of patients. Preoperative "Cervical Axis" was an important factor and it increased the risk of distal adding-on by 5.4 times. Other significant predictive factors were Risser grade and lumbar Cobb angle at final follow-up. Immediate postoperative shoulder or neck imbalance was not a significant factor for postoperative distal adding-on phenomenon.

  5. Chan CYW, Gani SMA, Chung WH, Chiu CK, Hasan MS, Kwan MK
    Global Spine J, 2023 Jan;13(1):81-88.
    PMID: 33648369 DOI: 10.1177/2192568221991510
    STUDY DESIGN: Retrospective propensity score matching (PSM) study.

    OBJECTIVE: To investigate the perioperative outcomes comparing adolescent idiopathic scoliosis (AIS) and adult idiopathic scoliosis (AdIS) patients following posterior spinal fusion (PSF).

    METHODS: 425 female AIS and AdIS patients who were operated (between January 2015 to March 2020) using a dual attending surgeon strategy were stratified into G1 (AIS aged 10-16 years old) and G2 (AdIS > 20 years old). PSM analysis with one-to-one, nearest neighbor matching technique with match tolerance of 0.001 was used to matched 357 AIS patients to 68 AdIS patients. Operation duration, intraoperative blood loss (IBL), blood loss percentage, hemoglobin drift, blood salvaged, postoperative wound length, allogenic blood transfusion requirement, postoperative hospital stay, postoperative Cobb, correction rate and postoperative complications were documented and reported.

    RESULTS: Following PSM, G1 and G2 each had 50 patients with comparable and balanced covariates. As anticipated, G2 patients were heavier, taller and had higher body mass index compared to G1 patients (P < 0.05). We could not find any significant differences in the perioperative outcome comparing this 2 groups. AIS and AdIS patients had similar operation duration (125.9 ± 27.2 min vs 127.3 ± 37.8 min), IBL (749.8 ± 315.7 ml vs 723.8 ± 342.1 ml) and length of hospital stay (3.3 ± 0.4 days vs 3.5 ± 0.8 days) (P > 0.05). Hemoglobin drift and amount of blood salvaged were comparable (P > 0.05). G2 had stiffer curves. There was a trend toward a lower correction rate in G2 in the immediate postoperative period, however it did not reach statistical significance (61.8 ± 11.2% vs. 66.3 ± 11.6%, P = 0.051). No patients required blood transfusion and none had any postoperative complications.

    CONCLUSION: Adolescent and adult female scoliosis patients had comparable perioperative outcome following PSF surgery that was carried out using a dual attending surgeon strategy.

  6. Chan CYW, Lee SY, Ch'ng PY, Chung WH, Chiu CK, Hasan MS, et al.
    Spine (Phila Pa 1976), 2021 Jun 15;46(12):E663-E670.
    PMID: 33306608 DOI: 10.1097/BRS.0000000000003866
    STUDY DESIGN: Retrospective study.

    OBJECTIVE: To assess the learning curve of a dual attending surgeon strategy in severe adolescent idiopathic scoliosis patients.

    SUMMARY OF BACKGROUND DATA: The advantages of a dual attending surgeon strategy in improving the perioperative outcome in scoliosis surgery had been reported. However, the learning curve of this strategy in severe scoliosis had not been widely studied.

    METHODS: A total of 105 patients with adolescent idiopathic scoliosis with Cobb angle of 90° or greater, who underwent posterior spinal fusion using a dual attending surgeon strategy were recruited. Primary outcomes were operative time, total blood loss, allogeneic blood transfusion requirement, length of hospital stay from time of operation and perioperative complications. Cases were sorted chronologically into group 1: cases 1 to 35, group 2: cases 36 to 70, and group 3: case 71 to 105. Mean operative time (≤193.3 min), total blood loss (≤1612.2 mL), combination of both and allogeneic blood transfusion were the selected criteria for receiver operating characteristic analysis of the learning curve.

    RESULTS: The mean Cobb angle was 104.5° ± 12.3°. The operative time, total blood loss, and allogeneic blood transfusion requirement reduced significantly for group 1 (220.6 ± 54.8 min; 2011.3 ± 881.8 mL; 12 cases) versus group 2 (183.6 ± 36.7 min; 1481.6 ± 1035.5 mL; 3 cases) and group 1 versus group 3 (175.6 ± 38.4 min; 1343.7 ± 477.8 mL; 3 cases) (P 

  7. Chan CYW, Tan YWE, Chandren JR, Chandirasegaran S, Chung WH, Chiu CK, et al.
    Spine J, 2024 Mar 16.
    PMID: 38499066 DOI: 10.1016/j.spinee.2024.03.012
    BACKGROUND CONTEXT: Preoperative supine radiographs are mandatory in the new adult idiopathic scoliosis (AdIS) classification. Supine radiographs are easily reproducible and highly predictive of side bending radiographs. However, few studies evaluated the use of supine radiographs in predicting postoperative curve correction after posterior spinal fusion (PSF) in AdIS.

    PURPOSE: To investigate the use of supine and side bending (SB) radiographs in predicting postoperative curve correction in AdIS patients who underwent PSF.

    STUDY DESIGN: Retrospective study.

    PATIENT SAMPLE: 93 AdIS patients who underwent PSF between 2022 and 2023 were included.

    OUTCOME MEASURES: Demographic data were age, gender, height, weight, body mass index (BMI), Risser grade, Lenke curve types and Cobb angles. Main outcome measures were preoperative and immediate postoperative Cobb angle (proximal thoracic [PT], main thoracic [MT] and thoracolumbar/lumbar [TL/L] curves), Supine Cobb angle and Flexibility rate (PT, MT and TL/L), and Correction rate (PT, MT and TL/L).

    METHODS: Correlation study was performed between Supine Cobb angle vs. postoperative Cobb angle for PT, MT and TL/L curves. A predictive formula was derived from the correlation plots.

    RESULTS: A total of 93 subjects were included in our study with a median age of 24.7 years and comprised of 80 females (86.0%). Preoperative Supine Cobb angle (r=0.835, r=0.881, r=0.767, p

  8. Chandirasegaran S, Chan CYW, Chiu CK, Chung WH, Hasan MS, Kwan MK
    Eur Spine J, 2024 Apr;33(4):1683-1690.
    PMID: 38294535 DOI: 10.1007/s00586-023-08124-2
    PURPOSE: Prolonged surgical duration in severe adolescent idiopathic scoliosis (AIS) patients is associated with increased blood loss and perioperative complications. The aim of this study was to compare the duration of each stage of posterior spinal fusion (PSF) in severe AIS (Cobb angle ≥ 90°) with non-severe AIS patients. This analysis will identify the most time-consuming stage of PSF and help surgeons formulate strategies to shorten operative time.

    METHODS: Retrospective study whereby 90 AIS patients (Lenke type 2, 3, 4, and 6) who underwent PSF from 2019 to 2023 were recruited. Twenty-five severe AIS patients were categorized in Gp1 and 65 non-severe AIS patients in Gp2. Propensity score matching (PSM) with one-to-one with nearest neighbor matching (match tolerance 0.05) was performed. Outcomes measured via operation duration of each stage of surgery, blood loss, number of screws, fusion levels and screw density.

    RESULTS: Twenty-five patients from each group were matched. Total operative time was significantly higher in Gp1 (168.2 ± 30.8 vs. 133.3 ± 24.0 min, p 

  9. Chang CC, Ng CC, Too CL, Choon SE, Lee CK, Chung WH, et al.
    Pharmacogenomics J, 2017 03;17(2):170-173.
    PMID: 26927288 DOI: 10.1038/tpj.2016.10
    Phenytoin (PHT) is a common cause of severe cutaneous adverse reactions (SCARs), including Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN) and drug reaction with eosinophilia and systemic symptoms (DRESS). Although HLA-B*15:02 is associated with PHT-induced SJS/TEN (PHT-SJS/TEN) in Han Chinese and Thais, the genetic basis for susceptibility to PHT-induced SCARs (PHT-SCAR) in other populations remains unclear. We performed a case-control association study by genotyping the human leukocyte antigen (HLA)-B alleles of 16 Malay PHT-SCAR patients (13 SJS/TEN and 3 DRESS), 32 PHT-tolerant controls and 300 healthy ethnicity-matched controls. A novel genetic biomarker, HLA-B*15:13, showed significant association with PHT-SJS/TEN (53.8%, 7/13 cases) (odds ratio (OR) 11.28, P=0.003) and PHT-DRESS (100%, 3/3 cases) (OR 59.00, P=0.003) when compared with PHT-tolerant controls (9.4%, 3/32 controls). We also confirmed HLA-B*15:02 association with PHT-SJS/TEN (61.5%, 8/13 cases vs 21.9%, 7/32 controls; OR 5.71, P=0.016) when compared with PHT-tolerant controls. These alleles may serve as markers to predict PHT-SCAR in Malays.
  10. Chen WT, Wang CW, Lu CW, Chen CB, Lee HE, Hung SI, et al.
    J Invest Dermatol, 2018 07;138(7):1546-1554.
    PMID: 29458119 DOI: 10.1016/j.jid.2018.02.004
    Dapsone-induced hypersensitivity reactions may cause severe cutaneous adverse reactions, such as drug reaction with eosinophilia and systemic symptoms (DRESS). It has been reported that HLA-B*13:01 is strongly associated with dapsone-induced hypersensitivity reactions among leprosy patients. However, the phenotype specificity and detailed immune mechanism of HLA-B*13:01 remain unclear. We investigated the genetic predisposition, HLA-B*13:01 function, and cytotoxic T cells involved in the pathogenesis of dapsone-induced severe cutaneous adverse reactions. We enrolled patients from Taiwan and Malaysia with DRESS and maculopapular eruption with chronic inflammatory dermatoses. Our results showed that the HLA-B*13:01 allele was present in 85.7% (6/7) of patients with dapsone DRESS (odds ratio = 49.64, 95% confidence interval = 5.89-418.13; corrected P = 2.92 × 10-4) but in only 10.8% (73/677) of general population control individuals in Taiwan. The level of granulysin, the severe cutaneous adverse reaction-specific cytotoxic protein released from cytotoxic T cells, was increased in both the plasma of DRESS patients (36.14 ± 9.02 ng/ml, P < 0.05) and in vitro lymphocyte activation test (71.4%, 5/7 patients) compared with healthy control individuals. Furthermore, dapsone-specific cytotoxic T cells were significantly activated when co-cultured with HLA-B*13:01-expressing antigen presenting cells in the presence of dapsone (3.9-fold increase, compared with cells with no HLA-B*13:01 expression; P < 0.01). This study indicates that HLA-B*13:01 is strongly associated with dapsone DRESS and describes a functional role for the HLA-restricted immune mechanism induced by dapsone.
  11. Chiu CK, Tan RL, Gani SMA, Chong JSL, Chung WH, Chan CYW, et al.
    Asian Spine J, 2021 May 07.
    PMID: 33957021 DOI: 10.31616/asj.2020.0649
    Study Design: Retrospective study.

    Purpose: To report the perioperative and radiological outcomes of single-stage posterior passive correction and fusion (SSPPCF) in adolescent patients who present with congenital scoliosis.

    Overview of Literature: The surgical treatment for congenital scoliosis is complex. There is no definitive guide on surgical options for skeletally matured adolescent patients who have congenital scoliosis.

    Methods: Patients with congenital scoliosis who underwent SSPPCF using a pedicle screw system were reviewed. We identified the following three surgical indications: (1) hemivertebra or wedge vertebra over the thoracic or thoracolumbar region with structural lumbar curves, (2) hemivertebra or wedge vertebra at the lumbar region with significant pelvic obliquity or sacral slanting, and (3) mixed or complex congenital scoliosis. The demographic, perioperative, and radiographic data of these patients were collected.

    Results: Thirty-four patients were reviewed. The mean patient age was 14.6±3.4 years. There were 13 hemivertebrae, three wedged vertebrae, two butterfly vertebrae, three hemivertebrae with butterfly vertebra, eight unsegmented bars, and five multiple complex lesions. The average surgical duration was 219.4±68.8 minutes. The average blood loss was 1,208.4±763.5 mL. Seven patients required allogeneic blood transfusion. The mean hospital stay duration was 6.1±2.5 days. The complication rate was 11.8% (4/34): one patient had severe blood loss, one had rod breakage, and two had distal adding-on. The Cobb angle reduced from 65.9°±17.4° to 36.3°±15.3° (p<0.001) with a correction rate (CR) of 44.8%±17.4%. The regional kyphotic angle decreased from 39.9°±20.5° to 27.5°±13.9° (p=0.001) with a CR of 19.3%±49.6%. Radiographic parameters (radiographic shoulder height, clavicle angle, T1 tilt, cervical axis, pelvic obliquity, coronal balance, and apical vertebral translation) showed significant improvement postoperatively.

    Conclusions: SSPPCF was a feasible option for adolescent patients with congenital scoliosis who were skeletally matured.

  12. Chiu CK, Chan CYW, Tan PH, Goh SH, Ng SJ, Chian XH, et al.
    Spine (Phila Pa 1976), 2020 Mar 15;45(6):E319-E328.
    PMID: 31593064 DOI: 10.1097/BRS.0000000000003275
    STUDY DESIGN: Retrospective study.

    OBJECTIVE: The primary objective of this study was to assess the conformity of the radiological neck and shoulder balance parameters throughout a follow-up period of more than 2 years.

    SUMMARY OF BACKGROUND DATA: Postoperative shoulder and neck imbalance are undesirable features among Adolescent Idiopathic Scoliosis patients who underwent Posterior Spinal Fusion. There are many clinical and radiological parameters used to assess this clinical outcome. However, we do not know whether these radiological parameters conform throughout the entire follow-up period.

    METHODS: This was a retrospective study done in a single academic institution. Inclusion criteria were patients with scoliosis who underwent posterior instrumented spinal fusion with pedicle screw fixation and attended all scheduled follow-ups for at least 24 months postoperatively. Radiological shoulder parameters were measured from both preoperative antero-posterior and postoperative antero-posterior radiographs. Lateral shoulder parameters were: Radiographic Shoulder Height, Clavicle Angle (Cla-A), Clavicle-Rib Intersection Difference, and Coracoid Height Difference. Medial shoulder and neck parameters were: T1 Tilt and Cervical Axis (CA).

    RESULTS: The radiographs of 50 patients who had surgery done from November 2013 to November 2015 were analyzed. Mean age of this cohort was 16.3 ± 7.0 years. There were 38 (76%) female patients and 12 (24%) male patients. Mean final follow-up was 38.6 ± 5.8 months. When conformity assessment of the radiological parameter using the interclass coefficient correlation was done, we found that all parameters had significant correlation (P 

  13. Chiu CK, Lee KJ, Chung WH, Chandren JR, Chan CYW, Kwan MK
    Spine (Phila Pa 1976), 2019 Jun 01;44(11):785-792.
    PMID: 30475346 DOI: 10.1097/BRS.0000000000002945
    STUDY DESIGN: Retrospective study of a prospectively-collected data.

    OBJECTIVE: To determine whether the severity of the curve magnitude in Lenke 1 and 2 Adolescent Idiopathic Scoliosis (AIS) patients affects the distance and position of the aorta from the vertebra.

    SUMMARY OF BACKGROUND DATA: There were studies that looked into the position of the aorta in scoliotic patients but none of them documented the change in distance of the aorta to the vertebra in relation to the magnitude of the scoliosis.

    METHODS: Patients with Lenke 1 and 2 AIS who underwent posterior spinal fusion using pedicle screw construct and had a preoperative computed tomography (CT) scan performed were recruited. The radiological parameters measured on preoperative CT scan were: Aortic-Vertebral Distance (AVD), Entry-Aortic Distance (EAD), Aortic-Vertebral angle (AVA), Pedicle Aorta angle/Aortic Alpha angle (α angle), and Aortic Beta angle (β angle).

    RESULTS: Thirty-nine patients were recruited. Significant moderate to strong positive correlation was found between AVD and Cobb angle from T8 to T12 vertebrae (r = 0.360 to 0.666). The EAD was generally small in the thoracic region (T4-T10) with mean EAD of less than 30 mm. Among all apical vertebrae, the mean AVD was 5.9 ± 2.2 mm with significant moderate-strong positive correlation to Cobb angle (r = 0.580). The mean α angle was 37.7 ± 8.7° with significant weak positive correlation with Cobb angle (r = 0.325).

    CONCLUSION: The larger the scoliotic curve, the aorta was located further away from the apical vertebral wall. The aorta has less risk of injury from the left lateral pedicle screw breach in larger scoliotic curve at the apical region. The distance from the pedicle screw entry point to the wall of the aorta was generally small (less than 30 mm) in the thoracic region (T4-T10).

    LEVEL OF EVIDENCE: 4.

  14. Chiu CK, Gani SMA, Chung WH, Mihara Y, Hasan MS, Chan CYW, et al.
    Spine (Phila Pa 1976), 2020 Aug 15;45(16):1128-1134.
    PMID: 32205708 DOI: 10.1097/BRS.0000000000003484
    STUDY DESIGN: Retrospective propensity score matching study.

    OBJECTIVE: To investigate whether menses affect intraoperative blood loss in female adolescent idiopathic scoliosis (AIS) patients undergoing posterior spinal fusion (PSF) surgeries.

    SUMMARY OF BACKGROUND DATA: There were concerns whether patients having menses will have higher intraoperative blood loss if surgery were to be done during this period.

    METHODS: This study included 372 females who were operated between May 2016 to May 2019. Fifty-five patients had menses during surgery (Group 1, G1) and 317 patients did not have menses during surgery (Group 2, G2). Propensity score matching (PSM) analysis with one-to-one, nearest neighbor matching technique and with a match tolerance of 0.001 was used. The main outcome measures were intraoperative blood loss (IBL), volume of blood salvaged, transfusion rate, preoperative hemoglobin, preoperative platelet, preoperative prothrombin time, preoperative activated partial thromboplastin time (APTT), international normalized ratio (INR), and postoperative hemoglobin. Postoperative Cobb angle and correction rate were also documented.

    RESULTS: At the end of PSM analysis, 46 patients from each group were matched and balanced. The average operation duration for G1 was 140.8 ± 43.0 minutes compared with 143.1 ± 48.3 minutes in G2 (P = 0.806). The intraoperative blood loss for G1 was 904.3 ± 496.3 mL and for G2 was 907.9 ± 482.8 mL (P = 0.972). There was no significant difference in terms of normalized blood loss (NBL), volume of blood salvaged during surgery, preoperative hemoglobin, postoperative hemoglobin, hemoglobin drift, estimated blood volume (EBV), IBL per EBV and IBL per level fused (P > 0.05). No postoperative complications were encountered in both groups. On average, the postoperative hospital stay was 3.5 ± 0.8 days for both groups (P = 0.143).

    CONCLUSION: Performing corrective surgery during the menstrual phase in female AIS patients is safe without risk of increased blood loss.

    LEVEL OF EVIDENCE: 4.

  15. Chiu CK, Tan CS, Chung WH, Mohamad SM, Kwan MK, Chan CYW
    Eur Spine J, 2021 07;30(7):1978-1987.
    PMID: 34023966 DOI: 10.1007/s00586-021-06874-5
    PURPOSE: To investigate mid-long-term effects of the lowest instrumented vertebra (LIV) selection on adolescent idiopathic scoliosis (AIS) patients who had posterior spinal fusion (PSF) surgery.

    METHODS: Forty-eight patients were recruited. Inclusion criteria were AIS patients who have had PSF surgery more than 10 years ago. Patients were divided into G1: LIV L3 or higher and G2: LIV L4 or lower. MRI evaluation was classified using Pfirrmann grades. Pfirrmann scores were average of Pfirrmann grades for all unfused discs below LIV. SRS-22r, SF-36, Oswestry Disability Index (ODI) and Modified Cincinnati Sports Activity Scale (MCSAS) were used.

    RESULTS: There were 19 patients in G1 and 29 patients in G2. Demographic parameters showed no significant differences. We found no significant differences in Pfirrmann grades or scores between G1 and G2. There was significant correlation between age and mean Pfirrmann scores (r = 0.546, p 

  16. Chiu CK, Wang WJ, Lee YJ, Chung WH, Chan CYW, Kwan MK
    Spine J, 2023 Nov;23(11):1700-1708.
    PMID: 37453514 DOI: 10.1016/j.spinee.2023.07.006
    BACKGROUND CONTEXT: Patients with adolescent idiopathic scoliosis (AIS) have higher prevalence of abnormal or dysplastic pedicles.

    PURPOSE: To investigate the prevalence and distribution of narrow dysplastic and fully corticalized pedicles in Asian AIS patients with major main thoracic curves.

    DESIGN: Retrospective study.

    PATIENT SAMPLE: A total of 6,494 pedicles in 191 patients were measured and evaluated.

    OUTCOME MEASURES: The primary outcomes measures were the pedicle width measurements (total transverse pedicle width, transverse cancellous width, total transverse cortical width) and classification of pedicles. Demographic data (age, gender, height, weight, body mass index), proximal thoracic Cobb angle, main thoracic Cobb angle and lumbar Cobb angle were also obtained.

    METHODS: AIS patients with major (largest Cobb angle) main thoracic curves and had computed tomography (CT) scans prior to corrective spine surgery were reviewed. The pedicles were classified as Grade A: cancellous channel >4 mm; Grade B: cancellous channel 2 to 4 mm; Grade C: cancellous channel <2 mm or corticalized pedicle >4 mm; Grade D: corticalized pedicle ≤4 mm. Grades B, C, and D were dysplastic pedicles while grades C and D were narrow dysplastic pedicles.

    RESULTS: The prevalence of dysplastic pedicles (grades B, C, and D) was 61.7%. There were 22.6% narrow dysplastic pedicles (grades C and D) and 4.1% fully corticalized pedicles (grade D). In the thoracolumbar region, there was a sharp transition from larger and less dysplastic pedicles at T11 and T12 to narrower and more dysplastic pedicles at L1 and L2 (narrow dysplastic pedicles at T11: 3.1%, T12: 3.1%, L1: 39.8% and L2: 23.6%). Higher prevalences of narrow dysplastic pedicles were located at right T3 to T5 (71.2%-83.7%) and left T7-T9 (51.3%-61.2%). Higher prevalences of fully corticalized pedicles were located at right T3 to T5 (20.9%-34.0%) and left T7 to T8 (11.0%-12.0%). These were the concave pedicles of proximal thoracic and main thoracic curves, respectively.

    CONCLUSION: There were 95.9% pedicles with cancellous channels (grades A, B, and C) can allow pedicle screw fixation and only 4.1% fully corticalized pedicles (grade D) that require an alternative method of fixation. For grade C pedicles (18.5%), pedicle screws can still be attempted with caution. Precautions should also be observed at the L1 and L2 levels as there was a transition to narrower pedicles.

  17. Chiu CK, Chin TF, Chung WH, Chan CYW, Kwan MK
    Spine (Phila Pa 1976), 2024 Jan 01;49(1):64-70.
    PMID: 37146062 DOI: 10.1097/BRS.0000000000004711
    STUDY DESIGN: Retrospective Study.

    OBJECTIVE: This study aims to investigate variation in the number of thoracic and lumbar vertebrae, the prevalence of lumbosacral transitional vertebra (LSTV) and the prevalence of cervical ribs among surgical patients with adolescent idiopathic scoliosis (AIS).

    SUMMARY OF BACKGROUND DATA: Due to variation in the number of thoracic or lumbar vertebrae, inaccurate identification of vertebral levels has been found to be a contributory factor to wrong-level surgery.

    METHODS: This was a retrospective study on AIS patients who underwent posterior spinal fusion. Demographic and anthropometric data (age, gender, height, weight, and body mass index), radiographic data (Lenke curve type, pre-operative Cobb angle, vertebra numbering of cervical, thoracic, and lumbar spine, presence of LSTV based on the Castellvi classification and the presence of cervical ribs) and clinical data were collected. Data were analysed and reported with mean and standard deviation for quantitative parameters and number and percentage for qualitative parameters. Multinomial logistic regression analyses were performed to identify factors associated with the outcomes of interest.

    RESULTS: A total of 998 patients met inclusion criteria, of which 135 (13.5%) were males and 863 (86.5%) were females. The vertebrae number varied between 23 to 25 total vertebrae with 24 vertebrae considered as the typical number of vertebrae. The prevalence of atypical number of vertebrae (23 or 25) was 9.8% (98 patients). We found a total of 7 different variations in number of cervical, thoracic, and lumbar vertebrae (7C11T5L, 7C12T4L, 7C11T6L, 7C12T5L, 7C13T4L, 7C12T6L, and 7C13T5L) with 7C12T5L considered as the typical vertebrae variation. The total prevalence of patients with atypical vertebrae variation was 15.5% (155 patients). Cervical ribs were found in 2 (0.2%) patients while LSTV were found in 250 (25.1%) of patients. The odds of 13 thoracic vertebrae were higher in males (OR 5.17; 95% CI: 1.25, 21.39) and the odds of 6 lumbar vertebrae were higher in LSTV (OR 3.93; 95% CI: 2.58, 6.00).

    CONCLUSION: In this series, we identified a total of 7 different variations in the number of cervical, thoracic, and lumbar vertebrae. The total prevalence of patients with atypical vertebrae variation was 15.5%. LSTV was found in 25.1% of the cohort. It is important to ascertain atypical vertebrae variations rather than the absolute number of vertebrae because variants such as 7C11T6L and 7C13T4L may still have typical numbers of vertebrae in total. However, due to the differences in the number of morphologically thoracic and lumbar vetrebrae, there may still be a risk of inaccurate identification.

  18. Chiu CK, Wang WJ, Lee YJ, Chung WH, Chan CYW, Kwan MK
    Spine J, 2024 Feb 24.
    PMID: 38408520 DOI: 10.1016/j.spinee.2024.02.014
    BACKGROUND CONTEXT: The widths of medial and lateral pedicle walls in the normal spine of middle-aged and elderly adults had been investigated and these studies found that medial pedicle wall was thicker than lateral pedicle wall. However, none had evaluated the widths of medial and lateral pedicle walls on adolescent or young adult scoliotic spines.

    PURPOSE: This study aims to identify the distribution and variation of medial and lateral pedicle wall widths throughout the different vertebral levels of the scoliotic spine and its differences according to age, gender, body mass index (BMI), maturity, curve types and curve severity in adolescent idiopathic scoliotic (AIS) patients with major thoracic curves.

    STUDY DESIGN: Retrospective Study PATIENT SAMPLE: A total of 6230 pedicles (right: 3064, left: 3166) from 191 patients were included in this study with 264 (right: 183, left: 81) fully corticalized pedicles excluded from analysis.

    OUTCOME MEASURES: Demographic data were age, gender, height, weight, BMI, Risser grade, Lenke curve types and Cobb angles. Main outcome measures were medial and lateral pedicle wall widths. Associations between pedicle wall widths and demographic data were calculated.

    METHODS: This was a sub-analytical retrospective study done on the same patient population as the previously published study on pedicle grading. The data was obtained from the main computed tomography (CT) scan pedicle study dataset. Medial and lateral pedicle wall widths were measured in the axial slices of CT scans from T1 to L5 vertebrae.

    RESULTS: A total of 6230 pedicles (right: 3064, left: 3166) from 191 patients were included in this study with 264 (right: 183, left: 81) fully corticalized pedicles excluded from analysis. Right-sided medial pedicle wall widths were narrower from T4-T10 (0.75 ± 0.23 mm) compared to T1-T3 (0.89 ± 0.28 mm) and T11-L5 (0.92 ± 0.30 mm). Left-sided medial pedicle wall widths were narrower from T4 to T7 (0.76 ± 0.24 mm) compared to T1-T3 (0.88 ± 0.26 mm) and T8-L5 (0.90 ± 0.27 mm). Medial cortical wall widths were significantly thicker compared to lateral cortical wall widths for all vertebras from T1 to L5 (right medial 0.85 ± 0.28 mm vs lateral 0.64 ± 0.26 mm (p<0.001), left medial 0.86 ± 0.26 mm vs lateral 0.64 ± 0.26 mm (p<0.001)). The left medial pedicle wall widths were marginally significantly (p<0.001) thicker than right side (right medial 0.85 ± 0.28 mm vs left 0.86 ± 0.26 mm). Then main notable significant differences were located at the periapical region of the thoracic curve between T7 to T10 with left concave medial pedicle width being thicker than right convex medial pedicle width. The thinnest medial pedicle walls were located at right concave T7 (0.73 ± 0.24 mm) and T8 (0.73 ± 0.23 mm). We generally found no significant associations between the medial and lateral pedicle wall widths with age, gender, BMI, Risser grade, Cobb angle and curve types.

    CONCLUSION: Knowledge on the widths of medial and lateral pedicle walls, their distribution and differences in a scoliotic spine is important for pedicle screw fixation especially during pedicle probing to find the pedicle channel. The medial pedicle wall widths were significantly thicker than lateral pedicle wall widths in AIS patients with major thoracic curves. The right concave periapical region had the thinnest medial pedicle walls.

  19. Chung WH, Chang WC, Lee YS, Wu YY, Yang CH, Ho HC, et al.
    JAMA, 2014 Aug 6;312(5):525-34.
    PMID: 25096692 DOI: 10.1001/jama.2014.7859
    The antiepileptic drug phenytoin can cause cutaneous adverse reactions, ranging from maculopapular exanthema to severe cutaneous adverse reactions, which include drug reactions with eosinophilia and systemic symptoms, Stevens-Johnson syndrome, and toxic epidermal necrolysis. The pharmacogenomic basis of phenytoin-related severe cutaneous adverse reactions remains unknown.
  20. Chung WH, Tan RL, Chiu CK, Kwan MK, Chan C
    Malays Orthop J, 2020 Nov;14(3):170-173.
    PMID: 33403080 DOI: 10.5704/MOJ.2011.027
    Delayed post-operative spinal epidural haematoma (DPSEH) is diagnosed when the onset of symptoms is more than three days from the index surgery. DPSEH is a rare but serious complication of spinal surgery. Missed diagnosis will result in irreversible neurological deficit which may lead to permanent disabilities. We report two cases of DPSEH who presented with worsening neurological deficit four days after the index surgery. Magnetic resonance imaging (MRI) showed the presence of an epidural haematoma compressing the spinal cord. Surgical evacuation of haematoma were performed for both patients. Both patients experienced neurological improvement. Surgeons should have high index of suspicion to identify delayed onset of spinal epidural haematoma (SEH) and timely intervention should be taken to avoid irreversible neurological damage.
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