Analysis of duration of different stages of surgery in posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS) patients: comparison between severe versus non-severe AIS.

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 < 0.001). The lengthiest stage was screw insertion which took 58.5 ± 13.4 min in Gp1 and 44.7 ± 13.7 min in Gp2 (p = 0.001). Screw insertion contributed 39.5% of the overall increased surgical duration in Gp1. Intraoperative blood loss (1022.2 ± 412.5 vs. 714.2 ± 206.7 mL, p = 0.002), number of screws (17.1 ± 1.5 vs. 15.5 ± 1.1, p < 0.001) and fusion level (13.1 ± 0.9 vs. 12.5 ± 1.0, p = 0.026) were significantly higher in Gp1. CONCLUSION: Screw insertion was the most time-consuming stage of PSF and was significantly longer in severe AIS. Adjunct technologies such as CT-guided navigation and robotic-assisted navigation should be considered to reduce screw insertion time in severe AIS.

Optimising operating theatre (OT) efficiency while maintaining the standardised patient care in adolescent idiopathic scoliosis (AIS) surgery with the dedicated spine team approach: a specialised spine unit experience.

PURPOSE: To report the efficiency of OT utilisation and perioperative outcomes with a dedicated spine team approach in AIS patients who underwent posterior spinal fusion (PSF) surgeries in a consecutive case operation list. METHODS: Three AIS patients operated in a day (8:00 AM-8:00 PM) by a dedicated spine team were recruited between 2021 and 2022. The dedicated team comprised of three senior spine consultants who operated using a dual attending surgeon strategy, an anaesthetic consultant, dedicated surgical scrub nurses, anaesthesiology nurses, radiographers, and neuromonitoring technicians. Patients were categorised according to the sequence of operation list of the day (Case 1, Case 2, and Case 3). OT efficiency was represented by OT time in five stages (preoperative time, operative time, postoperative time, total OT time, and turnover time). OT time and perioperative outcomes were compared. RESULTS: 102 cases were analysed. On average, Case 1 began at 8:38 AM whereas Case 3 ended by 5:54 PM. OT efficiency was consistent throughout the day of operation with comparable OT time in all five stages between groups (p > 0.05). The mean turnover time was 15.1 ± 13.5 min and the mean operative time was 123.0 ± 28.1 min. Intraoperative arterial blood gas (ABG) parameters were maintained in an optimal range. The complication rate was 2.0% (N = 2/102). CONCLUSION: Consistent OT efficiency was demonstrated with a dedicated spine team approach. Despite performing three AIS cases in a consecutive case operation list, patients' safety was not compromised as perioperative outcomes between groups were comparable.

A comparison between Boston brace and European braces in the treatment of adolescent idiopathic scoliosis (AIS) patients: a systematic review based on the standardised Scoliosis Research Society (SRS) inclusion criteria for brace treatment.

PURPOSE: To compare the Boston brace and European braces using a standardised Scoliosis Research Society (SRS) inclusion criteria for brace treatment as well as consensus recommendations for treatment outcome. METHODS: This was a systematic review that was carried out using MeSH terminology in our search protocol in PubMed, Cochrane Library, Scopus, Clinicaltrials.gov and Web of Science database between 1976 and 29th of Jan 2023. All studies that were included in this review had applied fully/partially the SRS inclusion criteria for brace wear. Outcome measures were divided into primary and secondary outcome measures. RESULTS: 3830 literatures were found in which 176 literatures were deemed relevant to the study once duplicates were removed and titles and abstracts were screened. Of these literatures, only 15 had fulfilled the eligibility criteria and were included in the study. 8 of the studies were Level IV studies, 5 were Level III studies and 2 studies were Level I studies (1 prospective randomised controlled trial (RCT) and 1 Quasi-RCT). The percentage of patients who avoided surgery for European braces ranged from 88 to 100%, whereas for Boston brace ranged from 70 to 94%. When treatment success was assessed based on the final Cobb angle > 45°, approximately 15% of patients treated with European braces had treatment failure. In contrast, 20-63% of patients treated with Boston brace had curves > 45° at skeletal maturity. The BrAIST study used a cut-off point of 50° to define failure of treatment and the rate of treatment failure was 28%. Curve correction was not achieved in most patients (24-51% of patients) who were treated with the Chêneau brace and its derivatives. However, none of the patients treated with Boston brace achieved curve correction. CONCLUSION: Boston brace and European braces were effective in the prevention of surgery. In addition, curve stabilisation was achieved in most studies. Limitation in current literature included lack of studies providing high level of evidence and lack of standardisation in terms of compliance to brace as well as multidisciplinary management of brace wear.

Association between intraoperative remifentanil use and postoperative hyperalgesia in adolescent idiopathic scoliosis surgery: a retrospective study.

BACKGROUND: The liberal use of remifentanil in spine surgery has been associated with an increased incidence of postoperative hyperalgesia. Nevertheless, controversies remain as the existing evidence is inconclusive to determine the relationship between remifentanil use and the development of opioid-induced hyperalgesia. We hypothesized that intraoperative infusion of higher dose remifentanil during scoliosis surgery is associated with postoperative hyperalgesia, manifesting clinically as greater postoperative morphine consumption and pain scores. METHODS: Ninety-seven patients with adolescent idiopathic scoliosis (AIS) who underwent posterior spinal fusion surgery at a single tertiary institution from March 2019 until June 2020 were enrolled in this retrospective study. Anesthesia was maintained using a target-controlled infusion of remifentanil combined with volatile anesthetic desflurane in 92 patients, while five patients received it as part of total intravenous anesthesia. Intravenous ketamine, paracetamol, and fentanyl were administered as multimodal analgesia. All patients received patient-controlled analgesia (PCA) morphine postoperatively. Pain scores at rest and on movement, assessed using the numerical rating scale, and the cumulative PCA morphine consumption were collected at a six-hourly interval for up to 48 h. According to the median intraoperative remifentanil dose usage of 0.215 µg/kg/min, patients were divided into two groups: low dose and high dose group. RESULTS: There were no significant differences in the pain score and cumulative PCA morphine consumption between the low and high dose remifentanil group. The mean duration of remifentanil infusion was 134.9 ± 22.0 and 123.4 ± 23.7 min, respectively. CONCLUSION: Intraoperative use of remifentanil as an adjuvant in AIS patients undergoing posterior spinal fusion surgery was not associated with postoperative hyperalgesia.

Severe Lenke 1 and 2 adolescent idiopathic scoliosis had poorer perioperative outcome, higher complication rate, longer fusion and higher operative cost compared to non-severe scoliosis.

PURPOSE: To compare the perioperative outcome and operative cost of posterior spinal fusion (PSF) surgery between severe and non-severe Lenke 1 and 2 adolescent idiopathic scoliosis (AIS) patients. METHODS: A total of 509 AIS patients who underwent single-staged PSF between 2013 and 2020 were reviewed. Fifty-four severe scoliosis patients (Cobb angle ≥ 90°) were categorized into Gp1, and 455 non-severe scoliosis (Cobb angle < 90°) patients into Gp2. Propensity score matching (PSM) analysis using one-to-one nearest neighbor matching and match tolerance of 0.001 were performed. Outcome measures were operative time, intraoperative blood loss (IBL), allogeneic transfusion rate, perioperative complication, length of stay, fusion level, number of screws used, postoperative Cobb angle, correction rate (CR), side bending correction index (SBCI) and operative cost. RESULTS: From the PSM analysis, 35 patients from each group were matched. The operative time was 155.9 ± 41.4 and 130.0 ± 30.3 min for Gp1 and Gp2, respectively (p = 0.004). The IBL was 1349.2 ± 1019.0 and 781.9 ± 325.1 mLs for Gp1 and Gp2, respectively (p = 0.003). Fusion level (12.5 ± 0.8 vs. 11.2 ± 1.3, p < 0.001) and number of screws used (16.4 ± 1.6 vs. 14.6 ± 1.4, p < 0.001) were higher in Gp1. Four perioperative complications were observed in Gp1 compared to none in Gp2 (p < 0.039). Gp1 had larger postoperative Cobb angle (p < 0.001), lower CR (p = 0.005) and higher SBCI (p < 0.001). The operative cost was higher in Gp1 (p < 0.001). CONCLUSIONS: Severe Lenke 1 and 2 AIS patients had poorer perioperative outcome, higher complication rate, longer fusion and higher operative cost than non-severe AIS.

Mid-long-term outcome and degeneration of the remaining unfused lumbar intervertebral disc in adolescent idiopathic scoliosis patients who had posterior spinal fusion surgery.

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 < 0.001), Pfirrmann grade for adjacent disc + 1 below LIV (r = 0.475, p = 0.001) and adjacent disc below LIV (r = 0.365, p = 0.011). G2 had significantly lower scores for SRS-22r pain (G1: 4.3 ± 0.5, G2: 4.0 ± 0.6, p = 0.044) and the SF-36 bodily pain (G1: 88.7 ± 12.3, G2: 77.8 ± 18.7, p = 0.018) domains. There were no significant differences in ODI and MCSAS between the two groups. CONCLUSIONS: Patients with fusion to L4 or lower had more significant back pain. However, both groups had similar physical function, self-image, satisfaction with treatment, mental health, and functional sports activity. We did not find any significant association between lumbar discs degeneration and the selection of LIV.

Predictive factors for correction rate in severe idiopathic scoliosis (Cobb angle ≥ 90°): an analysis of 128 patients.

PURPOSE: Knowledge on the factors affecting the correction rate (CR) aids in the surgical planning among severe idiopathic scoliosis (IS) patients. This study aimed to investigate the independent factors affecting CR among patients with severe IS (Cobb angle ≥ 90°) who underwent single-staged posterior spinal fusion (PSF). METHODS: We retrospectively reviewed 128 severe IS patients who underwent single-staged PSF. Factors including age, height, weight, body mass index, Risser sign, Lenke subtypes, preoperative major Cobb angle, side bending major Cobb angle, side bending flexibility (SBF), motion segments of the major curve, AR curve, number of levels fused, screw density, operative time and postoperative major Cobb angle were analysed using linear regression analysis. RESULTS: The mean age was 15.5 ± 4.5 years with mean Risser sign of 3.1 ± 1.6. The mean preoperative Cobb, SBF, postoperative Cobb and CR were 102.8 ± 12.3°, 37.5 ± 13.7%, 44.4 ± 13.5° and 57.2 ± 10.8%, respectively. From stepwise multiple linear regression analysis, SBF, Risser sign and AR curve were the independent predictive factors for CR, with R2 value of 0.345 (p < 0.001). CR can be predicted using the formula: 47.21 + (0.34 × SBF)-(1.47 × Risser sign) + (3.69 × AR), where AR = 1 and non-AR = 0. CONCLUSION: The flexibility of the major curve, Risser sign and AR curve were the most important predictors for CR in a single-staged PSF among patients with severe IS.

Perioperative outcome and complications following single-staged Posterior Spinal Fusion (PSF) using pedicle screw instrumentation in Adolescent Idiopathic Scoliosis (AIS): a review of 1057 cases from a single centre.

BACKGROUND: There has been a growing interest in using all pedicle screw construct in posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS) surgery in recent years. However, studies focusing on perioperative outcome and complications utilizing only pedicle screw system in AIS population are lacking. This study aims to evaluate perioperative outcomes and to determine the prevalence of major and minor complications following single-staged PSF for AIS. METHODS: In this retrospective study of prospectively collected data, 1057 AIS patients operated between 2012 and 2019 were included. Main outcome measures were operative time, intraoperative blood loss, allogeneic blood transfusion rate, length of hospital stay after surgery, complication rate, and mean drop of haemoglobin (Hb) level. We documented the number of fusion levels, screw density, and postoperative radiographic parameters. RESULTS: There were 917 females and 140 males. Majority were Lenke 1 curve type (46.9%). Mean age was 15.6 ± 3.7 years, with mean BMI of 18.6 ± 3.2 kg/m2. Mean operative time was 146.8 ± 49.4 min. Average intraoperative blood loss was 952.9 ± 530.4 ml with allogeneic blood transfusion rate of 5%. Mean screw density was 1.27 ± 0.21 screws per fusion level. Average hospital stay after surgery was 3.5 ± 0.9 days. Twenty-four complications were documented: twelve superficial infections (1.14%), five transient neurological deficits (0.47%), two deep infections (0.19%), two superior mesenteric artery syndrome, and one case each (0.09%) for massive intraoperative blood loss, intraoperative seizure, and lung atelectasis. CONCLUSION: AIS patients treated with single-staged PSF using pedicle screw construct had a 0.95% rate of major complications and 1.32% rate of minor complications. Rate of neurologic complication was 0.47% while non-neurologic postoperative complications was 1.80% with infection being the leading complication at 1.32%.

Single vs two attending senior surgeons: assessment of intra-operative blood loss at different surgical stages of posterior spinal fusion surgery in Lenke 1 and 2 adolescent idiopathic scoliosis.

PURPOSE: To assess the pattern of intra-operative blood loss at various surgical stages comparing between single and two surgeons. METHODS: Lenke 1 and 2 adolescent idiopathic scoliosis (AIS) patients who underwent instrumented posterior spinal fusion (PSF) surgery from two centres between June 2014 and December 2015 were prospectively recruited into this study. The patients were grouped into Group 1 (single surgeon) and Group 2 (two surgeons). One to one matching using 'prospective propensity score-matched cohort patient sampling method' was done. The surgery was divided into six stages: stage 1-exposure, stage 2-screw insertion, stage 3-release, stage 4-correction, stage 5-corticotomies and bone grafting and stage 6-closure. RESULTS: A total of 116 patients were recruited. Of 86 patients who were operated by the two surgeons, 30 patients were matched with 30 patients that were operated by a single surgeon. Operation duration was significantly longer in Group 1 (257.3 ± 51.4 min) compared to Group 2 (164.0 ± 25.7 min). The total blood loss was significantly higher in Group 1 (1254.7 ± 521.5 mL) compared to Group 2 (893.7 ± 518.4 mL). Total blood loss/level fused was significantly higher in Group 1 (117.5 ± 42.8 mL/level) compared to Group 2 (82.6 ± 39.4 mL/level). Group 1 had significantly higher blood loss and blood loss/level fused for stages 1, 2 and 3. Group 2 had lower incidence of allogenic blood transfusion. CONCLUSIONS: In PSF surgery for AIS patients, two-surgeon strategy was associated with shorter operation duration, lesser blood loss and lower incidence of allogenic blood transfusion.

A comparison of feasibility and safety of percutaneous fluoroscopic guided thoracic pedicle screws between Europeans and Asians: is there any difference?

PURPOSE: To directly compare the safety of fluoroscopic guided percutaneous thoracic pedicle screw placement between Caucasians and Asians. METHODS: This was a retrospective computerized tomography (CT) evaluation study of 880 fluoroscopic guided percutaneous pedicle screws. 440 screws were inserted in 73 European patients and 440 screws were inserted in 75 Asian patients. Screw perforations were classified into Grade 0: no violation; Grade 1: <2 mm perforation; Grade 2: 2-4 mm perforation; and Grade 3: >4 mm perforation. For anterior perforations, the pedicle perforations were classified into Grade 0: no violation, Grade 1: <4 mm perforation; Grade 2: 4-6 mm perforation; and Grade 3: >6 mm perforation. RESULTS: The inter-rater reliability was adequate with a kappa value of 0.83. The mean age of the study group was 58.3 ± 15.6 years. The indications for surgery were tumor (70.3 %), infection (18.2 %), trauma (6.8 %), osteoporotic fracture (2.7 %) and degenerative diseases (2.0 %). The overall screw perforation rate was 9.7 %, in Europeans 9.1 % and in Asians 10.2 % (p > 0.05). Grade 1 perforation rate was 8.4 %, Grade 2 was 1.2 % and Grade 3 was 0.1 % with no difference in the grade of perforations between Europeans and Asians (p > 0.05). The perforation rate was the highest in T1 (33.3 %), followed by T6 (14.5 %) and T4 (14.0 %). Majority of perforations occurred medially (43.5 %), followed by laterally (25.9 %), and anteriorly (23.5 %). There was no statistical significant difference (p > 0.05) in the perforation rates between right-sided pedicle screws and left-sided pedicle screws (R: 10.0 %, L: 9.3 %). CONCLUSIONS: There were no statistical significant differences in the overall perforation rates, grades of perforations, direction of perforations for implantation of percutaneous thoracic pedicle screws insertion using fluoroscopic guidance between Europeans and Asians. The safety profile for this technique was comparable to the current reported perforation rates for conventional open pedicle screw technique.

Optimizing the distal anchorage in stabilization for the traumatic adjacent lumbar vertebra fracture in an adolescent idiopathic scoliosis patient who had posterior spinal fusion: a novel surgical technique.

The incidence of traumatic spine fractures (TSF) is increasing worldwide, with a reported annual incidence of up to 32.8 per 100000 persons. However, there are only a few cases of spine fractures reported in adolescent idiopathic scoliosis (AIS) patients after posterior spinal fusion (PSF) in the literature. Fractures adjacent to fusion blocks that extend into the lower lumbar spine pose a unique challenge as stabilization of such fractures might require an extension of instrumentation to L5 or the pelvis. We report a novel surgical technique where bilateral pedicle and cortical screws at L4 and supplementary rods that connect the cortical screws to the main rods via dominos were implemented for optimizing the distal anchorage for TSF stabilization following an L3 Chance fracture in an AIS patient who had undergone T4-L2 posterior spinal fusion.

Variations in the Number of Vertebrae, Prevalence of Lumbosacral Transitional Vertebra and Prevalence of Cervical Rib Among Surgical Patients With Adolescent Idiopathic Scoliosis: An Analysis of 998 Radiographs.

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.

Association of single bolus versus bolus followed by infusion of tranexamic acid with blood loss in adolescent idiopathic scoliosis surgery.

BACKGROUND: Adolescent idiopathic scoliosis (AIS) corrective surgery may involve significant blood loss and blood transfusion requirements. Antifibrinolytic agents such as tranexamic acid (TXA) have been used to reduce blood loss, but its optimal dose is uncertain. The objective of this study is to determine the estimated blood loss and rate of blood transfusion between two groups of AIS patients receiving TXA as a single bolus versus bolus followed by infusion in scoliosis surgery. METHODS: This was a retrospective analysis of a single bolus versus bolus followed by infusion of TXA in AIS surgery. AIS patients undergoing posterior spinal fusion (PSF) from December 2018 to September 2019 at a tertiary university hospital were identified. Inclusion criteria were patients aged between 10 and 21 years who received either a single bolus of 30 mg/kg TXA (Group A) or a single bolus of 30 mg/kg followed by continuous infusion of 10 mg/kg/h of TXA (Group B). Patient demographics, operative data, estimated blood loss, blood transfusion rate, and complications were recorded. RESULTS: A total of 129 AIS patients were included. All operative surgeries were performed by two senior consultants. The mean age was 14.8 ± 3.4 years old, and 89.1% were female. The Cobb angle, number of fusion levels, number of screws, length of skin incision, and duration of surgery were comparable between the two groups. There was no difference in the total estimated blood loss between the two groups: 723.3 ± 279.4 mL (range: 175.0-1607.0 mL) in Group A and 819.4 ± 302.6 mL (range: 330.0-1556.0 mL) in Group B (p = 0.065). There were no complications, and none received blood transfusion. CONCLUSION: TXA when administered as a single bolus or bolus followed by infusion in AIS patients undergoing PSF surgery was associated with similar estimated total surgical blood loss and blood transfusion requirement.

Prediction of postoperative curve correction based on the supine radiographs for adult idiopathic scoliosis patients.

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: A total of 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<.001) and preoperative SB Cobb angle (r=0.815, r=0.872, r=0.801, p<.001) showed similar strong positive correlation with postoperative PT, MT and TL/L Cobb angle, but preoperative Supine Cobb angle had slightly stronger correlation in PT and MT, whereas preoperative SB Cobb angle had stronger correlation in TL/L curve. Using the derived predictive formulae, there was a significant, strong, positive correlation between the predicted value and actual value of postoperative standing Cobb angle, (r=0.852, p<.001), with 71.0% of the patients had predicted postoperative Cobb angle from the supine radiographs within 5° of the actual value. CONCLUSION: Both supine radiographs and side bending radiographs had strong predictability of the postoperative Cobb angle for PT, MT and TL/L curves. In 71.0% of patients, the actual postoperative Cobb angle was within 5° of the predicted postoperative Cobb angle using the predictive formulae.

The widths of the medial and lateral pedicle walls in adolescent idiopathic scoliosis with major thoracic curves.

BACKGROUND CONTEXT: The widths of medial and lateral pedicle walls in the normal spine of middle-aged and elderly adults have been investigated and these studies found that the medial pedicle wall was thicker than the 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 6,230 pedicles (right: 3,064, left: 3,166) 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. The main outcome measures were medial and lateral pedicle wall widths. Associations between pedicle wall widths and demographic data were calculated. METHODS: This was a subanalytical 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 6,230 pedicles (right: 3,064, left: 3,166) 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<.001), left medial 0.86±0.26 mm vs lateral 0.64±0.26 mm (p<.001)). The left medial pedicle wall widths were marginally significantly (p<.001) thicker than the right side (right medial 0.85±0.28 mm vs left 0.86±0.26 mm). The main notable significant differences were located at the periapical region of the thoracic curve between T7 to T10 with the left concave medial pedicle width being thicker than the 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. CONCLUSIONS: 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 the lateral pedicle wall widths in AIS patients with major thoracic curves. The right concave periapical region had the thinnest medial pedicle walls.

What is the prevalence and distribution of narrow dysplastic and fully corticalized pedicles in Asian adolescent idiopathic scoliosis patients with major main thoracic curves? A computed tomography scan analysis of 6,494 pedicles.

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.

A Comparison Between the Perioperative Outcomes of Female Adolescent Idiopathic Scoliosis (AIS) Versus Adult Idiopathic Scoliosis (AdIS) Following Posterior Spinal Fusion: A Propensity Score Matching Analysis Involving 425 Patients.

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.

Preoperative "Cervical Axis" Deviation Increases the Risk of Distal Adding-On Following Surgery in Lenke 1 and 2 Adolescent Idiopathic Scoliosis Patients.

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.

Patients' Perception and Satisfaction on Neck and Shoulder Imbalance in Adolescent Idiopathic Scoliosis.

STUDY DESIGN: Cross-sectional. OBJECTIVES: To evaluate the perception and satisfaction among adolescent idiopathic scoliosis (AIS) patients on Neck Tilt with Medial Shoulder Imbalance and Lateral Shoulder Imbalance. METHODS: Lenke 1 and 2 AIS patients were stratified into 6 groups of preoperative/ postoperative Balanced (B), Lateral Shoulder Imbalance (LSI) (>2 cm), and Neck Tilt with Medial Shoulder Imbalance (NT) (Grade 3). Patients were interviewed using Modified Neck and Shoulder Appearance and SRS-22r questionnaires. T1 tilt, Cervical Axis (CA), Clavicle Angle (Cla-A) and Radiographic Shoulder Height (RSH) were measured. RESULTS: A total of 120 Lenke 1 and 2 AIS patients were recruited. NT patients were aware and unhappy with their abnormal neck with medial shoulder appearances (P < .001). Similarly, LSI patients were aware and unhappy with their abnormal lateral shoulder appearances (P < .001). NT group had larger preoperative/ postoperative T1 tilt (9.2 ± 5.0°; 9.5 ± 5.3°) and CA (4.6 ± 3.1°; 7.0 ± 2.0°) (P < .01). LSI group had larger preoperative/ postoperative Cla-A (4.8 ± 2.8°; 4.0 ± 1.3°) and RSH (20.1 ± 9.4 mm; 17.0 ± 6.6 mm) (P < .001). Postoperative B group scored higher in overall SRS-22r scores, self-image and satisfaction domains (4.2 ± 0.3; 4.0 ± 0.5; 4.4 ± 0.5) while preoperative LSI scored the lowest comparatively (3.5 ± 0.4; 2.4 ± 0.5; 3.3 ± 0.5) (P < .001). CONCLUSION: NT and LSI were major concerns among AIS patients. Both NT and LSI groups were unhappy with their appearances. NT group had larger T1 tilt/ CA whereas LSI group had larger Cla-A/ RSH. Postoperative B group scored higher in overall SRS-22r scores, self-image and satisfaction domains.

Factors Affecting Operation Duration in Posterior Spinal Fusion (PSF) Using Dual Attending Surgeon Strategy Among Lenke 1 and 2 Adolescent Idiopathic Scoliosis (AIS) Patients.

STUDY DESIGN: This was a retrospective study. SUMMARY OF BACKGROUND DATA: Prolonged operation duration in adolescent idiopathic scoliosis (AIS) surgery was associated with increased perioperative complications. However, the factors affecting operation duration in AIS surgery were unknown. OBJECTIVE: The aim of the study was to investigate the factors affecting operation duration in posterior spinal fusion (PSF) surgery using a dual attending surgeon strategy among Lenke 1 and 2 AIS patients. METHODS: In all, 260 AIS patients with Lenke 1 and 2 curves who underwent PSF were retrospectively reviewed. Preoperative and intraoperative factors affecting operation duration such as age, sex, height, weight, body mass index, Risser grade, Lenke subtypes, number of fusion level, number of screws, screw density, wound length, upper and lowest instrumented vertebrae level, preoperative Cobb angle, and flexibility of the major curve were assessed using univariate and multivariate linear regression analyses. Independent factors were determined when P-value <0.05. RESULTS: The mean operation duration was 122.2±28.6 minutes. Significant independent factors affecting operation duration in PSF among Lenke 1 and 2 AIS patients were Lenke 2 subtypes (ß=8.86, P=0.008), number of screws (ß=7.01, P<0.001), wound length (ß=1.14, P=0.009), and flexibility of the major curve (ß=-0.25, P=0.005). The overall model fit was R2=0.525. Operation duration can be predicted using the formula: (8.86×Lenke subtypes)+(7.01×number of screws)+(1.14×wound length)-(0.25×flexibility)-0.54, where Lenke 2=1 and Lenke 1=0. CONCLUSION: The factors affecting operation duration in PSF among Lenke 1 and 2 AIS patients were Lenke 2 curves, number of screws, wound length, and curve flexibility. The knowledge of these factors enables the spinal deformity surgeons to plan and estimate the operation duration before AIS surgery.