OBJECTIVE: To compare the outcomes of minimal invasive surgery (MIS) and conventional open surgery for spinal metastasis patients.
SUMMARY OF BACKGROUND DATA: There is lack of knowledge on whether MIS is comparable to conventional open surgery in treating spinal metastasis.
METHODS: Patients with spinal metastasis requiring surgery from January 2008 to December 2010 in two spine centers were recruited. The demographic, preoperative, operative, perioperative and postoperative data were collected and analyzed. Thirty MIS patients were matched with 30 open surgery patients using propensity score matching technique with a match tolerance of 0.02 based on the covariate age, tumor type, Tokuhashi score, and Tomita score.
RESULTS: Both groups had significant improvements in Eastern Cooperative Oncology Group (ECOG), Karnofsky scores, visual analogue scale (VAS) for pain and neurological status postoperatively. However, the difference comparing the MIS and open surgery group was not statistically significant. MIS group had significantly longer instrumented segments (5.5 ± 3.1) compared with open group (3.8 ± 1.7). Open group had significantly longer decompressed segment (1.8 ± 0.8) than MIS group (1.0 ± 1.0). Open group had significantly more blood loss (2062.1 ± 1148.0 mL) compared with MIS group (1156.0 ± 572.3 mL). More patients in the open group (76.7%) needed blood transfusions (with higher average units of blood transfused) compared with MIS group (40.0%). Fluoroscopy time was significantly longer in MIS group (116.1 ± 63.3 s) compared with open group (69.9 ± 42.6 s). Open group required longer hospitalization (21.1 ± 10.8 days) compared with MIS group (11.0 ± 5.0 days).
CONCLUSION: This study demonstrated that MIS resulted in comparable outcome to open surgery for patients with spinal metastasis but has the advantage of less blood loss, blood transfusions, and shorter hospital stay.
LEVEL OF EVIDENCE: 3.
OBJECTIVE: The present study investigated the effectiveness of chewing gum on promoting faster bowel function and its ability to hasten recovery for patients with adolescent idiopathic scoliosis (AIS) after posterior spinal fusion (PSF) surgery.
SUMMARY OF BACKGROUND DATA: Sham feeding with chewing gum had been reported to reduce the incidence of postoperative ileus by accelerating recovery of bowel function.
METHODS: We prospectively recruited and randomized 60 patients with AIS scheduled for PSF surgery into treatment (chewing gum) and control group. The patient-controlled anesthesia usage, wound pain score, abdominal pain score, nausea score, and abdominal girth were assessed and recorded at 12, 24, 36, 48, and 60 hours postoperatively. The timing for the first fluid intake, first oral intake, sitting up, walking, first flatus after surgery, first bowel opening after surgery, and duration of hospital stay were also assessed and recorded.
RESULTS: We found that there were no significant differences (P > 0.05) in patient-controlled anesthesia usage, wound pain score, abdominal pain score, nausea score, and abdominal girth between treatment (chewing gum) and control groups. We also found that there were no significant difference (P > 0.05) in postoperative recovery parameters, which were the first fluid intake, first oral intake, sitting up after surgery, walking after surgery, first flatus after surgery, first bowel opening after surgery, and duration of hospital stay between both groups. The wound pain was the worst at 12 hours postoperatively, which progressively improved in both groups. The abdominal pain progressively worsened to the highest score at 48 hours in the treatment group and 36 hours in the control group before improving after that. The pattern of severity and recovery of wound pain and abdominal pain was different.
CONCLUSION: We found that chewing gum did not significantly reduce the abdominal pain, promote faster bowel function, or hasten patient recovery.
LEVEL OF EVIDENCE: 1.
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.
METHODS:: This was a retrospective propensity score-matched study using prospectively collected data. Surgeries performed between 08:00 and 16:59 h were labeled as daytime surgeries (group 1) and surgeries performed between 17:00 and 06:00 h were labeled as after-hours surgeries (group 2). The perioperative outcome parameters were average operation time in and out, operation duration, intraoperative blood loss, blood transfusion, intraoperative hemodynamic parameters, preoperative hemoglobin, postoperative hemoglobin, and total patient-controlled anesthesia (PCA) morphine usage. Radiological variables assessed were Lenke subtypes, preoperative Cobb angle, number of fusion levels, number of screws used, postoperative Cobb angle, correction rate, side bending flexibility, side bending correction index, complications rate, and length of hospitalization.
RESULTS:: Average operation time in for daytime group was 11:32 ± 2:33 h versus 18:20 ± 1:05 h in after-hours group. Comparing daytime surgeries with after-hours surgeries, there were no significant differences ( p > 0.05) in the operation duration, intraoperative blood loss, intraoperative pH, bicarbonate, lactate, postoperative hemoglobin, hemoglobin drift, blood transfusion, postoperative Cobb angle, correction rate, side bending flexibility, side bending correction index, length of hospitalization, and complications rate. Total PCA morphine usage was significantly lesser in the after-hours group (18.2 ± 15.3 mg) compared with the daytime group (24.6 ± 16.6 mg; p = 0.042).
CONCLUSIONS:: After-hours elective spine deformity corrective surgeries for healthy ambulatory patients with AIS were as safe as when they were done during daytime.
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
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.
OBJECTIVE: The aim of this study was to compare the perioperative outcome of posterior spinal fusion (PSF) between overweight (OW) adolescent idiopathic scoliosis (AIS) patients and the healthy-weight (HW) patients using propensity score matching analysis.
SUMMARY OF BACKGROUND DATA: Obesity was found to increase postoperative surgical complications compared with the nonobese group. In scoliosis correction surgery, association of OW and perioperative risks had been explored, but most studies were retrospective in nature.
METHODS: From 374 patients, two comparable groups were matched using propensity score matching analysis with one-to-one nearest neighbor matching and a caliper of 0.2. There were 46 HW and OW patients in each group. The main outcome measures were intraoperative blood loss, use of allogeneic blood transfusion, operative time, duration of hospital stay post-surgery, total patient-controlled analgesia (PCA) morphine usage, perioperative complications, side bending flexibility (SBF), and correction rate (%).
RESULTS: The mean age was 13.3 ± 1.7 and 13.2 ± 1.7 years for HW and OW groups, respectively. The majority of the patients were Lenke 1 curves; 32.6% (HW) and 26.1% (OW) with an average Cobb angle of 69.0 ± 19.1° and 68.8 ± 18.4° for each group, respectively. The two groups were comparable. The operation time was 145.2 ± 42.2 and 154.4 ± 48.3 minutes for HW and OW groups, respectively (P > 0.05). The intraoperative blood loss was almost similar in both groups; 955.1 ± 497.7 mL (HW group) and 1011.8 ± 552.7 mL (OW group) (P > 0.05). Total PCA morphine used was higher in OW group (30.4 ± 22.7 mg) than in the HW group (16.2 ± 11.3 mg). No complication was observed in HW group, while in OW group, one patient (2.2%) developed intraoperative seizure.
CONCLUSION: OW AIS patients (≥85th percentile) had similar mean operative time, intraoperative blood loss, allogeneic transfusion rate, length of stay, and perioperative complications compared with HW AIS patients.
LEVEL OF EVIDENCE: 3.
OBJECTIVE: To evaluate the perioperative outcome of dual attending surgeon strategy for severe adolescent idiopathic scoliosis (AIS) patients with Cobb angle more than or equal to 90°.
SUMMARY OF BACKGROUND DATA: The overall complication rate for AIS remains significant and is higher in severe scoliosis. Various operative strategies had been reported for severe scoliosis. However the role of dual attending surgeon strategy in improving the perioperative outcome in severe scoliosis has not been investigated.
METHODS: The patients were stratified into two groups, Cobb angles 90° to 100° (Group 1) and more than 100° (Group 2). Demographic, intraoperative, preoperative, and postoperative day 2 data were collected. The main outcome measures were intraoperative blood loss, use of allogeneic blood transfusion, operative time, duration of hospital stay postsurgery, and documentation of any perioperative complications.
RESULTS: Eighty-five patients were recruited. The mean age for the whole cohort was 16.2 ± 5.2 years old. The mean age of Group 1 was 16.7 ± 5.7 and Group 2 was 15.6 ± 4.8 years old. The majority of the patients in both groups were Lenke 2 curves with the average Cobb angle of 93.9 ± 3.0° in Group 1 and 114.2 ± 10.2° in Group 2. The average operative time was 198.5 ± 47.5 minutes with an average blood loss of 1699.5 ± 939.3 mL. The allogeneic blood transfusion rate was 17.6%. The average length of stay postoperation was 71.6 ± 22.5 hours. When comparing the patients between Group 1 and Group 2, the operating time, total blood loss, allogeneic transfusion rate showed significant intergroup differences. Five complications were documented (one intraoperative seizure, one massive blood loss, one intraoperative loss of somatosensory evoked potential (SSEP) signal, and two superficial wound breakdown).
CONCLUSION: Dual attending surgeon strategy in severe AIS more than or equal to 90° demonstrated an average operative time of 199 minutes, intraoperative blood loss of 1.7 L, postoperative hospital stay of 71.6 hours, and a complication rate of 5.9% (5/85 patients). Curves with Cobb angle more than 100° lead to longer operating time, greater blood loss, and allogeneic transfusion rate.
LEVEL OF EVIDENCE: 4.
OBJECTIVE: To compare the perioperative outcome between after-hours and daytime surgery carried out by a dedicated spinal deformity team for severe Idiopathic Scoliosis (IS) patients with Cobb angle ≥ 90°.
SUMMARY OF BACKGROUND DATA: There were concerns that after-hours corrective surgeries in severe IS have higher morbidity compared to daytime surgeries.
METHODS: Seventy-one severe IS patients who underwent single-staged Posterior Spinal Fusion (PSF) were included. Surgeries performed between 08:00H and 16:59H were classified as "daytime" group and surgeries performed between 17:00H and 06:00H were classified as "after-hours" group. Perioperative outcome parameters were average operation start time and end time, operation duration, intraoperative blood loss, intraoperative hemodynamic parameters, preoperative and postoperative hemoglobin, blood transfusion rate, total patient-controlled anesthesia (PCA) morphine usage, length of postoperative hospitalization, and complications. Radiological variables assessed were preoperative and postoperative Cobb angle, side bending flexibility, number of fusion levels, number of screws used, Correction Rate, and Side Bending Correction Index.
RESULTS: Thirty patients were operated during daytime and 41 patients were operated after-hours. The mean age was 16.1 ± 5.8 years old. The mean operation start time for daytime group was 11:31 ± 2:45H versus 19:10 ± 1:24H for after-hours group. There were no significant differences between both groups in the operation duration, intraoperative blood loss, intraoperative hemodynamic parameters, postoperative hemoglobin, hemoglobin drift, transfusion rate, length of postoperative hospitalization, postoperative Cobb angle, Correction Rate, and Side Bending Correction Index. There were four complications (1 SSEP loss, 1 massive blood loss, and 2 superficial wound infections) with no difference between daytime and after-hours group.
CONCLUSION: After-hours elective spine deformity corrective surgeries in healthy ambulatory patients with severe IS performed by a dedicated spinal deformity team using dual attending surgeon strategy were as safe as those performed during daytime.
LEVEL OF EVIDENCE: 4.
OBJECTIVE: The aim of this study was to determine the feasibility of an accelerated recovery protocol for Asian adolescent idiopathic scoliosis (AIS) patients undergoing posterior spinal fusion (PSF).
SUMMARY OF BACKGROUND DATA: There has been successful implementation of an accelerated recovery protocol for AIS patients undergoing PSF in the western population. No similar studies have been reported in the Asian population.
METHODS: Seventy-four AIS (65 F, 9 M) patients scheduled for PSF surgery were recruited. The accelerated protocol encompasses preoperative regime, preoperative day of surgery counseling, intraoperative strategies, an accelerated postoperative rehabilitation and pain management regime. All patients were operated using a dual attending surgeon strategy. Outcome measures included pain scores at five time intervals, length of stay, and detailed recovery milestones. Any complications or readmissions during the first 4 months postoperative period were recorded.
RESULTS: Mean duration of operation was 2.2 ± 0.3 hours with a mean blood loss of 824.3 ± 418.2 mL. No patients received allogenic blood transfusion. The mean length of stay was 3.6 ± 0.6 days. Surgical wound pain score was 6.4 ± 2.1 at 12 hours, which reduced to 5.0 ± 2.0 at 60 hours. Abdominal pain peaked at 36 hours with pain scores 2.4 ± 2.9. First liquid intake was at 5.2 ± 7.5 hours, urinary catheter removal at 18.7 ± 4.8 hours, sitting up at 20.6 ± 9.1 hours, ambulation at 27.2 ± 0.5 hours, consumption of solid food at 32.2 ± 0.5 hours, first flatus at 39.0 ± 0.7 hours, and first bowel movement at 122.1 ± 2.0 hours. The complication rate was 1.4% due to superficial wound infection with one patient failed to comply with the accelerated protocol.
CONCLUSION: An accelerated recovery protocol following PSF for AIS is feasible without increasing the complication or readmission rates. The total length of stay was 3.6 days and this is comparable with the outcome in western population.
LEVEL OF EVIDENCE: 4.
OBJECTIVE: To describe the technical difficulties on performing posterior spinal fusion (PSF) on a pacemaker-dependent patient with complete congenital heart block and right thoracic scoliosis.
SUMMARY OF BACKGROUND DATA: Congenital complete heart block requires pacemaker implantation at birth through thoracotomy, which can result in scoliosis. Corrective surgery in this patient was challenging. Height gain after corrective surgery may potentially cause lead dislodgement. The usage of monopolar electrocautery may interfere with the function of the implanted cardiac device.
METHODS: A 17-year-old boy was referred to our institution for the treatment of right thoracic scoliosis of 70°. He had underlying complete congenital heart block secondary to maternal systemic lupus erythematosus. Pacemaker was implanted through thoracotomy since birth and later changed for four times. PSF was performed by two attending surgeons with a temporary pacing inserted before the surgery. The monopolar electrocautery device was used throughout the surgery.
RESULTS: The PSF was successfully performed without any technical issues and complications. Postoperatively, his permanent pacemaker was functioning normally. Three days later, he was recovering well and was discharged home from hospital.
CONCLUSION: This case indicates that PSF can be performed successfully with thoughtful anticipation of technical difficulties on a pacemaker-dependent patient with underlying congenital heart block.
LEVEL OF EVIDENCE: 5.
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
PURPOSE: To evaluate the accuracy, safety, and diagnostic outcome of fluoroscopic guided and CT transpedicular biopsy techniques.
STUDY DESIGN: Prospective randomized trial.
PATIENT SAMPLE: Sixty consecutive patients with clinical symptoms and radiological features suggestive of spinal infection or malignancy were recruited and randomized into fluoroscopic or CT guided spinal biopsy groups. Both groups were similar in terms of patient demographics, distribution of spinal infections and malignancy cases, and the level of biopsies.
OUTCOME MEASURES: The primary outcome measure was diagnostic accuracy of both methods, determined based on true positive, true negative, false positive, and false negative biopsy findings. Secondary outcome measures included radiation exposure to patients and doctors, complications, and postbiopsy pain score.
METHODS: A transpedicular approach was performed with an 8G core biopsy needle. Specimens were sent for histopathological and microbiological examinations. Diagnosis was made based on biopsy results, clinical criteria and monitoring of disease progression during a 6-month follow up duration. Clinical criteria included presence of risk factors, level of inflammatory markers and magnetic resonance imaging findings. Radiation exposure to patients and doctors was measured with dosimeters.
RESULTS: There was no significant difference between the diagnostic accuracy of fluoroscopic and CT guided spinal biopsy (p=0.67) or between the diagnostic accuracy of spinal infection and spinal tumor in both groups (p=0.402 for fluoroscopy group and p=0.223 for CT group). Radiation exposure to patients was approximately 26 times higher in the CT group. Radiation exposure to doctors in the CT group was approximately 2 times higher compared to the fluoroscopic group if a lead shield was not used. Lead shields significantly reduced radiation exposure to doctors anywhere from 2 to 8 times. No complications were observed for either group and the differences in postbiopsy pain scores were not significant.
CONCLUSIONS: The accuracy, procedure time, complication rate and pain score for both groups were similar. However, radiation exposure to patients and doctors were significantly higher in the CT group without lead protection. With lead protection, radiation to doctors reduced significantly.
OBJECTIVE: This study aimed to assess the radiological and clinical outcome of patients with Lenke 1C and 2C curves treated with STF.
STUDY DESIGN: This is a retrospective study.
PATIENT SAMPLE: A total of 44 patients comprised the study sample.
METHODS: Forty-four patients with Lenke 1C and 2C curves with adolescent idiopathic scoliosis who underwent STF were reviewed. Radiological parameters and Scoliosis Research Society (SRS)-22r scores were assessed preoperatively, postoperatively, and on final follow-up. The incidence of coronal decompensation, lumbar decompensation, and adding-on phenomenon were reported.
RESULTS: Mean follow-up duration was 45.1±12.3 months and mean age was 17.0±5.1 years. The preoperative middle thoracic and thoracolumbar/lumbar (MT:TL/L) Cobb angle ratio was 1.4±0.3 and the MT:TL/L apical vertebra translation (AVT) ratio was 1.6±0.8. Final follow-up coronal balance was -13.0±11.5 mm, main thoracic AVT was 6.9±11.8 mm, and lumbar AVT was -20.4±13.8 mm (p
METHODS: An online REDCap questionnaire was circulated to surgeons in the Asia-Pacific region during the period of July 2019 to September 2019 to inquire about various components of nonoperative treatment for AIS. Aspects under study included access to screening, when MRIs were obtained, quality-of-life assessments used, role of scoliosis-specific exercises, bracing criteria, type of brace used, maturity parameters used, brace wear regimen, follow-up criteria, and how braces were weaned. Comparisons were made between middle-high income and low-income countries, and experience with nonoperative treatment.
RESULTS: A total of 103 responses were collected. About half (52.4%) of the responders had scoliosis screening programs and were particularly situated in middle-high income countries. Up to 34% obtained MRIs for all cases, while most would obtain MRIs for neurological problems. The brace criteria were highly variable and was usually based on menarche status (74.7%), age (59%), and Risser staging (92.8%). Up to 52.4% of surgeons elected to brace patients with large curves before offering surgery. Only 28% of responders utilized CAD-CAM techniques for brace fabrication and most (76.8%) still utilized negative molds. There were no standardized criteria for brace weaning.
CONCLUSION: There are highly variable practices related to nonoperative treatment for AIS and may be related to availability of resources in certain countries. Relative consensus was achieved for when MRI should be obtained and an acceptable brace compliance should be more than 16 hours a day.
OBJECTIVE: To investigate the association between postoperative upper instrumented vertebrae (UIV) tilt angle with postoperative medial shoulder and neck imbalance.
SUMMARY OF BACKGROUND DATA: Studies had found that current recommendations for UIV selection were not predictive of good postoperative shoulder balance.
METHODS: A total of 98 patients with adolescent idiopathic scoliosis with Lenke 1/2 curves who underwent posterior spinal fusion between 2013 and 2014 with minimum follow-up of 2 years were recruited. Radiological parameters: UIV tilt angle, T1 tilt, cervical axis, and clavicle angle were measured preoperatively, postoperatively, and at final follow-up.
RESULTS: Mean age was 16.2 ± 6.2 years. Mean follow-up was 37.9 ± 6.5 months. There were 73.5% Lenke 1 and 26.5% Lenke 2 curves. Significant factors affecting postoperative T1 Tilt were postoperative UIV tilt angle, preoperative T1 tilt, and preoperative UIV tilt angle. Postoperative UIV tilt angle and preoperative cervical axis were significant factors affecting cervical axis at final follow-up. UIV level was not significant independent factor that affected postoperative T1 tilt and cervical axis. There was strong correlation between postoperative UIV tilt angle and T1 tilt for the whole cohort (P