Faculty Bibliography

Background: The number of elderly patients undergoing adult spinal deformity (ASD) surgery has increased with the advent of new techniques and more nuanced understanding of global malalignment as patients age. The relationship between inpatient physical activity after ASD surgery and postoperative complications in elderly patients has not been reported; thus, we sought to investigate this relationship. Methods: We performed a medical record review of 185 ASD patients older than 65 years (age: 71.5 ± 4.7; body mass index: 30.0 ± 6.1, American Society of Anesthesiologists: 2.7 ± 0.5, and levels fused: 10.5 ± 3.4). We derived the number of feet walked over the first 3 days after surgery from physical therapy documentation and evaluated for association with 90-day perioperative complications. Patients who sustained an incidental durotomy were excluded from the study. Results: The 185 patients were divided into groups based on whether they were among the 50th percentile for number of feet walked (62 ft). Walking less than 62 ft after ASD surgery was associated with higher incidence of postoperative complications (54.3%, P = 0.05), cardiac complications (34.8%, P = 0.03), pulmonary complications (21.7%, P = 0.01), and ileus (15.2%, P = 0.03). Patients who developed any postoperative complication (106 ± 172 vs 211 ± 279 ft, P = 0.001), ileus (26 ± 49 vs 174 ± 248 ft, P = 0.001), deep venous thrombosis (23 ± 30 vs 171 ± 247 ft, P = 0.001), and cardiac complications (58 ± 94 vs 192 ± 261 ft) walked less than patients who did not. Conclusion: Elderly patients who walked less than 62 ft in the first 3 days after ASD surgery have a higher rate of postoperative complications, specifically pulmonary and ileus compared with those patients who walked more. Steps walked after ASD surgery may be a helpful and practical addition to the surgeon"™s armamentarium for monitoring the recovery of their patients. Clinical Relevence: Monitoring the steps walked by patients after ASD surgery can be a practical and useful tool for surgeons to track and improve their patients"™ recovery.

Background: Identify the external applicability of the American College of Surgeons"™ National Surgical Quality Improvement Program (NSQIP) risk calculator in the setting of adult spinal deformity (ASD) and subsets of patients based on deformity and frailty status. Methods: ASD patients were isolated in our single-center database and analyzed for the shared predictive variables displayed in the NSQIP calculator. Patients were stratified by frailty (not frail <0.03, frail 0.3"“0.5, severely frail >0.5), deformity [T1 pelvic angle (TPA) > 30, pelvic incidence minus lumbar lordosis (PI-LL) > 20], and reoperation status. Brier scores were calculated for each variable to validate the calculator"™s predictability in a single center"™s database (Quality). External validity of the calculator in our ASD patients was assessed via Hosmer-Lemeshow test, which identified whether the differences between observed and expected proportions are significant. Results: A total of 1606 ASD patients were isolated from the Quality database (48.7 years, 63.8% women, 25.8 kg/m²); 33.4% received decompressions, and 100% received a fusion. For each subset of ASD patients, the calculator predicted lower outcome rates than what was identified in the Quality database. The calculator showed poor predictability for frail, deformed, and reoperation patients for the category "any complication" because they had Brier scores closer to 1. External validity of the calculator in each stratified patient group identified that the calculator was not valid, displaying P values >0.05. Conclusion: The NSQIP calculator was not a valid calculator in our single institutional database. It is unable to comment on surgical complications such as return to operating room, surgical site infection, urinary tract infection, and cardiac complications that are typically associated with poor patient outcomes. Physicians should not base their surgical plan solely on the NSQIP calculator but should consider multiple preoperative risk assessment tools.

STUDY DESIGN/METHODS:Retrospective analysis of outcomes in cervical spine and shoulder arthroscopy patients. OBJECTIVE:The objective of this study is to assess differential improvements in health-related quality of life for cervical spine surgery compared with shoulder surgery. SUMMARY OF BACKGROUND DATA/BACKGROUND:An understanding of outcome differences between different types of orthopedic surgeries is helpful in counseling patients about expected postoperative recovery. This study compares outcomes in patients undergoing cervical spine surgery with arthroscopic shoulder surgery using computer-adaptive Patient-reported Outcome Information System scores. MATERIALS AND METHODS/METHODS:Patients undergoing cervical spine surgery (1-level or 2-level anterior cervical discectomy and fusion, cervical disc replacement) or arthroscopic shoulder surgery (rotator cuff repair±biceps tenodesis) were grouped. Patient-reported Outcome Information System scores of physical function, pain interference, and pain intensity at baseline and at 3, 6, and 12 months were compared using paired t tests. RESULTS:Cervical spine (n=127) and shoulder (n=91) groups were similar in sex (25.8% vs. 41.8% female, P=0.731) but differed in age (51.6±11.6 vs. 58.60±11.2, P<0.05), operative time (148.3±68.6 vs. 75.9±26.9 min, P<0.05), American Society of Anesthesiologists (ASAs) (2.3±0.6 vs. 2.0±0.5, P=0.001), smoking status (15.7% vs. 4.4%, P=0.008), and length of stay (1.1±1.0 vs. 0.3±0.1, P=0.000). Spine patients had worse physical function (36.9 ±12.6 vs. 49.4±8.6, P<0.05) and greater pain interference (67.0±13.6 vs. 61.7±4.8, P=0.001) at baseline. Significant improvements were seen in all domains by 3 months for both groups, except for physical function after shoulder surgery. Spine patients had greater physical function improvements at all timepoints (3.33 vs. -0.43, P=0.003; 4.81 vs. 0.08, P=0.001; 6.5 vs. -5.24, P=<0.05). Conversely, shoulder surgery patients showed better 6-month improvement in pain intensity over spine patients (-8.86 vs. -4.46, P=0.001), but this difference resolved by 12 months. CONCLUSIONS:Cervical spine patients had greater relative early improvement in physical function compared with shoulder patients, whereas pain interference and intensity did not significantly differ between the 2 groups after surgery. This will help in counseling patients about relative difference in recovery and improvement between the 2 surgery types. LEVEL OF EVIDENCE/METHODS:III.

BACKGROUND:Patients with less severe adult spinal deformity undergo surgical correction and often achieve good clinical outcomes. However, it is not well understood how much clinical improvement is due to sagittal correction rather than treatment of the spondylotic process. PURPOSE/OBJECTIVE:Determine baseline thresholds in radiographic parameters that, when exceeded, may result in substantive clinical improvement from surgical correction. STUDY DESIGN/METHODS:Retrospective. METHODS:ASD patients with BL and 2-year(2Y) data were included. Parameters assessed: SVA, PI-LL, PT, T1PA, L1PA, L4-S1 Lordosis, C2-C7 SVA(cSVA), C2-T3, C2 Slope(C2S). Outcomes: Good Outcome(GO) at 2Y: [Meeting either: 1) SCB for ODI(change greater than 18.8), or 2) ODI<15 and SRS-Total>4.5. Binary logistic regression assessed each parameter to determine if correction was more likely needed to achieve GO. Conditional inference tree(CIT) run machine learning analysis generated baseline thresholds for each parameter, above which, correction was necessary to achieve GO. RESULTS:We included 431 ASD patients. There were 223(50%) that achieved a GO by two years. Binary logistic regression analysis demonstrated, with increasing baseline severity in deformity, sagittal correction was more often seen in those achieving GO for each parameter(all P<0.001). Of patients with baseline T1PA above the threshold, 95% required correction to meet Good Outcome(95% vs. 54%,P<0.001). A baseline PI-LL above 10° (74% of patients meeting GO) needed correction to achieve GO (OR: 2.6,[95% CI 1.4-4.8]). A baseline C2 slope above 15° also necessitated correction to obtain clinical success (OR: 7.7,[95% CI 3.7-15.7]). CONCLUSION/CONCLUSIONS:Our study highlighted point may be present at which sagittal correction has an outsized influence on clinical improvement, reflecting the line where deformity becomes a significant contributor to disability. These new thresholds give us insight into which patients may be more suitable for sagittal correction, as opposed to intervention for the spondylotic process only, leading to a more efficient utility of surgical intervention for adult spinal deformity. LEVEL OF EVIDENCE/METHODS:III.

BACKGROUND CONTEXT: Indirect decompression technique may be limited in that it does not include direct removal of the offending intervertebral disc or osteophyte protruding into the canal. PURPOSE: This study evaluates resolution of radiculopathy and perioperative complications in lumbar fusion with indirect or direct decompression techniques. STUDY DESIGN/SETTING: Retrospective analysis of large single center academic institution. PATIENT SAMPLE: This study included 116 single-level lumbar fusion patients with preoperative radiculopathy from 2012 to 2021. OUTCOME MEASURES: Resolution of radiculopathy, visual analog scores (VAS), perioperative complications, motor scores.
METHOD(S): Patients 18 years of age diagnosed with preoperative radiculopathy undergoing single-level lumbar fusion with up to two-year follow-up were grouped by indirect and direct decompression. Direct decompression group included TLIF with or without direct decompression procedure as well as ALIF and LLIF with direct decompression procedure. Indirect decompression group included ALIF and LLIF without direct decompression procedure. Propensity score matching (PSM) was used to control for differences in age between groups. Outcome measures were compared between groups using means comparison tests. Logistic regression analysis was used to correlate decompression type with symptom resolution over time.
RESULT(S): A total of 116 patients were included in this analysis: 58 direct decompression (mean 53.9y, 67.2% female) and 58 indirect decompression (mean 54.6y, 61.4% female). Direct decompression patients experienced greater blood loss relative to indirect decompression patients (242.4 +/- 128.5 vs 171.79 +/- 143.9 mL, p=0.007). Additionally, direct decompressionpatients experienced full resolution of radiculopathy at 3 months postop at a greater rate than those in the indirect decompression group (OR: 4.742, [1.97-11.41]; 53.1% vs 13.73%, p=0.002). At 6 months, direct decompression patients demonstrated a significantly larger reduction in VAS score 6 months postop (-2.889 +/- 2.3 vs -0.897 +/- 4.3, p=0.044). With regard to motor function, direct decompression patients had improved motor score with respect to the L5 dermatome at 6 months compared to indirect decompression patients (DELTAmotor score from baseline: 0.1714 +/- 0.453 vs -0.024 +/- 0.154, p=0.019).
CONCLUSION(S): Patients who underwent direct decompression experienced significantly greater resolution of preoperative lower extremity radiculopathy at 3 months compared with those who underwent ID alone. At 6 and 12 months, no differences were noted between the two groups. There were no differences in complication rates. At 6 months postop, direct decompression patients had greater improvement in preoperative motor deficit than ID patients. In particularly debilitated patients, these findings may influence surgeons to perform a direct decompression to achieve more rapid resolution of radiculopathy symptoms. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
Copyright

PURPOSE/OBJECTIVE:Single position surgery has demonstrated to reduce hospital length of stay, operative times, blood loss, postoperative pain, ileus, and complications. ALIF and LLIF surgeries offer advantages of placing large interbody devices under direct compression and can be performed by a minimally invasive approach in the lateral position. Furthermore, simultaneous access to the anterior and posterior column is possible in the lateral position without the need for patient repositioning. The purpose of this study is to outline the anatomical and technical considerations for performing anterior lumbar interbody fusion (ALIF) in the lateral decubitus position. METHODS:Surgical technique and technical considerations for reconstruction of the anterior column in the lateral position by ALIF at the L4-5 and L5-S1 levels. RESULTS:Topics outlined in this review include: Operating room layout and patient positioning; surgical anatomy and approach; vessel mobilization and retractor placement for L4-5 and L5-S1 lateral ALIF exposure, in addition to comparative technique of disc space preparation, trialing and implant placement compared to the supine ALIF procedure. CONCLUSIONS:Anterior exposure performed in the lateral decubitus position allows safe-, minimally invasive access and implant placement in ALIF. The approach requires less peritoneal and vessel retraction than in a supine position, in addition to allowing simultaneous access to the anterior and posterior columns when performing 360° Anterior-Posterior fusion.

BACKGROUND CONTEXT: In recent years spine surgeons have utilized different techniques and approaches to perform lumbar interbody fusion surgery. We sought to analyze the difference in outcomes between traditional open transforaminal lumbar interbody fusion (O-TLIF), minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF), dual position anterior/lateral lumbar interbody fusion with posterior instrumentation (Dual ALIF/LLIF), and single position anterior/lateral lumbar interbody fusion with posterior instrumentation (Single ALIF/LLIF). PURPOSE: To analyze the perioperative and postoperative outcomes of patient undergoing TLIF, MIS TLIF, Dual ALIF/LLIF, and Single ALIF/LLIF. STUDY DESIGN/SETTING: Retrospective cohort study at a single institution. PATIENT SAMPLE: Patients undergoing O-TLIF, MIS TLIF, Dual ALIF/LLIF, or Single ALIF/LLIF from 2014 to 2020. OUTCOME MEASURES: Operative time, estimated blood loss (EBL), length of stay (LOS), radiation dose, intraoperative and postoperative complications, and return to OR within 90 days.
METHOD(S): Patients who underwent single level lumbar interbody fusion surgery were analyzed. Patient charts were reviewed for operative time, EBL, LOS, radiation dose, intraoperative and postoperative complications, and return to OR within 90 days. Differences were assessed by ANOVA.
RESULT(S): A total of 1,226 patients underwent a single level lumbar interbody fusion (440 O-TLIF, 423 MIS TLIF, 316 Dual ALIF/LLIF, 47 Single ALIF/LLIF). There were no significant differences in BMI or gender between the groups, but in the O-TLIF cohort average age (60) was higher than MIS-TLIF (54), Dual ALIF/LLIF(52), and Single ALIF/LLIF (50) p < 0.001. There were also significant differences in average operative time (221 mins O-TLIF, 212 mins MIS TLIF, 277 mins dual ALIF/LLIF, 277 mins single ALIF/LLIF, p < 0.001), EBL (360 ml O-TLIF, 167ml MIS TLIF, 235 ml Dual ALIF/LLIF, 253 ml Single ALIF/LLIF, p<0.001), radiation dose (20 mGy O-TLIF, 51 mGy MIS TLIF, 43 mGy Dual ALIF/LLIF, 62 mGy Single ALIF/LLIF, p < 0.001). There was no difference in LOS, intraoperative complications, or 90-day complications between the groups, except a higher rate of neurological deficit in dual ALIF/LLIF (1.6%, p < 0.03). Post hoc analysis demonstrated statistical significance in operative time in the Dual ALIF/LLIF as compared to all the other groups. O-TLIF demonstrated a larger EBL and less radiation as compared to all the other groups as well as a longer operative time than Single ALIF/LLIF. Dual ALIF/LLIF demonstrated a longer operative time and increased rate of neurological deficit as compared to MIS TLIF.
CONCLUSION(S): In comparing different techniques for single level lumbar interbody fusion there were similar outcomes in LOS, perioperative complications and 90-day complications between all the groups. Open TLIF was associated with increased estimate blood loss and less radiation than all the other groups Dual position ALIF/LLIF surgery was associated with a longer operative time than all the other groups. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
Copyright

BACKGROUND CONTEXT: VBT takes advantage of the Hueter-Volkmann principle, and modulates growth across intervertebral disc spaces with a tensioned tether secured at the lateral aspects of vertebral bodies. Cervical deformity in AIS patients is associated with lower health related quality of life. PSF constructs have been shown to improve cervical deformity, however, to date, these relationships have not been described in patients treated with VBT. PURPOSE: Determine if cervical sagittal alignment parameters following VBT for correction of AIS are similar to what is observed following PSF. STUDY DESIGN/SETTING: Multi-center retrospective cohort study. PATIENT SAMPLE: Patients with AIS that undergo correction surgeries with LIV in the lumbar spine from 2013 to 2021 with pre- and 2-year postop standing full body plain films available. OUTCOME MEASURES: Outcome measures: Age, height, weight, BMI, Risser score, LIV and levels instrumented. Radiographic analysis included pre- and postop C2 to C7 sagittal vertical axis (cSVA), cervical lordosis angle (CL), T1 slope and thoracic kyphosis (TK).
METHOD(S): Measures were compared using independent samples t-tests, significance set at p<0.05.
RESULT(S): A total of 99 patients: 49 VBT and 50 fusions. The VBT cohort Lenke class breakdown is 23% 1A, 13% 1C, 31% 3C; 18% 5C, and 15% 6C, while the PSF cohort consisted of 42% 1A, 6% 1B, 2% 2C, 2% 3B, 12% 3C, 2% 5B, 24% 5C, and 10% 6C. There were no significant differences with regard to patient age or number of levels instrumented. Patients included in the VBT cohort had a lower level of bone maturity as defined by Risser class (1.6+/-0.9 vs 2.6+/-1.8, p=0.001). The VBT cohort had higher baseline cSVA (3.4mm+/-1.6 vs -1.0mm+/-3.1, 0.001) and less CL (-0.6degree+/-18.2 vs 11.6degree+/-12.8, p=0.001) than the fusion cohort. No differences in baseline T1 slope or Thoracic Kyphosis was observed. VBT patients also had higher 2-year cSVA (3.4mm+/-1.4 vs -3.7mm+/-2.1, p=0.001) and less CL (-4.0+/-18.5 vs 7.0+/-12.2, p=0.001) compared to fusion patients. The PSF group had a significantly greater correction in cSVA than the VBT group (2.8mm+/-4.0 vs 0mm+/-1.6, p=0.001). Both groups displayed improvement in radiographic parameters of cervical and thoracic alignment including CL (VBT 3.3degreevs 4.3degree, p=0.74), T1 slope (VBT -4.3degreevs -4.9degree, p=0.81) and TK (VBT -6.1degreevs -3.9degree, p=0.47). After PSM for Lenke classification, 66 patients remained: 33 VBT, 33 PSF. The PSF group continued to demonstrate greater improvement in cSVA than the VBT group (3.2mm+/-3.0 vs -0.3+/-1.8, p=0.001.
CONCLUSION(S): VBT and PSF both improve radiographic parameters of cervical alignment in AIS patients; however, PSF showed greater correction of cSVA at 2-year followup. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
Copyright

BACKGROUND CONTEXT: Diabetic patients with elevated hemoglobin A1C (HbA1C) are at higher risk of developing complications after surgery than their nondiabetic peers. This is especially true of wound complications, including wound infections. Previous research has shown this relationship to be multifactorial, so more investigation is needed into these complications. PURPOSE: Establish pertinent factors which contribute to increased wound complication incidence among diabetic patients undergoing thoracolumbar fusion. STUDY DESIGN/SETTING: Single center retrospective cohort study. PATIENT SAMPLE: This study included 228 patients with a diagnosis of diabetes mellitus who underwent thoracic, lumbar, or thoracolumbar posterior spinal fusion (PSF) from 2013-2018 with preoperative HbA1C values. Patients without preoperative HbA1C results or undergoing cervical fusions were excluded. OUTCOME MEASURES: Development of wound complications and infection in the perioperative period were recorded for analysis. Wound complications were defined as dehiscence, superficial SSI and deep SSI.
METHOD(S): Significant perioperative complications were determined using t-test and chi-square analyses. Complications were tested against confounding factors using binary logistic regressions. Efficacy of various preoperative demographic measures as markers for complication was determined using Receiver Operating Characteristic (ROC) analyses. Cutoff points were calculated by Youden's index. Significance set at p <0.05.
RESULT(S): A total of 228 patients met inclusion. Significant differences in BMI were noted between patients who developed infection (n=7) and those who did not (37.5 kg/m² vs 32.0 kg/m²; p=0.039). In addition, binary logistic regression showed that, controlled for HbA1C, BMI was a significant predictor of infection (OR: 1.110; p=0.043). ROC curve demonstrated an AUC of 0.754 (p=0.022) and Youden's J calculated the cutoff point to be 34.08 kg/m² (Spec: 64.3%, Sens: 85.7%). No differences between those with postop wound complications were noted in HbA1C (7.29 vs 6.88; p=0.345), age (70.14 vs 64.92; p=0.197), gender (vs 71.4% female vs 55.5% female; p=0.469), smoking status (28.6% smoking history vs 33.9% smoking history), levels fused (2.71 vs 2.62; p=0.931), LOS (3.29 vs 4.82; p=0.243). Sub-analysis of superficial infections revealed no significant differences in HbA1C (7.15 vs 6.88; p=0.565), age (70.8 vs 64.9; p=0.175), BMI (36.5 vs 32.1; p=0.114), levels fused (2.5 vs 2.6; p=0.911), gender (66.7% female vs 55.4% female; p=0.697), smoking status (33.3% smoking history vs 33.7% smoking history; p=1.000), or LOS (2.8 vs 4.8; p=0.159). Subanalysis of deep SSI revealed only one infection.
CONCLUSION(S): BMI above 34.08 kg/m² is a significant predictor of postoperative infection in diabetic patients undergoing posterior fusion. To ensure optimal outcomes, diabetic patients should be encouraged to get below this threshold before surgery. More research must be done to further establish the relationship of BMI with regard to superficial and deep infections. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
Copyright

BACKGROUND CONTEXT: Sagittal alignment is integral to a patient's quality of life. Posterior spinal fusion (PSF) is currently the standard for correcting adolescent idiopathic scoliosis (AIS). Vertebral body tethering (VBT) is a fusionless growth modulating surgical technique used to treat AIS. It relies on the Hueter-Volkmann Law. Indications for this procedure include patients who have coronal curves up to 50degree, growth remaining, and no excessive thoracic kyphosis. VBT has been shown to have good coronal plane deformity correction. There have been fewer examinations of the sagittal effects of VBT. PURPOSE: To determine if VBT is a non-inferior treatment for correction of AIS with regard to sagittal alignment compared to PSF. STUDY DESIGN/SETTING: Multicenter retrospective cohort study. PATIENT SAMPLE: Patients with AIS who underwent correction surgeries with LIV in the lumbar spine from 2013 to 2021 with pre- and minimum two-year postoperative standing full spine plain films. OUTCOME MEASURES: Sagittal vertical axis (SVA), cervical SVA (cSVA), pelvic tilt (PT), thoracic kyphosis (TK), cervical lordosis (CL), L4-S1 lordosis (L4L), T1 pelvic angle (TPA) and pelvic incidence lumbar lordosis mismatch (PI-LL).
METHOD(S): Radiographic analyses was completed with independent samples t-test with significance set to p <0.05.
RESULT(S): A total of 99 patients were included, 49 VBT and 50 PSF. There were no differences in age or levels instrumented between groups. The VBT cohort Lenke class breakdown is 23% 1A, 13% 1C, 31% 3C. 18% 5C, and 15% 6C, while the PSF cohort consisted of 42% 1A, 6% 1B, 2% 2C, 2% 3B, 12% 3C, 2% 5B, 24% 5C, and 10% 6C. At Baseline, the VBT cohort had lower SVA (-0.7mm+/-3.7 vs 2.2mm+/-5.0, p=0.001), CL (-0.9degree+/-18.2 vs 11.6degree+/-12.8, p=0.001), L4-S1 Lordosis (20.7degree+/-16.0 vs 41.6degree+/-10.2, p=0.001), and higher cSVA (3.3mm+/-1.6 vs -0.95mm+/-3.1, p=0.001) than those who were fused. Postoperatively, VBT patients have an overall higher L4-S1 Lordosis (36.0degree+/-10.1vs 18.3degree+/-12.5, p=0.001), cSVA (3.4mm+/-1.4 vs -3.7mm+/-2.1, p=0.001), and lower CL (-4.3degree+/-18.4 vs 7.0degree+/-12.2, p=0.001). The PSF cohort had a larger change in cSVA (2.8mm+/-4.0 vs 0mm+/-1.6, p=0.001) from baseline to 2-year follow-up compared to VBT. No differences in the change of L4-S1 Lordosis (VBT 1.5degree+/-12.3 vs 4.1degree+/-10.9, p=0.3), TPA (VBT -1.6degree+/-6.8 vs -1.4degree+/-8.5, p=0.89), PT (VBT -0.5degree+/-7.8 vs -1.9degree+/-8.5, p=0.42), or PI-LL (0.2degree+/-12.0 vs -0.5degree+/-14.0, p=0.81) were observed.
CONCLUSION(S): VBT and PSF for AIS result in statistically similar changes in sagittal alignment parameters. The fact that we showed similar results comparing sagittal alignment in fusion and VBT groups indicates that VBT is non-inferior from a sagittal perspective. It is important to maintain sagittal alignment when correcting AIS. Future work can examine the long-term effect of VBT on sagittal alignment. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
Copyright